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                 (print-quoted t))
  41             (prin1 object (current-buffer)))
  42           (goto-char (point-min))
  43           (while (not (eobp))
  44             ;; (message "%06d" (- (point-max) (point)))
  45             (cond
  46              ((condition-case err-var
  47                   (prog1 t (down-list 1))
  48                 (error nil))
  49               (save-excursion
  50                 (backward-char 1)
  51                 (skip-chars-backward "'`#^")
  52                 (when (and (not (bobp)) (= ?\ (char-before)))
  53                   (delete-char -1)
  54                   (insert "\n"))))
  55              ((condition-case err-var
  56                   (prog1 t (up-list 1))
  57                 (error nil))
  58               (while (looking-at "\\s)")
  59                 (forward-char 1))
  60               (delete-region
  61                (point)
  62                (progn (skip-chars-forward " \t") (point)))
  63               (insert ?\n))
  64              (t (goto-char (point-max)))))
  65           (goto-char (point-min))
  66           (indent-sexp)
  67           (buffer-string))
  68       (kill-buffer (current-buffer)))))
  69
  70 ;;;###autoload
  71 (defun pp (object &optional stream)
  72   "Output the pretty-printed representation of OBJECT, any Lisp object.
  73 Quoting characters are printed when needed to make output that `read'
  74 can handle, whenever this is possible.
  75 Output stream is STREAM, or value of `standard-output' (which see)."
  76   (princ (pp-to-string object) (or stream standard-output)))
  77
  78 ;;;###autoload
  79 (defun pp-eval-expression (expression)
  80   "Evaluate EXPRESSION and pretty-print value into a new display buffer.
  81 If the pretty-printed value fits on one line, the message line is used
  82 instead.  Value is also consed on to front of variable  values 's
  83 value."
  84   (interactive "xPp-eval: ")
  85   (setq values (cons (eval expression) values))
  86   (let* ((old-show-function temp-buffer-show-function)
  87          ;; Use this function to display the buffer.
  88          ;; This function either decides not to display it at all
  89          ;; or displays it in the usual way.
  90          (temp-buffer-show-function
  91           (function
  92            (lambda (buf)
  93              (save-excursion
  94                (set-buffer buf)
  95                (goto-char (point-min))
  96                (end-of-line 1)
  97                (if (or (< (1+ (point)) (point-max))
  98                        (>= (- (point) (point-min)) (frame-width)))
  99                    (let ((temp-buffer-show-function old-show-function)
 100                          (old-selected (selected-window))
 101                          (window (display-buffer buf)))
 102                      (goto-char (point-min)) ; expected by some hooks ...
 103                      (make-frame-visible (window-frame window))
 104                      (unwind-protect
 105                          (progn
 106                            (select-window window)
 107                            (run-hooks 'temp-buffer-show-hook))
 108                        (select-window old-selected)))
 109                  (message "%s" (buffer-substring (point-min) (point)))
 110                  ))))))
 111     (with-output-to-temp-buffer "*Pp Eval Output*"
 112       (pp (car values)))
 113     (save-excursion
 114       (set-buffer "*Pp Eval Output*")
 115       (emacs-lisp-mode)
 116       (make-local-variable 'font-lock-verbose)
 117       (setq font-lock-verbose nil))))
 118
 119 ;;;###autoload
 120 (defun pp-eval-last-sexp (arg)
 121   "Run `pp-eval-expression' on sexp before point (which see).
 122 With argument, pretty-print output into current buffer.
 123 Ignores leading comment characters."
 124   (interactive "P")
 125   (let ((stab (syntax-table)) (pt (point)) start exp)
 126     (set-syntax-table emacs-lisp-mode-syntax-table)
 127     (save-excursion
 128       (forward-sexp -1)
 129       ;; If first line is commented, ignore all leading comments:
 130       (if (save-excursion (beginning-of-line) (looking-at "[ \t]*;"))
 131           (progn
 132             (setq exp (buffer-substring (point) pt))
 133             (while (string-match "\n[ \t]*;+" exp start)
 134               (setq start (1+ (match-beginning 0))
 135                     exp (concat (substring exp 0 start)
 136                                 (substring exp (match-end 0)))))
 137             (setq exp (read exp)))
 138         (setq exp (read (current-buffer)))))
 139     (set-syntax-table stab)
 140     (if arg
 141         (insert (pp-to-string (eval exp)))
 142       (pp-eval-expression exp))))
 143
 144 ;;; Test cases for quote
 145 ;; (pp-eval-expression ''(quote quote))
 146 ;; (pp-eval-expression ''((quote a) (quote b)))
 147 ;; (pp-eval-expression ''('a 'b))       ; same as above
 148 ;; (pp-eval-expression ''((quote (quote quote)) (quote quote)))
 149 ;; These do not satisfy the quote test.
 150 ;; (pp-eval-expression ''quote)
 151 ;; (pp-eval-expression ''(quote))
 152 ;; (pp-eval-expression ''(quote . quote))
 153 ;; (pp-eval-expression ''(quote a b))
 154 ;; (pp-eval-expression ''(quotefoo))
 155 ;; (pp-eval-expression ''(a b))
 156
 157 (provide 'pp)                           ; so (require 'pp) works
 158
 159 ;;; pp.el ends here.