lisp/emacs-lisp/pp.el

   1 ;;; pp.el --- pretty printer for Emacs Lisp
   2
   3 ;; Copyright (C) 1989, 1993, 2001 Free Software Foundation, Inc.
   4
   5 ;; Author: Randal Schwartz <merlyn@stonehenge.com>
   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 the
  22 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  23 ;; Boston, MA 02111-1307, USA.
  24
  25 ;;; Commentary:
  26
  27 ;;; Code:
  28
  29 (defgroup pp nil
  30   "Pretty printer for Emacs Lisp."
  31   :prefix "pp-"
  32   :group 'lisp)
  33
  34 (defcustom pp-escape-newlines t
  35   "*Value of `print-escape-newlines' used by pp-* functions."
  36   :type 'boolean
  37   :group 'pp)
  38
  39 ;;;###autoload
  40 (defun pp-to-string (object)
  41   "Return a string containing the pretty-printed representation of OBJECT.
  42 OBJECT can be any Lisp object.  Quoting characters are used as needed
  43 to make output that `read' can handle, whenever this is possible."
  44   (save-excursion
  45     (set-buffer (generate-new-buffer " pp-to-string"))
  46     (unwind-protect
  47         (progn
  48           (lisp-mode-variables nil)
  49           (set-syntax-table emacs-lisp-mode-syntax-table)
  50           (let ((print-escape-newlines pp-escape-newlines)
  51                 (print-quoted t))
  52             (prin1 object (current-buffer)))
  53           (goto-char (point-min))
  54           (while (not (eobp))
  55             ;; (message "%06d" (- (point-max) (point)))
  56             (cond
  57              ((condition-case err-var
  58                   (prog1 t (down-list 1))
  59                 (error nil))
  60               (save-excursion
  61                 (backward-char 1)
  62                 (skip-chars-backward "'`#^")
  63                 (when (and (not (bobp)) (= ?\ (char-before)))
  64                   (delete-char -1)
  65                   (insert "\n"))))
  66              ((condition-case err-var
  67                   (prog1 t (up-list 1))
  68                 (error nil))
  69               (while (looking-at "\\s)")
  70                 (forward-char 1))
  71               (delete-region
  72                (point)
  73                (progn (skip-chars-forward " \t") (point)))
  74               (insert ?\n))
  75              (t (goto-char (point-max)))))
  76           (goto-char (point-min))
  77           (indent-sexp)
  78           (buffer-string))
  79       (kill-buffer (current-buffer)))))
  80
  81 ;;;###autoload
  82 (defun pp (object &optional stream)
  83   "Output the pretty-printed representation of OBJECT, any Lisp object.
  84 Quoting characters are printed as needed to make output that `read'
  85 can handle, whenever this is possible.
  86 Output stream is STREAM, or value of `standard-output' (which see)."
  87   (princ (pp-to-string object) (or stream standard-output)))
  88
  89 ;;;###autoload
  90 (defun pp-eval-expression (expression)
  91   "Evaluate EXPRESSION and pretty-print value into a new display buffer.
  92 If the pretty-printed value fits on one line, the message line is used
  93 instead.  The value is also consed onto the front of the list
  94 in the variable `values'."
  95   (interactive "xPp-eval: ")
  96   (setq values (cons (eval expression) values))
  97   (let* ((old-show-function temp-buffer-show-function)
  98          ;; Use this function to display the buffer.
  99          ;; This function either decides not to display it at all
 100          ;; or displays it in the usual way.
 101          (temp-buffer-show-function
 102           (function
 103            (lambda (buf)
 104              (save-excursion
 105                (set-buffer buf)
 106                (goto-char (point-min))
 107                (end-of-line 1)
 108                (if (or (< (1+ (point)) (point-max))
 109                        (>= (- (point) (point-min)) (frame-width)))
 110                    (let ((temp-buffer-show-function old-show-function)
 111                          (old-selected (selected-window))
 112                          (window (display-buffer buf)))
 113                      (goto-char (point-min)) ; expected by some hooks ...
 114                      (make-frame-visible (window-frame window))
 115                      (unwind-protect
 116                          (progn
 117                            (select-window window)
 118                            (run-hooks 'temp-buffer-show-hook))
 119                        (select-window old-selected)))
 120                  (message "%s" (buffer-substring (point-min) (point)))
 121                  ))))))
 122     (with-output-to-temp-buffer "*Pp Eval Output*"
 123       (pp (car values)))
 124     (save-excursion
 125       (set-buffer "*Pp Eval Output*")
 126       (emacs-lisp-mode)
 127       (make-local-variable 'font-lock-verbose)
 128       (setq font-lock-verbose nil))))
 129
 130 ;;;###autoload
 131 (defun pp-eval-last-sexp (arg)
 132   "Run `pp-eval-expression' on sexp before point (which see).
 133 With argument, pretty-print output into current buffer.
 134 Ignores leading comment characters."
 135   (interactive "P")
 136   (let ((stab (syntax-table)) (pt (point)) start exp)
 137     (set-syntax-table emacs-lisp-mode-syntax-table)
 138     (save-excursion
 139       (forward-sexp -1)
 140       ;; If first line is commented, ignore all leading comments:
 141       (if (save-excursion (beginning-of-line) (looking-at "[ \t]*;"))
 142           (progn
 143             (setq exp (buffer-substring (point) pt))
 144             (while (string-match "\n[ \t]*;+" exp start)
 145               (setq start (1+ (match-beginning 0))
 146                     exp (concat (substring exp 0 start)
 147                                 (substring exp (match-end 0)))))
 148             (setq exp (read exp)))
 149         (setq exp (read (current-buffer)))))
 150     (set-syntax-table stab)
 151     (if arg
 152         (insert (pp-to-string (eval exp)))
 153       (pp-eval-expression exp))))
 154
 155 ;;; Test cases for quote
 156 ;; (pp-eval-expression ''(quote quote))
 157 ;; (pp-eval-expression ''((quote a) (quote b)))
 158 ;; (pp-eval-expression ''('a 'b))       ; same as above
 159 ;; (pp-eval-expression ''((quote (quote quote)) (quote quote)))
 160 ;; These do not satisfy the quote test.
 161 ;; (pp-eval-expression ''quote)
 162 ;; (pp-eval-expression ''(quote))
 163 ;; (pp-eval-expression ''(quote . quote))
 164 ;; (pp-eval-expression ''(quote a b))
 165 ;; (pp-eval-expression ''(quotefoo))
 166 ;; (pp-eval-expression ''(a b))
 167
 168 (provide 'pp)                           ; so (require 'pp) works
 169
 170 ;;; pp.el ends here