Clarify wording about functions' argument lists

[emacs.git] / lisp / subr.el

;;; subr.el --- basic lisp subroutines for Emacs  -*- lexical-binding:t -*-

;; Copyright (C) 1985-1986, 1992, 1994-1995, 1999-2018 Free Software
;; Foundation, Inc.

;; Maintainer: emacs-devel@gnu.org
;; Keywords: internal
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;; Beware: while this file has tag `utf-8', before it's compiled, it gets
;; loaded as "raw-text", so non-ASCII chars won't work right during bootstrap.


;; declare-function's args use &rest, not &optional, for compatibility
;; with byte-compile-macroexpand-declare-function.

(defmacro declare-function (_fn _file &rest _args)
  "Tell the byte-compiler that function FN is defined, in FILE.
The FILE argument is not used by the byte-compiler, but by the
`check-declare' package, which checks that FILE contains a
definition for FN.

FILE can be either a Lisp file (in which case the \".el\"
extension is optional), or a C file.  C files are expanded
relative to the Emacs \"src/\" directory.  Lisp files are
searched for using `locate-library', and if that fails they are
expanded relative to the location of the file containing the
declaration.  A FILE with an \"ext:\" prefix is an external file.
`check-declare' will check such files if they are found, and skip
them without error if they are not.

Optional ARGLIST specifies FN's arguments, or is t to not specify
FN's arguments.  An omitted ARGLIST defaults to t, not nil: a nil
ARGLIST specifies an empty argument list, and an explicit t
ARGLIST is a placeholder that allows supplying a later arg.

Optional FILEONLY non-nil means that `check-declare' will check
only that FILE exists, not that it defines FN.  This is intended
for function definitions that `check-declare' does not recognize,
e.g., `defstruct'.

Note that for the purposes of `check-declare', this statement
must be the first non-whitespace on a line.

For more information, see Info node `(elisp)Declaring Functions'."
  (declare (advertised-calling-convention
            (fn file &optional arglist fileonly) nil))
  ;; Does nothing - byte-compile-declare-function does the work.
  nil)

\f
;;;; Basic Lisp macros.

(defalias 'not 'null)
(defalias 'sxhash 'sxhash-equal)

(defmacro noreturn (form)
  "Evaluate FORM, expecting it not to return.
If FORM does return, signal an error."
  (declare (debug t))
  `(prog1 ,form
     (error "Form marked with `noreturn' did return")))

(defmacro 1value (form)
  "Evaluate FORM, expecting a constant return value.
This is the global do-nothing version.  There is also `testcover-1value'
that complains if FORM ever does return differing values."
  (declare (debug t))
  form)

(defmacro def-edebug-spec (symbol spec)
  "Set the `edebug-form-spec' property of SYMBOL according to SPEC.
Both SYMBOL and SPEC are unevaluated.  The SPEC can be:
0 (instrument no arguments); t (instrument all arguments);
a symbol (naming a function with an Edebug specification); or a list.
The elements of the list describe the argument types; see
Info node `(elisp)Specification List' for details."
  `(put (quote ,symbol) 'edebug-form-spec (quote ,spec)))

(defmacro lambda (&rest cdr)
  "Return a lambda expression.
A call of the form (lambda ARGS DOCSTRING INTERACTIVE BODY) is
self-quoting; the result of evaluating the lambda expression is the
expression itself.  The lambda expression may then be treated as a
function, i.e., stored as the function value of a symbol, passed to
`funcall' or `mapcar', etc.

ARGS should take the same form as an argument list for a `defun'.
DOCSTRING is an optional documentation string.
 If present, it should describe how to call the function.
 But documentation strings are usually not useful in nameless functions.
INTERACTIVE should be a call to the function `interactive', which see.
It may also be omitted.
BODY should be a list of Lisp expressions.

\(fn ARGS [DOCSTRING] [INTERACTIVE] BODY)"
  (declare (doc-string 2) (indent defun)
           (debug (&define lambda-list lambda-doc
                           [&optional ("interactive" interactive)]
                           def-body)))
  ;; Note that this definition should not use backquotes; subr.el should not
  ;; depend on backquote.el.
  (list 'function (cons 'lambda cdr)))

(defmacro setq-local (var val)
  "Set variable VAR to value VAL in current buffer."
  ;; Can't use backquote here, it's too early in the bootstrap.
  (declare (debug (symbolp form)))
  (list 'set (list 'make-local-variable (list 'quote var)) val))

(defmacro defvar-local (var val &optional docstring)
  "Define VAR as a buffer-local variable with default value VAL.
Like `defvar' but additionally marks the variable as being automatically
buffer-local wherever it is set."
  (declare (debug defvar) (doc-string 3))
  ;; Can't use backquote here, it's too early in the bootstrap.
  (list 'progn (list 'defvar var val docstring)
        (list 'make-variable-buffer-local (list 'quote var))))

(defmacro push (newelt place)
  "Add NEWELT to the list stored in the generalized variable PLACE.
This is morally equivalent to (setf PLACE (cons NEWELT PLACE)),
except that PLACE is only evaluated once (after NEWELT)."
  (declare (debug (form gv-place)))
  (if (symbolp place)
      ;; Important special case, to avoid triggering GV too early in
      ;; the bootstrap.
      (list 'setq place
            (list 'cons newelt place))
    (require 'macroexp)
    (macroexp-let2 macroexp-copyable-p v newelt
      (gv-letplace (getter setter) place
        (funcall setter `(cons ,v ,getter))))))

(defmacro pop (place)
  "Return the first element of PLACE's value, and remove it from the list.
PLACE must be a generalized variable whose value is a list.
If the value is nil, `pop' returns nil but does not actually
change the list."
  (declare (debug (gv-place)))
  ;; We use `car-safe' here instead of `car' because the behavior is the same
  ;; (if it's not a cons cell, the `cdr' would have signaled an error already),
  ;; but `car-safe' is total, so the byte-compiler can safely remove it if the
  ;; result is not used.
  `(car-safe
    ,(if (symbolp place)
         ;; So we can use `pop' in the bootstrap before `gv' can be used.
         (list 'prog1 place (list 'setq place (list 'cdr place)))
       (gv-letplace (getter setter) place
         (macroexp-let2 macroexp-copyable-p x getter
           `(prog1 ,x ,(funcall setter `(cdr ,x))))))))

(defmacro when (cond &rest body)
  "If COND yields non-nil, do BODY, else return nil.
When COND yields non-nil, eval BODY forms sequentially and return
value of last one, or nil if there are none.

\(fn COND BODY...)"
  (declare (indent 1) (debug t))
  (list 'if cond (cons 'progn body)))

(defmacro unless (cond &rest body)
  "If COND yields nil, do BODY, else return nil.
When COND yields nil, eval BODY forms sequentially and return
value of last one, or nil if there are none.

\(fn COND BODY...)"
  (declare (indent 1) (debug t))
  (cons 'if (cons cond (cons nil body))))

(defmacro dolist (spec &rest body)
  "Loop over a list.
Evaluate BODY with VAR bound to each car from LIST, in turn.
Then evaluate RESULT to get return value, default nil.

\(fn (VAR LIST [RESULT]) BODY...)"
  (declare (indent 1) (debug ((symbolp form &optional form) body)))
  (unless (consp spec)
    (signal 'wrong-type-argument (list 'consp spec)))
  (unless (<= 2 (length spec) 3)
    (signal 'wrong-number-of-arguments (list '(2 . 3) (length spec))))
  ;; It would be cleaner to create an uninterned symbol,
  ;; but that uses a lot more space when many functions in many files
  ;; use dolist.
  ;; FIXME: This cost disappears in byte-compiled lexical-binding files.
  (let ((temp '--dolist-tail--))
    ;; This is not a reliable test, but it does not matter because both
    ;; semantics are acceptable, tho one is slightly faster with dynamic
    ;; scoping and the other is slightly faster (and has cleaner semantics)
    ;; with lexical scoping.
    (if lexical-binding
        `(let ((,temp ,(nth 1 spec)))
           (while ,temp
             (let ((,(car spec) (car ,temp)))
               ,@body
               (setq ,temp (cdr ,temp))))
           ,@(cdr (cdr spec)))
      `(let ((,temp ,(nth 1 spec))
             ,(car spec))
         (while ,temp
           (setq ,(car spec) (car ,temp))
           ,@body
           (setq ,temp (cdr ,temp)))
         ,@(if (cdr (cdr spec))
               `((setq ,(car spec) nil) ,@(cdr (cdr spec))))))))

(defmacro dotimes (spec &rest body)
  "Loop a certain number of times.
Evaluate BODY with VAR bound to successive integers running from 0,
inclusive, to COUNT, exclusive.  Then evaluate RESULT to get
the return value (nil if RESULT is omitted).

\(fn (VAR COUNT [RESULT]) BODY...)"
  (declare (indent 1) (debug dolist))
  ;; It would be cleaner to create an uninterned symbol,
  ;; but that uses a lot more space when many functions in many files
  ;; use dotimes.
  ;; FIXME: This cost disappears in byte-compiled lexical-binding files.
  (let ((temp '--dotimes-limit--)
        (start 0)
        (end (nth 1 spec)))
    ;; This is not a reliable test, but it does not matter because both
    ;; semantics are acceptable, tho one is slightly faster with dynamic
    ;; scoping and the other has cleaner semantics.
    (if lexical-binding
        (let ((counter '--dotimes-counter--))
          `(let ((,temp ,end)
                 (,counter ,start))
             (while (< ,counter ,temp)
               (let ((,(car spec) ,counter))
                 ,@body)
               (setq ,counter (1+ ,counter)))
             ,@(if (cddr spec)
                   ;; FIXME: This let often leads to "unused var" warnings.
                   `((let ((,(car spec) ,counter)) ,@(cddr spec))))))
      `(let ((,temp ,end)
             (,(car spec) ,start))
         (while (< ,(car spec) ,temp)
           ,@body
           (setq ,(car spec) (1+ ,(car spec))))
         ,@(cdr (cdr spec))))))

(defmacro declare (&rest _specs)
  "Do not evaluate any arguments, and return nil.
If a `declare' form appears as the first form in the body of a
`defun' or `defmacro' form, SPECS specifies various additional
information about the function or macro; these go into effect
during the evaluation of the `defun' or `defmacro' form.

The possible values of SPECS are specified by
`defun-declarations-alist' and `macro-declarations-alist'.

For more information, see info node `(elisp)Declare Form'."
  ;; FIXME: edebug spec should pay attention to defun-declarations-alist.
  nil)

(defmacro ignore-errors (&rest body)
  "Execute BODY; if an error occurs, return nil.
Otherwise, return result of last form in BODY.
See also `with-demoted-errors' that does something similar
without silencing all errors."
  (declare (debug t) (indent 0))
  `(condition-case nil (progn ,@body) (error nil)))
\f
;;;; Basic Lisp functions.

(defvar gensym-counter 0
  "Number used to construct the name of the next symbol created by `gensym'.")

(defun gensym (&optional prefix)
  "Return a new uninterned symbol.
The name is made by appending `gensym-counter' to PREFIX.
PREFIX is a string, and defaults to \"g\"."
  (let ((num (prog1 gensym-counter
               (setq gensym-counter (1+ gensym-counter)))))
    (make-symbol (format "%s%d" (or prefix "g") num))))

(defun ignore (&rest _ignore)
  "Do nothing and return nil.
This function accepts any number of arguments, but ignores them."
  (interactive)
  nil)

;; Signal a compile-error if the first arg is missing.
(defun error (&rest args)
  "Signal an error, making a message by passing args to `format-message'.
In Emacs, the convention is that error messages start with a capital
letter but *do not* end with a period.  Please follow this convention
for the sake of consistency.

Note: (error \"%s\" VALUE) makes the message VALUE without
interpreting format characters like `%', `\\=`', and `\\=''."
  (declare (advertised-calling-convention (string &rest args) "23.1"))
  (signal 'error (list (apply #'format-message args))))

(defun user-error (format &rest args)
  "Signal a pilot error, making a message by passing args to `format-message'.
In Emacs, the convention is that error messages start with a capital
letter but *do not* end with a period.  Please follow this convention
for the sake of consistency.
This is just like `error' except that `user-error's are expected to be the
result of an incorrect manipulation on the part of the user, rather than the
result of an actual problem.

Note: (user-error \"%s\" VALUE) makes the message VALUE without
interpreting format characters like `%', `\\=`', and `\\=''."
  (signal 'user-error (list (apply #'format-message format args))))

(defun define-error (name message &optional parent)
  "Define NAME as a new error signal.
MESSAGE is a string that will be output to the echo area if such an error
is signaled without being caught by a `condition-case'.
PARENT is either a signal or a list of signals from which it inherits.
Defaults to `error'."
  (unless parent (setq parent 'error))
  (let ((conditions
         (if (consp parent)
             (apply #'append
                    (mapcar (lambda (parent)
                              (cons parent
                                    (or (get parent 'error-conditions)
                                        (error "Unknown signal `%s'" parent))))
                            parent))
           (cons parent (get parent 'error-conditions)))))
    (put name 'error-conditions
         (delete-dups (copy-sequence (cons name conditions))))
    (when message (put name 'error-message message))))

;; We put this here instead of in frame.el so that it's defined even on
;; systems where frame.el isn't loaded.
(defun frame-configuration-p (object)
  "Return non-nil if OBJECT seems to be a frame configuration.
Any list whose car is `frame-configuration' is assumed to be a frame
configuration."
  (and (consp object)
       (eq (car object) 'frame-configuration)))

(defun apply-partially (fun &rest args)
  "Return a function that is a partial application of FUN to ARGS.
ARGS is a list of the first N arguments to pass to FUN.
The result is a new function which does the same as FUN, except that
the first N arguments are fixed at the values with which this function
was called."
  (lambda (&rest args2)
    (apply fun (append args args2))))

\f
;;;; List functions.

;; Note: `internal--compiler-macro-cXXr' was copied from
;; `cl--compiler-macro-cXXr' in cl-macs.el.  If you amend either one,
;; you may want to amend the other, too.
(defun internal--compiler-macro-cXXr (form x)
  (let* ((head (car form))
         (n (symbol-name (car form)))
         (i (- (length n) 2)))
    (if (not (string-match "c[ad]+r\\'" n))
        (if (and (fboundp head) (symbolp (symbol-function head)))
            (internal--compiler-macro-cXXr (cons (symbol-function head) (cdr form))
                                     x)
          (error "Compiler macro for cXXr applied to non-cXXr form"))
      (while (> i (match-beginning 0))
        (setq x (list (if (eq (aref n i) ?a) 'car 'cdr) x))
        (setq i (1- i)))
      x)))

(defun caar (x)
  "Return the car of the car of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car x)))

(defun cadr (x)
  "Return the car of the cdr of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr x)))

(defun cdar (x)
  "Return the cdr of the car of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car x)))

(defun cddr (x)
  "Return the cdr of the cdr of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr x)))

(defun caaar (x)
  "Return the `car' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (car x))))

(defun caadr (x)
  "Return the `car' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (cdr x))))

(defun cadar (x)
  "Return the `car' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (car x))))

(defun caddr (x)
  "Return the `car' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (cdr x))))

(defun cdaar (x)
  "Return the `cdr' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (car x))))

(defun cdadr (x)
  "Return the `cdr' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (cdr x))))

(defun cddar (x)
  "Return the `cdr' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (car x))))

(defun cdddr (x)
  "Return the `cdr' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (cdr x))))

(defun caaaar (x)
  "Return the `car' of the `car' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (car (car x)))))

(defun caaadr (x)
  "Return the `car' of the `car' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (car (cdr x)))))

(defun caadar (x)
  "Return the `car' of the `car' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (cdr (car x)))))

(defun caaddr (x)
  "Return the `car' of the `car' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (car (cdr (cdr x)))))

(defun cadaar (x)
  "Return the `car' of the `cdr' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (car (car x)))))

(defun cadadr (x)
  "Return the `car' of the `cdr' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (car (cdr x)))))

(defun caddar (x)
  "Return the `car' of the `cdr' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (cdr (car x)))))

(defun cadddr (x)
  "Return the `car' of the `cdr' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (car (cdr (cdr (cdr x)))))

(defun cdaaar (x)
  "Return the `cdr' of the `car' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (car (car x)))))

(defun cdaadr (x)
  "Return the `cdr' of the `car' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (car (cdr x)))))

(defun cdadar (x)
  "Return the `cdr' of the `car' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (cdr (car x)))))

(defun cdaddr (x)
  "Return the `cdr' of the `car' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (car (cdr (cdr x)))))

(defun cddaar (x)
  "Return the `cdr' of the `cdr' of the `car' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (car (car x)))))

(defun cddadr (x)
  "Return the `cdr' of the `cdr' of the `car' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (car (cdr x)))))

(defun cdddar (x)
  "Return the `cdr' of the `cdr' of the `cdr' of the `car' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (cdr (car x)))))

(defun cddddr (x)
  "Return the `cdr' of the `cdr' of the `cdr' of the `cdr' of X."
  (declare (compiler-macro internal--compiler-macro-cXXr))
  (cdr (cdr (cdr (cdr x)))))

(defun last (list &optional n)
  "Return the last link of LIST.  Its car is the last element.
If LIST is nil, return nil.
If N is non-nil, return the Nth-to-last link of LIST.
If N is bigger than the length of LIST, return LIST."
  (if n
      (and (>= n 0)
           (let ((m (safe-length list)))
             (if (< n m) (nthcdr (- m n) list) list)))
    (and list
         (nthcdr (1- (safe-length list)) list))))

(defun butlast (list &optional n)
  "Return a copy of LIST with the last N elements removed.
If N is omitted or nil, the last element is removed from the
copy."
  (if (and n (<= n 0)) list
    (nbutlast (copy-sequence list) n)))

(defun nbutlast (list &optional n)
  "Modifies LIST to remove the last N elements.
If N is omitted or nil, remove the last element."
  (let ((m (length list)))
    (or n (setq n 1))
    (and (< n m)
         (progn
           (if (> n 0) (setcdr (nthcdr (- (1- m) n) list) nil))
           list))))

(defun zerop (number)
  "Return t if NUMBER is zero."
  ;; Used to be in C, but it's pointless since (= 0 n) is faster anyway because
  ;; = has a byte-code.
  (declare (compiler-macro (lambda (_) `(= 0 ,number))))
  (= 0 number))

(defun delete-dups (list)
  "Destructively remove `equal' duplicates from LIST.
Store the result in LIST and return it.  LIST must be a proper list.
Of several `equal' occurrences of an element in LIST, the first
one is kept."
  (let ((l (length list)))
    (if (> l 100)
        (let ((hash (make-hash-table :test #'equal :size l))
              (tail list) retail)
          (puthash (car list) t hash)
          (while (setq retail (cdr tail))
            (let ((elt (car retail)))
              (if (gethash elt hash)
                  (setcdr tail (cdr retail))
                (puthash elt t hash)
                (setq tail retail)))))
      (let ((tail list))
        (while tail
          (setcdr tail (delete (car tail) (cdr tail)))
          (setq tail (cdr tail))))))
  list)

;; See https://lists.gnu.org/r/emacs-devel/2013-05/msg00204.html
(defun delete-consecutive-dups (list &optional circular)
  "Destructively remove `equal' consecutive duplicates from LIST.
First and last elements are considered consecutive if CIRCULAR is
non-nil."
  (let ((tail list) last)
    (while (cdr tail)
      (if (equal (car tail) (cadr tail))
          (setcdr tail (cddr tail))
        (setq last tail
              tail (cdr tail))))
    (if (and circular
             last
             (equal (car tail) (car list)))
        (setcdr last nil)))
  list)

(defun number-sequence (from &optional to inc)
  "Return a sequence of numbers from FROM to TO (both inclusive) as a list.
INC is the increment used between numbers in the sequence and defaults to 1.
So, the Nth element of the list is (+ FROM (* N INC)) where N counts from
zero.  TO is only included if there is an N for which TO = FROM + N * INC.
If TO is nil or numerically equal to FROM, return (FROM).
If INC is positive and TO is less than FROM, or INC is negative
and TO is larger than FROM, return nil.
If INC is zero and TO is neither nil nor numerically equal to
FROM, signal an error.

This function is primarily designed for integer arguments.
Nevertheless, FROM, TO and INC can be integer or float.  However,
floating point arithmetic is inexact.  For instance, depending on
the machine, it may quite well happen that
\(number-sequence 0.4 0.6 0.2) returns the one element list (0.4),
whereas (number-sequence 0.4 0.8 0.2) returns a list with three
elements.  Thus, if some of the arguments are floats and one wants
to make sure that TO is included, one may have to explicitly write
TO as (+ FROM (* N INC)) or use a variable whose value was
computed with this exact expression.  Alternatively, you can,
of course, also replace TO with a slightly larger value
\(or a slightly more negative value if INC is negative)."
  (if (or (not to) (= from to))
      (list from)
    (or inc (setq inc 1))
    (when (zerop inc) (error "The increment can not be zero"))
    (let (seq (n 0) (next from) (last from))
      (if (> inc 0)
          ;; The (>= next last) condition protects against integer
          ;; overflow in computing NEXT.
          (while (and (>= next last) (<= next to))
            (setq seq (cons next seq)
                  n (1+ n)
                  last next
                  next (+ from (* n inc))))
        (while (and (<= next last) (>= next to))
          (setq seq (cons next seq)
                n (1+ n)
                next (+ from (* n inc)))))
      (nreverse seq))))

(defun copy-tree (tree &optional vecp)
  "Make a copy of TREE.
If TREE is a cons cell, this recursively copies both its car and its cdr.
Contrast to `copy-sequence', which copies only along the cdrs.  With second
argument VECP, this copies vectors as well as conses."
  (if (consp tree)
      (let (result)
        (while (consp tree)
          (let ((newcar (car tree)))
            (if (or (consp (car tree)) (and vecp (vectorp (car tree))))
                (setq newcar (copy-tree (car tree) vecp)))
            (push newcar result))
          (setq tree (cdr tree)))
        (nconc (nreverse result)
               (if (and vecp (vectorp tree)) (copy-tree tree vecp) tree)))
    (if (and vecp (vectorp tree))
        (let ((i (length (setq tree (copy-sequence tree)))))
          (while (>= (setq i (1- i)) 0)
            (aset tree i (copy-tree (aref tree i) vecp)))
          tree)
      tree)))
\f
;;;; Various list-search functions.

(defun assoc-default (key alist &optional test default)
  "Find object KEY in a pseudo-alist ALIST.
ALIST is a list of conses or objects.  Each element
 (or the element's car, if it is a cons) is compared with KEY by
 calling TEST, with two arguments: (i) the element or its car,
 and (ii) KEY.
If that is non-nil, the element matches; then `assoc-default'
 returns the element's cdr, if it is a cons, or DEFAULT if the
 element is not a cons.

If no element matches, the value is nil.
If TEST is omitted or nil, `equal' is used."
  (let (found (tail alist) value)
    (while (and tail (not found))
      (let ((elt (car tail)))
        (when (funcall (or test 'equal) (if (consp elt) (car elt) elt) key)
          (setq found t value (if (consp elt) (cdr elt) default))))
      (setq tail (cdr tail)))
    value))

(defun assoc-ignore-case (key alist)
  "Like `assoc', but ignores differences in case and text representation.
KEY must be a string.  Upper-case and lower-case letters are treated as equal.
Unibyte strings are converted to multibyte for comparison."
  (declare (obsolete assoc-string "22.1"))
  (assoc-string key alist t))

(defun assoc-ignore-representation (key alist)
  "Like `assoc', but ignores differences in text representation.
KEY must be a string.
Unibyte strings are converted to multibyte for comparison."
  (declare (obsolete assoc-string "22.1"))
  (assoc-string key alist nil))

(defun member-ignore-case (elt list)
  "Like `member', but ignore differences in case and text representation.
ELT must be a string.  Upper-case and lower-case letters are treated as equal.
Unibyte strings are converted to multibyte for comparison.
Non-strings in LIST are ignored."
  (while (and list
              (not (and (stringp (car list))
                        (eq t (compare-strings elt 0 nil (car list) 0 nil t)))))
    (setq list (cdr list)))
  list)

(defun assq-delete-all (key alist)
  "Delete from ALIST all elements whose car is `eq' to KEY.
Return the modified alist.
Elements of ALIST that are not conses are ignored."
  (while (and (consp (car alist))
              (eq (car (car alist)) key))
    (setq alist (cdr alist)))
  (let ((tail alist) tail-cdr)
    (while (setq tail-cdr (cdr tail))
      (if (and (consp (car tail-cdr))
               (eq (car (car tail-cdr)) key))
          (setcdr tail (cdr tail-cdr))
        (setq tail tail-cdr))))
  alist)

(defun rassq-delete-all (value alist)
  "Delete from ALIST all elements whose cdr is `eq' to VALUE.
Return the modified alist.
Elements of ALIST that are not conses are ignored."
  (while (and (consp (car alist))
              (eq (cdr (car alist)) value))
    (setq alist (cdr alist)))
  (let ((tail alist) tail-cdr)
    (while (setq tail-cdr (cdr tail))
      (if (and (consp (car tail-cdr))
               (eq (cdr (car tail-cdr)) value))
          (setcdr tail (cdr tail-cdr))
        (setq tail tail-cdr))))
  alist)

(defun alist-get (key alist &optional default remove testfn)
  "Return the value associated with KEY in ALIST.
If KEY is not found in ALIST, return DEFAULT.
Use TESTFN to lookup in the alist if non-nil.  Otherwise, use `assq'.

This is a generalized variable suitable for use with `setf'.
When using it to set a value, optional argument REMOVE non-nil
means to remove KEY from ALIST if the new value is `eql' to DEFAULT."
  (ignore remove) ;;Silence byte-compiler.
  (let ((x (if (not testfn)
               (assq key alist)
             (assoc key alist testfn))))
    (if x (cdr x) default)))

(defun remove (elt seq)
  "Return a copy of SEQ with all occurrences of ELT removed.
SEQ must be a list, vector, or string.  The comparison is done with `equal'."
  (if (nlistp seq)
      ;; If SEQ isn't a list, there's no need to copy SEQ because
      ;; `delete' will return a new object.
      (delete elt seq)
    (delete elt (copy-sequence seq))))

(defun remq (elt list)
  "Return LIST with all occurrences of ELT removed.
The comparison is done with `eq'.  Contrary to `delq', this does not use
side-effects, and the argument LIST is not modified."
  (while (and (eq elt (car list)) (setq list (cdr list))))
  (if (memq elt list)
      (delq elt (copy-sequence list))
    list))
\f
;;;; Keymap support.

(defun kbd (keys)
  "Convert KEYS to the internal Emacs key representation.
KEYS should be a string in the format returned by commands such
as `C-h k' (`describe-key').
This is the same format used for saving keyboard macros (see
`edmacro-mode').

For an approximate inverse of this, see `key-description'."
  ;; Don't use a defalias, since the `pure' property is only true for
  ;; the calling convention of `kbd'.
  (read-kbd-macro keys))
(put 'kbd 'pure t)

(defun undefined ()
  "Beep to tell the user this binding is undefined."
  (interactive)
  (ding)
  (if defining-kbd-macro
      (error "%s is undefined" (key-description (this-single-command-keys)))
    (message "%s is undefined" (key-description (this-single-command-keys))))
  (force-mode-line-update)
  ;; If this is a down-mouse event, don't reset prefix-arg;
  ;; pass it to the command run by the up event.
  (setq prefix-arg
        (when (memq 'down (event-modifiers last-command-event))
          current-prefix-arg)))

;; Prevent the \{...} documentation construct
;; from mentioning keys that run this command.
(put 'undefined 'suppress-keymap t)

(defun suppress-keymap (map &optional nodigits)
  "Make MAP override all normally self-inserting keys to be undefined.
Normally, as an exception, digits and minus-sign are set to make prefix args,
but optional second arg NODIGITS non-nil treats them like other chars."
  (define-key map [remap self-insert-command] 'undefined)
  (or nodigits
      (let (loop)
        (define-key map "-" 'negative-argument)
        ;; Make plain numbers do numeric args.
        (setq loop ?0)
        (while (<= loop ?9)
          (define-key map (char-to-string loop) 'digit-argument)
          (setq loop (1+ loop))))))

(defun make-composed-keymap (maps &optional parent)
  "Construct a new keymap composed of MAPS and inheriting from PARENT.
When looking up a key in the returned map, the key is looked in each
keymap of MAPS in turn until a binding is found.
If no binding is found in MAPS, the lookup continues in PARENT, if non-nil.
As always with keymap inheritance, a nil binding in MAPS overrides
any corresponding binding in PARENT, but it does not override corresponding
bindings in other keymaps of MAPS.
MAPS can be a list of keymaps or a single keymap.
PARENT if non-nil should be a keymap."
  `(keymap
    ,@(if (keymapp maps) (list maps) maps)
    ,@parent))

(defun define-key-after (keymap key definition &optional after)
  "Add binding in KEYMAP for KEY => DEFINITION, right after AFTER's binding.
This is like `define-key' except that the binding for KEY is placed
just after the binding for the event AFTER, instead of at the beginning
of the map.  Note that AFTER must be an event type (like KEY), NOT a command
\(like DEFINITION).

If AFTER is t or omitted, the new binding goes at the end of the keymap.
AFTER should be a single event type--a symbol or a character, not a sequence.

Bindings are always added before any inherited map.

The order of bindings in a keymap only matters when it is used as
a menu, so this function is not useful for non-menu keymaps."
  (unless after (setq after t))
  (or (keymapp keymap)
      (signal 'wrong-type-argument (list 'keymapp keymap)))
  (setq key
        (if (<= (length key) 1) (aref key 0)
          (setq keymap (lookup-key keymap
                                   (apply 'vector
                                          (butlast (mapcar 'identity key)))))
          (aref key (1- (length key)))))
  (let ((tail keymap) done inserted)
    (while (and (not done) tail)
      ;; Delete any earlier bindings for the same key.
      (if (eq (car-safe (car (cdr tail))) key)
          (setcdr tail (cdr (cdr tail))))
      ;; If we hit an included map, go down that one.
      (if (keymapp (car tail)) (setq tail (car tail)))
      ;; When we reach AFTER's binding, insert the new binding after.
      ;; If we reach an inherited keymap, insert just before that.
      ;; If we reach the end of this keymap, insert at the end.
      (if (or (and (eq (car-safe (car tail)) after)
                   (not (eq after t)))
              (eq (car (cdr tail)) 'keymap)
              (null (cdr tail)))
          (progn
            ;; Stop the scan only if we find a parent keymap.
            ;; Keep going past the inserted element
            ;; so we can delete any duplications that come later.
            (if (eq (car (cdr tail)) 'keymap)
                (setq done t))
            ;; Don't insert more than once.
            (or inserted
                (setcdr tail (cons (cons key definition) (cdr tail))))
            (setq inserted t)))
      (setq tail (cdr tail)))))

(defun map-keymap-sorted (function keymap)
  "Implement `map-keymap' with sorting.
Don't call this function; it is for internal use only."
  (let (list)
    (map-keymap (lambda (a b) (push (cons a b) list))
                keymap)
    (setq list (sort list
                     (lambda (a b)
                       (setq a (car a) b (car b))
                       (if (integerp a)
                           (if (integerp b) (< a b)
                             t)
                         (if (integerp b) t
                           ;; string< also accepts symbols.
                           (string< a b))))))
    (dolist (p list)
      (funcall function (car p) (cdr p)))))

(defun keymap--menu-item-binding (val)
  "Return the binding part of a menu-item."
  (cond
   ((not (consp val)) val)              ;Not a menu-item.
   ((eq 'menu-item (car val))
    (let* ((binding (nth 2 val))
           (plist (nthcdr 3 val))
           (filter (plist-get plist :filter)))
      (if filter (funcall filter binding)
        binding)))
   ((and (consp (cdr val)) (stringp (cadr val)))
    (cddr val))
   ((stringp (car val))
    (cdr val))
   (t val)))                            ;Not a menu-item either.

(defun keymap--menu-item-with-binding (item binding)
  "Build a menu-item like ITEM but with its binding changed to BINDING."
  (cond
   ((not (consp item)) binding)         ;Not a menu-item.
   ((eq 'menu-item (car item))
    (setq item (copy-sequence item))
    (let ((tail (nthcdr 2 item)))
      (setcar tail binding)
      ;; Remove any potential filter.
      (if (plist-get (cdr tail) :filter)
          (setcdr tail (plist-put (cdr tail) :filter nil))))
    item)
   ((and (consp (cdr item)) (stringp (cadr item)))
    (cons (car item) (cons (cadr item) binding)))
   (t (cons (car item) binding))))

(defun keymap--merge-bindings (val1 val2)
  "Merge bindings VAL1 and VAL2."
  (let ((map1 (keymap--menu-item-binding val1))
        (map2 (keymap--menu-item-binding val2)))
    (if (not (and (keymapp map1) (keymapp map2)))
        ;; There's nothing to merge: val1 takes precedence.
        val1
      (let ((map (list 'keymap map1 map2))
            (item (if (keymapp val1) (if (keymapp val2) nil val2) val1)))
        (keymap--menu-item-with-binding item map)))))

(defun keymap-canonicalize (map)
  "Return a simpler equivalent keymap.
This resolves inheritance and redefinitions.  The returned keymap
should behave identically to a copy of KEYMAP w.r.t `lookup-key'
and use in active keymaps and menus.
Subkeymaps may be modified but are not canonicalized."
  ;; FIXME: Problem with the difference between a nil binding
  ;; that hides a binding in an inherited map and a nil binding that's ignored
  ;; to let some further binding visible.  Currently a nil binding hides all.
  ;; FIXME: we may want to carefully (re)order elements in case they're
  ;; menu-entries.
  (let ((bindings ())
        (ranges ())
        (prompt (keymap-prompt map)))
    (while (keymapp map)
      (setq map (map-keymap ;; -internal
                 (lambda (key item)
                   (if (consp key)
                       ;; Treat char-ranges specially.
                       (push (cons key item) ranges)
                     (push (cons key item) bindings)))
                 map)))
    ;; Create the new map.
    (setq map (funcall (if ranges 'make-keymap 'make-sparse-keymap) prompt))
    (dolist (binding ranges)
      ;; Treat char-ranges specially.  FIXME: need to merge as well.
      (define-key map (vector (car binding)) (cdr binding)))
    ;; Process the bindings starting from the end.
    (dolist (binding (prog1 bindings (setq bindings ())))
      (let* ((key (car binding))
             (oldbind (assq key bindings)))
        (push (if (not oldbind)
                  ;; The normal case: no duplicate bindings.
                  binding
                ;; This is the second binding for this key.
                (setq bindings (delq oldbind bindings))
                (cons key (keymap--merge-bindings (cdr binding)
                                                  (cdr oldbind))))
              bindings)))
    (nconc map bindings)))

(put 'keyboard-translate-table 'char-table-extra-slots 0)

(defun keyboard-translate (from to)
  "Translate character FROM to TO on the current terminal.
This function creates a `keyboard-translate-table' if necessary
and then modifies one entry in it."
  (or (char-table-p keyboard-translate-table)
      (setq keyboard-translate-table
            (make-char-table 'keyboard-translate-table nil)))
  (aset keyboard-translate-table from to))
\f
;;;; Key binding commands.

(defun global-set-key (key command)
  "Give KEY a global binding as COMMAND.
COMMAND is the command definition to use; usually it is
a symbol naming an interactively-callable function.
KEY is a key sequence; noninteractively, it is a string or vector
of characters or event types, and non-ASCII characters with codes
above 127 (such as ISO Latin-1) can be included if you use a vector.

Note that if KEY has a local binding in the current buffer,
that local binding will continue to shadow any global binding
that you make with this function."
  (interactive
   (let* ((menu-prompting nil)
          (key (read-key-sequence "Set key globally: ")))
     (list key
           (read-command (format "Set key %s to command: "
                                 (key-description key))))))
  (or (vectorp key) (stringp key)
      (signal 'wrong-type-argument (list 'arrayp key)))
  (define-key (current-global-map) key command))

(defun local-set-key (key command)
  "Give KEY a local binding as COMMAND.
COMMAND is the command definition to use; usually it is
a symbol naming an interactively-callable function.
KEY is a key sequence; noninteractively, it is a string or vector
of characters or event types, and non-ASCII characters with codes
above 127 (such as ISO Latin-1) can be included if you use a vector.

The binding goes in the current buffer's local map, which in most
cases is shared with all other buffers in the same major mode."
  (interactive "KSet key locally: \nCSet key %s locally to command: ")
  (let ((map (current-local-map)))
    (or map
        (use-local-map (setq map (make-sparse-keymap))))
    (or (vectorp key) (stringp key)
        (signal 'wrong-type-argument (list 'arrayp key)))
    (define-key map key command)))

(defun global-unset-key (key)
  "Remove global binding of KEY.
KEY is a string or vector representing a sequence of keystrokes."
  (interactive "kUnset key globally: ")
  (global-set-key key nil))

(defun local-unset-key (key)
  "Remove local binding of KEY.
KEY is a string or vector representing a sequence of keystrokes."
  (interactive "kUnset key locally: ")
  (if (current-local-map)
      (local-set-key key nil))
  nil)
\f
;;;; substitute-key-definition and its subroutines.

(defvar key-substitution-in-progress nil
  "Used internally by `substitute-key-definition'.")

(defun substitute-key-definition (olddef newdef keymap &optional oldmap prefix)
  "Replace OLDDEF with NEWDEF for any keys in KEYMAP now defined as OLDDEF.
In other words, OLDDEF is replaced with NEWDEF wherever it appears.
Alternatively, if optional fourth argument OLDMAP is specified, we redefine
in KEYMAP as NEWDEF those keys which are defined as OLDDEF in OLDMAP.

If you don't specify OLDMAP, you can usually get the same results
in a cleaner way with command remapping, like this:
  (define-key KEYMAP [remap OLDDEF] NEWDEF)
\n(fn OLDDEF NEWDEF KEYMAP &optional OLDMAP)"
  ;; Don't document PREFIX in the doc string because we don't want to
  ;; advertise it.  It's meant for recursive calls only.  Here's its
  ;; meaning

  ;; If optional argument PREFIX is specified, it should be a key
  ;; prefix, a string.  Redefined bindings will then be bound to the
  ;; original key, with PREFIX added at the front.
  (or prefix (setq prefix ""))
  (let* ((scan (or oldmap keymap))
         (prefix1 (vconcat prefix [nil]))
         (key-substitution-in-progress
          (cons scan key-substitution-in-progress)))
    ;; Scan OLDMAP, finding each char or event-symbol that
    ;; has any definition, and act on it with hack-key.
    (map-keymap
     (lambda (char defn)
       (aset prefix1 (length prefix) char)
       (substitute-key-definition-key defn olddef newdef prefix1 keymap))
     scan)))

(defun substitute-key-definition-key (defn olddef newdef prefix keymap)
  (let (inner-def skipped menu-item)
    ;; Find the actual command name within the binding.
    (if (eq (car-safe defn) 'menu-item)
        (setq menu-item defn defn (nth 2 defn))
      ;; Skip past menu-prompt.
      (while (stringp (car-safe defn))
        (push (pop defn) skipped))
      ;; Skip past cached key-equivalence data for menu items.
      (if (consp (car-safe defn))
          (setq defn (cdr defn))))
    (if (or (eq defn olddef)
            ;; Compare with equal if definition is a key sequence.
            ;; That is useful for operating on function-key-map.
            (and (or (stringp defn) (vectorp defn))
                 (equal defn olddef)))
        (define-key keymap prefix
          (if menu-item
              (let ((copy (copy-sequence menu-item)))
                (setcar (nthcdr 2 copy) newdef)
                copy)
            (nconc (nreverse skipped) newdef)))
      ;; Look past a symbol that names a keymap.
      (setq inner-def
            (or (indirect-function defn) defn))
      ;; For nested keymaps, we use `inner-def' rather than `defn' so as to
      ;; avoid autoloading a keymap.  This is mostly done to preserve the
      ;; original non-autoloading behavior of pre-map-keymap times.
      (if (and (keymapp inner-def)
               ;; Avoid recursively scanning
               ;; where KEYMAP does not have a submap.
               (let ((elt (lookup-key keymap prefix)))
                 (or (null elt) (natnump elt) (keymapp elt)))
               ;; Avoid recursively rescanning keymap being scanned.
               (not (memq inner-def key-substitution-in-progress)))
          ;; If this one isn't being scanned already, scan it now.
          (substitute-key-definition olddef newdef keymap inner-def prefix)))))

\f
;;;; The global keymap tree.

;; global-map, esc-map, and ctl-x-map have their values set up in
;; keymap.c; we just give them docstrings here.

(defvar global-map nil
  "Default global keymap mapping Emacs keyboard input into commands.
The value is a keymap which is usually (but not necessarily) Emacs's
global map.")

(defvar esc-map nil
  "Default keymap for ESC (meta) commands.
The normal global definition of the character ESC indirects to this keymap.")

(defvar ctl-x-map nil
  "Default keymap for C-x commands.
The normal global definition of the character C-x indirects to this keymap.")

(defvar ctl-x-4-map (make-sparse-keymap)
  "Keymap for subcommands of C-x 4.")
(defalias 'ctl-x-4-prefix ctl-x-4-map)
(define-key ctl-x-map "4" 'ctl-x-4-prefix)

(defvar ctl-x-5-map (make-sparse-keymap)
  "Keymap for frame commands.")
(defalias 'ctl-x-5-prefix ctl-x-5-map)
(define-key ctl-x-map "5" 'ctl-x-5-prefix)

\f
;;;; Event manipulation functions.

(defconst listify-key-sequence-1 (logior 128 ?\M-\C-@))

(defun listify-key-sequence (key)
  "Convert a key sequence to a list of events."
  (if (vectorp key)
      (append key nil)
    (mapcar (function (lambda (c)
                        (if (> c 127)
                            (logxor c listify-key-sequence-1)
                          c)))
            key)))

(defun eventp (obj)
  "True if the argument is an event object."
  (when obj
    (or (integerp obj)
        (and (symbolp obj) obj (not (keywordp obj)))
        (and (consp obj) (symbolp (car obj))))))

(defun event-modifiers (event)
  "Return a list of symbols representing the modifier keys in event EVENT.
The elements of the list may include `meta', `control',
`shift', `hyper', `super', `alt', `click', `double', `triple', `drag',
and `down'.
EVENT may be an event or an event type.  If EVENT is a symbol
that has never been used in an event that has been read as input
in the current Emacs session, then this function may fail to include
the `click' modifier."
  (let ((type event))
    (if (listp type)
        (setq type (car type)))
    (if (symbolp type)
        ;; Don't read event-symbol-elements directly since we're not
        ;; sure the symbol has already been parsed.
        (cdr (internal-event-symbol-parse-modifiers type))
      (let ((list nil)
            (char (logand type (lognot (logior ?\M-\^@ ?\C-\^@ ?\S-\^@
                                               ?\H-\^@ ?\s-\^@ ?\A-\^@)))))
        (if (not (zerop (logand type ?\M-\^@)))
            (push 'meta list))
        (if (or (not (zerop (logand type ?\C-\^@)))
                (< char 32))
            (push 'control list))
        (if (or (not (zerop (logand type ?\S-\^@)))
                (/= char (downcase char)))
            (push 'shift list))
        (or (zerop (logand type ?\H-\^@))
            (push 'hyper list))
        (or (zerop (logand type ?\s-\^@))
            (push 'super list))
        (or (zerop (logand type ?\A-\^@))
            (push 'alt list))
        list))))

(defun event-basic-type (event)
  "Return the basic type of the given event (all modifiers removed).
The value is a printing character (not upper case) or a symbol.
EVENT may be an event or an event type.  If EVENT is a symbol
that has never been used in an event that has been read as input
in the current Emacs session, then this function may return nil."
  (if (consp event)
      (setq event (car event)))
  (if (symbolp event)
      (car (get event 'event-symbol-elements))
    (let* ((base (logand event (1- ?\A-\^@)))
           (uncontrolled (if (< base 32) (logior base 64) base)))
      ;; There are some numbers that are invalid characters and
      ;; cause `downcase' to get an error.
      (condition-case ()
          (downcase uncontrolled)
        (error uncontrolled)))))

(defsubst mouse-movement-p (object)
  "Return non-nil if OBJECT is a mouse movement event."
  (eq (car-safe object) 'mouse-movement))

(defun mouse-event-p (object)
  "Return non-nil if OBJECT is a mouse click event."
  ;; is this really correct? maybe remove mouse-movement?
  (memq (event-basic-type object) '(mouse-1 mouse-2 mouse-3 mouse-movement)))

(defun event-start (event)
  "Return the starting position of EVENT.
EVENT should be a mouse click, drag, or key press event.  If
EVENT is nil, the value of `posn-at-point' is used instead.

The following accessor functions are used to access the elements
of the position:

`posn-window': The window the event is in.
`posn-area': A symbol identifying the area the event occurred in,
or nil if the event occurred in the text area.
`posn-point': The buffer position of the event.
`posn-x-y': The pixel-based coordinates of the event.
`posn-col-row': The estimated column and row corresponding to the
position of the event.
`posn-actual-col-row': The actual column and row corresponding to the
position of the event.
`posn-string': The string object of the event, which is either
nil or (STRING . POSITION)'.
`posn-image': The image object of the event, if any.
`posn-object': The image or string object of the event, if any.
`posn-timestamp': The time the event occurred, in milliseconds.

For more information, see Info node `(elisp)Click Events'."
  (if (consp event) (nth 1 event)
    (or (posn-at-point)
        (list (selected-window) (point) '(0 . 0) 0))))

(defun event-end (event)
  "Return the ending position of EVENT.
EVENT should be a click, drag, or key press event.

See `event-start' for a description of the value returned."
  (if (consp event) (nth (if (consp (nth 2 event)) 2 1) event)
    (or (posn-at-point)
        (list (selected-window) (point) '(0 . 0) 0))))

(defsubst event-click-count (event)
  "Return the multi-click count of EVENT, a click or drag event.
The return value is a positive integer."
  (if (and (consp event) (integerp (nth 2 event))) (nth 2 event) 1))

(defsubst event-line-count (event)
  "Return the line count of EVENT, a mousewheel event.
The return value is a positive integer."
  (if (and (consp event) (integerp (nth 3 event))) (nth 3 event) 1))
\f
;;;; Extracting fields of the positions in an event.

(defun posnp (obj)
  "Return non-nil if OBJ appears to be a valid `posn' object specifying a window.
A `posn' object is returned from functions such as `event-start'.
If OBJ is a valid `posn' object, but specifies a frame rather
than a window, return nil."
  ;; FIXME: Correct the behavior of this function so that all valid
  ;; `posn' objects are recognized, after updating other code that
  ;; depends on its present behavior.
  (and (windowp (car-safe obj))
       (atom (car-safe (setq obj (cdr obj))))                ;AREA-OR-POS.
       (integerp (car-safe (car-safe (setq obj (cdr obj))))) ;XOFFSET.
       (integerp (car-safe (cdr obj)))))                     ;TIMESTAMP.

(defsubst posn-window (position)
  "Return the window in POSITION.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (nth 0 position))

(defsubst posn-area (position)
  "Return the window area recorded in POSITION, or nil for the text area.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (let ((area (if (consp (nth 1 position))
                  (car (nth 1 position))
                (nth 1 position))))
    (and (symbolp area) area)))

(defun posn-point (position)
  "Return the buffer location in POSITION.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions.
Returns nil if POSITION does not correspond to any buffer location (e.g.
a click on a scroll bar)."
  (or (nth 5 position)
      (let ((pt (nth 1 position)))
        (or (car-safe pt)
            ;; Apparently this can also be `vertical-scroll-bar' (bug#13979).
            (if (integerp pt) pt)))))

(defun posn-set-point (position)
  "Move point to POSITION.
Select the corresponding window as well."
  (if (not (windowp (posn-window position)))
      (error "Position not in text area of window"))
  (select-window (posn-window position))
  (if (numberp (posn-point position))
      (goto-char (posn-point position))))

(defsubst posn-x-y (position)
  "Return the x and y coordinates in POSITION.
The return value has the form (X . Y), where X and Y are given in
pixels.  POSITION should be a list of the form returned by
`event-start' and `event-end'."
  (nth 2 position))

(declare-function scroll-bar-scale "scroll-bar" (num-denom whole))

(defun posn-col-row (position)
  "Return the nominal column and row in POSITION, measured in characters.
The column and row values are approximations calculated from the x
and y coordinates in POSITION and the frame's default character width
and default line height, including spacing.
For a scroll-bar event, the result column is 0, and the row
corresponds to the vertical position of the click in the scroll bar.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (let* ((pair            (posn-x-y position))
         (frame-or-window (posn-window position))
         (frame           (if (framep frame-or-window)
                              frame-or-window
                            (window-frame frame-or-window)))
         (window          (when (windowp frame-or-window) frame-or-window))
         (area            (posn-area position)))
    (cond
     ((null frame-or-window)
      '(0 . 0))
     ((eq area 'vertical-scroll-bar)
      (cons 0 (scroll-bar-scale pair (1- (window-height window)))))
     ((eq area 'horizontal-scroll-bar)
      (cons (scroll-bar-scale pair (window-width window)) 0))
     (t
      ;; FIXME: This should take line-spacing properties on
      ;; newlines into account.
      (let* ((spacing (when (display-graphic-p frame)
                        (or (with-current-buffer
                                (window-buffer (frame-selected-window frame))
                              line-spacing)
                            (frame-parameter frame 'line-spacing)))))
        (cond ((floatp spacing)
               (setq spacing (truncate (* spacing
                                          (frame-char-height frame)))))
              ((null spacing)
               (setq spacing 0)))
        (cons (/ (car pair) (frame-char-width frame))
              (/ (cdr pair) (+ (frame-char-height frame) spacing))))))))

(defun posn-actual-col-row (position)
  "Return the window row number in POSITION and character number in that row.

Return nil if POSITION does not contain the actual position; in that case
`posn-col-row' can be used to get approximate values.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions.

This function does not account for the width on display, like the
number of visual columns taken by a TAB or image.  If you need
the coordinates of POSITION in character units, you should use
`posn-col-row', not this function."
  (nth 6 position))

(defsubst posn-timestamp (position)
  "Return the timestamp of POSITION.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (nth 3 position))

(defun posn-string (position)
  "Return the string object of POSITION.
Value is a cons (STRING . STRING-POS), or nil if not a string.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (let ((x (nth 4 position)))
    ;; Apparently this can also be `handle' or `below-handle' (bug#13979).
    (when (consp x) x)))

(defsubst posn-image (position)
  "Return the image object of POSITION.
Value is a list (image ...), or nil if not an image.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (nth 7 position))

(defsubst posn-object (position)
  "Return the object (image or string) of POSITION.
Value is a list (image ...) for an image object, a cons cell
\(STRING . STRING-POS) for a string object, and nil for a buffer position.
POSITION should be a list of the form returned by the `event-start'
and `event-end' functions."
  (or (posn-image position) (posn-string position)))

(defsubst posn-object-x-y (position)
  "Return the x and y coordinates relative to the object of POSITION.
The return value has the form (DX . DY), where DX and DY are
given in pixels.  POSITION should be a list of the form returned
by `event-start' and `event-end'."
  (nth 8 position))

(defsubst posn-object-width-height (position)
  "Return the pixel width and height of the object of POSITION.
The return value has the form (WIDTH . HEIGHT).  POSITION should
be a list of the form returned by `event-start' and `event-end'."
  (nth 9 position))

\f
;;;; Obsolescent names for functions.

(make-obsolete 'forward-point "use (+ (point) N) instead." "23.1")
(make-obsolete 'buffer-has-markers-at nil "24.3")

;; bug#23850
(make-obsolete 'string-to-unibyte   "use `encode-coding-string'." "26.1")
(make-obsolete 'string-as-unibyte   "use `encode-coding-string'." "26.1")
(make-obsolete 'string-make-unibyte   "use `encode-coding-string'." "26.1")
(make-obsolete 'string-to-multibyte "use `decode-coding-string'." "26.1")
(make-obsolete 'string-as-multibyte "use `decode-coding-string'." "26.1")
(make-obsolete 'string-make-multibyte "use `decode-coding-string'." "26.1")

(defun log10 (x)
  "Return (log X 10), the log base 10 of X."
  (declare (obsolete log "24.4"))
  (log x 10))

;; These are used by VM and some old programs
(defalias 'focus-frame 'ignore "")
(make-obsolete 'focus-frame "it does nothing." "22.1")
(defalias 'unfocus-frame 'ignore "")
(make-obsolete 'unfocus-frame "it does nothing." "22.1")

(set-advertised-calling-convention
 'all-completions '(string collection &optional predicate) "23.1")
(set-advertised-calling-convention 'unintern '(name obarray) "23.3")
(set-advertised-calling-convention 'indirect-function '(object) "25.1")
(set-advertised-calling-convention 'redirect-frame-focus '(frame focus-frame) "24.3")
\f
;;;; Obsolescence declarations for variables, and aliases.

(make-obsolete-variable 'define-key-rebound-commands nil "23.2")
(make-obsolete-variable 'redisplay-end-trigger-functions 'jit-lock-register "23.1")
(make-obsolete-variable 'deferred-action-list 'post-command-hook "24.1")
(make-obsolete-variable 'deferred-action-function 'post-command-hook "24.1")
(make-obsolete-variable 'redisplay-dont-pause nil "24.5")
(make-obsolete 'window-redisplay-end-trigger nil "23.1")
(make-obsolete 'set-window-redisplay-end-trigger nil "23.1")

(make-obsolete 'process-filter-multibyte-p nil "23.1")
(make-obsolete 'set-process-filter-multibyte nil "23.1")

(make-obsolete-variable 'command-debug-status
                        "expect it to be removed in a future version." "25.2")

;; Lisp manual only updated in 22.1.
(define-obsolete-variable-alias 'executing-macro 'executing-kbd-macro
  "before 19.34")

(define-obsolete-variable-alias 'x-lost-selection-hooks
  'x-lost-selection-functions "22.1")
(define-obsolete-variable-alias 'x-sent-selection-hooks
  'x-sent-selection-functions "22.1")

;; This was introduced in 21.4 for pre-unicode unification.  That
;; usage was rendered obsolete in 23.1 which uses Unicode internally.
;; Other uses are possible, so this variable is not _really_ obsolete,
;; but Stefan insists to mark it so.
(make-obsolete-variable 'translation-table-for-input nil "23.1")

(make-obsolete-variable 'x-gtk-use-window-move nil "26.1")

(defvaralias 'messages-buffer-max-lines 'message-log-max)
\f
;;;; Alternate names for functions - these are not being phased out.

(defalias 'send-string 'process-send-string)
(defalias 'send-region 'process-send-region)
(defalias 'string= 'string-equal)
(defalias 'string< 'string-lessp)
(defalias 'string> 'string-greaterp)
(defalias 'move-marker 'set-marker)
(defalias 'rplaca 'setcar)
(defalias 'rplacd 'setcdr)
(defalias 'beep 'ding) ;preserve lingual purity
(defalias 'indent-to-column 'indent-to)
(defalias 'backward-delete-char 'delete-backward-char)
(defalias 'search-forward-regexp (symbol-function 're-search-forward))
(defalias 'search-backward-regexp (symbol-function 're-search-backward))
(defalias 'int-to-string 'number-to-string)
(defalias 'store-match-data 'set-match-data)
(defalias 'chmod 'set-file-modes)
(defalias 'mkdir 'make-directory)
;; These are the XEmacs names:
(defalias 'point-at-eol 'line-end-position)
(defalias 'point-at-bol 'line-beginning-position)

(defalias 'user-original-login-name 'user-login-name)

\f
;;;; Hook manipulation functions.

(defun add-hook (hook function &optional append local)
  "Add to the value of HOOK the function FUNCTION.
FUNCTION is not added if already present.
FUNCTION is added (if necessary) at the beginning of the hook list
unless the optional argument APPEND is non-nil, in which case
FUNCTION is added at the end.

The optional fourth argument, LOCAL, if non-nil, says to modify
the hook's buffer-local value rather than its global value.
This makes the hook buffer-local, and it makes t a member of the
buffer-local value.  That acts as a flag to run the hook
functions of the global value as well as in the local value.

HOOK should be a symbol, and FUNCTION may be any valid function.  If
HOOK is void, it is first set to nil.  If HOOK's value is a single
function, it is changed to a list of functions."
  (or (boundp hook) (set hook nil))
  (or (default-boundp hook) (set-default hook nil))
  (if local (unless (local-variable-if-set-p hook)
              (set (make-local-variable hook) (list t)))
    ;; Detect the case where make-local-variable was used on a hook
    ;; and do what we used to do.
    (unless (and (consp (symbol-value hook)) (memq t (symbol-value hook)))
      (setq local t)))
  (let ((hook-value (if local (symbol-value hook) (default-value hook))))
    ;; If the hook value is a single function, turn it into a list.
    (when (or (not (listp hook-value)) (functionp hook-value))
      (setq hook-value (list hook-value)))
    ;; Do the actual addition if necessary
    (unless (member function hook-value)
      (when (stringp function)
        (setq function (purecopy function)))
      (setq hook-value
            (if append
                (append hook-value (list function))
              (cons function hook-value))))
    ;; Set the actual variable
    (if local
        (progn
          ;; If HOOK isn't a permanent local,
          ;; but FUNCTION wants to survive a change of modes,
          ;; mark HOOK as partially permanent.
          (and (symbolp function)
               (get function 'permanent-local-hook)
               (not (get hook 'permanent-local))
               (put hook 'permanent-local 'permanent-local-hook))
          (set hook hook-value))
      (set-default hook hook-value))))

(defun remove-hook (hook function &optional local)
  "Remove from the value of HOOK the function FUNCTION.
HOOK should be a symbol, and FUNCTION may be any valid function.  If
FUNCTION isn't the value of HOOK, or, if FUNCTION doesn't appear in the
list of hooks to run in HOOK, then nothing is done.  See `add-hook'.

The optional third argument, LOCAL, if non-nil, says to modify
the hook's buffer-local value rather than its default value."
  (or (boundp hook) (set hook nil))
  (or (default-boundp hook) (set-default hook nil))
  ;; Do nothing if LOCAL is t but this hook has no local binding.
  (unless (and local (not (local-variable-p hook)))
    ;; Detect the case where make-local-variable was used on a hook
    ;; and do what we used to do.
    (when (and (local-variable-p hook)
               (not (and (consp (symbol-value hook))
                         (memq t (symbol-value hook)))))
      (setq local t))
    (let ((hook-value (if local (symbol-value hook) (default-value hook))))
      ;; Remove the function, for both the list and the non-list cases.
      (if (or (not (listp hook-value)) (eq (car hook-value) 'lambda))
          (if (equal hook-value function) (setq hook-value nil))
        (setq hook-value (delete function (copy-sequence hook-value))))
      ;; If the function is on the global hook, we need to shadow it locally
      ;;(when (and local (member function (default-value hook))
      ;;               (not (member (cons 'not function) hook-value)))
      ;;  (push (cons 'not function) hook-value))
      ;; Set the actual variable
      (if (not local)
          (set-default hook hook-value)
        (if (equal hook-value '(t))
            (kill-local-variable hook)
          (set hook hook-value))))))

(defmacro letrec (binders &rest body)
  "Bind variables according to BINDERS then eval BODY.
The value of the last form in BODY is returned.
Each element of BINDERS is a list (SYMBOL VALUEFORM) which binds
SYMBOL to the value of VALUEFORM.
All symbols are bound before the VALUEFORMs are evalled."
  ;; Only useful in lexical-binding mode.
  ;; As a special-form, we could implement it more efficiently (and cleanly,
  ;; making the vars actually unbound during evaluation of the binders).
  (declare (debug let) (indent 1))
  `(let ,(mapcar #'car binders)
     ,@(mapcar (lambda (binder) `(setq ,@binder)) binders)
     ,@body))

(defmacro with-wrapper-hook (hook args &rest body)
  "Run BODY, using wrapper functions from HOOK with additional ARGS.
HOOK is an abnormal hook.  Each hook function in HOOK \"wraps\"
around the preceding ones, like a set of nested `around' advices.

Each hook function should accept an argument list consisting of a
function FUN, followed by the additional arguments in ARGS.

The first hook function in HOOK is passed a FUN that, if it is called
with arguments ARGS, performs BODY (i.e., the default operation).
The FUN passed to each successive hook function is defined based
on the preceding hook functions; if called with arguments ARGS,
it does what the `with-wrapper-hook' call would do if the
preceding hook functions were the only ones present in HOOK.

Each hook function may call its FUN argument as many times as it wishes,
including never.  In that case, such a hook function acts to replace
the default definition altogether, and any preceding hook functions.
Of course, a subsequent hook function may do the same thing.

Each hook function definition is used to construct the FUN passed
to the next hook function, if any.  The last (or \"outermost\")
FUN is then called once."
  (declare (indent 2) (debug (form sexp body))
           (obsolete "use a <foo>-function variable modified by `add-function'."
                     "24.4"))
  `(subr--with-wrapper-hook-no-warnings ,hook ,args ,@body))

(defmacro subr--with-wrapper-hook-no-warnings (hook args &rest body)
  "Like (with-wrapper-hook HOOK ARGS BODY), but without warnings."
  ;; We need those two gensyms because CL's lexical scoping is not available
  ;; for function arguments :-(
  (let ((funs (make-symbol "funs"))
        (global (make-symbol "global"))
        (argssym (make-symbol "args"))
        (runrestofhook (make-symbol "runrestofhook")))
    ;; Since the hook is a wrapper, the loop has to be done via
    ;; recursion: a given hook function will call its parameter in order to
    ;; continue looping.
    `(letrec ((,runrestofhook
               (lambda (,funs ,global ,argssym)
                 ;; `funs' holds the functions left on the hook and `global'
                 ;; holds the functions left on the global part of the hook
                 ;; (in case the hook is local).
                 (if (consp ,funs)
                     (if (eq t (car ,funs))
                         (funcall ,runrestofhook
                                  (append ,global (cdr ,funs)) nil ,argssym)
                       (apply (car ,funs)
                              (apply-partially
                               (lambda (,funs ,global &rest ,argssym)
                                 (funcall ,runrestofhook ,funs ,global ,argssym))
                               (cdr ,funs) ,global)
                              ,argssym))
                   ;; Once there are no more functions on the hook, run
                   ;; the original body.
                   (apply (lambda ,args ,@body) ,argssym)))))
       (funcall ,runrestofhook ,hook
                ;; The global part of the hook, if any.
                ,(if (symbolp hook)
                     `(if (local-variable-p ',hook)
                          (default-value ',hook)))
                (list ,@args)))))

(defun add-to-list (list-var element &optional append compare-fn)
  "Add ELEMENT to the value of LIST-VAR if it isn't there yet.
The test for presence of ELEMENT is done with `equal', or with
COMPARE-FN if that's non-nil.
If ELEMENT is added, it is added at the beginning of the list,
unless the optional argument APPEND is non-nil, in which case
ELEMENT is added at the end.

The return value is the new value of LIST-VAR.

This is handy to add some elements to configuration variables,
but please do not abuse it in Elisp code, where you are usually
better off using `push' or `cl-pushnew'.

If you want to use `add-to-list' on a variable that is not
defined until a certain package is loaded, you should put the
call to `add-to-list' into a hook function that will be run only
after loading the package.  `eval-after-load' provides one way to
do this.  In some cases other hooks, such as major mode hooks,
can do the job."
  (declare
   (compiler-macro
    (lambda (exp)
      ;; FIXME: Something like this could be used for `set' as well.
      (if (or (not (eq 'quote (car-safe list-var)))
              (special-variable-p (cadr list-var))
              (not (macroexp-const-p append)))
          exp
        (let* ((sym (cadr list-var))
               (append (eval append))
               (msg (format-message
                     "`add-to-list' can't use lexical var `%s'; use `push' or `cl-pushnew'"
                     sym))
               ;; Big ugly hack so we only output a warning during
               ;; byte-compilation, and so we can use
               ;; byte-compile-not-lexical-var-p to silence the warning
               ;; when a defvar has been seen but not yet executed.
               (warnfun (lambda ()
                          ;; FIXME: We should also emit a warning for let-bound
                          ;; variables with dynamic binding.
                          (when (assq sym byte-compile--lexical-environment)
                            (byte-compile-report-error msg :fill))))
               (code
                (macroexp-let2 macroexp-copyable-p x element
                  `(if ,(if compare-fn
                            (progn
                              (require 'cl-lib)
                              `(cl-member ,x ,sym :test ,compare-fn))
                          ;; For bootstrapping reasons, don't rely on
                          ;; cl--compiler-macro-member for the base case.
                          `(member ,x ,sym))
                       ,sym
                     ,(if append
                          `(setq ,sym (append ,sym (list ,x)))
                        `(push ,x ,sym))))))
          (if (not (macroexp--compiling-p))
              code
            `(progn
               (macroexp--funcall-if-compiled ',warnfun)
               ,code)))))))
  (if (cond
       ((null compare-fn)
        (member element (symbol-value list-var)))
       ((eq compare-fn 'eq)
        (memq element (symbol-value list-var)))
       ((eq compare-fn 'eql)
        (memql element (symbol-value list-var)))
       (t
        (let ((lst (symbol-value list-var)))
          (while (and lst
                      (not (funcall compare-fn element (car lst))))
            (setq lst (cdr lst)))
          lst)))
      (symbol-value list-var)
    (set list-var
         (if append
             (append (symbol-value list-var) (list element))
           (cons element (symbol-value list-var))))))


(defun add-to-ordered-list (list-var element &optional order)
  "Add ELEMENT to the value of LIST-VAR if it isn't there yet.
The test for presence of ELEMENT is done with `eq'.

The resulting list is reordered so that the elements are in the
order given by each element's numeric list order.  Elements
without a numeric list order are placed at the end of the list.

If the third optional argument ORDER is a number (integer or
float), set the element's list order to the given value.  If
ORDER is nil or omitted, do not change the numeric order of
ELEMENT.  If ORDER has any other value, remove the numeric order
of ELEMENT if it has one.

The list order for each element is stored in LIST-VAR's
`list-order' property.

The return value is the new value of LIST-VAR."
  (let ((ordering (get list-var 'list-order)))
    (unless ordering
      (put list-var 'list-order
           (setq ordering (make-hash-table :weakness 'key :test 'eq))))
    (when order
      (puthash element (and (numberp order) order) ordering))
    (unless (memq element (symbol-value list-var))
      (set list-var (cons element (symbol-value list-var))))
    (set list-var (sort (symbol-value list-var)
                        (lambda (a b)
                          (let ((oa (gethash a ordering))
                                (ob (gethash b ordering)))
                            (if (and oa ob)
                                (< oa ob)
                              oa)))))))

(defun add-to-history (history-var newelt &optional maxelt keep-all)
  "Add NEWELT to the history list stored in the variable HISTORY-VAR.
Return the new history list.
If MAXELT is non-nil, it specifies the maximum length of the history.
Otherwise, the maximum history length is the value of the `history-length'
property on symbol HISTORY-VAR, if set, or the value of the `history-length'
variable.  The possible values of maximum length have the same meaning as
the values of `history-length'.
Remove duplicates of NEWELT if `history-delete-duplicates' is non-nil.
If optional fourth arg KEEP-ALL is non-nil, add NEWELT to history even
if it is empty or a duplicate."
  (unless maxelt
    (setq maxelt (or (get history-var 'history-length)
                     history-length)))
  (let ((history (symbol-value history-var))
        tail)
    (when (and (listp history)
               (or keep-all
                   (not (stringp newelt))
                   (> (length newelt) 0))
               (or keep-all
                   (not (equal (car history) newelt))))
      (if history-delete-duplicates
          (setq history (delete newelt history)))
      (setq history (cons newelt history))
      (when (integerp maxelt)
        (if (= 0 maxelt)
            (setq history nil)
          (setq tail (nthcdr (1- maxelt) history))
          (when (consp tail)
            (setcdr tail nil)))))
    (set history-var history)))

\f
;;;; Mode hooks.

(defvar delay-mode-hooks nil
  "If non-nil, `run-mode-hooks' should delay running the hooks.")
(defvar delayed-mode-hooks nil
  "List of delayed mode hooks waiting to be run.")
(make-variable-buffer-local 'delayed-mode-hooks)
(put 'delay-mode-hooks 'permanent-local t)

(defvar delayed-after-hook-functions nil
  "List of delayed :after-hook forms waiting to be run.
These forms come from `define-derived-mode'.")
(make-variable-buffer-local 'delayed-after-hook-functions)

(defvar change-major-mode-after-body-hook nil
  "Normal hook run in major mode functions, before the mode hooks.")

(defvar after-change-major-mode-hook nil
  "Normal hook run at the very end of major mode functions.")

(defun run-mode-hooks (&rest hooks)
  "Run mode hooks `delayed-mode-hooks' and HOOKS, or delay HOOKS.
Call `hack-local-variables' to set up file local and directory local
variables.

If the variable `delay-mode-hooks' is non-nil, does not do anything,
just adds the HOOKS to the list `delayed-mode-hooks'.
Otherwise, runs hooks in the sequence: `change-major-mode-after-body-hook',
`delayed-mode-hooks' (in reverse order), HOOKS, then runs
`hack-local-variables', runs the hook `after-change-major-mode-hook', and
finally evaluates the functions in `delayed-after-hook-functions' (see
`define-derived-mode').

Major mode functions should use this instead of `run-hooks' when
running their FOO-mode-hook."
  (if delay-mode-hooks
      ;; Delaying case.
      (dolist (hook hooks)
        (push hook delayed-mode-hooks))
    ;; Normal case, just run the hook as before plus any delayed hooks.
    (setq hooks (nconc (nreverse delayed-mode-hooks) hooks))
    (setq delayed-mode-hooks nil)
    (apply 'run-hooks (cons 'change-major-mode-after-body-hook hooks))
    (if (buffer-file-name)
        (with-demoted-errors "File local-variables error: %s"
          (hack-local-variables 'no-mode)))
    (run-hooks 'after-change-major-mode-hook)
    (dolist (fun (nreverse delayed-after-hook-functions))
      (funcall fun))
    (setq delayed-after-hook-functions nil)))

(defmacro delay-mode-hooks (&rest body)
  "Execute BODY, but delay any `run-mode-hooks'.
These hooks will be executed by the first following call to
`run-mode-hooks' that occurs outside any `delay-mode-hooks' form.
Only affects hooks run in the current buffer."
  (declare (debug t) (indent 0))
  `(progn
     (make-local-variable 'delay-mode-hooks)
     (let ((delay-mode-hooks t))
       ,@body)))

;; PUBLIC: find if the current mode derives from another.

(defun provided-mode-derived-p (mode &rest modes)
  "Non-nil if MODE is derived from one of MODES.
Uses the `derived-mode-parent' property of the symbol to trace backwards.
If you just want to check `major-mode', use `derived-mode-p'."
  (while (and (not (memq mode modes))
              (setq mode (get mode 'derived-mode-parent))))
  mode)

(defun derived-mode-p (&rest modes)
  "Non-nil if the current major mode is derived from one of MODES.
Uses the `derived-mode-parent' property of the symbol to trace backwards."
  (apply #'provided-mode-derived-p major-mode modes))
\f
;;;; Minor modes.

;; If a minor mode is not defined with define-minor-mode,
;; add it here explicitly.
;; isearch-mode is deliberately excluded, since you should
;; not call it yourself.
(defvar minor-mode-list '(auto-save-mode auto-fill-mode abbrev-mode
                                         overwrite-mode view-mode
                                         hs-minor-mode)
  "List of all minor mode functions.")

(defun add-minor-mode (toggle name &optional keymap after toggle-fun)
  "Register a new minor mode.

This is an XEmacs-compatibility function.  Use `define-minor-mode' instead.

TOGGLE is a symbol which is the name of a buffer-local variable that
is toggled on or off to say whether the minor mode is active or not.

NAME specifies what will appear in the mode line when the minor mode
is active.  NAME should be either a string starting with a space, or a
symbol whose value is such a string.

Optional KEYMAP is the keymap for the minor mode that will be added
to `minor-mode-map-alist'.

Optional AFTER specifies that TOGGLE should be added after AFTER
in `minor-mode-alist'.

Optional TOGGLE-FUN is an interactive function to toggle the mode.
It defaults to (and should by convention be) TOGGLE.

If TOGGLE has a non-nil `:included' property, an entry for the mode is
included in the mode-line minor mode menu.
If TOGGLE has a `:menu-tag', that is used for the menu item's label."
  (unless (memq toggle minor-mode-list)
    (push toggle minor-mode-list))

  (unless toggle-fun (setq toggle-fun toggle))
  (unless (eq toggle-fun toggle)
    (put toggle :minor-mode-function toggle-fun))
  ;; Add the name to the minor-mode-alist.
  (when name
    (let ((existing (assq toggle minor-mode-alist)))
      (if existing
          (setcdr existing (list name))
        (let ((tail minor-mode-alist) found)
          (while (and tail (not found))
            (if (eq after (caar tail))
                (setq found tail)
              (setq tail (cdr tail))))
          (if found
              (let ((rest (cdr found)))
                (setcdr found nil)
                (nconc found (list (list toggle name)) rest))
            (push (list toggle name) minor-mode-alist))))))
  ;; Add the toggle to the minor-modes menu if requested.
  (when (get toggle :included)
    (define-key mode-line-mode-menu
      (vector toggle)
      (list 'menu-item
            (concat
             (or (get toggle :menu-tag)
                 (if (stringp name) name (symbol-name toggle)))
             (let ((mode-name (if (symbolp name) (symbol-value name))))
               (if (and (stringp mode-name) (string-match "[^ ]+" mode-name))
                   (concat " (" (match-string 0 mode-name) ")"))))
            toggle-fun
            :button (cons :toggle toggle))))

  ;; Add the map to the minor-mode-map-alist.
  (when keymap
    (let ((existing (assq toggle minor-mode-map-alist)))
      (if existing
          (setcdr existing keymap)
        (let ((tail minor-mode-map-alist) found)
          (while (and tail (not found))
            (if (eq after (caar tail))
                (setq found tail)
              (setq tail (cdr tail))))
          (if found
              (let ((rest (cdr found)))
                (setcdr found nil)
                (nconc found (list (cons toggle keymap)) rest))
            (push (cons toggle keymap) minor-mode-map-alist)))))))
\f
;;;; Load history

(defsubst autoloadp (object)
  "Non-nil if OBJECT is an autoload."
  (eq 'autoload (car-safe object)))

;; (defun autoload-type (object)
;;   "Returns the type of OBJECT or `function' or `command' if the type is nil.
;; OBJECT should be an autoload object."
;;   (when (autoloadp object)
;;     (let ((type (nth 3 object)))
;;       (cond ((null type) (if (nth 2 object) 'command 'function))
;;             ((eq 'keymap t) 'macro)
;;             (type)))))

;; (defalias 'autoload-file #'cadr
;;   "Return the name of the file from which AUTOLOAD will be loaded.
;; \n\(fn AUTOLOAD)")

(defun define-symbol-prop (symbol prop val)
  "Define the property PROP of SYMBOL to be VAL.
This is to `put' what `defalias' is to `fset'."
  ;; Can't use `cl-pushnew' here (nor `push' on (cdr foo)).
  ;; (cl-pushnew symbol (alist-get prop
  ;;                               (alist-get 'define-symbol-props
  ;;                                          current-load-list)))
  (let ((sps (assq 'define-symbol-props current-load-list)))
    (unless sps
      (setq sps (list 'define-symbol-props))
      (push sps current-load-list))
    (let ((ps (assq prop sps)))
      (unless ps
        (setq ps (list prop))
        (setcdr sps (cons ps (cdr sps))))
      (unless (member symbol (cdr ps))
        (setcdr ps (cons symbol (cdr ps))))))
  (put symbol prop val))

(defun symbol-file (symbol &optional type)
  "Return the name of the file that defined SYMBOL.
The value is normally an absolute file name.  It can also be nil,
if the definition is not associated with any file.  If SYMBOL
specifies an autoloaded function, the value can be a relative
file name without extension.

If TYPE is nil, then any kind of definition is acceptable.  If
TYPE is `defun', `defvar', or `defface', that specifies function
definition, variable definition, or face definition only.
Otherwise TYPE is assumed to be a symbol property."
  (if (and (or (null type) (eq type 'defun))
           (symbolp symbol)
           (autoloadp (symbol-function symbol)))
      (nth 1 (symbol-function symbol))
    (catch 'found
      (pcase-dolist (`(,file . ,elems) load-history)
        (when (if type
                  (if (eq type 'defvar)
                      ;; Variables are present just as their names.
                      (member symbol elems)
                    ;; Many other types are represented as (TYPE . NAME).
                    (or (member (cons type symbol) elems)
                        (memq symbol (alist-get type
                                                (alist-get 'define-symbol-props
                                                           elems)))))
                ;; We accept all types, so look for variable def
                ;; and then for any other kind.
                (or (member symbol elems)
                    (let ((match (rassq symbol elems)))
                      (and match
                           (not (eq 'require (car match)))))))
          (throw 'found file))))))

(defun locate-library (library &optional nosuffix path interactive-call)
  "Show the precise file name of Emacs library LIBRARY.
LIBRARY should be a relative file name of the library, a string.
It can omit the suffix (a.k.a. file-name extension) if NOSUFFIX is
nil (which is the default, see below).
This command searches the directories in `load-path' like `\\[load-library]'
to find the file that `\\[load-library] RET LIBRARY RET' would load.
Optional second arg NOSUFFIX non-nil means don't add suffixes `load-suffixes'
to the specified name LIBRARY.

If the optional third arg PATH is specified, that list of directories
is used instead of `load-path'.

When called from a program, the file name is normally returned as a
string.  When run interactively, the argument INTERACTIVE-CALL is t,
and the file name is displayed in the echo area."
  (interactive (list (completing-read "Locate library: "
                                      (apply-partially
                                       'locate-file-completion-table
                                       load-path (get-load-suffixes)))
                     nil nil
                     t))
  (let ((file (locate-file library
                           (or path load-path)
                           (append (unless nosuffix (get-load-suffixes))
                                   load-file-rep-suffixes))))
    (if interactive-call
        (if file
            (message "Library is file %s" (abbreviate-file-name file))
          (message "No library %s in search path" library)))
    file))

\f
;;;; Process stuff.

(defun start-process (name buffer program &rest program-args)
  "Start a program in a subprocess.  Return the process object for it.
NAME is name for process.  It is modified if necessary to make it unique.
BUFFER is the buffer (or buffer name) to associate with the process.

Process output (both standard output and standard error streams)
goes at end of BUFFER, unless you specify a filter function to
handle the output.  BUFFER may also be nil, meaning that this
process is not associated with any buffer.

PROGRAM is the program file name.  It is searched for in `exec-path'
\(which see).  If nil, just associate a pty with the buffer.  Remaining
arguments PROGRAM-ARGS are strings to give program as arguments.

If you want to separate standard output from standard error, use
`make-process' or invoke the command through a shell and redirect
one of them using the shell syntax.

The process runs in `default-directory' if that is local (as
determined by `unhandled-file-name-directory'), or \"~\"
otherwise.  If you want to run a process in a remote directory
use `start-file-process'."
  (unless (fboundp 'make-process)
    (error "Emacs was compiled without subprocess support"))
  (apply #'make-process
         (append (list :name name :buffer buffer)
                 (if program
                     (list :command (cons program program-args))))))

(defun process-lines (program &rest args)
  "Execute PROGRAM with ARGS, returning its output as a list of lines.
Signal an error if the program returns with a non-zero exit status."
  (with-temp-buffer
    (let ((status (apply 'call-process program nil (current-buffer) nil args)))
      (unless (eq status 0)
        (error "%s exited with status %s" program status))
      (goto-char (point-min))
      (let (lines)
        (while (not (eobp))
          (setq lines (cons (buffer-substring-no-properties
                             (line-beginning-position)
                             (line-end-position))
                            lines))
          (forward-line 1))
        (nreverse lines)))))

(defun process-live-p (process)
  "Returns non-nil if PROCESS is alive.
A process is considered alive if its status is `run', `open',
`listen', `connect' or `stop'.  Value is nil if PROCESS is not a
process."
  (and (processp process)
       (memq (process-status process)
             '(run open listen connect stop))))

;; compatibility

(defun process-kill-without-query (process &optional _flag)
  "Say no query needed if PROCESS is running when Emacs is exited.
Optional second argument if non-nil says to require a query.
Value is t if a query was formerly required."
  (declare (obsolete
            "use `process-query-on-exit-flag' or `set-process-query-on-exit-flag'."
            "22.1"))
  (let ((old (process-query-on-exit-flag process)))
    (set-process-query-on-exit-flag process nil)
    old))

(defun process-kill-buffer-query-function ()
  "Ask before killing a buffer that has a running process."
  (let ((process (get-buffer-process (current-buffer))))
    (or (not process)
        (not (memq (process-status process) '(run stop open listen)))
        (not (process-query-on-exit-flag process))
        (yes-or-no-p
         (format "Buffer %S has a running process; kill it? "
                 (buffer-name (current-buffer)))))))

(add-hook 'kill-buffer-query-functions 'process-kill-buffer-query-function)

;; process plist management

(defun process-get (process propname)
  "Return the value of PROCESS' PROPNAME property.
This is the last value stored with `(process-put PROCESS PROPNAME VALUE)'."
  (plist-get (process-plist process) propname))

(defun process-put (process propname value)
  "Change PROCESS' PROPNAME property to VALUE.
It can be retrieved with `(process-get PROCESS PROPNAME)'."
  (set-process-plist process
                     (plist-put (process-plist process) propname value)))

\f
;;;; Input and display facilities.

(defconst read-key-empty-map (make-sparse-keymap))

(defvar read-key-delay 0.01) ;Fast enough for 100Hz repeat rate, hopefully.

(defun read-key (&optional prompt)
  "Read a key from the keyboard.
Contrary to `read-event' this will not return a raw event but instead will
obey the input decoding and translations usually done by `read-key-sequence'.
So escape sequences and keyboard encoding are taken into account.
When there's an ambiguity because the key looks like the prefix of
some sort of escape sequence, the ambiguity is resolved via `read-key-delay'."
  ;; This overriding-terminal-local-map binding also happens to
  ;; disable quail's input methods, so although read-key-sequence
  ;; always inherits the input method, in practice read-key does not
  ;; inherit the input method (at least not if it's based on quail).
  (let ((overriding-terminal-local-map nil)
        (overriding-local-map read-key-empty-map)
        (echo-keystrokes 0)
        (old-global-map (current-global-map))
        (timer (run-with-idle-timer
                ;; Wait long enough that Emacs has the time to receive and
                ;; process all the raw events associated with the single-key.
                ;; But don't wait too long, or the user may find the delay
                ;; annoying (or keep hitting more keys which may then get
                ;; lost or misinterpreted).
                ;; This is only relevant for keys which Emacs perceives as
                ;; "prefixes", such as C-x (because of the C-x 8 map in
                ;; key-translate-table and the C-x @ map in function-key-map)
                ;; or ESC (because of terminal escape sequences in
                ;; input-decode-map).
                read-key-delay t
                (lambda ()
                  (let ((keys (this-command-keys-vector)))
                    (unless (zerop (length keys))
                      ;; `keys' is non-empty, so the user has hit at least
                      ;; one key; there's no point waiting any longer, even
                      ;; though read-key-sequence thinks we should wait
                      ;; for more input to decide how to interpret the
                      ;; current input.
                      (throw 'read-key keys)))))))
    (unwind-protect
        (progn
          (use-global-map
           (let ((map (make-sparse-keymap)))
             ;; Don't hide the menu-bar and tool-bar entries.
             (define-key map [menu-bar] (lookup-key global-map [menu-bar]))
             (define-key map [tool-bar]
               ;; This hack avoids evaluating the :filter (Bug#9922).
               (or (cdr (assq 'tool-bar global-map))
                   (lookup-key global-map [tool-bar])))
             map))
          (let* ((keys
                  (catch 'read-key (read-key-sequence-vector prompt nil t)))
                 (key (aref keys 0)))
            (if (and (> (length keys) 1)
                     (memq key '(mode-line header-line
                                 left-fringe right-fringe)))
                (aref keys 1)
              key)))
      (cancel-timer timer)
      ;; For some reason, `read-key(-sequence)' leaves the prompt in the echo
      ;; area, whereas `read-event' seems to empty it just before returning
      ;; (bug#22714).  So, let's mimic the behavior of `read-event'.
      (message nil)
      (use-global-map old-global-map))))

(defvar read-passwd-map
  ;; BEWARE: `defconst' would purecopy it, breaking the sharing with
  ;; minibuffer-local-map along the way!
  (let ((map (make-sparse-keymap)))
    (set-keymap-parent map minibuffer-local-map)
    (define-key map "\C-u" #'delete-minibuffer-contents) ;bug#12570
    map)
  "Keymap used while reading passwords.")

(defun read-passwd (prompt &optional confirm default)
  "Read a password, prompting with PROMPT, and return it.
If optional CONFIRM is non-nil, read the password twice to make sure.
Optional DEFAULT is a default password to use instead of empty input.

This function echoes `.' for each character that the user types.
You could let-bind `read-hide-char' to another hiding character, though.

Once the caller uses the password, it can erase the password
by doing (clear-string STRING)."
  (if confirm
      (let (success)
        (while (not success)
          (let ((first (read-passwd prompt nil default))
                (second (read-passwd "Confirm password: " nil default)))
            (if (equal first second)
                (progn
                  (and (arrayp second) (not (eq first second)) (clear-string second))
                  (setq success first))
              (and (arrayp first) (clear-string first))
              (and (arrayp second) (clear-string second))
              (message "Password not repeated accurately; please start over")
              (sit-for 1))))
        success)
    (let ((hide-chars-fun
           (lambda (beg end _len)
             (clear-this-command-keys)
             (setq beg (min end (max (minibuffer-prompt-end)
                                     beg)))
             (dotimes (i (- end beg))
               (put-text-property (+ i beg) (+ 1 i beg)
                                  'display (string (or read-hide-char ?.))))))
          minibuf)
      (minibuffer-with-setup-hook
          (lambda ()
            (setq minibuf (current-buffer))
            ;; Turn off electricity.
            (setq-local post-self-insert-hook nil)
            (setq-local buffer-undo-list t)
            (setq-local select-active-regions nil)
            (use-local-map read-passwd-map)
            (setq-local inhibit-modification-hooks nil) ;bug#15501.
            (setq-local show-paren-mode nil)            ;bug#16091.
            (add-hook 'after-change-functions hide-chars-fun nil 'local))
        (unwind-protect
            (let ((enable-recursive-minibuffers t)
                  (read-hide-char (or read-hide-char ?.)))
              (read-string prompt nil t default)) ; t = "no history"
          (when (buffer-live-p minibuf)
            (with-current-buffer minibuf
              ;; Not sure why but it seems that there might be cases where the
              ;; minibuffer is not always properly reset later on, so undo
              ;; whatever we've done here (bug#11392).
              (remove-hook 'after-change-functions hide-chars-fun 'local)
              (kill-local-variable 'post-self-insert-hook)
              ;; And of course, don't keep the sensitive data around.
              (erase-buffer))))))))

(defun read-number (prompt &optional default)
  "Read a numeric value in the minibuffer, prompting with PROMPT.
DEFAULT specifies a default value to return if the user just types RET.
The value of DEFAULT is inserted into PROMPT.
This function is used by the `interactive' code letter `n'."
  (let ((n nil)
        (default1 (if (consp default) (car default) default)))
    (when default1
      (setq prompt
            (if (string-match "\\(\\):[ \t]*\\'" prompt)
                (replace-match (format " (default %s)" default1) t t prompt 1)
              (replace-regexp-in-string "[ \t]*\\'"
                                        (format " (default %s) " default1)
                                        prompt t t))))
    (while
        (progn
          (let ((str (read-from-minibuffer
                      prompt nil nil nil nil
                      (when default
                        (if (consp default)
                            (mapcar 'number-to-string (delq nil default))
                          (number-to-string default))))))
            (condition-case nil
                (setq n (cond
                         ((zerop (length str)) default1)
                         ((stringp str) (read str))))
              (error nil)))
          (unless (numberp n)
            (message "Please enter a number.")
            (sit-for 1)
            t)))
    n))

(defun read-char-choice (prompt chars &optional inhibit-keyboard-quit)
  "Read and return one of CHARS, prompting for PROMPT.
Any input that is not one of CHARS is ignored.

If optional argument INHIBIT-KEYBOARD-QUIT is non-nil, ignore
keyboard-quit events while waiting for a valid input."
  (unless (consp chars)
    (error "Called `read-char-choice' without valid char choices"))
  (let (char done show-help (helpbuf " *Char Help*"))
    (let ((cursor-in-echo-area t)
          (executing-kbd-macro executing-kbd-macro)
          (esc-flag nil))
      (save-window-excursion          ; in case we call help-form-show
        (while (not done)
          (unless (get-text-property 0 'face prompt)
            (setq prompt (propertize prompt 'face 'minibuffer-prompt)))
          (setq char (let ((inhibit-quit inhibit-keyboard-quit))
                       (read-key prompt)))
          (and show-help (buffer-live-p (get-buffer helpbuf))
               (kill-buffer helpbuf))
          (cond
           ((not (numberp char)))
           ;; If caller has set help-form, that's enough.
           ;; They don't explicitly have to add help-char to chars.
           ((and help-form
                 (eq char help-char)
                 (setq show-help t)
                 (help-form-show)))
           ((memq char chars)
            (setq done t))
           ((and executing-kbd-macro (= char -1))
            ;; read-event returns -1 if we are in a kbd macro and
            ;; there are no more events in the macro.  Attempt to
            ;; get an event interactively.
            (setq executing-kbd-macro nil))
           ((not inhibit-keyboard-quit)
            (cond
             ((and (null esc-flag) (eq char ?\e))
              (setq esc-flag t))
             ((memq char '(?\C-g ?\e))
              (keyboard-quit))))))))
    ;; Display the question with the answer.  But without cursor-in-echo-area.
    (message "%s%s" prompt (char-to-string char))
    char))

(defun sit-for (seconds &optional nodisp obsolete)
  "Redisplay, then wait for SECONDS seconds.  Stop when input is available.
SECONDS may be a floating-point value.
\(On operating systems that do not support waiting for fractions of a
second, floating-point values are rounded down to the nearest integer.)

If optional arg NODISP is t, don't redisplay, just wait for input.
Redisplay does not happen if input is available before it starts.

Value is t if waited the full time with no input arriving, and nil otherwise.

An obsolete, but still supported form is
\(sit-for SECONDS &optional MILLISECONDS NODISP)
where the optional arg MILLISECONDS specifies an additional wait period,
in milliseconds; this was useful when Emacs was built without
floating point support."
  (declare (advertised-calling-convention (seconds &optional nodisp) "22.1"))
  ;; This used to be implemented in C until the following discussion:
  ;; https://lists.gnu.org/r/emacs-devel/2006-07/msg00401.html
  ;; Then it was moved here using an implementation based on an idle timer,
  ;; which was then replaced by the use of read-event.
  (if (numberp nodisp)
      (setq seconds (+ seconds (* 1e-3 nodisp))
            nodisp obsolete)
    (if obsolete (setq nodisp obsolete)))
  (cond
   (noninteractive
    (sleep-for seconds)
    t)
   ((input-pending-p t)
    nil)
   ((or (<= seconds 0)
        ;; We are going to call read-event below, which will record
        ;; the next key as part of the macro, even if that key
        ;; invokes kmacro-end-macro, so if we are recording a macro,
        ;; the macro will recursively call itself.  In addition, when
        ;; that key is removed from unread-command-events, it will be
        ;; recorded the second time, so the macro will have each key
        ;; doubled.  This used to happen if a macro was defined with
        ;; Flyspell mode active (because Flyspell calls sit-for in its
        ;; post-command-hook, see bug #21329.)  To avoid all that, we
        ;; simply disable the wait when we are recording a macro.
        defining-kbd-macro)
    (or nodisp (redisplay)))
   (t
    (or nodisp (redisplay))
    ;; FIXME: we should not read-event here at all, because it's much too
    ;; difficult to reliably "undo" a read-event by pushing it onto
    ;; unread-command-events.
    ;; For bug#14782, we need read-event to do the keyboard-coding-system
    ;; decoding (hence non-nil as second arg under POSIX ttys).
    ;; For bug#15614, we need read-event not to inherit-input-method.
    ;; So we temporarily suspend input-method-function.
    (let ((read (let ((input-method-function nil))
                  (read-event nil t seconds))))
      (or (null read)
          (progn
            ;; https://lists.gnu.org/r/emacs-devel/2006-10/msg00394.html
            ;; We want `read' appear in the next command's this-command-event
            ;; but not in the current one.
            ;; By pushing (cons t read), we indicate that `read' has not
            ;; yet been recorded in this-command-keys, so it will be recorded
            ;; next time it's read.
            ;; And indeed the `seconds' argument to read-event correctly
            ;; prevented recording this event in the current command's
            ;; this-command-keys.
            (push (cons t read) unread-command-events)
            nil))))))

;; Behind display-popup-menus-p test.
(declare-function x-popup-dialog "menu.c" (position contents &optional header))

(defun y-or-n-p (prompt)
  "Ask user a \"y or n\" question.
Return t if answer is \"y\" and nil if it is \"n\".
PROMPT is the string to display to ask the question.  It should
end in a space; `y-or-n-p' adds \"(y or n) \" to it.

No confirmation of the answer is requested; a single character is
enough.  SPC also means yes, and DEL means no.

To be precise, this function translates user input into responses
by consulting the bindings in `query-replace-map'; see the
documentation of that variable for more information.  In this
case, the useful bindings are `act', `skip', `recenter',
`scroll-up', `scroll-down', and `quit'.
An `act' response means yes, and a `skip' response means no.
A `quit' response means to invoke `keyboard-quit'.
If the user enters `recenter', `scroll-up', or `scroll-down'
responses, perform the requested window recentering or scrolling
and ask again.

Under a windowing system a dialog box will be used if `last-nonmenu-event'
is nil and `use-dialog-box' is non-nil."
  ;; ¡Beware! when I tried to edebug this code, Emacs got into a weird state
  ;; where all the keys were unbound (i.e. it somehow got triggered
  ;; within read-key, apparently).  I had to kill it.
  (let ((answer 'recenter)
        (padded (lambda (prompt &optional dialog)
                  (let ((l (length prompt)))
                    (concat prompt
                            (if (or (zerop l) (eq ?\s (aref prompt (1- l))))
                                "" " ")
                            (if dialog "" "(y or n) "))))))
    (cond
     (noninteractive
      (setq prompt (funcall padded prompt))
      (let ((temp-prompt prompt))
        (while (not (memq answer '(act skip)))
          (let ((str (read-string temp-prompt)))
            (cond ((member str '("y" "Y")) (setq answer 'act))
                  ((member str '("n" "N")) (setq answer 'skip))
                  (t (setq temp-prompt (concat "Please answer y or n.  "
                                               prompt))))))))
     ((and (display-popup-menus-p)
           last-input-event             ; not during startup
           (listp last-nonmenu-event)
           use-dialog-box)
      (setq prompt (funcall padded prompt t)
            answer (x-popup-dialog t `(,prompt ("Yes" . act) ("No" . skip)))))
     (t
      (setq prompt (funcall padded prompt))
      (while
          (let* ((scroll-actions '(recenter scroll-up scroll-down
                                   scroll-other-window scroll-other-window-down))
                 (key
                  (let ((cursor-in-echo-area t))
                    (when minibuffer-auto-raise
                      (raise-frame (window-frame (minibuffer-window))))
                    (read-key (propertize (if (memq answer scroll-actions)
                                              prompt
                                            (concat "Please answer y or n.  "
                                                    prompt))
                                          'face 'minibuffer-prompt)))))
            (setq answer (lookup-key query-replace-map (vector key) t))
            (cond
             ((memq answer '(skip act)) nil)
             ((eq answer 'recenter)
              (recenter) t)
             ((eq answer 'scroll-up)
              (ignore-errors (scroll-up-command)) t)
             ((eq answer 'scroll-down)
              (ignore-errors (scroll-down-command)) t)
             ((eq answer 'scroll-other-window)
              (ignore-errors (scroll-other-window)) t)
             ((eq answer 'scroll-other-window-down)
              (ignore-errors (scroll-other-window-down)) t)
             ((or (memq answer '(exit-prefix quit)) (eq key ?\e))
              (signal 'quit nil) t)
             (t t)))
        (ding)
        (discard-input))))
    (let ((ret (eq answer 'act)))
      (unless noninteractive
        (message "%s%c" prompt (if ret ?y ?n)))
      ret)))

\f
;;; Atomic change groups.

(defmacro atomic-change-group (&rest body)
  "Perform BODY as an atomic change group.
This means that if BODY exits abnormally,
all of its changes to the current buffer are undone.
This works regardless of whether undo is enabled in the buffer.

This mechanism is transparent to ordinary use of undo;
if undo is enabled in the buffer and BODY succeeds, the
user can undo the change normally."
  (declare (indent 0) (debug t))
  (let ((handle (make-symbol "--change-group-handle--"))
        (success (make-symbol "--change-group-success--")))
    `(let ((,handle (prepare-change-group))
           ;; Don't truncate any undo data in the middle of this.
           (undo-outer-limit nil)
           (undo-limit most-positive-fixnum)
           (undo-strong-limit most-positive-fixnum)
           (,success nil))
       (unwind-protect
           (progn
             ;; This is inside the unwind-protect because
             ;; it enables undo if that was disabled; we need
             ;; to make sure that it gets disabled again.
             (activate-change-group ,handle)
             ,@body
             (setq ,success t))
         ;; Either of these functions will disable undo
         ;; if it was disabled before.
         (if ,success
             (accept-change-group ,handle)
           (cancel-change-group ,handle))))))

(defun prepare-change-group (&optional buffer)
  "Return a handle for the current buffer's state, for a change group.
If you specify BUFFER, make a handle for BUFFER's state instead.

Pass the handle to `activate-change-group' afterward to initiate
the actual changes of the change group.

To finish the change group, call either `accept-change-group' or
`cancel-change-group' passing the same handle as argument.  Call
`accept-change-group' to accept the changes in the group as final;
call `cancel-change-group' to undo them all.  You should use
`unwind-protect' to make sure the group is always finished.  The call
to `activate-change-group' should be inside the `unwind-protect'.
Once you finish the group, don't use the handle again--don't try to
finish the same group twice.  For a simple example of correct use, see
the source code of `atomic-change-group'.

The handle records only the specified buffer.  To make a multibuffer
change group, call this function once for each buffer you want to
cover, then use `nconc' to combine the returned values, like this:

  (nconc (prepare-change-group buffer-1)
         (prepare-change-group buffer-2))

You can then activate that multibuffer change group with a single
call to `activate-change-group' and finish it with a single call
to `accept-change-group' or `cancel-change-group'."

  (if buffer
      (list (cons buffer (with-current-buffer buffer buffer-undo-list)))
    (list (cons (current-buffer) buffer-undo-list))))

(defun activate-change-group (handle)
  "Activate a change group made with `prepare-change-group' (which see)."
  (dolist (elt handle)
    (with-current-buffer (car elt)
      (if (eq buffer-undo-list t)
          (setq buffer-undo-list nil)))))

(defun accept-change-group (handle)
  "Finish a change group made with `prepare-change-group' (which see).
This finishes the change group by accepting its changes as final."
  (dolist (elt handle)
    (with-current-buffer (car elt)
      (if (eq (cdr elt) t)
          (setq buffer-undo-list t)))))

(defun cancel-change-group (handle)
  "Finish a change group made with `prepare-change-group' (which see).
This finishes the change group by reverting all of its changes."
  (dolist (elt handle)
    (with-current-buffer (car elt)
      (setq elt (cdr elt))
      (save-restriction
        ;; Widen buffer temporarily so if the buffer was narrowed within
        ;; the body of `atomic-change-group' all changes can be undone.
        (widen)
        (let ((old-car (car-safe elt))
              (old-cdr (cdr-safe elt)))
          (unwind-protect
              (progn
                ;; Temporarily truncate the undo log at ELT.
                (when (consp elt)
                  (setcar elt nil) (setcdr elt nil))
                (unless (eq last-command 'undo) (undo-start))
                ;; Make sure there's no confusion.
                (when (and (consp elt) (not (eq elt (last pending-undo-list))))
                  (error "Undoing to some unrelated state"))
                ;; Undo it all.
                (save-excursion
                  (while (listp pending-undo-list) (undo-more 1)))
                ;; Revert the undo info to what it was when we grabbed
                ;; the state.
                (setq buffer-undo-list elt))
            ;; Reset the modified cons cell ELT to its original content.
            (when (consp elt)
              (setcar elt old-car)
              (setcdr elt old-cdr))))))))
\f
;;;; Display-related functions.

;; For compatibility.
(define-obsolete-function-alias 'redraw-modeline
  'force-mode-line-update "24.3")

(defun momentary-string-display (string pos &optional exit-char message)
  "Momentarily display STRING in the buffer at POS.
Display remains until next event is input.
If POS is a marker, only its position is used; its buffer is ignored.
Optional third arg EXIT-CHAR can be a character, event or event
description list.  EXIT-CHAR defaults to SPC.  If the input is
EXIT-CHAR it is swallowed; otherwise it is then available as
input (as a command if nothing else).
Display MESSAGE (optional fourth arg) in the echo area.
If MESSAGE is nil, instructions to type EXIT-CHAR are displayed there."
  (or exit-char (setq exit-char ?\s))
  (let ((ol (make-overlay pos pos))
        (str (copy-sequence string)))
    (unwind-protect
        (progn
          (save-excursion
            (overlay-put ol 'after-string str)
            (goto-char pos)
            ;; To avoid trouble with out-of-bounds position
            (setq pos (point))
            ;; If the string end is off screen, recenter now.
            (if (<= (window-end nil t) pos)
                (recenter (/ (window-height) 2))))
          (message (or message "Type %s to continue editing.")
                   (single-key-description exit-char))
          (let ((event (read-key)))
            ;; `exit-char' can be an event, or an event description list.
            (or (eq event exit-char)
                (eq event (event-convert-list exit-char))
                (setq unread-command-events
                      (append (this-single-command-raw-keys)
                              unread-command-events)))))
      (delete-overlay ol))))

\f
;;;; Overlay operations

(defun copy-overlay (o)
  "Return a copy of overlay O."
  (let ((o1 (if (overlay-buffer o)
                (make-overlay (overlay-start o) (overlay-end o)
                              ;; FIXME: there's no easy way to find the
                              ;; insertion-type of the two markers.
                              (overlay-buffer o))
              (let ((o1 (make-overlay (point-min) (point-min))))
                (delete-overlay o1)
                o1)))
        (props (overlay-properties o)))
    (while props
      (overlay-put o1 (pop props) (pop props)))
    o1))

(defun remove-overlays (&optional beg end name val)
  "Clear BEG and END of overlays whose property NAME has value VAL.
Overlays might be moved and/or split.
BEG and END default respectively to the beginning and end of buffer."
  ;; This speeds up the loops over overlays.
  (unless beg (setq beg (point-min)))
  (unless end (setq end (point-max)))
  (overlay-recenter end)
  (if (< end beg)
      (setq beg (prog1 end (setq end beg))))
  (save-excursion
    (dolist (o (overlays-in beg end))
      (when (eq (overlay-get o name) val)
        ;; Either push this overlay outside beg...end
        ;; or split it to exclude beg...end
        ;; or delete it entirely (if it is contained in beg...end).
        (if (< (overlay-start o) beg)
            (if (> (overlay-end o) end)
                (progn
                  (move-overlay (copy-overlay o)
                                (overlay-start o) beg)
                  (move-overlay o end (overlay-end o)))
              (move-overlay o (overlay-start o) beg))
          (if (> (overlay-end o) end)
              (move-overlay o end (overlay-end o))
            (delete-overlay o)))))))
\f
;;;; Miscellanea.

(defvar suspend-hook nil
  "Normal hook run by `suspend-emacs', before suspending.")

(defvar suspend-resume-hook nil
  "Normal hook run by `suspend-emacs', after Emacs is continued.")

(defvar temp-buffer-show-hook nil
  "Normal hook run by `with-output-to-temp-buffer' after displaying the buffer.
When the hook runs, the temporary buffer is current, and the window it
was displayed in is selected.")

(defvar temp-buffer-setup-hook nil
  "Normal hook run by `with-output-to-temp-buffer' at the start.
When the hook runs, the temporary buffer is current.
This hook is normally set up with a function to put the buffer in Help
mode.")

(defconst user-emacs-directory
  (if (eq system-type 'ms-dos)
      ;; MS-DOS cannot have initial dot.
      "~/_emacs.d/"
    "~/.emacs.d/")
  "Directory beneath which additional per-user Emacs-specific files are placed.
Various programs in Emacs store information in this directory.
Note that this should end with a directory separator.
See also `locate-user-emacs-file'.")
\f
;;;; Misc. useful functions.

(defsubst buffer-narrowed-p ()
  "Return non-nil if the current buffer is narrowed."
  (/= (- (point-max) (point-min)) (buffer-size)))

(defun find-tag-default-bounds ()
  "Determine the boundaries of the default tag, based on text at point.
Return a cons cell with the beginning and end of the found tag.
If there is no plausible default, return nil."
  (bounds-of-thing-at-point 'symbol))

(defun find-tag-default ()
  "Determine default tag to search for, based on text at point.
If there is no plausible default, return nil."
  (let ((bounds (find-tag-default-bounds)))
    (when bounds
      (buffer-substring-no-properties (car bounds) (cdr bounds)))))

(defun find-tag-default-as-regexp ()
  "Return regexp that matches the default tag at point.
If there is no tag at point, return nil.

When in a major mode that does not provide its own
`find-tag-default-function', return a regexp that matches the
symbol at point exactly."
  (let ((tag (funcall (or find-tag-default-function
                          (get major-mode 'find-tag-default-function)
                          'find-tag-default))))
    (if tag (regexp-quote tag))))

(defun find-tag-default-as-symbol-regexp ()
  "Return regexp that matches the default tag at point as symbol.
If there is no tag at point, return nil.

When in a major mode that does not provide its own
`find-tag-default-function', return a regexp that matches the
symbol at point exactly."
  (let ((tag-regexp (find-tag-default-as-regexp)))
    (if (and tag-regexp
             (eq (or find-tag-default-function
                     (get major-mode 'find-tag-default-function)
                     'find-tag-default)
                 'find-tag-default))
        (format "\\_<%s\\_>" tag-regexp)
      tag-regexp)))

(defun play-sound (sound)
  "SOUND is a list of the form `(sound KEYWORD VALUE...)'.
The following keywords are recognized:

  :file FILE - read sound data from FILE.  If FILE isn't an
absolute file name, it is searched in `data-directory'.

  :data DATA - read sound data from string DATA.

Exactly one of :file or :data must be present.

  :volume VOL - set volume to VOL.  VOL must an integer in the
range 0..100 or a float in the range 0..1.0.  If not specified,
don't change the volume setting of the sound device.

  :device DEVICE - play sound on DEVICE.  If not specified,
a system-dependent default device name is used.

Note: :data and :device are currently not supported on Windows."
  (if (fboundp 'play-sound-internal)
      (play-sound-internal sound)
    (error "This Emacs binary lacks sound support")))

(declare-function w32-shell-dos-semantics "w32-fns" nil)

(defun shell-quote-argument (argument)
  "Quote ARGUMENT for passing as argument to an inferior shell.

This function is designed to work with the syntax of your system's
standard shell, and might produce incorrect results with unusual shells.
See Info node `(elisp)Security Considerations'."
  (cond
   ((eq system-type 'ms-dos)
    ;; Quote using double quotes, but escape any existing quotes in
    ;; the argument with backslashes.
    (let ((result "")
          (start 0)
          end)
      (if (or (null (string-match "[^\"]" argument))
              (< (match-end 0) (length argument)))
          (while (string-match "[\"]" argument start)
            (setq end (match-beginning 0)
                  result (concat result (substring argument start end)
                                 "\\" (substring argument end (1+ end)))
                  start (1+ end))))
      (concat "\"" result (substring argument start) "\"")))

   ((and (eq system-type 'windows-nt) (w32-shell-dos-semantics))

    ;; First, quote argument so that CommandLineToArgvW will
    ;; understand it.  See
    ;; http://msdn.microsoft.com/en-us/library/17w5ykft%28v=vs.85%29.aspx
    ;; After we perform that level of quoting, escape shell
    ;; metacharacters so that cmd won't mangle our argument.  If the
    ;; argument contains no double quote characters, we can just
    ;; surround it with double quotes.  Otherwise, we need to prefix
    ;; each shell metacharacter with a caret.

    (setq argument
          ;; escape backslashes at end of string
          (replace-regexp-in-string
           "\\(\\\\*\\)$"
           "\\1\\1"
           ;; escape backslashes and quotes in string body
           (replace-regexp-in-string
            "\\(\\\\*\\)\""
            "\\1\\1\\\\\""
            argument)))

    (if (string-match "[%!\"]" argument)
        (concat
         "^\""
         (replace-regexp-in-string
          "\\([%!()\"<>&|^]\\)"
          "^\\1"
          argument)
         "^\"")
      (concat "\"" argument "\"")))

   (t
    (if (equal argument "")
        "''"
      ;; Quote everything except POSIX filename characters.
      ;; This should be safe enough even for really weird shells.
      (replace-regexp-in-string
       "\n" "'\n'"
       (replace-regexp-in-string "[^-0-9a-zA-Z_./\n]" "\\\\\\&" argument))))
   ))

(defsubst string-to-list (string)
  "Return a list of characters in STRING."
  (append string nil))

(defsubst string-to-vector (string)
  "Return a vector of characters in STRING."
  (vconcat string))

(defun string-or-null-p (object)
  "Return t if OBJECT is a string or nil.
Otherwise, return nil."
  (or (stringp object) (null object)))

(defun booleanp (object)
  "Return t if OBJECT is one of the two canonical boolean values: t or nil.
Otherwise, return nil."
  (and (memq object '(nil t)) t))

(defun special-form-p (object)
  "Non-nil if and only if OBJECT is a special form."
  (if (and (symbolp object) (fboundp object))
      (setq object (indirect-function object)))
  (and (subrp object) (eq (cdr (subr-arity object)) 'unevalled)))

(defun macrop (object)
  "Non-nil if and only if OBJECT is a macro."
  (let ((def (indirect-function object)))
    (when (consp def)
      (or (eq 'macro (car def))
          (and (autoloadp def) (memq (nth 4 def) '(macro t)))))))

(defun field-at-pos (pos)
  "Return the field at position POS, taking stickiness etc into account."
  (let ((raw-field (get-char-property (field-beginning pos) 'field)))
    (if (eq raw-field 'boundary)
        (get-char-property (1- (field-end pos)) 'field)
      raw-field)))

(defun sha1 (object &optional start end binary)
  "Return the SHA1 (Secure Hash Algorithm) of an OBJECT.
OBJECT is either a string or a buffer.  Optional arguments START and
END are character positions specifying which portion of OBJECT for
computing the hash.  If BINARY is non-nil, return a string in binary
form."
  (secure-hash 'sha1 object start end binary))

(defun function-get (f prop &optional autoload)
  "Return the value of property PROP of function F.
If AUTOLOAD is non-nil and F is autoloaded, try to autoload it
in the hope that it will set PROP.  If AUTOLOAD is `macro', only do it
if it's an autoloaded macro."
  (let ((val nil))
    (while (and (symbolp f)
                (null (setq val (get f prop)))
                (fboundp f))
      (let ((fundef (symbol-function f)))
        (if (and autoload (autoloadp fundef)
                 (not (equal fundef
                             (autoload-do-load fundef f
                                               (if (eq autoload 'macro)
                                                   'macro)))))
            nil                         ;Re-try `get' on the same `f'.
          (setq f fundef))))
    val))
\f
;;;; Support for yanking and text properties.
;; Why here in subr.el rather than in simple.el?  --Stef

(defvar yank-handled-properties)
(defvar yank-excluded-properties)

(defun remove-yank-excluded-properties (start end)
  "Process text properties between START and END, inserted for a `yank'.
Perform the handling specified by `yank-handled-properties', then
remove properties specified by `yank-excluded-properties'."
  (let ((inhibit-read-only t))
    (dolist (handler yank-handled-properties)
      (let ((prop (car handler))
            (fun  (cdr handler))
            (run-start start))
        (while (< run-start end)
          (let ((value (get-text-property run-start prop))
                (run-end (next-single-property-change
                          run-start prop nil end)))
            (funcall fun value run-start run-end)
            (setq run-start run-end)))))
    (if (eq yank-excluded-properties t)
        (set-text-properties start end nil)
      (remove-list-of-text-properties start end yank-excluded-properties))))

(defvar yank-undo-function)

(defun insert-for-yank (string)
  "Insert STRING at point for the `yank' command.

This function is like `insert', except it honors the variables
`yank-handled-properties' and `yank-excluded-properties', and the
`yank-handler' text property, in the way that `yank' does."
  (let (to)
    (while (setq to (next-single-property-change 0 'yank-handler string))
      (insert-for-yank-1 (substring string 0 to))
      (setq string (substring string to))))
  (insert-for-yank-1 string))

(defun insert-for-yank-1 (string)
  "Helper for `insert-for-yank', which see."
  (let* ((handler (and (stringp string)
                       (get-text-property 0 'yank-handler string)))
         (param (or (nth 1 handler) string))
         (opoint (point))
         (inhibit-read-only inhibit-read-only)
         end)

    (setq yank-undo-function t)
    (if (nth 0 handler) ; FUNCTION
        (funcall (car handler) param)
      (insert param))
    (setq end (point))

    ;; Prevent read-only properties from interfering with the
    ;; following text property changes.
    (setq inhibit-read-only t)

    (unless (nth 2 handler) ; NOEXCLUDE
      (remove-yank-excluded-properties opoint end))

    ;; If last inserted char has properties, mark them as rear-nonsticky.
    (if (and (> end opoint)
             (text-properties-at (1- end)))
        (put-text-property (1- end) end 'rear-nonsticky t))

    (if (eq yank-undo-function t)                  ; not set by FUNCTION
        (setq yank-undo-function (nth 3 handler))) ; UNDO
    (if (nth 4 handler)                            ; COMMAND
        (setq this-command (nth 4 handler)))))

(defun insert-buffer-substring-no-properties (buffer &optional start end)
  "Insert before point a substring of BUFFER, without text properties.
BUFFER may be a buffer or a buffer name.
Arguments START and END are character positions specifying the substring.
They default to the values of (point-min) and (point-max) in BUFFER."
  (let ((opoint (point)))
    (insert-buffer-substring buffer start end)
    (let ((inhibit-read-only t))
      (set-text-properties opoint (point) nil))))

(defun insert-buffer-substring-as-yank (buffer &optional start end)
  "Insert before point a part of BUFFER, stripping some text properties.
BUFFER may be a buffer or a buffer name.
Arguments START and END are character positions specifying the substring.
They default to the values of (point-min) and (point-max) in BUFFER.
Before insertion, process text properties according to
`yank-handled-properties' and `yank-excluded-properties'."
  ;; Since the buffer text should not normally have yank-handler properties,
  ;; there is no need to handle them here.
  (let ((opoint (point)))
    (insert-buffer-substring buffer start end)
    (remove-yank-excluded-properties opoint (point))))

(defun yank-handle-font-lock-face-property (face start end)
  "If `font-lock-defaults' is nil, apply FACE as a `face' property.
START and END denote the start and end of the text to act on.
Do nothing if FACE is nil."
  (and face
       (null font-lock-defaults)
       (put-text-property start end 'face face)))

;; This removes `mouse-face' properties in *Help* buffer buttons:
;; https://lists.gnu.org/r/emacs-devel/2002-04/msg00648.html
(defun yank-handle-category-property (category start end)
  "Apply property category CATEGORY's properties between START and END."
  (when category
    (let ((start2 start))
      (while (< start2 end)
        (let ((end2     (next-property-change start2 nil end))
              (original (text-properties-at start2)))
          (set-text-properties start2 end2 (symbol-plist category))
          (add-text-properties start2 end2 original)
          (setq start2 end2))))))

\f
;;;; Synchronous shell commands.

(defun start-process-shell-command (name buffer &rest args)
  "Start a program in a subprocess.  Return the process object for it.
NAME is name for process.  It is modified if necessary to make it unique.
BUFFER is the buffer (or buffer name) to associate with the process.
 Process output goes at end of that buffer, unless you specify
 an output stream or filter function to handle the output.
 BUFFER may be also nil, meaning that this process is not associated
 with any buffer
COMMAND is the shell command to run.

An old calling convention accepted any number of arguments after COMMAND,
which were just concatenated to COMMAND.  This is still supported but strongly
discouraged."
  (declare (advertised-calling-convention (name buffer command) "23.1"))
  ;; We used to use `exec' to replace the shell with the command,
  ;; but that failed to handle (...) and semicolon, etc.
  (start-process name buffer shell-file-name shell-command-switch
                 (mapconcat 'identity args " ")))

(defun start-file-process-shell-command (name buffer &rest args)
  "Start a program in a subprocess.  Return the process object for it.
Similar to `start-process-shell-command', but calls `start-file-process'."
  (declare (advertised-calling-convention (name buffer command) "23.1"))
  (start-file-process
   name buffer
   (if (file-remote-p default-directory) "/bin/sh" shell-file-name)
   (if (file-remote-p default-directory) "-c" shell-command-switch)
   (mapconcat 'identity args " ")))

(defun call-process-shell-command (command &optional infile buffer display
                                           &rest args)
  "Execute the shell command COMMAND synchronously in separate process.
The remaining arguments are optional.
The program's input comes from file INFILE (nil means `/dev/null').
Insert output in BUFFER before point; t means current buffer;
 nil for BUFFER means discard it; 0 means discard and don't wait.
BUFFER can also have the form (REAL-BUFFER STDERR-FILE); in that case,
REAL-BUFFER says what to do with standard output, as above,
while STDERR-FILE says what to do with standard error in the child.
STDERR-FILE may be nil (discard standard error output),
t (mix it with ordinary output), or a file name string.

Fourth arg DISPLAY non-nil means redisplay buffer as output is inserted.
Wildcards and redirection are handled as usual in the shell.

If BUFFER is 0, `call-process-shell-command' returns immediately with value nil.
Otherwise it waits for COMMAND to terminate and returns a numeric exit
status or a signal description string.
If you quit, the process is killed with SIGINT, or SIGKILL if you quit again.

An old calling convention accepted any number of arguments after DISPLAY,
which were just concatenated to COMMAND.  This is still supported but strongly
discouraged."
  (declare (advertised-calling-convention
            (command &optional infile buffer display) "24.5"))
  ;; We used to use `exec' to replace the shell with the command,
  ;; but that failed to handle (...) and semicolon, etc.
  (call-process shell-file-name
                infile buffer display
                shell-command-switch
                (mapconcat 'identity (cons command args) " ")))

(defun process-file-shell-command (command &optional infile buffer display
                                           &rest args)
  "Process files synchronously in a separate process.
Similar to `call-process-shell-command', but calls `process-file'."
  (declare (advertised-calling-convention
            (command &optional infile buffer display) "24.5"))
  (process-file
   (if (file-remote-p default-directory) "/bin/sh" shell-file-name)
   infile buffer display
   (if (file-remote-p default-directory) "-c" shell-command-switch)
   (mapconcat 'identity (cons command args) " ")))

(defun call-shell-region (start end command &optional delete buffer)
  "Send text from START to END as input to an inferior shell running COMMAND.
Delete the text if fourth arg DELETE is non-nil.

Insert output in BUFFER before point; t means current buffer; nil for
 BUFFER means discard it; 0 means discard and don't wait; and `(:file
 FILE)', where FILE is a file name string, means that it should be
 written to that file (if the file already exists it is overwritten).
BUFFER can also have the form (REAL-BUFFER STDERR-FILE); in that case,
REAL-BUFFER says what to do with standard output, as above,
while STDERR-FILE says what to do with standard error in the child.
STDERR-FILE may be nil (discard standard error output),
t (mix it with ordinary output), or a file name string.

If BUFFER is 0, `call-shell-region' returns immediately with value nil.
Otherwise it waits for COMMAND to terminate
and returns a numeric exit status or a signal description string.
If you quit, the process is killed with SIGINT, or SIGKILL if you quit again."
  (call-process-region start end
                       shell-file-name delete buffer nil
                       shell-command-switch command))
\f
;;;; Lisp macros to do various things temporarily.

(defmacro track-mouse (&rest body)
  "Evaluate BODY with mouse movement events enabled.
Within a `track-mouse' form, mouse motion generates input events that
 you can read with `read-event'.
Normally, mouse motion is ignored."
  (declare (debug t) (indent 0))
  `(internal--track-mouse (lambda () ,@body)))

(defmacro with-current-buffer (buffer-or-name &rest body)
  "Execute the forms in BODY with BUFFER-OR-NAME temporarily current.
BUFFER-OR-NAME must be a buffer or the name of an existing buffer.
The value returned is the value of the last form in BODY.  See
also `with-temp-buffer'."
  (declare (indent 1) (debug t))
  `(save-current-buffer
     (set-buffer ,buffer-or-name)
     ,@body))

(defun internal--before-with-selected-window (window)
  (let ((other-frame (window-frame window)))
    (list window (selected-window)
          ;; Selecting a window on another frame also changes that
          ;; frame's frame-selected-window.  We must save&restore it.
          (unless (eq (selected-frame) other-frame)
            (frame-selected-window other-frame))
          ;; Also remember the top-frame if on ttys.
          (unless (eq (selected-frame) other-frame)
            (tty-top-frame other-frame)))))

(defun internal--after-with-selected-window (state)
  ;; First reset frame-selected-window.
  (when (window-live-p (nth 2 state))
    ;; We don't use set-frame-selected-window because it does not
    ;; pass the `norecord' argument to Fselect_window.
    (select-window (nth 2 state) 'norecord)
    (and (frame-live-p (nth 3 state))
         (not (eq (tty-top-frame) (nth 3 state)))
         (select-frame (nth 3 state) 'norecord)))
  ;; Then reset the actual selected-window.
  (when (window-live-p (nth 1 state))
    (select-window (nth 1 state) 'norecord)))

(defmacro with-selected-window (window &rest body)
  "Execute the forms in BODY with WINDOW as the selected window.
The value returned is the value of the last form in BODY.

This macro saves and restores the selected window, as well as the
selected window of each frame.  It does not change the order of
recently selected windows.  If the previously selected window of
some frame is no longer live at the end of BODY, that frame's
selected window is left alone.  If the selected window is no
longer live, then whatever window is selected at the end of BODY
remains selected.

This macro uses `save-current-buffer' to save and restore the
current buffer, since otherwise its normal operation could
potentially make a different buffer current.  It does not alter
the buffer list ordering."
  (declare (indent 1) (debug t))
  `(let ((save-selected-window--state
          (internal--before-with-selected-window ,window)))
     (save-current-buffer
       (unwind-protect
           (progn (select-window (car save-selected-window--state) 'norecord)
                  ,@body)
         (internal--after-with-selected-window save-selected-window--state)))))

(defmacro with-selected-frame (frame &rest body)
  "Execute the forms in BODY with FRAME as the selected frame.
The value returned is the value of the last form in BODY.

This macro saves and restores the selected frame, and changes the
order of neither the recently selected windows nor the buffers in
the buffer list."
  (declare (indent 1) (debug t))
  (let ((old-frame (make-symbol "old-frame"))
        (old-buffer (make-symbol "old-buffer")))
    `(let ((,old-frame (selected-frame))
           (,old-buffer (current-buffer)))
       (unwind-protect
           (progn (select-frame ,frame 'norecord)
                  ,@body)
         (when (frame-live-p ,old-frame)
           (select-frame ,old-frame 'norecord))
         (when (buffer-live-p ,old-buffer)
           (set-buffer ,old-buffer))))))

(defmacro save-window-excursion (&rest body)
  "Execute BODY, then restore previous window configuration.
This macro saves the window configuration on the selected frame,
executes BODY, then calls `set-window-configuration' to restore
the saved window configuration.  The return value is the last
form in BODY.  The window configuration is also restored if BODY
exits nonlocally.

BEWARE: Most uses of this macro introduce bugs.
E.g. it should not be used to try and prevent some code from opening
a new window, since that window may sometimes appear in another frame,
in which case `save-window-excursion' cannot help."
  (declare (indent 0) (debug t))
  (let ((c (make-symbol "wconfig")))
    `(let ((,c (current-window-configuration)))
       (unwind-protect (progn ,@body)
         (set-window-configuration ,c)))))

(defun internal-temp-output-buffer-show (buffer)
  "Internal function for `with-output-to-temp-buffer'."
  (with-current-buffer buffer
    (set-buffer-modified-p nil)
    (goto-char (point-min)))

  (if temp-buffer-show-function
      (funcall temp-buffer-show-function buffer)
    (with-current-buffer buffer
      (let* ((window
              (let ((window-combination-limit
                   ;; When `window-combination-limit' equals
                   ;; `temp-buffer' or `temp-buffer-resize' and
                   ;; `temp-buffer-resize-mode' is enabled in this
                   ;; buffer bind it to t so resizing steals space
                   ;; preferably from the window that was split.
                   (if (or (eq window-combination-limit 'temp-buffer)
                           (and (eq window-combination-limit
                                    'temp-buffer-resize)
                                temp-buffer-resize-mode))
                       t
                     window-combination-limit)))
                (display-buffer buffer)))
             (frame (and window (window-frame window))))
        (when window
          (unless (eq frame (selected-frame))
            (make-frame-visible frame))
          (setq minibuffer-scroll-window window)
          (set-window-hscroll window 0)
          ;; Don't try this with NOFORCE non-nil!
          (set-window-start window (point-min) t)
          ;; This should not be necessary.
          (set-window-point window (point-min))
          ;; Run `temp-buffer-show-hook', with the chosen window selected.
          (with-selected-window window
            (run-hooks 'temp-buffer-show-hook))))))
  ;; Return nil.
  nil)

;; Doc is very similar to with-temp-buffer-window.
(defmacro with-output-to-temp-buffer (bufname &rest body)
  "Bind `standard-output' to buffer BUFNAME, eval BODY, then show that buffer.

This construct makes buffer BUFNAME empty before running BODY.
It does not make the buffer current for BODY.
Instead it binds `standard-output' to that buffer, so that output
generated with `prin1' and similar functions in BODY goes into
the buffer.

At the end of BODY, this marks buffer BUFNAME unmodified and displays
it in a window, but does not select it.  The normal way to do this is
by calling `display-buffer', then running `temp-buffer-show-hook'.
However, if `temp-buffer-show-function' is non-nil, it calls that
function instead (and does not run `temp-buffer-show-hook').  The
function gets one argument, the buffer to display.

The return value of `with-output-to-temp-buffer' is the value of the
last form in BODY.  If BODY does not finish normally, the buffer
BUFNAME is not displayed.

This runs the hook `temp-buffer-setup-hook' before BODY,
with the buffer BUFNAME temporarily current.  It runs the hook
`temp-buffer-show-hook' after displaying buffer BUFNAME, with that
buffer temporarily current, and the window that was used to display it
temporarily selected.  But it doesn't run `temp-buffer-show-hook'
if it uses `temp-buffer-show-function'.

By default, the setup hook puts the buffer into Help mode before running BODY.
If BODY does not change the major mode, the show hook makes the buffer
read-only, and scans it for function and variable names to make them into
clickable cross-references.

See the related form `with-temp-buffer-window'."
  (declare (debug t))
  (let ((old-dir (make-symbol "old-dir"))
        (buf (make-symbol "buf")))
    `(let* ((,old-dir default-directory)
            (,buf
             (with-current-buffer (get-buffer-create ,bufname)
               (prog1 (current-buffer)
                 (kill-all-local-variables)
                 ;; FIXME: delete_all_overlays
                 (setq default-directory ,old-dir)
                 (setq buffer-read-only nil)
                 (setq buffer-file-name nil)
                 (setq buffer-undo-list t)
                 (let ((inhibit-read-only t)
                       (inhibit-modification-hooks t))
                   (erase-buffer)
                   (run-hooks 'temp-buffer-setup-hook)))))
            (standard-output ,buf))
       (prog1 (progn ,@body)
         (internal-temp-output-buffer-show ,buf)))))

(defmacro with-temp-file (file &rest body)
  "Create a new buffer, evaluate BODY there, and write the buffer to FILE.
The value returned is the value of the last form in BODY.
See also `with-temp-buffer'."
  (declare (indent 1) (debug t))
  (let ((temp-file (make-symbol "temp-file"))
        (temp-buffer (make-symbol "temp-buffer")))
    `(let ((,temp-file ,file)
           (,temp-buffer
            (get-buffer-create (generate-new-buffer-name " *temp file*"))))
       (unwind-protect
           (prog1
               (with-current-buffer ,temp-buffer
                 ,@body)
             (with-current-buffer ,temp-buffer
               (write-region nil nil ,temp-file nil 0)))
         (and (buffer-name ,temp-buffer)
              (kill-buffer ,temp-buffer))))))

(defmacro with-temp-message (message &rest body)
  "Display MESSAGE temporarily if non-nil while BODY is evaluated.
The original message is restored to the echo area after BODY has finished.
The value returned is the value of the last form in BODY.
MESSAGE is written to the message log buffer if `message-log-max' is non-nil.
If MESSAGE is nil, the echo area and message log buffer are unchanged.
Use a MESSAGE of \"\" to temporarily clear the echo area."
  (declare (debug t) (indent 1))
  (let ((current-message (make-symbol "current-message"))
        (temp-message (make-symbol "with-temp-message")))
    `(let ((,temp-message ,message)
           (,current-message))
       (unwind-protect
           (progn
             (when ,temp-message
               (setq ,current-message (current-message))
               (message "%s" ,temp-message))
             ,@body)
         (and ,temp-message
              (if ,current-message
                  (message "%s" ,current-message)
                (message nil)))))))

(defmacro with-temp-buffer (&rest body)
  "Create a temporary buffer, and evaluate BODY there like `progn'.
See also `with-temp-file' and `with-output-to-string'."
  (declare (indent 0) (debug t))
  (let ((temp-buffer (make-symbol "temp-buffer")))
    `(let ((,temp-buffer (generate-new-buffer " *temp*")))
       ;; FIXME: kill-buffer can change current-buffer in some odd cases.
       (with-current-buffer ,temp-buffer
         (unwind-protect
             (progn ,@body)
           (and (buffer-name ,temp-buffer)
                (kill-buffer ,temp-buffer)))))))

(defmacro with-silent-modifications (&rest body)
  "Execute BODY, pretending it does not modify the buffer.
This macro is typically used around modifications of
text properties which do not really affect the buffer's content.
If BODY performs real modifications to the buffer's text, other
than cosmetic ones, undo data may become corrupted.

This macro will run BODY normally, but doesn't count its buffer
modifications as being buffer modifications.  This affects things
like `buffer-modified-p', checking whether the file is locked by
someone else, running buffer modification hooks, and other things
of that nature."
  (declare (debug t) (indent 0))
  (let ((modified (make-symbol "modified")))
    `(let* ((,modified (buffer-modified-p))
            (buffer-undo-list t)
            (inhibit-read-only t)
            (inhibit-modification-hooks t))
       (unwind-protect
           (progn
             ,@body)
         (unless ,modified
           (restore-buffer-modified-p nil))))))

(defmacro with-output-to-string (&rest body)
  "Execute BODY, return the text it sent to `standard-output', as a string."
  (declare (indent 0) (debug t))
  `(let ((standard-output
          (get-buffer-create (generate-new-buffer-name " *string-output*"))))
     (unwind-protect
         (progn
           (let ((standard-output standard-output))
             ,@body)
           (with-current-buffer standard-output
             (buffer-string)))
       (kill-buffer standard-output))))

(defmacro with-local-quit (&rest body)
  "Execute BODY, allowing quits to terminate BODY but not escape further.
When a quit terminates BODY, `with-local-quit' returns nil but
requests another quit.  That quit will be processed as soon as quitting
is allowed once again.  (Immediately, if `inhibit-quit' is nil.)"
  (declare (debug t) (indent 0))
  `(condition-case nil
       (let ((inhibit-quit nil))
         ,@body)
     (quit (setq quit-flag t)
           ;; This call is to give a chance to handle quit-flag
           ;; in case inhibit-quit is nil.
           ;; Without this, it will not be handled until the next function
           ;; call, and that might allow it to exit thru a condition-case
           ;; that intends to handle the quit signal next time.
           (eval '(ignore nil)))))

;; Don't throw `throw-on-input' on those events by default.
(setq while-no-input-ignore-events
      '(focus-in focus-out help-echo iconify-frame
        make-frame-visible selection-request))

(defmacro while-no-input (&rest body)
  "Execute BODY only as long as there's no pending input.
If input arrives, that ends the execution of BODY,
and `while-no-input' returns t.  Quitting makes it return nil.
If BODY finishes, `while-no-input' returns whatever value BODY produced."
  (declare (debug t) (indent 0))
  (let ((catch-sym (make-symbol "input")))
    `(with-local-quit
       (catch ',catch-sym
         (let ((throw-on-input ',catch-sym))
           (or (input-pending-p)
               (progn ,@body)))))))

(defmacro condition-case-unless-debug (var bodyform &rest handlers)
  "Like `condition-case' except that it does not prevent debugging.
More specifically if `debug-on-error' is set then the debugger will be invoked
even if this catches the signal."
  (declare (debug condition-case) (indent 2))
  `(condition-case ,var
       ,bodyform
     ,@(mapcar (lambda (handler)
                 `((debug ,@(if (listp (car handler)) (car handler)
                              (list (car handler))))
                   ,@(cdr handler)))
               handlers)))

(define-obsolete-function-alias 'condition-case-no-debug
  'condition-case-unless-debug "24.1")

(defmacro with-demoted-errors (format &rest body)
  "Run BODY and demote any errors to simple messages.
FORMAT is a string passed to `message' to format any error message.
It should contain a single %-sequence; e.g., \"Error: %S\".

If `debug-on-error' is non-nil, run BODY without catching its errors.
This is to be used around code which is not expected to signal an error
but which should be robust in the unexpected case that an error is signaled.

For backward compatibility, if FORMAT is not a constant string, it
is assumed to be part of BODY, in which case the message format
used is \"Error: %S\"."
  (declare (debug t) (indent 1))
  (let ((err (make-symbol "err"))
        (format (if (and (stringp format) body) format
                  (prog1 "Error: %S"
                    (if format (push format body))))))
    `(condition-case-unless-debug ,err
         ,(macroexp-progn body)
       (error (message ,format ,err) nil))))

(defmacro combine-after-change-calls (&rest body)
  "Execute BODY, but don't call the after-change functions till the end.
If BODY makes changes in the buffer, they are recorded
and the functions on `after-change-functions' are called several times
when BODY is finished.
The return value is the value of the last form in BODY.

If `before-change-functions' is non-nil, then calls to the after-change
functions can't be deferred, so in that case this macro has no effect.

Do not alter `after-change-functions' or `before-change-functions'
in BODY."
  (declare (indent 0) (debug t))
  `(unwind-protect
       (let ((combine-after-change-calls t))
         . ,body)
     (combine-after-change-execute)))

(defmacro with-case-table (table &rest body)
  "Execute the forms in BODY with TABLE as the current case table.
The value returned is the value of the last form in BODY."
  (declare (indent 1) (debug t))
  (let ((old-case-table (make-symbol "table"))
        (old-buffer (make-symbol "buffer")))
    `(let ((,old-case-table (current-case-table))
           (,old-buffer (current-buffer)))
       (unwind-protect
           (progn (set-case-table ,table)
                  ,@body)
         (with-current-buffer ,old-buffer
           (set-case-table ,old-case-table))))))

(defmacro with-file-modes (modes &rest body)
  "Execute BODY with default file permissions temporarily set to MODES.
MODES is as for `set-default-file-modes'."
  (declare (indent 1) (debug t))
  (let ((umask (make-symbol "umask")))
    `(let ((,umask (default-file-modes)))
       (unwind-protect
           (progn
             (set-default-file-modes ,modes)
             ,@body)
         (set-default-file-modes ,umask)))))

\f
;;; Matching and match data.

(defvar save-match-data-internal)

;; We use save-match-data-internal as the local variable because
;; that works ok in practice (people should not use that variable elsewhere).
;; We used to use an uninterned symbol; the compiler handles that properly
;; now, but it generates slower code.
(defmacro save-match-data (&rest body)
  "Execute the BODY forms, restoring the global value of the match data.
The value returned is the value of the last form in BODY."
  ;; It is better not to use backquote here,
  ;; because that makes a bootstrapping problem
  ;; if you need to recompile all the Lisp files using interpreted code.
  (declare (indent 0) (debug t))
  (list 'let
        '((save-match-data-internal (match-data)))
        (list 'unwind-protect
              (cons 'progn body)
              ;; It is safe to free (evaporate) markers immediately here,
              ;; as Lisp programs should not copy from save-match-data-internal.
              '(set-match-data save-match-data-internal 'evaporate))))

(defun match-string (num &optional string)
  "Return string of text matched by last search.
NUM specifies which parenthesized expression in the last regexp.
 Value is nil if NUMth pair didn't match, or there were less than NUM pairs.
Zero means the entire text matched by the whole regexp or whole string.
STRING should be given if the last search was by `string-match' on STRING.
If STRING is nil, the current buffer should be the same buffer
the search/match was performed in."
  (if (match-beginning num)
      (if string
          (substring string (match-beginning num) (match-end num))
        (buffer-substring (match-beginning num) (match-end num)))))

(defun match-string-no-properties (num &optional string)
  "Return string of text matched by last search, without text properties.
NUM specifies which parenthesized expression in the last regexp.
 Value is nil if NUMth pair didn't match, or there were less than NUM pairs.
Zero means the entire text matched by the whole regexp or whole string.
STRING should be given if the last search was by `string-match' on STRING.
If STRING is nil, the current buffer should be the same buffer
the search/match was performed in."
  (if (match-beginning num)
      (if string
          (substring-no-properties string (match-beginning num)
                                   (match-end num))
        (buffer-substring-no-properties (match-beginning num)
                                        (match-end num)))))


(defun match-substitute-replacement (replacement
                                     &optional fixedcase literal string subexp)
  "Return REPLACEMENT as it will be inserted by `replace-match'.
In other words, all back-references in the form `\\&' and `\\N'
are substituted with actual strings matched by the last search.
Optional FIXEDCASE, LITERAL, STRING and SUBEXP have the same
meaning as for `replace-match'."
  (let ((match (match-string 0 string)))
    (save-match-data
      (set-match-data (mapcar (lambda (x)
                                (if (numberp x)
                                    (- x (match-beginning 0))
                                  x))
                              (match-data t)))
      (replace-match replacement fixedcase literal match subexp))))


(defun looking-back (regexp &optional limit greedy)
  "Return non-nil if text before point matches regular expression REGEXP.
Like `looking-at' except matches before point, and is slower.
LIMIT if non-nil speeds up the search by specifying a minimum
starting position, to avoid checking matches that would start
before LIMIT.

If GREEDY is non-nil, extend the match backwards as far as
possible, stopping when a single additional previous character
cannot be part of a match for REGEXP.  When the match is
extended, its starting position is allowed to occur before
LIMIT.

As a general recommendation, try to avoid using `looking-back'
wherever possible, since it is slow."
  (declare
   (advertised-calling-convention (regexp limit &optional greedy) "25.1"))
  (let ((start (point))
        (pos
         (save-excursion
           (and (re-search-backward (concat "\\(?:" regexp "\\)\\=") limit t)
                (point)))))
    (if (and greedy pos)
        (save-restriction
          (narrow-to-region (point-min) start)
          (while (and (> pos (point-min))
                      (save-excursion
                        (goto-char pos)
                        (backward-char 1)
                        (looking-at (concat "\\(?:"  regexp "\\)\\'"))))
            (setq pos (1- pos)))
          (save-excursion
            (goto-char pos)
            (looking-at (concat "\\(?:"  regexp "\\)\\'")))))
    (not (null pos))))

(defsubst looking-at-p (regexp)
  "\
Same as `looking-at' except this function does not change the match data."
  (let ((inhibit-changing-match-data t))
    (looking-at regexp)))

(defsubst string-match-p (regexp string &optional start)
  "\
Same as `string-match' except this function does not change the match data."
  (let ((inhibit-changing-match-data t))
    (string-match regexp string start)))

(defun subregexp-context-p (regexp pos &optional start)
  "Return non-nil if POS is in a normal subregexp context in REGEXP.
A subregexp context is one where a sub-regexp can appear.
A non-subregexp context is for example within brackets, or within a
repetition bounds operator `\\=\\{...\\}', or right after a `\\'.
If START is non-nil, it should be a position in REGEXP, smaller
than POS, and known to be in a subregexp context."
  ;; Here's one possible implementation, with the great benefit that it
  ;; reuses the regexp-matcher's own parser, so it understands all the
  ;; details of the syntax.  A disadvantage is that it needs to match the
  ;; error string.
  (condition-case err
      (progn
        (string-match (substring regexp (or start 0) pos) "")
        t)
    (invalid-regexp
     (not (member (cadr err) '("Unmatched [ or [^"
                               "Unmatched \\{"
                               "Trailing backslash")))))
  ;; An alternative implementation:
  ;; (defconst re-context-re
  ;;   (let* ((harmless-ch "[^\\[]")
  ;;          (harmless-esc "\\\\[^{]")
  ;;          (class-harmless-ch "[^][]")
  ;;          (class-lb-harmless "[^]:]")
  ;;          (class-lb-colon-maybe-charclass ":\\([a-z]+:]\\)?")
  ;;          (class-lb (concat "\\[\\(" class-lb-harmless
  ;;                            "\\|" class-lb-colon-maybe-charclass "\\)"))
  ;;          (class
  ;;           (concat "\\[^?]?"
  ;;                   "\\(" class-harmless-ch
  ;;                   "\\|" class-lb "\\)*"
  ;;                   "\\[?]"))     ; special handling for bare [ at end of re
  ;;          (braces "\\\\{[0-9,]+\\\\}"))
  ;;     (concat "\\`\\(" harmless-ch "\\|" harmless-esc
  ;;             "\\|" class "\\|" braces "\\)*\\'"))
  ;;   "Matches any prefix that corresponds to a normal subregexp context.")
  ;; (string-match re-context-re (substring regexp (or start 0) pos))
  )
\f
;;;; split-string

(defconst split-string-default-separators "[ \f\t\n\r\v]+"
  "The default value of separators for `split-string'.

A regexp matching strings of whitespace.  May be locale-dependent
\(as yet unimplemented).  Should not match non-breaking spaces.

Warning: binding this to a different value and using it as default is
likely to have undesired semantics.")

;; The specification says that if both SEPARATORS and OMIT-NULLS are
;; defaulted, OMIT-NULLS should be treated as t.  Simplifying the logical
;; expression leads to the equivalent implementation that if SEPARATORS
;; is defaulted, OMIT-NULLS is treated as t.
(defun split-string (string &optional separators omit-nulls trim)
  "Split STRING into substrings bounded by matches for SEPARATORS.

The beginning and end of STRING, and each match for SEPARATORS, are
splitting points.  The substrings matching SEPARATORS are removed, and
the substrings between the splitting points are collected as a list,
which is returned.

If SEPARATORS is non-nil, it should be a regular expression matching text
which separates, but is not part of, the substrings.  If nil it defaults to
`split-string-default-separators', normally \"[ \\f\\t\\n\\r\\v]+\", and
OMIT-NULLS is forced to t.

If OMIT-NULLS is t, zero-length substrings are omitted from the list (so
that for the default value of SEPARATORS leading and trailing whitespace
are effectively trimmed).  If nil, all zero-length substrings are retained,
which correctly parses CSV format, for example.

If TRIM is non-nil, it should be a regular expression to match
text to trim from the beginning and end of each substring.  If trimming
makes the substring empty, it is treated as null.

If you want to trim whitespace from the substrings, the reliably correct
way is using TRIM.  Making SEPARATORS match that whitespace gives incorrect
results when there is whitespace at the start or end of STRING.  If you
see such calls to `split-string', please fix them.

Note that the effect of `(split-string STRING)' is the same as
`(split-string STRING split-string-default-separators t)'.  In the rare
case that you wish to retain zero-length substrings when splitting on
whitespace, use `(split-string STRING split-string-default-separators)'.

Modifies the match data; use `save-match-data' if necessary."
  (let* ((keep-nulls (not (if separators omit-nulls t)))
         (rexp (or separators split-string-default-separators))
         (start 0)
         this-start this-end
         notfirst
         (list nil)
         (push-one
          ;; Push the substring in range THIS-START to THIS-END
          ;; onto LIST, trimming it and perhaps discarding it.
          (lambda ()
            (when trim
              ;; Discard the trim from start of this substring.
              (let ((tem (string-match trim string this-start)))
                (and (eq tem this-start)
                     (setq this-start (match-end 0)))))

            (when (or keep-nulls (< this-start this-end))
              (let ((this (substring string this-start this-end)))

                ;; Discard the trim from end of this substring.
                (when trim
                  (let ((tem (string-match (concat trim "\\'") this 0)))
                    (and tem (< tem (length this))
                         (setq this (substring this 0 tem)))))

                ;; Trimming could make it empty; check again.
                (when (or keep-nulls (> (length this) 0))
                  (push this list)))))))

    (while (and (string-match rexp string
                              (if (and notfirst
                                       (= start (match-beginning 0))
                                       (< start (length string)))
                                  (1+ start) start))
                (< start (length string)))
      (setq notfirst t)
      (setq this-start start this-end (match-beginning 0)
            start (match-end 0))

      (funcall push-one))

    ;; Handle the substring at the end of STRING.
    (setq this-start start this-end (length string))
    (funcall push-one)

    (nreverse list)))

(defun combine-and-quote-strings (strings &optional separator)
  "Concatenate the STRINGS, adding the SEPARATOR (default \" \").
This tries to quote the strings to avoid ambiguity such that
  (split-string-and-unquote (combine-and-quote-strings strs)) == strs
Only some SEPARATORs will work properly.

Note that this is not intended to protect STRINGS from
interpretation by shells, use `shell-quote-argument' for that."
  (let* ((sep (or separator " "))
         (re (concat "[\\\"]" "\\|" (regexp-quote sep))))
    (mapconcat
     (lambda (str)
       (if (string-match re str)
           (concat "\"" (replace-regexp-in-string "[\\\"]" "\\\\\\&" str) "\"")
         str))
     strings sep)))

(defun split-string-and-unquote (string &optional separator)
  "Split the STRING into a list of strings.
It understands Emacs Lisp quoting within STRING, such that
  (split-string-and-unquote (combine-and-quote-strings strs)) == strs
The SEPARATOR regexp defaults to \"\\s-+\"."
  (let ((sep (or separator "\\s-+"))
        (i (string-match "\"" string)))
    (if (null i)
        (split-string string sep t)     ; no quoting:  easy
      (append (unless (eq i 0) (split-string (substring string 0 i) sep t))
              (let ((rfs (read-from-string string i)))
                (cons (car rfs)
                      (split-string-and-unquote (substring string (cdr rfs))
                                                sep)))))))

\f
;;;; Replacement in strings.

(defun subst-char-in-string (fromchar tochar string &optional inplace)
  "Replace FROMCHAR with TOCHAR in STRING each time it occurs.
Unless optional argument INPLACE is non-nil, return a new string."
  (let ((i (length string))
        (newstr (if inplace string (copy-sequence string))))
    (while (> i 0)
      (setq i (1- i))
      (if (eq (aref newstr i) fromchar)
          (aset newstr i tochar)))
    newstr))

(defun replace-regexp-in-string (regexp rep string &optional
                                        fixedcase literal subexp start)
  "Replace all matches for REGEXP with REP in STRING.

Return a new string containing the replacements.

Optional arguments FIXEDCASE, LITERAL and SUBEXP are like the
arguments with the same names of function `replace-match'.  If START
is non-nil, start replacements at that index in STRING.

REP is either a string used as the NEWTEXT arg of `replace-match' or a
function.  If it is a function, it is called with the actual text of each
match, and its value is used as the replacement text.  When REP is called,
the match data are the result of matching REGEXP against a substring
of STRING, the same substring that is the actual text of the match which
is passed to REP as its argument.

To replace only the first match (if any), make REGEXP match up to \\\\='
and replace a sub-expression, e.g.
  (replace-regexp-in-string \"\\\\(foo\\\\).*\\\\\\='\" \"bar\" \" foo foo\" nil nil 1)
    => \" bar foo\""

  ;; To avoid excessive consing from multiple matches in long strings,
  ;; don't just call `replace-match' continually.  Walk down the
  ;; string looking for matches of REGEXP and building up a (reversed)
  ;; list MATCHES.  This comprises segments of STRING which weren't
  ;; matched interspersed with replacements for segments that were.
  ;; [For a `large' number of replacements it's more efficient to
  ;; operate in a temporary buffer; we can't tell from the function's
  ;; args whether to choose the buffer-based implementation, though it
  ;; might be reasonable to do so for long enough STRING.]
  (let ((l (length string))
        (start (or start 0))
        matches str mb me)
    (save-match-data
      (while (and (< start l) (string-match regexp string start))
        (setq mb (match-beginning 0)
              me (match-end 0))
        ;; If we matched the empty string, make sure we advance by one char
        (when (= me mb) (setq me (min l (1+ mb))))
        ;; Generate a replacement for the matched substring.
        ;; Operate only on the substring to minimize string consing.
        ;; Set up match data for the substring for replacement;
        ;; presumably this is likely to be faster than munging the
        ;; match data directly in Lisp.
        (string-match regexp (setq str (substring string mb me)))
        (setq matches
              (cons (replace-match (if (stringp rep)
                                       rep
                                     (funcall rep (match-string 0 str)))
                                   fixedcase literal str subexp)
                    (cons (substring string start mb) ; unmatched prefix
                          matches)))
        (setq start me))
      ;; Reconstruct a string from the pieces.
      (setq matches (cons (substring string start l) matches)) ; leftover
      (apply #'concat (nreverse matches)))))
\f
(defun string-prefix-p (prefix string &optional ignore-case)
  "Return non-nil if PREFIX is a prefix of STRING.
If IGNORE-CASE is non-nil, the comparison is done without paying attention
to case differences."
  (let ((prefix-length (length prefix)))
    (if (> prefix-length (length string)) nil
      (eq t (compare-strings prefix 0 prefix-length string
                             0 prefix-length ignore-case)))))

(defun string-suffix-p (suffix string  &optional ignore-case)
  "Return non-nil if SUFFIX is a suffix of STRING.
If IGNORE-CASE is non-nil, the comparison is done without paying
attention to case differences."
  (let ((start-pos (- (length string) (length suffix))))
    (and (>= start-pos 0)
         (eq t (compare-strings suffix nil nil
                                string start-pos nil ignore-case)))))

(defun bidi-string-mark-left-to-right (str)
  "Return a string that can be safely inserted in left-to-right text.

Normally, inserting a string with right-to-left (RTL) script into
a buffer may cause some subsequent text to be displayed as part
of the RTL segment (usually this affects punctuation characters).
This function returns a string which displays as STR but forces
subsequent text to be displayed as left-to-right.

If STR contains any RTL character, this function returns a string
consisting of STR followed by an invisible left-to-right mark
\(LRM) character.  Otherwise, it returns STR."
  (unless (stringp str)
    (signal 'wrong-type-argument (list 'stringp str)))
  (if (string-match "\\cR" str)
      (concat str (propertize (string ?\x200e) 'invisible t))
    str))

(defun string-greaterp (string1 string2)
  "Return non-nil if STRING1 is greater than STRING2 in lexicographic order.
Case is significant.
Symbols are also allowed; their print names are used instead."
  (string-lessp string2 string1))

\f
;;;; Specifying things to do later.

(defun load-history-regexp (file)
  "Form a regexp to find FILE in `load-history'.
FILE, a string, is described in the function `eval-after-load'."
  (if (file-name-absolute-p file)
      (setq file (file-truename file)))
  (concat (if (file-name-absolute-p file) "\\`" "\\(\\`\\|/\\)")
          (regexp-quote file)
          (if (file-name-extension file)
              ""
            ;; Note: regexp-opt can't be used here, since we need to call
            ;; this before Emacs has been fully started.  2006-05-21
            (concat "\\(" (mapconcat 'regexp-quote load-suffixes "\\|") "\\)?"))
          "\\(" (mapconcat 'regexp-quote jka-compr-load-suffixes "\\|")
          "\\)?\\'"))

(defun load-history-filename-element (file-regexp)
  "Get the first elt of `load-history' whose car matches FILE-REGEXP.
Return nil if there isn't one."
  (let* ((loads load-history)
         (load-elt (and loads (car loads))))
    (save-match-data
      (while (and loads
                  (or (null (car load-elt))
                      (not (string-match file-regexp (car load-elt)))))
        (setq loads (cdr loads)
              load-elt (and loads (car loads)))))
    load-elt))

(put 'eval-after-load 'lisp-indent-function 1)
(defun eval-after-load (file form)
  "Arrange that if FILE is loaded, FORM will be run immediately afterwards.
If FILE is already loaded, evaluate FORM right now.
FORM can be an Elisp expression (in which case it's passed to `eval'),
or a function (in which case it's passed to `funcall' with no argument).

If a matching file is loaded again, FORM will be evaluated again.

If FILE is a string, it may be either an absolute or a relative file
name, and may have an extension (e.g. \".el\") or may lack one, and
additionally may or may not have an extension denoting a compressed
format (e.g. \".gz\").

When FILE is absolute, this first converts it to a true name by chasing
symbolic links.  Only a file of this name (see next paragraph regarding
extensions) will trigger the evaluation of FORM.  When FILE is relative,
a file whose absolute true name ends in FILE will trigger evaluation.

When FILE lacks an extension, a file name with any extension will trigger
evaluation.  Otherwise, its extension must match FILE's.  A further
extension for a compressed format (e.g. \".gz\") on FILE will not affect
this name matching.

Alternatively, FILE can be a feature (i.e. a symbol), in which case FORM
is evaluated at the end of any file that `provide's this feature.
If the feature is provided when evaluating code not associated with a
file, FORM is evaluated immediately after the provide statement.

Usually FILE is just a library name like \"font-lock\" or a feature name
like `font-lock'.

This function makes or adds to an entry on `after-load-alist'."
  (declare (compiler-macro
            (lambda (whole)
              (if (eq 'quote (car-safe form))
                  ;; Quote with lambda so the compiler can look inside.
                  `(eval-after-load ,file (lambda () ,(nth 1 form)))
                whole))))
  ;; Add this FORM into after-load-alist (regardless of whether we'll be
  ;; evaluating it now).
  (let* ((regexp-or-feature
          (if (stringp file)
              (setq file (purecopy (load-history-regexp file)))
            file))
         (elt (assoc regexp-or-feature after-load-alist))
         (func
          (if (functionp form) form
            ;; Try to use the "current" lexical/dynamic mode for `form'.
            (eval `(lambda () ,form) lexical-binding))))
    (unless elt
      (setq elt (list regexp-or-feature))
      (push elt after-load-alist))
    ;; Is there an already loaded file whose name (or `provide' name)
    ;; matches FILE?
    (prog1 (if (if (stringp file)
                   (load-history-filename-element regexp-or-feature)
                 (featurep file))
               (funcall func))
      (let ((delayed-func
             (if (not (symbolp regexp-or-feature)) func
               ;; For features, the after-load-alist elements get run when
               ;; `provide' is called rather than at the end of the file.
               ;; So add an indirection to make sure that `func' is really run
               ;; "after-load" in case the provide call happens early.
               (lambda ()
                 (if (not load-file-name)
                     ;; Not being provided from a file, run func right now.
                     (funcall func)
                   (let ((lfn load-file-name)
                         ;; Don't use letrec, because equal (in
                         ;; add/remove-hook) would get trapped in a cycle.
                         (fun (make-symbol "eval-after-load-helper")))
                     (fset fun (lambda (file)
                                 (when (equal file lfn)
                                   (remove-hook 'after-load-functions fun)
                                   (funcall func))))
                     (add-hook 'after-load-functions fun 'append)))))))
        ;; Add FORM to the element unless it's already there.
        (unless (member delayed-func (cdr elt))
          (nconc elt (list delayed-func)))))))

(defmacro with-eval-after-load (file &rest body)
  "Execute BODY after FILE is loaded.
FILE is normally a feature name, but it can also be a file name,
in case that file does not provide any feature.  See `eval-after-load'
for more details about the different forms of FILE and their semantics."
  (declare (indent 1) (debug t))
  `(eval-after-load ,file (lambda () ,@body)))

(defvar after-load-functions nil
  "Special hook run after loading a file.
Each function there is called with a single argument, the absolute
name of the file just loaded.")

(defun do-after-load-evaluation (abs-file)
  "Evaluate all `eval-after-load' forms, if any, for ABS-FILE.
ABS-FILE, a string, should be the absolute true name of a file just loaded.
This function is called directly from the C code."
  ;; Run the relevant eval-after-load forms.
  (dolist (a-l-element after-load-alist)
    (when (and (stringp (car a-l-element))
               (string-match-p (car a-l-element) abs-file))
      ;; discard the file name regexp
      (mapc #'funcall (cdr a-l-element))))
  ;; Complain when the user uses obsolete files.
  (when (string-match-p "/obsolete/\\([^/]*\\)\\'" abs-file)
    ;; Maybe we should just use display-warning?  This seems yucky...
    (let* ((file (file-name-nondirectory abs-file))
           (msg (format "Package %s is obsolete!"
                        (substring file 0
                                   (string-match "\\.elc?\\>" file)))))
      ;; Cribbed from cl--compiling-file.
      (if (and (boundp 'byte-compile--outbuffer)
               (bufferp (symbol-value 'byte-compile--outbuffer))
               (equal (buffer-name (symbol-value 'byte-compile--outbuffer))
                      " *Compiler Output*"))
          ;; Don't warn about obsolete files using other obsolete files.
          (unless (and (stringp byte-compile-current-file)
                       (string-match-p "/obsolete/[^/]*\\'"
                                       (expand-file-name
                                        byte-compile-current-file
                                        byte-compile-root-dir)))
            (byte-compile-warn "%s" msg))
        (run-with-timer 0 nil
                        (lambda (msg)
                          (message "%s" msg))
                        msg))))

  ;; Finally, run any other hook.
  (run-hook-with-args 'after-load-functions abs-file))

(defun eval-next-after-load (file)
  "Read the following input sexp, and run it whenever FILE is loaded.
This makes or adds to an entry on `after-load-alist'.
FILE should be the name of a library, with no directory name."
  (declare (obsolete eval-after-load "23.2"))
  (eval-after-load file (read)))

\f
(defun display-delayed-warnings ()
  "Display delayed warnings from `delayed-warnings-list'.
Used from `delayed-warnings-hook' (which see)."
  (dolist (warning (nreverse delayed-warnings-list))
    (apply 'display-warning warning))
  (setq delayed-warnings-list nil))

(defun collapse-delayed-warnings ()
  "Remove duplicates from `delayed-warnings-list'.
Collapse identical adjacent warnings into one (plus count).
Used from `delayed-warnings-hook' (which see)."
  (let ((count 1)
        collapsed warning)
    (while delayed-warnings-list
      (setq warning (pop delayed-warnings-list))
      (if (equal warning (car delayed-warnings-list))
          (setq count (1+ count))
        (when (> count 1)
          (setcdr warning (cons (format "%s [%d times]" (cadr warning) count)
                                (cddr warning)))
          (setq count 1))
        (push warning collapsed)))
    (setq delayed-warnings-list (nreverse collapsed))))

;; At present this is only used for Emacs internals.
;; Ref https://lists.gnu.org/r/emacs-devel/2012-02/msg00085.html
(defvar delayed-warnings-hook '(collapse-delayed-warnings
                                display-delayed-warnings)
  "Normal hook run to process and display delayed warnings.
By default, this hook contains functions to consolidate the
warnings listed in `delayed-warnings-list', display them, and set
`delayed-warnings-list' back to nil.")

(defun delay-warning (type message &optional level buffer-name)
  "Display a delayed warning.
Aside from going through `delayed-warnings-list', this is equivalent
to `display-warning'."
  (push (list type message level buffer-name) delayed-warnings-list))

\f
;;;; invisibility specs

(defun add-to-invisibility-spec (element)
  "Add ELEMENT to `buffer-invisibility-spec'.
See documentation for `buffer-invisibility-spec' for the kind of elements
that can be added."
  (if (eq buffer-invisibility-spec t)
      (setq buffer-invisibility-spec (list t)))
  (setq buffer-invisibility-spec
        (cons element buffer-invisibility-spec)))

(defun remove-from-invisibility-spec (element)
  "Remove ELEMENT from `buffer-invisibility-spec'."
  (setq buffer-invisibility-spec
        (if (consp buffer-invisibility-spec)
            (delete element buffer-invisibility-spec)
          (list t))))
\f
;;;; Syntax tables.

(defmacro with-syntax-table (table &rest body)
  "Evaluate BODY with syntax table of current buffer set to TABLE.
The syntax table of the current buffer is saved, BODY is evaluated, and the
saved table is restored, even in case of an abnormal exit.
Value is what BODY returns."
  (declare (debug t) (indent 1))
  (let ((old-table (make-symbol "table"))
        (old-buffer (make-symbol "buffer")))
    `(let ((,old-table (syntax-table))
           (,old-buffer (current-buffer)))
       (unwind-protect
           (progn
             (set-syntax-table ,table)
             ,@body)
         (save-current-buffer
           (set-buffer ,old-buffer)
           (set-syntax-table ,old-table))))))

(defun make-syntax-table (&optional oldtable)
  "Return a new syntax table.
Create a syntax table which inherits from OLDTABLE (if non-nil) or
from `standard-syntax-table' otherwise."
  (let ((table (make-char-table 'syntax-table nil)))
    (set-char-table-parent table (or oldtable (standard-syntax-table)))
    table))

(defun syntax-after (pos)
  "Return the raw syntax descriptor for the char after POS.
If POS is outside the buffer's accessible portion, return nil."
  (unless (or (< pos (point-min)) (>= pos (point-max)))
    (let ((st (if parse-sexp-lookup-properties
                  (get-char-property pos 'syntax-table))))
      (if (consp st) st
        (aref (or st (syntax-table)) (char-after pos))))))

(defun syntax-class (syntax)
  "Return the code for the syntax class described by SYNTAX.

SYNTAX should be a raw syntax descriptor; the return value is a
integer which encodes the corresponding syntax class.  See Info
node `(elisp)Syntax Table Internals' for a list of codes.

If SYNTAX is nil, return nil."
  (and syntax (logand (car syntax) 65535)))
\f
;; Utility motion commands

(defvar word-move-empty-char-table nil
  "Used in `forward-word-strictly' and `backward-word-strictly'
to countermand the effect of `find-word-boundary-function-table'.")

(defun forward-word-strictly (&optional arg)
  "Move point forward ARG words (backward if ARG is negative).
If ARG is omitted or nil, move point forward one word.
Normally returns t.
If an edge of the buffer or a field boundary is reached, point is left there
and the function returns nil.  Field boundaries are not noticed if
`inhibit-field-text-motion' is non-nil.

This function is like `forward-word', but it is not affected
by `find-word-boundary-function-table'.  It is also not interactive."
  (let ((find-word-boundary-function-table
         (if (char-table-p word-move-empty-char-table)
             word-move-empty-char-table
           (setq word-move-empty-char-table (make-char-table nil)))))
    (forward-word (or arg 1))))

(defun backward-word-strictly (&optional arg)
  "Move backward until encountering the beginning of a word.
With argument ARG, do this that many times.
If ARG is omitted or nil, move point backward one word.

This function is like `forward-word', but it is not affected
by `find-word-boundary-function-table'.  It is also not interactive."
  (let ((find-word-boundary-function-table
         (if (char-table-p word-move-empty-char-table)
             word-move-empty-char-table
           (setq word-move-empty-char-table (make-char-table nil)))))
    (forward-word (- (or arg 1)))))

;;  Whitespace

(defun forward-whitespace (arg)
  "Move point to the end of the next sequence of whitespace chars.
Each such sequence may be a single newline, or a sequence of
consecutive space and/or tab characters.
With prefix argument ARG, do it ARG times if positive, or move
backwards ARG times if negative."
  (interactive "^p")
  (if (natnump arg)
      (re-search-forward "[ \t]+\\|\n" nil 'move arg)
    (while (< arg 0)
      (if (re-search-backward "[ \t]+\\|\n" nil 'move)
          (or (eq (char-after (match-beginning 0)) ?\n)
              (skip-chars-backward " \t")))
      (setq arg (1+ arg)))))

;;  Symbols

(defun forward-symbol (arg)
  "Move point to the next position that is the end of a symbol.
A symbol is any sequence of characters that are in either the
word constituent or symbol constituent syntax class.
With prefix argument ARG, do it ARG times if positive, or move
backwards ARG times if negative."
  (interactive "^p")
  (if (natnump arg)
      (re-search-forward "\\(\\sw\\|\\s_\\)+" nil 'move arg)
    (while (< arg 0)
      (if (re-search-backward "\\(\\sw\\|\\s_\\)+" nil 'move)
          (skip-syntax-backward "w_"))
      (setq arg (1+ arg)))))

;;  Syntax blocks

(defun forward-same-syntax (&optional arg)
  "Move point past all characters with the same syntax class.
With prefix argument ARG, do it ARG times if positive, or move
backwards ARG times if negative."
  (interactive "^p")
  (or arg (setq arg 1))
  (while (< arg 0)
    (skip-syntax-backward
     (char-to-string (char-syntax (char-before))))
    (setq arg (1+ arg)))
  (while (> arg 0)
    (skip-syntax-forward (char-to-string (char-syntax (char-after))))
    (setq arg (1- arg))))

\f
;;;; Text clones

(defvar text-clone--maintaining nil)

(defun text-clone--maintain (ol1 after beg end &optional _len)
  "Propagate the changes made under the overlay OL1 to the other clones.
This is used on the `modification-hooks' property of text clones."
  (when (and after (not undo-in-progress)
             (not text-clone--maintaining)
             (overlay-start ol1))
    (let ((margin (if (overlay-get ol1 'text-clone-spreadp) 1 0)))
      (setq beg (max beg (+ (overlay-start ol1) margin)))
      (setq end (min end (- (overlay-end ol1) margin)))
      (when (<= beg end)
        (save-excursion
          (when (overlay-get ol1 'text-clone-syntax)
            ;; Check content of the clone's text.
            (let ((cbeg (+ (overlay-start ol1) margin))
                  (cend (- (overlay-end ol1) margin)))
              (goto-char cbeg)
              (save-match-data
                (if (not (re-search-forward
                          (overlay-get ol1 'text-clone-syntax) cend t))
                    ;; Mark the overlay for deletion.
                    (setq end cbeg)
                  (when (< (match-end 0) cend)
                    ;; Shrink the clone at its end.
                    (setq end (min end (match-end 0)))
                    (move-overlay ol1 (overlay-start ol1)
                                  (+ (match-end 0) margin)))
                  (when (> (match-beginning 0) cbeg)
                    ;; Shrink the clone at its beginning.
                    (setq beg (max (match-beginning 0) beg))
                    (move-overlay ol1 (- (match-beginning 0) margin)
                                  (overlay-end ol1)))))))
          ;; Now go ahead and update the clones.
          (let ((head (- beg (overlay-start ol1)))
                (tail (- (overlay-end ol1) end))
                (str (buffer-substring beg end))
                (nothing-left t)
                (text-clone--maintaining t))
            (dolist (ol2 (overlay-get ol1 'text-clones))
              (let ((oe (overlay-end ol2)))
                (unless (or (eq ol1 ol2) (null oe))
                  (setq nothing-left nil)
                  (let ((mod-beg (+ (overlay-start ol2) head)))
                    ;;(overlay-put ol2 'modification-hooks nil)
                    (goto-char (- (overlay-end ol2) tail))
                    (unless (> mod-beg (point))
                      (save-excursion (insert str))
                      (delete-region mod-beg (point)))
                    ;;(overlay-put ol2 'modification-hooks '(text-clone--maintain))
                    ))))
            (if nothing-left (delete-overlay ol1))))))))

(defun text-clone-create (start end &optional spreadp syntax)
  "Create a text clone of START...END at point.
Text clones are chunks of text that are automatically kept identical:
changes done to one of the clones will be immediately propagated to the other.

The buffer's content at point is assumed to be already identical to
the one between START and END.
If SYNTAX is provided it's a regexp that describes the possible text of
the clones; the clone will be shrunk or killed if necessary to ensure that
its text matches the regexp.
If SPREADP is non-nil it indicates that text inserted before/after the
clone should be incorporated in the clone."
  ;; To deal with SPREADP we can either use an overlay with `nil t' along
  ;; with insert-(behind|in-front-of)-hooks or use a slightly larger overlay
  ;; (with a one-char margin at each end) with `t nil'.
  ;; We opted for a larger overlay because it behaves better in the case
  ;; where the clone is reduced to the empty string (we want the overlay to
  ;; stay when the clone's content is the empty string and we want to use
  ;; `evaporate' to make sure those overlays get deleted when needed).
  ;;
  (let* ((pt-end (+ (point) (- end start)))
         (start-margin (if (or (not spreadp) (bobp) (<= start (point-min)))
                           0 1))
         (end-margin (if (or (not spreadp)
                             (>= pt-end (point-max))
                             (>= start (point-max)))
                         0 1))
         ;; FIXME: Reuse overlays at point to extend dups!
         (ol1 (make-overlay (- start start-margin) (+ end end-margin) nil t))
         (ol2 (make-overlay (- (point) start-margin) (+ pt-end end-margin) nil t))
         (dups (list ol1 ol2)))
    (overlay-put ol1 'modification-hooks '(text-clone--maintain))
    (when spreadp (overlay-put ol1 'text-clone-spreadp t))
    (when syntax (overlay-put ol1 'text-clone-syntax syntax))
    ;;(overlay-put ol1 'face 'underline)
    (overlay-put ol1 'evaporate t)
    (overlay-put ol1 'text-clones dups)
    ;;
    (overlay-put ol2 'modification-hooks '(text-clone--maintain))
    (when spreadp (overlay-put ol2 'text-clone-spreadp t))
    (when syntax (overlay-put ol2 'text-clone-syntax syntax))
    ;;(overlay-put ol2 'face 'underline)
    (overlay-put ol2 'evaporate t)
    (overlay-put ol2 'text-clones dups)))
\f
;;;; Mail user agents.

;; Here we include just enough for other packages to be able
;; to define them.

(defun define-mail-user-agent (symbol composefunc sendfunc
                                      &optional abortfunc hookvar)
  "Define a symbol to identify a mail-sending package for `mail-user-agent'.

SYMBOL can be any Lisp symbol.  Its function definition and/or
value as a variable do not matter for this usage; we use only certain
properties on its property list, to encode the rest of the arguments.

COMPOSEFUNC is program callable function that composes an outgoing
mail message buffer.  This function should set up the basics of the
buffer without requiring user interaction.  It should populate the
standard mail headers, leaving the `to:' and `subject:' headers blank
by default.

COMPOSEFUNC should accept several optional arguments--the same
arguments that `compose-mail' takes.  See that function's documentation.

SENDFUNC is the command a user would run to send the message.

Optional ABORTFUNC is the command a user would run to abort the
message.  For mail packages that don't have a separate abort function,
this can be `kill-buffer' (the equivalent of omitting this argument).

Optional HOOKVAR is a hook variable that gets run before the message
is actually sent.  Callers that use the `mail-user-agent' may
install a hook function temporarily on this hook variable.
If HOOKVAR is nil, `mail-send-hook' is used.

The properties used on SYMBOL are `composefunc', `sendfunc',
`abortfunc', and `hookvar'."
  (put symbol 'composefunc composefunc)
  (put symbol 'sendfunc sendfunc)
  (put symbol 'abortfunc (or abortfunc 'kill-buffer))
  (put symbol 'hookvar (or hookvar 'mail-send-hook)))

\f
(defun backtrace--print-frame (evald func args flags)
  "Print a trace of a single stack frame to `standard-output'.
EVALD, FUNC, ARGS, FLAGS are as in `mapbacktrace'."
  (princ (if (plist-get flags :debug-on-exit) "* " "  "))
  (cond
   ((and evald (not debugger-stack-frame-as-list))
    (prin1 func)
    (if args (prin1 args) (princ "()")))
   (t
    (prin1 (cons func args))))
  (princ "\n"))

(defun backtrace ()
  "Print a trace of Lisp function calls currently active.
Output stream used is value of `standard-output'."
  (let ((print-level (or print-level 8))
        (print-escape-control-characters t))
    (mapbacktrace #'backtrace--print-frame 'backtrace)))

(defun backtrace-frames (&optional base)
  "Collect all frames of current backtrace into a list.
If non-nil, BASE should be a function, and frames before its
nearest activation frames are discarded."
  (let ((frames nil))
    (mapbacktrace (lambda (&rest frame) (push frame frames))
                  (or base 'backtrace-frames))
    (nreverse frames)))

(defun backtrace-frame (nframes &optional base)
  "Return the function and arguments NFRAMES up from current execution point.
If non-nil, BASE should be a function, and NFRAMES counts from its
nearest activation frame.
If the frame has not evaluated the arguments yet (or is a special form),
the value is (nil FUNCTION ARG-FORMS...).
If the frame has evaluated its arguments and called its function already,
the value is (t FUNCTION ARG-VALUES...).
A &rest arg is represented as the tail of the list ARG-VALUES.
FUNCTION is whatever was supplied as car of evaluated list,
or a lambda expression for macro calls.
If NFRAMES is more than the number of frames, the value is nil."
  (backtrace-frame--internal
   (lambda (evald func args _) `(,evald ,func ,@args))
   nframes (or base 'backtrace-frame)))

\f
(defvar called-interactively-p-functions nil
  "Special hook called to skip special frames in `called-interactively-p'.
The functions are called with 3 arguments: (I FRAME1 FRAME2),
where FRAME1 is a \"current frame\", FRAME2 is the next frame,
I is the index of the frame after FRAME2.  It should return nil
if those frames don't seem special and otherwise, it should return
the number of frames to skip (minus 1).")

(defconst internal--funcall-interactively
  (symbol-function 'funcall-interactively))

(defun called-interactively-p (&optional kind)
  "Return t if the containing function was called by `call-interactively'.
If KIND is `interactive', then only return t if the call was made
interactively by the user, i.e. not in `noninteractive' mode nor
when `executing-kbd-macro'.
If KIND is `any', on the other hand, it will return t for any kind of
interactive call, including being called as the binding of a key or
from a keyboard macro, even in `noninteractive' mode.

This function is very brittle, it may fail to return the intended result when
the code is debugged, advised, or instrumented in some form.  Some macros and
special forms (such as `condition-case') may also sometimes wrap their bodies
in a `lambda', so any call to `called-interactively-p' from those bodies will
indicate whether that lambda (rather than the surrounding function) was called
interactively.

Instead of using this function, it is cleaner and more reliable to give your
function an extra optional argument whose `interactive' spec specifies
non-nil unconditionally (\"p\" is a good way to do this), or via
\(not (or executing-kbd-macro noninteractive)).

The only known proper use of `interactive' for KIND is in deciding
whether to display a helpful message, or how to display it.  If you're
thinking of using it for any other purpose, it is quite likely that
you're making a mistake.  Think: what do you want to do when the
command is called from a keyboard macro?"
  (declare (advertised-calling-convention (kind) "23.1"))
  (when (not (and (eq kind 'interactive)
                  (or executing-kbd-macro noninteractive)))
    (let* ((i 1) ;; 0 is the called-interactively-p frame.
           frame nextframe
           (get-next-frame
            (lambda ()
              (setq frame nextframe)
              (setq nextframe (backtrace-frame i 'called-interactively-p))
              ;; (message "Frame %d = %S" i nextframe)
              (setq i (1+ i)))))
      (funcall get-next-frame) ;; Get the first frame.
      (while
          ;; FIXME: The edebug and advice handling should be made modular and
          ;; provided directly by edebug.el and nadvice.el.
          (progn
            ;; frame    =(backtrace-frame i-2)
            ;; nextframe=(backtrace-frame i-1)
            (funcall get-next-frame)
            ;; `pcase' would be a fairly good fit here, but it sometimes moves
            ;; branches within local functions, which then messes up the
            ;; `backtrace-frame' data we get,
            (or
             ;; Skip special forms (from non-compiled code).
             (and frame (null (car frame)))
             ;; Skip also `interactive-p' (because we don't want to know if
             ;; interactive-p was called interactively but if it's caller was)
             ;; and `byte-code' (idem; this appears in subexpressions of things
             ;; like condition-case, which are wrapped in a separate bytecode
             ;; chunk).
             ;; FIXME: For lexical-binding code, this is much worse,
             ;; because the frames look like "byte-code -> funcall -> #[...]",
             ;; which is not a reliable signature.
             (memq (nth 1 frame) '(interactive-p 'byte-code))
             ;; Skip package-specific stack-frames.
             (let ((skip (run-hook-with-args-until-success
                          'called-interactively-p-functions
                          i frame nextframe)))
               (pcase skip
                 (`nil nil)
                 (`0 t)
                 (_ (setq i (+ i skip -1)) (funcall get-next-frame)))))))
      ;; Now `frame' should be "the function from which we were called".
      (pcase (cons frame nextframe)
        ;; No subr calls `interactive-p', so we can rule that out.
        (`((,_ ,(pred (lambda (f) (subrp (indirect-function f)))) . ,_) . ,_) nil)
        ;; In case #<subr funcall-interactively> without going through the
        ;; `funcall-interactively' symbol (bug#3984).
        (`(,_ . (t ,(pred (lambda (f)
                            (eq internal--funcall-interactively
                                (indirect-function f))))
                   . ,_))
         t)))))

(defun interactive-p ()
  "Return t if the containing function was run directly by user input.
This means that the function was called with `call-interactively'
\(which includes being called as the binding of a key)
and input is currently coming from the keyboard (not a keyboard macro),
and Emacs is not running in batch mode (`noninteractive' is nil).

The only known proper use of `interactive-p' is in deciding whether to
display a helpful message, or how to display it.  If you're thinking
of using it for any other purpose, it is quite likely that you're
making a mistake.  Think: what do you want to do when the command is
called from a keyboard macro or in batch mode?

To test whether your function was called with `call-interactively',
either (i) add an extra optional argument and give it an `interactive'
spec that specifies non-nil unconditionally (such as \"p\"); or (ii)
use `called-interactively-p'.

To test whether a function can be called interactively, use
`commandp'."
  (declare (obsolete called-interactively-p "23.2"))
  (called-interactively-p 'interactive))

(defun internal-push-keymap (keymap symbol)
  (let ((map (symbol-value symbol)))
    (unless (memq keymap map)
      (unless (memq 'add-keymap-witness (symbol-value symbol))
        (setq map (make-composed-keymap nil (symbol-value symbol)))
        (push 'add-keymap-witness (cdr map))
        (set symbol map))
      (push keymap (cdr map)))))

(defun internal-pop-keymap (keymap symbol)
  (let ((map (symbol-value symbol)))
    (when (memq keymap map)
      (setf (cdr map) (delq keymap (cdr map))))
    (let ((tail (cddr map)))
      (and (or (null tail) (keymapp tail))
           (eq 'add-keymap-witness (nth 1 map))
           (set symbol tail)))))

(define-obsolete-function-alias
  'set-temporary-overlay-map 'set-transient-map "24.4")

(defun set-transient-map (map &optional keep-pred on-exit)
  "Set MAP as a temporary keymap taking precedence over other keymaps.
Normally, MAP is used only once, to look up the very next key.
However, if the optional argument KEEP-PRED is t, MAP stays
active if a key from MAP is used.  KEEP-PRED can also be a
function of no arguments: it is called from `pre-command-hook' and
if it returns non-nil, then MAP stays active.

Optional arg ON-EXIT, if non-nil, specifies a function that is
called, with no arguments, after MAP is deactivated.

This uses `overriding-terminal-local-map' which takes precedence over all other
keymaps.  As usual, if no match for a key is found in MAP, the normal key
lookup sequence then continues.

This returns an \"exit function\", which can be called with no argument
to deactivate this transient map, regardless of KEEP-PRED."
  (let* ((clearfun (make-symbol "clear-transient-map"))
         (exitfun
          (lambda ()
            (internal-pop-keymap map 'overriding-terminal-local-map)
            (remove-hook 'pre-command-hook clearfun)
            (when on-exit (funcall on-exit)))))
    ;; Don't use letrec, because equal (in add/remove-hook) would get trapped
    ;; in a cycle.
    (fset clearfun
          (lambda ()
            (with-demoted-errors "set-transient-map PCH: %S"
              (unless (cond
                       ((null keep-pred) nil)
                       ((and (not (eq map (cadr overriding-terminal-local-map)))
                             (memq map (cddr overriding-terminal-local-map)))
                        ;; There's presumably some other transient-map in
                        ;; effect.  Wait for that one to terminate before we
                        ;; remove ourselves.
                        ;; For example, if isearch and C-u both use transient
                        ;; maps, then the lifetime of the C-u should be nested
                        ;; within isearch's, so the pre-command-hook of
                        ;; isearch should be suspended during the C-u one so
                        ;; we don't exit isearch just because we hit 1 after
                        ;; C-u and that 1 exits isearch whereas it doesn't
                        ;; exit C-u.
                        t)
                       ((eq t keep-pred)
                        (let ((mc (lookup-key map (this-command-keys-vector))))
                          ;; If the key is unbound `this-command` is
                          ;; nil and so is `mc`.
                          (and mc (eq this-command mc))))
                       (t (funcall keep-pred)))
                (funcall exitfun)))))
    (add-hook 'pre-command-hook clearfun)
    (internal-push-keymap map 'overriding-terminal-local-map)
    exitfun))

;;;; Progress reporters.

;; Progress reporter has the following structure:
;;
;;      (NEXT-UPDATE-VALUE . [NEXT-UPDATE-TIME
;;                            MIN-VALUE
;;                            MAX-VALUE
;;                            MESSAGE
;;                            MIN-CHANGE
;;                            MIN-TIME])
;;
;; This weirdness is for optimization reasons: we want
;; `progress-reporter-update' to be as fast as possible, so
;; `(car reporter)' is better than `(aref reporter 0)'.
;;
;; NEXT-UPDATE-TIME is a float.  While `float-time' loses a couple
;; digits of precision, it doesn't really matter here.  On the other
;; hand, it greatly simplifies the code.

(defsubst progress-reporter-update (reporter &optional value)
  "Report progress of an operation in the echo area.
REPORTER should be the result of a call to `make-progress-reporter'.

If REPORTER is a numerical progress reporter---i.e. if it was
 made using non-nil MIN-VALUE and MAX-VALUE arguments to
 `make-progress-reporter'---then VALUE should be a number between
 MIN-VALUE and MAX-VALUE.

If REPORTER is a non-numerical reporter, VALUE should be nil.

This function is relatively inexpensive.  If the change since
last update is too small or insufficient time has passed, it does
nothing."
  (when (or (not (numberp value))      ; For pulsing reporter
            (>= value (car reporter))) ; For numerical reporter
    (progress-reporter-do-update reporter value)))

(defun make-progress-reporter (message &optional min-value max-value
                                       current-value min-change min-time)
  "Return progress reporter object for use with `progress-reporter-update'.

MESSAGE is shown in the echo area, with a status indicator
appended to the end.  When you call `progress-reporter-done', the
word \"done\" is printed after the MESSAGE.  You can change the
MESSAGE of an existing progress reporter by calling
`progress-reporter-force-update'.

MIN-VALUE and MAX-VALUE, if non-nil, are starting (0% complete)
and final (100% complete) states of operation; the latter should
be larger.  In this case, the status message shows the percentage
progress.

If MIN-VALUE and/or MAX-VALUE is omitted or nil, the status
message shows a \"spinning\", non-numeric indicator.

Optional CURRENT-VALUE is the initial progress; the default is
MIN-VALUE.
Optional MIN-CHANGE is the minimal change in percents to report;
the default is 1%.
CURRENT-VALUE and MIN-CHANGE do not have any effect if MIN-VALUE
and/or MAX-VALUE are nil.

Optional MIN-TIME specifies the minimum interval time between
echo area updates (default is 0.2 seconds.)  If the OS is not
capable of measuring fractions of seconds, this parameter is
effectively rounded up."
  (when (string-match "[[:alnum:]]\\'" message)
    (setq message (concat message "...")))
  (unless min-time
    (setq min-time 0.2))
  (let ((reporter
         ;; Force a call to `message' now
         (cons (or min-value 0)
               (vector (if (>= min-time 0.02)
                           (float-time) nil)
                       min-value
                       max-value
                       message
                       (if min-change (max (min min-change 50) 1) 1)
                       min-time))))
    (progress-reporter-update reporter (or current-value min-value))
    reporter))

(defun progress-reporter-force-update (reporter &optional value new-message)
  "Report progress of an operation in the echo area unconditionally.

The first two arguments are the same as in `progress-reporter-update'.
NEW-MESSAGE, if non-nil, sets a new message for the reporter."
  (let ((parameters (cdr reporter)))
    (when new-message
      (aset parameters 3 new-message))
    (when (aref parameters 0)
      (aset parameters 0 (float-time)))
    (progress-reporter-do-update reporter value)))

(defvar progress-reporter--pulse-characters ["-" "\\" "|" "/"]
  "Characters to use for pulsing progress reporters.")

(defun progress-reporter-do-update (reporter value)
  (let* ((parameters   (cdr reporter))
         (update-time  (aref parameters 0))
         (min-value    (aref parameters 1))
         (max-value    (aref parameters 2))
         (text         (aref parameters 3))
         (enough-time-passed
          ;; See if enough time has passed since the last update.
          (or (not update-time)
              (when (>= (float-time) update-time)
                ;; Calculate time for the next update
                (aset parameters 0 (+ update-time (aref parameters 5)))))))
    (cond ((and min-value max-value)
           ;; Numerical indicator
           (let* ((one-percent (/ (- max-value min-value) 100.0))
                  (percentage  (if (= max-value min-value)
                                   0
                                 (truncate (/ (- value min-value)
                                              one-percent)))))
             ;; Calculate NEXT-UPDATE-VALUE.  If we are not printing
             ;; message because not enough time has passed, use 1
             ;; instead of MIN-CHANGE.  This makes delays between echo
             ;; area updates closer to MIN-TIME.
             (setcar reporter
                     (min (+ min-value (* (+ percentage
                                             (if enough-time-passed
                                                 ;; MIN-CHANGE
                                                 (aref parameters 4)
                                               1))
                                          one-percent))
                          max-value))
             (when (integerp value)
               (setcar reporter (ceiling (car reporter))))
             ;; Only print message if enough time has passed
             (when enough-time-passed
               (if (> percentage 0)
                   (message "%s%d%%" text percentage)
                 (message "%s" text)))))
          ;; Pulsing indicator
          (enough-time-passed
           (let ((index (mod (1+ (car reporter)) 4))
                 (message-log-max nil))
             (setcar reporter index)
             (message "%s %s"
                      text
                      (aref progress-reporter--pulse-characters
                            index)))))))

(defun progress-reporter-done (reporter)
  "Print reporter's message followed by word \"done\" in echo area."
  (message "%sdone" (aref (cdr reporter) 3)))

(defmacro dotimes-with-progress-reporter (spec message &rest body)
  "Loop a certain number of times and report progress in the echo area.
Evaluate BODY with VAR bound to successive integers running from
0, inclusive, to COUNT, exclusive.  Then evaluate RESULT to get
the return value (nil if RESULT is omitted).

At each iteration MESSAGE followed by progress percentage is
printed in the echo area.  After the loop is finished, MESSAGE
followed by word \"done\" is printed.  This macro is a
convenience wrapper around `make-progress-reporter' and friends.

\(fn (VAR COUNT [RESULT]) MESSAGE BODY...)"
  (declare (indent 2) (debug ((symbolp form &optional form) form body)))
  (let ((temp (make-symbol "--dotimes-temp--"))
        (temp2 (make-symbol "--dotimes-temp2--"))
        (start 0)
        (end (nth 1 spec)))
    `(let ((,temp ,end)
           (,(car spec) ,start)
           (,temp2 (make-progress-reporter ,message ,start ,end)))
       (while (< ,(car spec) ,temp)
         ,@body
         (progress-reporter-update ,temp2
                                   (setq ,(car spec) (1+ ,(car spec)))))
       (progress-reporter-done ,temp2)
       nil ,@(cdr (cdr spec)))))

\f
;;;; Comparing version strings.

(defconst version-separator "."
  "Specify the string used to separate the version elements.

Usually the separator is \".\", but it can be any other string.")


(defconst version-regexp-alist
  '(("^[-._+ ]?snapshot$"                                 . -4)
    ;; treat "1.2.3-20050920" and "1.2-3" as snapshot releases
    ("^[-._+]$"                                           . -4)
    ;; treat "1.2.3-CVS" as snapshot release
    ("^[-._+ ]?\\(cvs\\|git\\|bzr\\|svn\\|hg\\|darcs\\)$" . -4)
    ("^[-._+ ]?alpha$"                                    . -3)
    ("^[-._+ ]?beta$"                                     . -2)
    ("^[-._+ ]?\\(pre\\|rc\\)$"                           . -1))
  "Specify association between non-numeric version and its priority.

This association is used to handle version string like \"1.0pre2\",
\"0.9alpha1\", etc.  It's used by `version-to-list' (which see) to convert the
non-numeric part of a version string to an integer.  For example:

   String Version    Integer List Version
   \"0.9snapshot\"     (0  9 -4)
   \"1.0-git\"         (1  0 -4)
   \"1.0.cvs\"         (1  0 -4)
   \"1.0pre2\"         (1  0 -1 2)
   \"1.0PRE2\"         (1  0 -1 2)
   \"22.8beta3\"       (22 8 -2 3)
   \"22.8 Beta3\"      (22 8 -2 3)
   \"0.9alpha1\"       (0  9 -3 1)
   \"0.9AlphA1\"       (0  9 -3 1)
   \"0.9 alpha\"       (0  9 -3)

Each element has the following form:

   (REGEXP . PRIORITY)

Where:

REGEXP          regexp used to match non-numeric part of a version string.
                It should begin with the `^' anchor and end with a `$' to
                prevent false hits.  Letter-case is ignored while matching
                REGEXP.

PRIORITY        a negative integer specifying non-numeric priority of REGEXP.")


(defun version-to-list (ver)
  "Convert version string VER into a list of integers.

The version syntax is given by the following EBNF:

   VERSION ::= NUMBER ( SEPARATOR NUMBER )*.

   NUMBER ::= (0|1|2|3|4|5|6|7|8|9)+.

   SEPARATOR ::= `version-separator' (which see)
               | `version-regexp-alist' (which see).

The NUMBER part is optional if SEPARATOR is a match for an element
in `version-regexp-alist'.

Examples of valid version syntax:

   1.0pre2   1.0.7.5   22.8beta3   0.9alpha1   6.9.30Beta   2.4.snapshot   .5

Examples of invalid version syntax:

   1.0prepre2   1.0..7.5   22.8X3   alpha3.2

Examples of version conversion:

   Version String    Version as a List of Integers
   \".5\"              (0 5)
   \"0.9 alpha\"       (0  9 -3)
   \"0.9AlphA1\"       (0  9 -3 1)
   \"0.9snapshot\"     (0  9 -4)
   \"1.0-git\"         (1  0 -4)
   \"1.0.7.5\"         (1  0  7 5)
   \"1.0.cvs\"         (1  0 -4)
   \"1.0PRE2\"         (1  0 -1 2)
   \"1.0pre2\"         (1  0 -1 2)
   \"22.8 Beta3\"      (22 8 -2 3)
   \"22.8beta3\"       (22 8 -2 3)

See documentation for `version-separator' and `version-regexp-alist'."
  (unless (stringp ver)
    (error "Version must be a string"))
  ;; Change .x.y to 0.x.y
  (if (and (>= (length ver) (length version-separator))
           (string-equal (substring ver 0 (length version-separator))
                         version-separator))
      (setq ver (concat "0" ver)))
  (unless (string-match-p "^[0-9]" ver)
    (error "Invalid version syntax: `%s' (must start with a number)" ver))

  (save-match-data
    (let ((i 0)
          (case-fold-search t)          ; ignore case in matching
          lst s al)
      ;; Parse the version-string up to a separator until there are none left
      (while (and (setq s (string-match "[0-9]+" ver i))
                  (= s i))
        ;; Add the numeric part to the beginning of the version list;
        ;; lst gets reversed at the end
        (setq lst (cons (string-to-number (substring ver i (match-end 0)))
                        lst)
              i   (match-end 0))
        ;; handle non-numeric part
        (when (and (setq s (string-match "[^0-9]+" ver i))
                   (= s i))
          (setq s (substring ver i (match-end 0))
                i (match-end 0))
          ;; handle alpha, beta, pre, etc. separator
          (unless (string= s version-separator)
            (setq al version-regexp-alist)
            (while (and al (not (string-match (caar al) s)))
              (setq al (cdr al)))
            (cond (al
                   (push (cdar al) lst))
        ;; Convert 22.3a to 22.3.1, 22.3b to 22.3.2, etc., but only if
        ;; the letter is the end of the version-string, to avoid
        ;; 22.8X3 being valid
        ((and (string-match "^[-._+ ]?\\([a-zA-Z]\\)$" s)
           (= i (length ver)))
                   (push (- (aref (downcase (match-string 1 s)) 0) ?a -1)
                         lst))
                  (t (error "Invalid version syntax: `%s'" ver))))))
    (nreverse lst))))

(defun version-list-< (l1 l2)
  "Return t if L1, a list specification of a version, is lower than L2.

Note that a version specified by the list (1) is equal to (1 0),
\(1 0 0), (1 0 0 0), etc.  That is, the trailing zeros are insignificant.
Also, a version given by the list (1) is higher than (1 -1), which in
turn is higher than (1 -2), which is higher than (1 -3)."
  (while (and l1 l2 (= (car l1) (car l2)))
    (setq l1 (cdr l1)
          l2 (cdr l2)))
  (cond
   ;; l1 not null and l2 not null
   ((and l1 l2) (< (car l1) (car l2)))
   ;; l1 null and l2 null         ==> l1 length = l2 length
   ((and (null l1) (null l2)) nil)
   ;; l1 not null and l2 null     ==> l1 length > l2 length
   (l1 (< (version-list-not-zero l1) 0))
   ;; l1 null and l2 not null     ==> l2 length > l1 length
   (t  (< 0 (version-list-not-zero l2)))))


(defun version-list-= (l1 l2)
  "Return t if L1, a list specification of a version, is equal to L2.

Note that a version specified by the list (1) is equal to (1 0),
\(1 0 0), (1 0 0 0), etc.  That is, the trailing zeros are insignificant.
Also, a version given by the list (1) is higher than (1 -1), which in
turn is higher than (1 -2), which is higher than (1 -3)."
  (while (and l1 l2 (= (car l1) (car l2)))
    (setq l1 (cdr l1)
          l2 (cdr l2)))
  (cond
   ;; l1 not null and l2 not null
   ((and l1 l2) nil)
   ;; l1 null and l2 null     ==> l1 length = l2 length
   ((and (null l1) (null l2)))
   ;; l1 not null and l2 null ==> l1 length > l2 length
   (l1 (zerop (version-list-not-zero l1)))
   ;; l1 null and l2 not null ==> l2 length > l1 length
   (t  (zerop (version-list-not-zero l2)))))


(defun version-list-<= (l1 l2)
  "Return t if L1, a list specification of a version, is lower or equal to L2.

Note that integer list (1) is equal to (1 0), (1 0 0), (1 0 0 0),
etc.  That is, the trailing zeroes are insignificant.  Also, integer
list (1) is greater than (1 -1) which is greater than (1 -2)
which is greater than (1 -3)."
  (while (and l1 l2 (= (car l1) (car l2)))
    (setq l1 (cdr l1)
          l2 (cdr l2)))
  (cond
   ;; l1 not null and l2 not null
   ((and l1 l2) (< (car l1) (car l2)))
   ;; l1 null and l2 null     ==> l1 length = l2 length
   ((and (null l1) (null l2)))
   ;; l1 not null and l2 null ==> l1 length > l2 length
   (l1 (<= (version-list-not-zero l1) 0))
   ;; l1 null and l2 not null ==> l2 length > l1 length
   (t  (<= 0 (version-list-not-zero l2)))))

(defun version-list-not-zero (lst)
  "Return the first non-zero element of LST, which is a list of integers.

If all LST elements are zeros or LST is nil, return zero."
  (while (and lst (zerop (car lst)))
    (setq lst (cdr lst)))
  (if lst
      (car lst)
    ;; there is no element different of zero
    0))


(defun version< (v1 v2)
  "Return t if version V1 is lower (older) than V2.

Note that version string \"1\" is equal to \"1.0\", \"1.0.0\", \"1.0.0.0\",
etc.  That is, the trailing \".0\"s are insignificant.  Also, version
string \"1\" is higher (newer) than \"1pre\", which is higher than \"1beta\",
which is higher than \"1alpha\", which is higher than \"1snapshot\".
Also, \"-GIT\", \"-CVS\" and \"-NNN\" are treated as snapshot versions."
  (version-list-< (version-to-list v1) (version-to-list v2)))

(defun version<= (v1 v2)
  "Return t if version V1 is lower (older) than or equal to V2.

Note that version string \"1\" is equal to \"1.0\", \"1.0.0\", \"1.0.0.0\",
etc.  That is, the trailing \".0\"s are insignificant.  Also, version
string \"1\" is higher (newer) than \"1pre\", which is higher than \"1beta\",
which is higher than \"1alpha\", which is higher than \"1snapshot\".
Also, \"-GIT\", \"-CVS\" and \"-NNN\" are treated as snapshot versions."
  (version-list-<= (version-to-list v1) (version-to-list v2)))

(defun version= (v1 v2)
  "Return t if version V1 is equal to V2.

Note that version string \"1\" is equal to \"1.0\", \"1.0.0\", \"1.0.0.0\",
etc.  That is, the trailing \".0\"s are insignificant.  Also, version
string \"1\" is higher (newer) than \"1pre\", which is higher than \"1beta\",
which is higher than \"1alpha\", which is higher than \"1snapshot\".
Also, \"-GIT\", \"-CVS\" and \"-NNN\" are treated as snapshot versions."
  (version-list-= (version-to-list v1) (version-to-list v2)))

(defvar package--builtin-versions
  ;; Mostly populated by loaddefs.el via autoload-builtin-package-versions.
  (purecopy `((emacs . ,(version-to-list emacs-version))))
  "Alist giving the version of each versioned builtin package.
I.e. each element of the list is of the form (NAME . VERSION) where
NAME is the package name as a symbol, and VERSION is its version
as a list.")

(defun package--description-file (dir)
  (concat (let ((subdir (file-name-nondirectory
                         (directory-file-name dir))))
            (if (string-match "\\([^.].*?\\)-\\([0-9]+\\(?:[.][0-9]+\\|\\(?:pre\\|beta\\|alpha\\)[0-9]+\\)*\\)" subdir)
                (match-string 1 subdir) subdir))
          "-pkg.el"))

\f
;;; Thread support.

(defmacro with-mutex (mutex &rest body)
  "Invoke BODY with MUTEX held, releasing MUTEX when done.
This is the simplest safe way to acquire and release a mutex."
  (declare (indent 1) (debug t))
  (let ((sym (make-symbol "mutex")))
    `(let ((,sym ,mutex))
       (mutex-lock ,sym)
       (unwind-protect
           (progn ,@body)
         (mutex-unlock ,sym)))))

\f
;;; Misc.

(defvar definition-prefixes (make-hash-table :test 'equal)
  "Hash table mapping prefixes to the files in which they're used.
This can be used to automatically fetch not-yet-loaded definitions.
More specifically, if there is a value of the form (FILES...) for a string PREFIX
it means that the FILES define variables or functions with names that start
with PREFIX.

Note that it does not imply that all definitions starting with PREFIX can
be found in those files.  E.g. if prefix is \"gnus-article-\" there might
still be definitions of the form \"gnus-article-toto-titi\" in other files, which would
presumably appear in this table under another prefix such as \"gnus-\"
or \"gnus-article-toto-\".")

(defun register-definition-prefixes (file prefixes)
  "Register that FILE uses PREFIXES."
  (dolist (prefix prefixes)
    (puthash prefix (cons file (gethash prefix definition-prefixes))
             definition-prefixes)))

(defconst menu-bar-separator '("--")
  "Separator for menus.")

;; The following statement ought to be in print.c, but `provide' can't
;; be used there.
;; https://lists.gnu.org/r/emacs-devel/2009-08/msg00236.html
(when (hash-table-p (car (read-from-string
                          (prin1-to-string (make-hash-table)))))
  (provide 'hashtable-print-readable))

;; This is used in lisp/Makefile.in and in leim/Makefile.in to
;; generate file names for autoloads, custom-deps, and finder-data.
(defun unmsys--file-name (file)
  "Produce the canonical file name for FILE from its MSYS form.

On systems other than MS-Windows, just returns FILE.
On MS-Windows, converts /d/foo/bar form of file names
passed by MSYS Make into d:/foo/bar that Emacs can grok.

This function is called from lisp/Makefile and leim/Makefile."
  (when (and (eq system-type 'windows-nt)
             (string-match "\\`/[a-zA-Z]/" file))
    (setq file (concat (substring file 1 2) ":" (substring file 2))))
  file)


;;; subr.el ends here