lisp/emacs-lisp/pp.el

   1 ;;; pp.el --- pretty printer for Emacs Lisp
   2
   3 ;; Copyright (C) 1989, 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Randal Schwartz <merlyn@stonehenge.com>
   6
   7 ;; This file is part of GNU Emacs.
   8
   9 ;; GNU Emacs is free software; you can redistribute it and/or modify
  10 ;; it under the terms of the GNU General Public License as published by
  11 ;; the Free Software Foundation; either version 2, or (at your option)
  12 ;; any later version.
  13
  14 ;; GNU Emacs is distributed in the hope that it will be useful,
  15 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  16 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17 ;; GNU General Public License for more details.
  18
  19 ;; You should have received a copy of the GNU General Public License
  20 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  21 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  22 ;; Boston, MA 02111-1307, USA.
  23
  24 ;;; Code:
  25
  26 (defvar pp-escape-newlines t
  27   "*Value of print-escape-newlines used by pp-* functions.")
  28
  29 (defun pp-to-string (object)
  30   "Return a string containing the pretty-printed representation of OBJECT,
  31 any Lisp object.  Quoting characters are used when needed to make output
  32 that `read' can handle, whenever this is possible."
  33   (save-excursion
  34     (set-buffer (generate-new-buffer " pp-to-string"))
  35     (unwind-protect
  36         (progn
  37           (lisp-mode-variables nil)
  38           (set-syntax-table emacs-lisp-mode-syntax-table)
  39           (let ((print-escape-newlines pp-escape-newlines))
  40             (prin1 object (current-buffer)))
  41           (goto-char (point-min))
  42           (while (not (eobp))
  43             ;; (message "%06d" (- (point-max) (point)))
  44             (cond
  45              ((looking-at "\\s(\\|#\\s(")
  46               (while (looking-at "\\s(\\|#\\s(")
  47                 (forward-char 1)))
  48              ((and (looking-at "\\(quote[ \t]+\\)\\([^.)]\\)")
  49                    (> (match-beginning 1) 1)
  50                    (= ?\( (char-after (1- (match-beginning 1))))
  51                    ;; Make sure this is a two-element list.
  52                    (save-excursion
  53                      (goto-char (match-beginning 2))
  54                      (forward-sexp)
  55                      ;; (looking-at "[ \t]*\)")
  56                      ;; Avoid mucking with match-data; does this test work?
  57                      (char-equal ?\) (char-after (point)))))
  58               ;; -1 gets the paren preceding the quote as well.
  59               (delete-region (1- (match-beginning 1)) (match-end 1))
  60               (insert "'")
  61               (forward-sexp 1)
  62               (if (looking-at "[ \t]*\)")
  63                   (delete-region (match-beginning 0) (match-end 0))
  64                 (error "Malformed quote"))
  65               (backward-sexp 1))
  66              ((condition-case err-var
  67                   (prog1 t (down-list 1))
  68                 (error nil))
  69               (backward-char 1)
  70               (skip-chars-backward " \t")
  71               (delete-region
  72                (point)
  73                (progn (skip-chars-forward " \t") (point)))
  74               (if (not (char-equal ?' (char-after (1- (point)))))
  75                   (insert ?\n)))
  76              ((condition-case err-var
  77                   (prog1 t (up-list 1))
  78                 (error nil))
  79               (while (looking-at "\\s)")
  80                 (forward-char 1))
  81               (skip-chars-backward " \t")
  82               (delete-region
  83                (point)
  84                (progn (skip-chars-forward " \t") (point)))
  85               (if (not (char-equal ?' (char-after (1- (point)))))
  86                   (insert ?\n)))
  87              (t (goto-char (point-max)))))
  88           (goto-char (point-min))
  89           (indent-sexp)
  90           (buffer-string))
  91       (kill-buffer (current-buffer)))))
  92
  93 ;;;###autoload
  94 (defun pp (object &optional stream)
  95   "Output the pretty-printed representation of OBJECT, any Lisp object.
  96 Quoting characters are printed when needed to make output that `read'
  97 can handle, whenever this is possible.
  98 Output stream is STREAM, or value of `standard-output' (which see)."
  99   (princ (pp-to-string object) (or stream standard-output)))
 100
 101 ;;;###autoload
 102 (defun pp-eval-expression (expression)
 103   "Evaluate EXPRESSION and pretty-print value into a new display buffer.
 104 If the pretty-printed value fits on one line, the message line is used
 105 instead.  Value is also consed on to front of variable  values 's
 106 value."
 107   (interactive "xPp-eval: ")
 108   (setq values (cons (eval expression) values))
 109   (let* ((old-show-function temp-buffer-show-function)
 110          ;; Use this function to display the buffer.
 111          ;; This function either decides not to display it at all
 112          ;; or displays it in the usual way.
 113          (temp-buffer-show-function
 114           (function
 115            (lambda (buf)
 116              (save-excursion
 117                (set-buffer buf)
 118                (goto-char (point-min))
 119                (end-of-line 1)
 120                (if (or (< (1+ (point)) (point-max))
 121                        (>= (- (point) (point-min)) (frame-width)))
 122                    (let ((temp-buffer-show-function old-show-function)
 123                          (old-selected (selected-window))
 124                          (window (display-buffer buf)))
 125                      (goto-char (point-min)) ; expected by some hooks ...
 126                      (make-frame-visible (window-frame window))
 127                      (unwind-protect
 128                          (progn
 129                            (select-window window)
 130                            (run-hooks 'temp-buffer-show-hook))
 131                        (select-window old-selected)))
 132                  (message "%s" (buffer-substring (point-min) (point)))
 133                  ))))))
 134     (with-output-to-temp-buffer "*Pp Eval Output*"
 135       (pp (car values)))
 136     (save-excursion
 137       (set-buffer "*Pp Eval Output*")
 138       (emacs-lisp-mode)
 139       (make-local-variable 'font-lock-verbose)
 140       (setq font-lock-verbose nil))))
 141
 142 ;;;###autoload
 143 (defun pp-eval-last-sexp (arg)
 144   "Run `pp-eval-expression' on sexp before point (which see).
 145 With argument, pretty-print output into current buffer.
 146 Ignores leading comment characters."
 147   (interactive "P")
 148   (let ((stab (syntax-table)) (pt (point)) start exp)
 149     (set-syntax-table emacs-lisp-mode-syntax-table)
 150     (save-excursion
 151       (forward-sexp -1)
 152       ;; If first line is commented, ignore all leading comments:
 153       (if (save-excursion (beginning-of-line) (looking-at "[ \t]*;"))
 154           (progn
 155             (setq exp (buffer-substring (point) pt))
 156             (while (string-match "\n[ \t]*;+" exp start)
 157               (setq start (1+ (match-beginning 0))
 158                     exp (concat (substring exp 0 start)
 159                                 (substring exp (match-end 0)))))
 160             (setq exp (read exp)))
 161         (setq exp (read (current-buffer)))))
 162     (set-syntax-table stab)
 163     (if arg
 164         (insert (pp-to-string (eval exp)))
 165       (pp-eval-expression exp))))
 166
 167 ;;; Test cases for quote
 168 ;; (pp-eval-expression ''(quote quote))
 169 ;; (pp-eval-expression ''((quote a) (quote b)))
 170 ;; (pp-eval-expression ''('a 'b))       ; same as above
 171 ;; (pp-eval-expression ''((quote (quote quote)) (quote quote)))
 172 ;; These do not satisfy the quote test.
 173 ;; (pp-eval-expression ''quote)
 174 ;; (pp-eval-expression ''(quote))
 175 ;; (pp-eval-expression ''(quote . quote))
 176 ;; (pp-eval-expression ''(quote a b))
 177 ;; (pp-eval-expression ''(quotefoo))
 178 ;; (pp-eval-expression ''(a b))
 179
 180 (provide 'pp)                           ; so (require 'pp) works
 181
 182 ;;; pp.el ends here.