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1 | ;;; regi.el --- REGular expression Interpreting engine |
2 | ||
3 | ;; Copyright (C) 1993 Free Software Foundation, Inc. | |
4 | ||
5 | ;; Author: 1993 Barry A. Warsaw, Century Computing, Inc. <bwarsaw@cen.com> | |
6 | ;; Maintainer: bwarsaw@cen.com | |
7 | ;; Created: 24-Feb-1993 | |
8 | ;; Version: 1.8 | |
9 | ;; Last Modified: 1993/06/01 21:33:00 | |
10 | ;; Keywords: extensions, matching | |
11 | ||
12 | ;; This file is part of GNU Emacs. | |
13 | ||
14 | ;; GNU Emacs is free software; you can redistribute it and/or modify | |
15 | ;; it under the terms of the GNU General Public License as published by | |
16 | ;; the Free Software Foundation; either version 2, or (at your option) | |
17 | ;; any later version. | |
18 | ||
19 | ;; GNU Emacs is distributed in the hope that it will be useful, | |
20 | ;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | ;; GNU General Public License for more details. | |
23 | ||
24 | ;; You should have received a copy of the GNU General Public License | |
25 | ;; along with GNU Emacs; see the file COPYING. If not, write to the | |
26 | ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
27 | ;; Boston, MA 02111-1307, USA. | |
28 | ||
29 | ;;; Commentary: | |
30 | ||
31 | ;;; Code: | |
32 | ||
33 | \f | |
34 | (defun regi-pos (&optional position col-p) | |
35 | "Return the character position at various buffer positions. | |
36 | Optional POSITION can be one of the following symbols: | |
37 | ||
38 | `bol' == beginning of line | |
39 | `boi' == beginning of indentation | |
40 | `eol' == end of line [default] | |
41 | `bonl' == beginning of next line | |
42 | `bopl' == beginning of previous line | |
43 | ||
44 | Optional COL-P non-nil returns `current-column' instead of character position." | |
45 | (save-excursion | |
46 | (cond | |
47 | ((eq position 'bol) (beginning-of-line)) | |
48 | ((eq position 'boi) (back-to-indentation)) | |
49 | ((eq position 'bonl) (forward-line 1)) | |
50 | ((eq position 'bopl) (forward-line -1)) | |
51 | (t (end-of-line))) | |
52 | (if col-p (current-column) (point)))) | |
53 | ||
54 | (defun regi-mapcar (predlist func &optional negate-p case-fold-search-p) | |
55 | "Build a regi frame where each element of PREDLIST appears exactly once. | |
56 | The frame contains elements where each member of PREDLIST is | |
57 | associated with FUNC, and optionally NEGATE-P and CASE-FOLD-SEARCH-P." | |
58 | (let (frame tail) | |
59 | (if (or negate-p case-fold-search-p) | |
60 | (setq tail (list negate-p))) | |
61 | (if case-fold-search-p | |
62 | (setq tail (append tail (list case-fold-search-p)))) | |
63 | (while predlist | |
64 | (let ((element (list (car predlist) func))) | |
65 | (if tail | |
66 | (setq element (append element tail))) | |
67 | (setq frame (append frame (list element)) | |
68 | predlist (cdr predlist)) | |
69 | )) | |
70 | frame)) | |
71 | ||
72 | \f | |
73 | (defun regi-interpret (frame &optional start end) | |
74 | "Interpret the regi frame FRAME. | |
75 | If optional START and END are supplied, they indicate the region of | |
76 | interest, and the buffer is narrowed to the beginning of the line | |
77 | containing START, and beginning of the line after the line containing | |
78 | END. Otherwise, point and mark are not set and processing continues | |
79 | until your FUNC returns the `abort' symbol (see below). Beware! Not | |
80 | supplying a START or END could put you in an infinite loop. | |
81 | ||
82 | A regi frame is a list of entries of the form: | |
83 | ||
84 | (PRED FUNC [NEGATE-P [CASE-FOLD-SEARCH]]) | |
85 | ||
86 | PRED is a predicate against which each line in the region is tested, | |
87 | and if a match occurs, FUNC is `eval'd. Point is then moved to the | |
88 | beginning of the next line, the frame is reset and checking continues. | |
89 | If a match doesn't occur, the next entry is checked against the | |
90 | current line until all entries in the frame are checked. At this | |
91 | point, if no match occurred, the frame is reset and point is moved to | |
92 | the next line. Checking continues until every line in the region is | |
93 | checked. Optional NEGATE-P inverts the result of PRED before FUNC is | |
94 | called and `case-fold-search' is bound to the optional value of | |
95 | CASE-FOLD-SEARCH for the PRED check. | |
96 | ||
97 | PRED can be a string, variable, function or one of the following | |
98 | symbols: t, nil, `begin', `end', and `every'. If PRED is a string, or | |
99 | a variable or list that evaluates to a string, it is interpreted as a | |
100 | regular expression and is matched against the current line (from the | |
101 | beginning) using `looking-at'. If PRED does not evaluate to a string, | |
102 | it is interpreted as a binary value (nil or non-nil). | |
103 | ||
104 | PRED can also be one of the following symbols: | |
105 | ||
106 | t -- always produces a true outcome | |
107 | `begin' -- always executes before anything else | |
108 | `end' -- always executes after everything else | |
109 | `every' -- execute after frame is matched on a line | |
110 | ||
111 | Note that NEGATE-P and CASE-FOLD-SEARCH are meaningless if PRED is one | |
112 | of these special symbols. Only the first occurrence of each symbol in | |
113 | a frame entry is used, the rest are ignored. | |
114 | ||
115 | Your FUNC can return values which control regi processing. If a list | |
116 | is returned from your function, it can contain any combination of the | |
117 | following elements: | |
118 | ||
119 | the symbol `continue' | |
120 | Tells regi to continue processing frame-entries after a match, | |
121 | instead of resetting to the first entry and advancing to the next | |
122 | line, as is the default behavior. When returning this symbol, | |
123 | you must take care not to enter an infinite loop. | |
124 | ||
125 | the symbol `abort' | |
126 | Tells regi to terminate processing this frame. any end | |
127 | frame-entry is still processed. | |
128 | ||
129 | the list `(frame . NEWFRAME)' | |
130 | Tells regi to use NEWFRAME as its current frame. In other words, | |
131 | your FUNC can modify the executing regi frame on the fly. | |
132 | ||
133 | the list `(step . STEP)' | |
134 | Tells regi to move STEP number of lines forward during normal | |
135 | processing. By default, regi moves forward 1 line. STEP can be | |
136 | negative, but be careful of infinite loops. | |
137 | ||
138 | You should usually take care to explicitly return nil from your | |
139 | function if no action is to take place. Your FUNC will always be | |
140 | `eval'ed. The following variables will be temporarily bound to some | |
141 | useful information: | |
142 | ||
143 | `curline' | |
144 | the current line in the buffer, as a string | |
145 | ||
146 | `curframe' | |
147 | the full, current frame being executed | |
148 | ||
149 | `curentry' | |
150 | the current frame entry being executed." | |
151 | ||
152 | (save-excursion | |
153 | (save-restriction | |
154 | (let (begin-tag end-tag every-tag current-frame working-frame donep) | |
155 | ||
156 | ;; set up the narrowed region | |
157 | (and start | |
158 | end | |
159 | (let* ((tstart start) | |
160 | (start (min start end)) | |
161 | (end (max start end))) | |
162 | (narrow-to-region | |
163 | (progn (goto-char end) (regi-pos 'bonl)) | |
164 | (progn (goto-char start) (regi-pos 'bol))))) | |
165 | ||
166 | ;; lets find the special tags and remove them from the working | |
167 | ;; frame. note that only the last special tag is used. | |
168 | (mapcar | |
169 | (function | |
170 | (lambda (entry) | |
171 | (let ((pred (car entry)) | |
172 | (func (car (cdr entry)))) | |
173 | (cond | |
174 | ((eq pred 'begin) (setq begin-tag func)) | |
175 | ((eq pred 'end) (setq end-tag func)) | |
176 | ((eq pred 'every) (setq every-tag func)) | |
177 | (t | |
178 | (setq working-frame (append working-frame (list entry)))) | |
179 | ) ; end-cond | |
180 | ))) | |
181 | frame) ; end-mapcar | |
182 | ||
183 | ;; execute the begin entry | |
184 | (eval begin-tag) | |
185 | ||
186 | ;; now process the frame | |
187 | (setq current-frame working-frame) | |
188 | (while (not (or donep (eobp))) | |
189 | (let* ((entry (car current-frame)) | |
190 | (pred (nth 0 entry)) | |
191 | (func (nth 1 entry)) | |
192 | (negate-p (nth 2 entry)) | |
193 | (case-fold-search (nth 3 entry)) | |
194 | match-p) | |
195 | (catch 'regi-throw-top | |
196 | (cond | |
197 | ;; we are finished processing the frame for this line | |
198 | ((not current-frame) | |
199 | (setq current-frame working-frame) ;reset frame | |
200 | (forward-line 1) | |
201 | (throw 'regi-throw-top t)) | |
202 | ;; see if predicate evaluates to a string | |
203 | ((stringp (setq match-p (eval pred))) | |
204 | (setq match-p (looking-at match-p))) | |
205 | ) ; end-cond | |
206 | ||
207 | ;; now that we've done the initial matching, check for | |
208 | ;; negation of match | |
209 | (and negate-p | |
210 | (setq match-p (not match-p))) | |
211 | ||
212 | ;; if the line matched, package up the argument list and | |
213 | ;; funcall the FUNC | |
214 | (if match-p | |
215 | (let* ((curline (buffer-substring | |
216 | (regi-pos 'bol) | |
217 | (regi-pos 'eol))) | |
218 | (curframe current-frame) | |
219 | (curentry entry) | |
220 | (result (eval func)) | |
221 | (step (or (cdr (assq 'step result)) 1)) | |
222 | ) | |
223 | ;; changing frame on the fly? | |
224 | (if (assq 'frame result) | |
225 | (setq working-frame (cdr (assq 'frame result)))) | |
226 | ||
227 | ;; continue processing current frame? | |
228 | (if (memq 'continue result) | |
229 | (setq current-frame (cdr current-frame)) | |
230 | (forward-line step) | |
231 | (setq current-frame working-frame)) | |
232 | ||
233 | ;; abort current frame? | |
234 | (if (memq 'abort result) | |
235 | (progn | |
236 | (setq donep t) | |
237 | (throw 'regi-throw-top t))) | |
238 | ) ; end-let | |
239 | ||
240 | ;; else if no match occurred, then process the next | |
241 | ;; frame-entry on the current line | |
242 | (setq current-frame (cdr current-frame)) | |
243 | ||
244 | ) ; end-if match-p | |
245 | ) ; end catch | |
246 | ) ; end let | |
247 | ||
248 | ;; after every cycle, evaluate every-tag | |
249 | (eval every-tag) | |
250 | ) ; end-while | |
251 | ||
252 | ;; now process the end entry | |
253 | (eval end-tag))))) | |
254 | ||
255 | \f | |
256 | (provide 'regi) | |
257 | ||
258 | ;;; regi.el ends here |