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 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, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;;; Commentary:
  25
  26 ;;; eval-region, eval-buffer, and eval-current-buffer are redefined in
  27 ;;; Lisp to allow customizations by Lisp code.  eval-region calls
  28 ;;; `read', `eval', and `prin1', so Lisp replacements of these
  29 ;;; functions will affect eval-region and anything else that calls it.
  30 ;;; eval-buffer and eval-current-buffer are redefined in Lisp to call
  31 ;;; eval-region on the buffer.
  32
  33 ;;; Because of dynamic binding, all local variables are protected from
  34 ;;; being seen by eval by giving them funky names.  But variables in
  35 ;;; routines that call eval-region are similarly exposed.
  36
  37 ;;; Perhaps this should be one of several files in an `elisp' package
  38 ;;; that replaces Emacs Lisp subroutines with Lisp versions of the
  39 ;;; same.
  40
  41 ;;; Eval-region may be installed, after loading, by calling:
  42 ;;; (elisp-eval-region-install).  Installation can be undone with:
  43 ;;; (elisp-eval-region-uninstall).
  44
  45 '(defpackage "elisp-eval-region"
  46    (:nicknames "elisp")
  47    (:use "elisp")
  48    (:export
  49     elisp-eval-region-install
  50     elisp-eval-region-uninstall
  51     elisp-eval-region-level
  52     with-elisp-eval-region
  53     eval-region
  54     eval-buffer
  55     eval-current-buffer
  56     ))
  57 '(in-package elisp-eval-region)
  58
  59 ;; Save standard versions.
  60 (if (not (fboundp 'original-eval-region))
  61     (defalias 'original-eval-region (symbol-function 'eval-region)))
  62 (if (not (fboundp 'original-eval-buffer))
  63     (defalias 'original-eval-buffer
  64           (if (fboundp 'eval-buffer)  ;; only in Emacs 19
  65               (symbol-function 'eval-buffer)
  66             'undefined)))
  67 (if (not (fboundp 'original-eval-current-buffer))
  68     (defalias 'original-eval-current-buffer
  69           (symbol-function 'eval-current-buffer)))
  70
  71 (defvar elisp-eval-region-level 0
  72   "If the value is 0, use the original version of `elisp-eval-region'.
  73 Callers of `elisp-eval-region' should increment `elisp-eval-region-level'
  74 while the Lisp version should be used.  Installing `elisp-eval-region'
  75 increments it once, and uninstalling decrements it.")
  76
  77 ;; Installing and uninstalling should always be used in pairs,
  78 ;; or just install once and never uninstall.
  79 (defun elisp-eval-region-install ()
  80   (interactive)
  81   (defalias 'eval-region 'elisp-eval-region)
  82   (defalias 'eval-buffer 'elisp-eval-buffer)
  83   (defalias 'eval-current-buffer 'elisp-eval-current-buffer)
  84   (setq elisp-eval-region-level (1+ elisp-eval-region-level)))
  85
  86 (defun elisp-eval-region-uninstall ()
  87   (interactive)
  88   (if (> 1 elisp-eval-region-level)
  89       (setq elisp-eval-region-level (1- elisp-eval-region-level))
  90     (setq elisp-eval-region-level 0)
  91     (defalias 'eval-region (symbol-function 'original-eval-region))
  92     (defalias 'eval-buffer (symbol-function 'original-eval-buffer))
  93     (defalias 'eval-current-buffer
  94       (symbol-function 'original-eval-current-buffer))
  95     ))
  96
  97 (put 'with-elisp-eval-region 'lisp-indent-function 1)
  98 (put 'with-elisp-eval-region 'lisp-indent-hook 1)
  99 (put 'with-elisp-eval-region 'edebug-form-spec t)
 100
 101 (defmacro with-elisp-eval-region (flag &rest body)
 102   "If FLAG is nil, decrement `eval-region-level' while executing BODY.
 103 The effect of decrementing all the way to zero is that `eval-region'
 104 will use the original `eval-region', which may be the Emacs subr or some
 105 previous redefinition.  Before calling this macro, this package should
 106 already have been installed, using `elisp-eval-region-install', which
 107 increments the count once.  So if another package still requires the
 108 Lisp version of the code, the count will still be non-zero.
 109
 110 The count is not bound locally by this macro, so changes by BODY to
 111 its value will not be lost."
 112   (` (let ((elisp-code (function (lambda () (,@ body)))))
 113        (if (not (, flag))
 114            (unwind-protect
 115                (progn
 116                  (setq elisp-eval-region-level (1- elisp-eval-region-level))
 117                  (funcall elisp-code))
 118              (setq elisp-eval-region-level (1+ elisp-eval-region-level)))
 119          (funcall elisp-code)))))
 120
 121
 122 (defun elisp-eval-region (elisp-start elisp-end &optional elisp-output)
 123   "Execute the region as Lisp code.
 124 When called from programs, expects two arguments,
 125 giving starting and ending indices in the current buffer
 126 of the text to be executed.
 127 Programs can pass third argument PRINTFLAG which controls printing of output:
 128 nil means discard it; anything else is stream for print.
 129
 130 This version, from `eval-reg.el', allows Lisp customization of read,
 131 eval, and the printer."
 132
 133   ;; Because this doesnt narrow to the region, one other difference
 134   ;; concerns inserting whitespace after the expression being evaluated.
 135
 136   (interactive "r")
 137   (if (= 0 elisp-eval-region-level)
 138       (original-eval-region elisp-start elisp-end elisp-output)
 139     (let ((elisp-pnt (point))
 140           (elisp-buf (current-buffer));; Outside buffer
 141           (elisp-inside-buf (current-buffer));; Buffer current while evaling
 142           ;; Mark the end because it may move.
 143           (elisp-end-marker (set-marker (make-marker) elisp-end))
 144           elisp-form
 145           elisp-val)
 146       (goto-char elisp-start)
 147       (elisp-skip-whitespace)
 148       (while (< (point) elisp-end-marker)
 149         (setq elisp-form (read elisp-buf))
 150
 151         (let ((elisp-current-buffer (current-buffer)))
 152           ;; Restore the inside current-buffer.
 153           (set-buffer elisp-inside-buf)
 154           (setq elisp-val (eval elisp-form))
 155           ;; Remember current buffer for next time.
 156           (setq elisp-inside-buf (current-buffer))
 157           ;; Should this be protected?
 158           (set-buffer elisp-current-buffer))
 159
 160         (if elisp-output
 161             (let ((standard-output (or elisp-output t)))
 162               (setq values (cons elisp-val values))
 163               (if (eq standard-output t)
 164                   (prin1 elisp-val)
 165                 (princ "\n")
 166                 (prin1 elisp-val)
 167                 (princ "\n")
 168                 )))
 169         (goto-char (min (max elisp-end-marker (point))
 170                         (progn (elisp-skip-whitespace) (point))))
 171         )                               ; while
 172       (if elisp-output nil
 173         ;; like save-excursion recovery, but done only if no error occurs
 174         ;; but mark is not restored
 175         (set-buffer elisp-buf)
 176         (goto-char elisp-pnt))
 177       nil)))
 178
 179
 180 (defun elisp-skip-whitespace ()
 181   ;; Leave point before the next token, skipping white space and comments.
 182   (skip-chars-forward " \t\r\n\f")
 183   (while (= (following-char) ?\;)
 184     (skip-chars-forward "^\n\r")  ; skip the comment
 185     (skip-chars-forward " \t\r\n\f")))
 186
 187
 188 (defun elisp-eval-current-buffer (&optional elisp-output)
 189   "Execute the current buffer as Lisp code.
 190 Programs can pass argument PRINTFLAG which controls printing of output:
 191 nil means discard it; anything else is stream for print.
 192
 193 This version calls `eval-region' on the whole buffer."
 194   ;; The standard eval-current-buffer doesn't use eval-region.
 195   (interactive)
 196   (eval-region (point-min) (point-max) elisp-output))
 197
 198
 199 (defun elisp-eval-buffer (&optional elisp-bufname elisp-printflag)
 200   "Execute BUFFER as Lisp code.  Use current buffer if BUFFER is nil.
 201 Programs can pass argument PRINTFLAG which controls printing of
 202 output: nil means discard it; anything else is stream for print.
 203
 204 This version calls `eval-region' on the whole buffer."
 205   (interactive)
 206   (if (null elisp-bufname)
 207       (setq elisp-bufname (current-buffer)))
 208   (save-excursion
 209     (set-buffer (or (get-buffer elisp-bufname)
 210                     (error "No such buffer: %s" elisp-bufname)))
 211     (eval-region (point-min) (point-max) elisp-printflag)))
 212
 213
 214 (provide 'eval-reg)
 215
 216 ;;; eval-reg.el ends here