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6a4d3cfd JB |
1 | ;;;; string-fun.scm --- string manipulation functions |
2 | ;;;; | |
1a179b03 | 3 | ;;;; Copyright (C) 1995, 1996, 1997, 1999, 2001 Free Software Foundation, Inc. |
6a4d3cfd JB |
4 | ;;;; |
5 | ;;;; This program is free software; you can redistribute it and/or modify | |
6 | ;;;; it under the terms of the GNU General Public License as published by | |
7 | ;;;; the Free Software Foundation; either version 2, or (at your option) | |
8 | ;;;; any later version. | |
9 | ;;;; | |
10 | ;;;; This program is distributed in the hope that it will be useful, | |
11 | ;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | ;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | ;;;; GNU General Public License for more details. | |
14 | ;;;; | |
15 | ;;;; You should have received a copy of the GNU General Public License | |
16 | ;;;; along with this software; see the file COPYING. If not, write to | |
17 | ;;;; the Free Software Foundation, Inc., 59 Temple Place, Suite 330, | |
18 | ;;;; Boston, MA 02111-1307 USA | |
a482f2cc MV |
19 | ;;;; |
20 | ;;;; As a special exception, the Free Software Foundation gives permission | |
21 | ;;;; for additional uses of the text contained in its release of GUILE. | |
22 | ;;;; | |
23 | ;;;; The exception is that, if you link the GUILE library with other files | |
24 | ;;;; to produce an executable, this does not by itself cause the | |
25 | ;;;; resulting executable to be covered by the GNU General Public License. | |
26 | ;;;; Your use of that executable is in no way restricted on account of | |
27 | ;;;; linking the GUILE library code into it. | |
28 | ;;;; | |
29 | ;;;; This exception does not however invalidate any other reasons why | |
30 | ;;;; the executable file might be covered by the GNU General Public License. | |
31 | ;;;; | |
32 | ;;;; This exception applies only to the code released by the | |
33 | ;;;; Free Software Foundation under the name GUILE. If you copy | |
34 | ;;;; code from other Free Software Foundation releases into a copy of | |
35 | ;;;; GUILE, as the General Public License permits, the exception does | |
36 | ;;;; not apply to the code that you add in this way. To avoid misleading | |
37 | ;;;; anyone as to the status of such modified files, you must delete | |
38 | ;;;; this exception notice from them. | |
39 | ;;;; | |
40 | ;;;; If you write modifications of your own for GUILE, it is your choice | |
41 | ;;;; whether to permit this exception to apply to your modifications. | |
42 | ;;;; If you do not wish that, delete this exception notice. | |
6a4d3cfd JB |
43 | ;;;; |
44 | \f | |
1a179b03 MD |
45 | (define-module (ice-9 string-fun) |
46 | :export (split-after-char split-before-char split-discarding-char | |
47 | split-after-char-last split-before-char-last | |
48 | split-discarding-char-last split-before-predicate | |
49 | split-after-predicate split-discarding-predicate | |
50 | separate-fields-discarding-char separate-fields-after-char | |
51 | separate-fields-before-char string-prefix-predicate string-prefix=? | |
52 | sans-surrounding-whitespace sans-trailing-whitespace | |
53 | sans-leading-whitespace sans-final-newline has-trailing-newline?)) | |
a6401ee0 JB |
54 | |
55 | ;;;; | |
56 | ;;; | |
57 | ;;; Various string funcitons, particularly those that take | |
58 | ;;; advantage of the "shared substring" capability. | |
59 | ;;; | |
60 | \f | |
61 | ;;; {String Fun: Dividing Strings Into Fields} | |
62 | ;;; | |
63 | ;;; The names of these functions are very regular. | |
64 | ;;; Here is a grammar of a call to one of these: | |
65 | ;;; | |
66 | ;;; <string-function-invocation> | |
67 | ;;; := (<action>-<seperator-disposition>-<seperator-determination> <seperator-param> <str> <ret>) | |
68 | ;;; | |
69 | ;;; <str> = the string | |
70 | ;;; | |
71 | ;;; <ret> = The continuation. String functions generally return | |
72 | ;;; multiple values by passing them to this procedure. | |
73 | ;;; | |
74 | ;;; <action> = split | |
75 | ;;; | separate-fields | |
76 | ;;; | |
77 | ;;; "split" means to divide a string into two parts. | |
78 | ;;; <ret> will be called with two arguments. | |
79 | ;;; | |
80 | ;;; "separate-fields" means to divide a string into as many | |
81 | ;;; parts as possible. <ret> will be called with | |
82 | ;;; however many fields are found. | |
83 | ;;; | |
84 | ;;; <seperator-disposition> = before | |
85 | ;;; | after | |
86 | ;;; | discarding | |
87 | ;;; | |
88 | ;;; "before" means to leave the seperator attached to | |
89 | ;;; the beginning of the field to its right. | |
90 | ;;; "after" means to leave the seperator attached to | |
91 | ;;; the end of the field to its left. | |
92 | ;;; "discarding" means to discard seperators. | |
93 | ;;; | |
94 | ;;; Other dispositions might be handy. For example, "isolate" | |
95 | ;;; could mean to treat the separator as a field unto itself. | |
96 | ;;; | |
97 | ;;; <seperator-determination> = char | |
98 | ;;; | predicate | |
99 | ;;; | |
100 | ;;; "char" means to use a particular character as field seperator. | |
101 | ;;; "predicate" means to check each character using a particular predicate. | |
102 | ;;; | |
103 | ;;; Other determinations might be handy. For example, "character-set-member". | |
104 | ;;; | |
105 | ;;; <seperator-param> = A parameter that completes the meaning of the determinations. | |
106 | ;;; For example, if the determination is "char", then this parameter | |
107 | ;;; says which character. If it is "predicate", the parameter is the | |
108 | ;;; predicate. | |
109 | ;;; | |
110 | ;;; | |
111 | ;;; For example: | |
112 | ;;; | |
113 | ;;; (separate-fields-discarding-char #\, "foo, bar, baz, , bat" list) | |
114 | ;;; => ("foo" " bar" " baz" " " " bat") | |
115 | ;;; | |
116 | ;;; (split-after-char #\- 'an-example-of-split list) | |
117 | ;;; => ("an-" "example-of-split") | |
118 | ;;; | |
119 | ;;; As an alternative to using a determination "predicate", or to trying to do anything | |
120 | ;;; complicated with these functions, consider using regular expressions. | |
121 | ;;; | |
122 | ||
1a179b03 | 123 | (define (split-after-char char str ret) |
a6401ee0 JB |
124 | (let ((end (cond |
125 | ((string-index str char) => 1+) | |
126 | (else (string-length str))))) | |
4e15fee8 DH |
127 | (ret (substring str 0 end) |
128 | (substring str end)))) | |
a6401ee0 | 129 | |
1a179b03 | 130 | (define (split-before-char char str ret) |
a6401ee0 JB |
131 | (let ((end (or (string-index str char) |
132 | (string-length str)))) | |
4e15fee8 DH |
133 | (ret (substring str 0 end) |
134 | (substring str end)))) | |
a6401ee0 | 135 | |
1a179b03 | 136 | (define (split-discarding-char char str ret) |
a6401ee0 JB |
137 | (let ((end (string-index str char))) |
138 | (if (not end) | |
139 | (ret str "") | |
4e15fee8 DH |
140 | (ret (substring str 0 end) |
141 | (substring str (1+ end)))))) | |
a6401ee0 | 142 | |
1a179b03 | 143 | (define (split-after-char-last char str ret) |
a6401ee0 JB |
144 | (let ((end (cond |
145 | ((string-rindex str char) => 1+) | |
146 | (else 0)))) | |
4e15fee8 DH |
147 | (ret (substring str 0 end) |
148 | (substring str end)))) | |
a6401ee0 | 149 | |
1a179b03 | 150 | (define (split-before-char-last char str ret) |
a6401ee0 | 151 | (let ((end (or (string-rindex str char) 0))) |
4e15fee8 DH |
152 | (ret (substring str 0 end) |
153 | (substring str end)))) | |
a6401ee0 | 154 | |
1a179b03 | 155 | (define (split-discarding-char-last char str ret) |
a6401ee0 JB |
156 | (let ((end (string-rindex str char))) |
157 | (if (not end) | |
158 | (ret str "") | |
4e15fee8 DH |
159 | (ret (substring str 0 end) |
160 | (substring str (1+ end)))))) | |
a6401ee0 | 161 | |
1a179b03 | 162 | (define (split-before-predicate pred str ret) |
a6401ee0 JB |
163 | (let loop ((n 0)) |
164 | (cond | |
165 | ((= n (string-length str)) (ret str "")) | |
166 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
4e15fee8 DH |
167 | (else (ret (substring str 0 n) |
168 | (substring str n)))))) | |
1a179b03 | 169 | (define (split-after-predicate pred str ret) |
a6401ee0 JB |
170 | (let loop ((n 0)) |
171 | (cond | |
172 | ((= n (string-length str)) (ret str "")) | |
173 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
4e15fee8 DH |
174 | (else (ret (substring str 0 (1+ n)) |
175 | (substring str (1+ n))))))) | |
a6401ee0 | 176 | |
1a179b03 | 177 | (define (split-discarding-predicate pred str ret) |
a6401ee0 JB |
178 | (let loop ((n 0)) |
179 | (cond | |
180 | ((= n (string-length str)) (ret str "")) | |
181 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
4e15fee8 DH |
182 | (else (ret (substring str 0 n) |
183 | (substring str (1+ n))))))) | |
a6401ee0 | 184 | |
1a179b03 | 185 | (define (separate-fields-discarding-char ch str ret) |
a6401ee0 JB |
186 | (let loop ((fields '()) |
187 | (str str)) | |
188 | (cond | |
189 | ((string-rindex str ch) | |
4e15fee8 DH |
190 | => (lambda (w) (loop (cons (substring str (+ 1 w)) fields) |
191 | (substring str 0 w)))) | |
a6401ee0 JB |
192 | (else (apply ret str fields))))) |
193 | ||
1a179b03 | 194 | (define (separate-fields-after-char ch str ret) |
a6401ee0 JB |
195 | (reverse |
196 | (let loop ((fields '()) | |
197 | (str str)) | |
198 | (cond | |
199 | ((string-index str ch) | |
4e15fee8 DH |
200 | => (lambda (w) (loop (cons (substring str 0 (+ 1 w)) fields) |
201 | (substring str (+ 1 w))))) | |
a6401ee0 JB |
202 | (else (apply ret str fields)))))) |
203 | ||
1a179b03 | 204 | (define (separate-fields-before-char ch str ret) |
a6401ee0 JB |
205 | (let loop ((fields '()) |
206 | (str str)) | |
207 | (cond | |
208 | ((string-rindex str ch) | |
4e15fee8 DH |
209 | => (lambda (w) (loop (cons (substring str w) fields) |
210 | (substring str 0 w)))) | |
a6401ee0 JB |
211 | (else (apply ret str fields))))) |
212 | ||
213 | \f | |
214 | ;;; {String Fun: String Prefix Predicates} | |
215 | ;;; | |
216 | ;;; Very simple: | |
217 | ;;; | |
218 | ;;; (define-public ((string-prefix-predicate pred?) prefix str) | |
219 | ;;; (and (<= (string-length prefix) (string-length str)) | |
4e15fee8 | 220 | ;;; (pred? prefix (substring str 0 (string-length prefix))))) |
a6401ee0 JB |
221 | ;;; |
222 | ;;; (define-public string-prefix=? (string-prefix-predicate string=?)) | |
223 | ;;; | |
224 | ||
1a179b03 | 225 | (define ((string-prefix-predicate pred?) prefix str) |
a6401ee0 | 226 | (and (<= (string-length prefix) (string-length str)) |
4e15fee8 | 227 | (pred? prefix (substring str 0 (string-length prefix))))) |
a6401ee0 | 228 | |
1a179b03 | 229 | (define string-prefix=? (string-prefix-predicate string=?)) |
a6401ee0 JB |
230 | |
231 | \f | |
232 | ;;; {String Fun: Strippers} | |
233 | ;;; | |
234 | ;;; <stripper> = sans-<removable-part> | |
235 | ;;; | |
236 | ;;; <removable-part> = surrounding-whitespace | |
237 | ;;; | trailing-whitespace | |
238 | ;;; | leading-whitespace | |
239 | ;;; | final-newline | |
240 | ;;; | |
241 | ||
1a179b03 | 242 | (define (sans-surrounding-whitespace s) |
a6401ee0 JB |
243 | (let ((st 0) |
244 | (end (string-length s))) | |
245 | (while (and (< st (string-length s)) | |
246 | (char-whitespace? (string-ref s st))) | |
247 | (set! st (1+ st))) | |
248 | (while (and (< 0 end) | |
249 | (char-whitespace? (string-ref s (1- end)))) | |
250 | (set! end (1- end))) | |
251 | (if (< end st) | |
252 | "" | |
4e15fee8 | 253 | (substring s st end)))) |
a6401ee0 | 254 | |
1a179b03 | 255 | (define (sans-trailing-whitespace s) |
a6401ee0 JB |
256 | (let ((st 0) |
257 | (end (string-length s))) | |
258 | (while (and (< 0 end) | |
259 | (char-whitespace? (string-ref s (1- end)))) | |
260 | (set! end (1- end))) | |
261 | (if (< end st) | |
262 | "" | |
4e15fee8 | 263 | (substring s st end)))) |
a6401ee0 | 264 | |
1a179b03 | 265 | (define (sans-leading-whitespace s) |
a6401ee0 JB |
266 | (let ((st 0) |
267 | (end (string-length s))) | |
268 | (while (and (< st (string-length s)) | |
269 | (char-whitespace? (string-ref s st))) | |
270 | (set! st (1+ st))) | |
271 | (if (< end st) | |
272 | "" | |
4e15fee8 | 273 | (substring s st end)))) |
a6401ee0 | 274 | |
1a179b03 | 275 | (define (sans-final-newline str) |
a6401ee0 JB |
276 | (cond |
277 | ((= 0 (string-length str)) | |
278 | str) | |
279 | ||
280 | ((char=? #\nl (string-ref str (1- (string-length str)))) | |
4e15fee8 | 281 | (substring str 0 (1- (string-length str)))) |
a6401ee0 JB |
282 | |
283 | (else str))) | |
284 | \f | |
285 | ;;; {String Fun: has-trailing-newline?} | |
286 | ;;; | |
287 | ||
1a179b03 | 288 | (define (has-trailing-newline? str) |
a6401ee0 JB |
289 | (and (< 0 (string-length str)) |
290 | (char=? #\nl (string-ref str (1- (string-length str)))))) | |
291 | ||
292 | ||
293 | \f | |
294 | ;;; {String Fun: with-regexp-parts} | |
295 | ||
296 | ;;; This relies on the older, hairier regexp interface, which we don't | |
297 | ;;; particularly want to implement, and it's not used anywhere, so | |
298 | ;;; we're just going to drop it for now. | |
299 | ;;; (define-public (with-regexp-parts regexp fields str return fail) | |
300 | ;;; (let ((parts (regexec regexp str fields))) | |
301 | ;;; (if (number? parts) | |
302 | ;;; (fail parts) | |
303 | ;;; (apply return parts)))) | |
304 |