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 (defgroup pp nil
  26   "Pretty printer for Emacs Lisp."
  27   :prefix "pp-"
  28   :group 'lisp)
  29
  30 (defcustom pp-escape-newlines t
  31   "*Value of `print-escape-newlines' used by pp-* functions."
  32   :type 'boolean
  33   :group 'pp)
  34
  35 (defun pp-to-string (object)
  36   "Return a string containing the pretty-printed representation of OBJECT.
  37 OBJECT can be any Lisp object.  Quoting characters are used as needed
  38 to make output that `read' can handle, whenever this is possible."
  39   (save-excursion
  40     (set-buffer (generate-new-buffer " pp-to-string"))
  41     (unwind-protect
  42         (progn
  43           (lisp-mode-variables nil)
  44           (set-syntax-table emacs-lisp-mode-syntax-table)
  45           (let ((print-escape-newlines pp-escape-newlines)
  46                 (print-quoted t))
  47             (prin1 object (current-buffer)))
  48           (goto-char (point-min))
  49           (while (not (eobp))
  50             ;; (message "%06d" (- (point-max) (point)))
  51             (cond
  52              ((condition-case err-var
  53                   (prog1 t (down-list 1))
  54                 (error nil))
  55               (save-excursion
  56                 (backward-char 1)
  57                 (skip-chars-backward "'`#^")
  58                 (when (and (not (bobp)) (= ?\ (char-before)))
  59                   (delete-char -1)
  60                   (insert "\n"))))
  61              ((condition-case err-var
  62                   (prog1 t (up-list 1))
  63                 (error nil))
  64               (while (looking-at "\\s)")
  65                 (forward-char 1))
  66               (delete-region
  67                (point)
  68                (progn (skip-chars-forward " \t") (point)))
  69               (insert ?\n))
  70              (t (goto-char (point-max)))))
  71           (goto-char (point-min))
  72           (indent-sexp)
  73           (buffer-string))
  74       (kill-buffer (current-buffer)))))
  75
  76 ;;;###autoload
  77 (defun pp (object &optional stream)
  78   "Output the pretty-printed representation of OBJECT, any Lisp object.
  79 Quoting characters are printed as needed to make output that `read'
  80 can handle, whenever this is possible.
  81 Output stream is STREAM, or value of `standard-output' (which see)."
  82   (princ (pp-to-string object) (or stream standard-output)))
  83
  84 ;;;###autoload
  85 (defun pp-eval-expression (expression)
  86   "Evaluate EXPRESSION and pretty-print value into a new display buffer.
  87 If the pretty-printed value fits on one line, the message line is used
  88 instead.  The value is also consed onto the front of the list
  89 in the variable `values'."
  90   (interactive "xPp-eval: ")
  91   (setq values (cons (eval expression) values))
  92   (let* ((old-show-function temp-buffer-show-function)
  93          ;; Use this function to display the buffer.
  94          ;; This function either decides not to display it at all
  95          ;; or displays it in the usual way.
  96          (temp-buffer-show-function
  97           (function
  98            (lambda (buf)
  99              (save-excursion
 100                (set-buffer buf)
 101                (goto-char (point-min))
 102                (end-of-line 1)
 103                (if (or (< (1+ (point)) (point-max))
 104                        (>= (- (point) (point-min)) (frame-width)))
 105                    (let ((temp-buffer-show-function old-show-function)
 106                          (old-selected (selected-window))
 107                          (window (display-buffer buf)))
 108                      (goto-char (point-min)) ; expected by some hooks ...
 109                      (make-frame-visible (window-frame window))
 110                      (unwind-protect
 111                          (progn
 112                            (select-window window)
 113                            (run-hooks 'temp-buffer-show-hook))
 114                        (select-window old-selected)))
 115                  (message "%s" (buffer-substring (point-min) (point)))
 116                  ))))))
 117     (with-output-to-temp-buffer "*Pp Eval Output*"
 118       (pp (car values)))
 119     (save-excursion
 120       (set-buffer "*Pp Eval Output*")
 121       (emacs-lisp-mode)
 122       (make-local-variable 'font-lock-verbose)
 123       (setq font-lock-verbose nil))))
 124
 125 ;;;###autoload
 126 (defun pp-eval-last-sexp (arg)
 127   "Run `pp-eval-expression' on sexp before point (which see).
 128 With argument, pretty-print output into current buffer.
 129 Ignores leading comment characters."
 130   (interactive "P")
 131   (let ((stab (syntax-table)) (pt (point)) start exp)
 132     (set-syntax-table emacs-lisp-mode-syntax-table)
 133     (save-excursion
 134       (forward-sexp -1)
 135       ;; If first line is commented, ignore all leading comments:
 136       (if (save-excursion (beginning-of-line) (looking-at "[ \t]*;"))
 137           (progn
 138             (setq exp (buffer-substring (point) pt))
 139             (while (string-match "\n[ \t]*;+" exp start)
 140               (setq start (1+ (match-beginning 0))
 141                     exp (concat (substring exp 0 start)
 142                                 (substring exp (match-end 0)))))
 143             (setq exp (read exp)))
 144         (setq exp (read (current-buffer)))))
 145     (set-syntax-table stab)
 146     (if arg
 147         (insert (pp-to-string (eval exp)))
 148       (pp-eval-expression exp))))
 149
 150 ;;; Test cases for quote
 151 ;; (pp-eval-expression ''(quote quote))
 152 ;; (pp-eval-expression ''((quote a) (quote b)))
 153 ;; (pp-eval-expression ''('a 'b))       ; same as above
 154 ;; (pp-eval-expression ''((quote (quote quote)) (quote quote)))
 155 ;; These do not satisfy the quote test.
 156 ;; (pp-eval-expression ''quote)
 157 ;; (pp-eval-expression ''(quote))
 158 ;; (pp-eval-expression ''(quote . quote))
 159 ;; (pp-eval-expression ''(quote a b))
 160 ;; (pp-eval-expression ''(quotefoo))
 161 ;; (pp-eval-expression ''(a b))
 162
 163 (provide 'pp)                           ; so (require 'pp) works
 164
 165 ;;; pp.el ends here.