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date Mon, 13 Aug 2007 08:45:50 +0200
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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