lisp/emacs-lisp/eval-reg.el

   1 ;;; eval-reg.el --- Redefine eval-region, and subrs that use it, in Lisp
   2
   3 ;; Copyright (C) 1994, 1996 Daniel LaLiberte
   4
   5 ;; Author: Daniel LaLiberte <liberte@cs.uiuc.edu>
   6 ;; Keywords: lisp
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;; eval-region, eval-buffer, and eval-current-buffer are redefined in
  28 ;; Lisp to allow customizations by Lisp code.  eval-region calls
  29 ;; `read', `eval', and `prin1', so Lisp replacements of these
  30 ;; functions will affect eval-region and anything else that calls it.
  31 ;; eval-buffer and eval-current-buffer are redefined in Lisp to call
  32 ;; eval-region on the buffer.
  33
  34 ;; Because of dynamic binding, all local variables are protected from
  35 ;; being seen by eval by giving them funky names.  But variables in
  36 ;; routines that call eval-region are similarly exposed.
  37
  38 ;; Perhaps this should be one of several files in an `elisp' package
  39 ;; that replaces Emacs Lisp subroutines with Lisp versions of the
  40 ;; same.
  41
  42 ;; Eval-region may be installed, after loading, by calling:
  43 ;; (elisp-eval-region-install).  Installation can be undone with:
  44 ;; (elisp-eval-region-uninstall).
  45
  46 ;;; Code:
  47
  48 '(defpackage "elisp-eval-region"
  49    (:nicknames "elisp")
  50    (:use "elisp")
  51    (:export
  52     elisp-eval-region-install
  53     elisp-eval-region-uninstall
  54     elisp-eval-region-level
  55     with-elisp-eval-region
  56     eval-region
  57     eval-buffer
  58     eval-current-buffer
  59     ))
  60 '(in-package elisp-eval-region)
  61
  62 ;; Save standard versions.
  63 (if (not (fboundp 'original-eval-region))
  64     (defalias 'original-eval-region (symbol-function 'eval-region)))
  65 (if (not (fboundp 'original-eval-buffer))
  66     (defalias 'original-eval-buffer
  67           (if (fboundp 'eval-buffer)  ;; only in Emacs 19
  68               (symbol-function 'eval-buffer)
  69             'undefined)))
  70 (if (not (fboundp 'original-eval-current-buffer))
  71     (defalias 'original-eval-current-buffer
  72           (symbol-function 'eval-current-buffer)))
  73
  74 (defvar elisp-eval-region-level 0
  75   "If the value is 0, use the original version of `elisp-eval-region'.
  76 Callers of `elisp-eval-region' should increment `elisp-eval-region-level'
  77 while the Lisp version should be used.  Installing `elisp-eval-region'
  78 increments it once, and uninstalling decrements it.")
  79
  80 ;; Installing and uninstalling should always be used in pairs,
  81 ;; or just install once and never uninstall.
  82 (defun elisp-eval-region-install ()
  83   (interactive)
  84   (defalias 'eval-region 'elisp-eval-region)
  85   (defalias 'eval-buffer 'elisp-eval-buffer)
  86   (defalias 'eval-current-buffer 'elisp-eval-current-buffer)
  87   (setq elisp-eval-region-level (1+ elisp-eval-region-level)))
  88
  89 (defun elisp-eval-region-uninstall ()
  90   (interactive)
  91   (if (> 1 elisp-eval-region-level)
  92       (setq elisp-eval-region-level (1- elisp-eval-region-level))
  93     (setq elisp-eval-region-level 0)
  94     (defalias 'eval-region (symbol-function 'original-eval-region))
  95     (defalias 'eval-buffer (symbol-function 'original-eval-buffer))
  96     (defalias 'eval-current-buffer
  97       (symbol-function 'original-eval-current-buffer))
  98     ))
  99
 100 (put 'with-elisp-eval-region 'lisp-indent-function 1)
 101 (put 'with-elisp-eval-region 'lisp-indent-hook 1)
 102 (put 'with-elisp-eval-region 'edebug-form-spec t)
 103
 104 (defmacro with-elisp-eval-region (flag &rest body)
 105   "If FLAG is nil, decrement `eval-region-level' while executing BODY.
 106 The effect of decrementing all the way to zero is that `eval-region'
 107 will use the original `eval-region', which may be the Emacs subr or some
 108 previous redefinition.  Before calling this macro, this package should
 109 already have been installed, using `elisp-eval-region-install', which
 110 increments the count once.  So if another package still requires the
 111 Lisp version of the code, the count will still be non-zero.
 112
 113 The count is not bound locally by this macro, so changes by BODY to
 114 its value will not be lost."
 115   (` (let ((elisp-code (function (lambda () (,@ body)))))
 116        (if (not (, flag))
 117            (unwind-protect
 118                (progn
 119                  (setq elisp-eval-region-level (1- elisp-eval-region-level))
 120                  (funcall elisp-code))
 121              (setq elisp-eval-region-level (1+ elisp-eval-region-level)))
 122          (funcall elisp-code)))))
 123
 124
 125 (defun elisp-eval-region (elisp-start elisp-end &optional elisp-output)
 126   "Execute the region as Lisp code.
 127 When called from programs, expects two arguments,
 128 giving starting and ending indices in the current buffer
 129 of the text to be executed.
 130 Programs can pass third argument PRINTFLAG which controls printing of output:
 131 nil means discard it; anything else is stream for print.
 132
 133 This version, from `eval-reg.el', allows Lisp customization of read,
 134 eval, and the printer."
 135
 136   ;; Because this doesn't narrow to the region, one other difference
 137   ;; concerns inserting whitespace after the expression being evaluated.
 138
 139   (interactive "r")
 140   (if (= 0 elisp-eval-region-level)
 141       (original-eval-region elisp-start elisp-end elisp-output)
 142     (let ((elisp-pnt (point))
 143           (elisp-buf (current-buffer));; Outside buffer
 144           (elisp-inside-buf (current-buffer));; Buffer current while evalling
 145           ;; Mark the end because it may move.
 146           (elisp-end-marker (set-marker (make-marker) elisp-end))
 147           elisp-form
 148           elisp-val)
 149       (goto-char elisp-start)
 150       (elisp-skip-whitespace)
 151       (while (< (point) elisp-end-marker)
 152         (setq elisp-form (read elisp-buf))
 153
 154         (let ((elisp-current-buffer (current-buffer)))
 155           ;; Restore the inside current-buffer.
 156           (set-buffer elisp-inside-buf)
 157           (setq elisp-val (eval elisp-form))
 158           ;; Remember current buffer for next time.
 159           (setq elisp-inside-buf (current-buffer))
 160           ;; Should this be protected?
 161           (set-buffer elisp-current-buffer))
 162
 163         (if elisp-output
 164             (let ((standard-output (or elisp-output t)))
 165               (setq values (cons elisp-val values))
 166               (if (eq standard-output t)
 167                   (prin1 elisp-val)
 168                 (princ "\n")
 169                 (prin1 elisp-val)
 170                 (princ "\n")
 171                 )))
 172         (goto-char (min (max elisp-end-marker (point))
 173                         (progn (elisp-skip-whitespace) (point))))
 174         )                               ; while
 175       (if elisp-output nil
 176         ;; like save-excursion recovery, but done only if no error occurs
 177         ;; but mark is not restored
 178         (set-buffer elisp-buf)
 179         (goto-char elisp-pnt))
 180       nil)))
 181
 182
 183 (defun elisp-skip-whitespace ()
 184   ;; Leave point before the next token, skipping white space and comments.
 185   (skip-chars-forward " \t\r\n\f")
 186   (while (= (following-char) ?\;)
 187     (skip-chars-forward "^\n\r")  ; skip the comment
 188     (skip-chars-forward " \t\r\n\f")))
 189
 190
 191 (defun elisp-eval-current-buffer (&optional elisp-output)
 192   "Execute the current buffer as Lisp code.
 193 Programs can pass argument PRINTFLAG which controls printing of output:
 194 nil means discard it; anything else is stream for print.
 195
 196 This version calls `eval-region' on the whole buffer."
 197   ;; The standard eval-current-buffer doesn't use eval-region.
 198   (interactive)
 199   (eval-region (point-min) (point-max) elisp-output))
 200
 201
 202 (defun elisp-eval-buffer (&optional elisp-bufname elisp-printflag)
 203   "Execute BUFFER as Lisp code.  Use current buffer if BUFFER is nil.
 204 Programs can pass argument PRINTFLAG which controls printing of
 205 output: nil means discard it; anything else is stream for print.
 206
 207 This version calls `eval-region' on the whole buffer."
 208   (interactive)
 209   (if (null elisp-bufname)
 210       (setq elisp-bufname (current-buffer)))
 211   (save-excursion
 212     (set-buffer (or (get-buffer elisp-bufname)
 213                     (error "No such buffer: %s" elisp-bufname)))
 214     (eval-region (point-min) (point-max) elisp-printflag)))
 215
 216
 217 (provide 'eval-reg)
 218
 219 ;;; eval-reg.el ends here