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1 | ;;;; string-fun.scm --- string manipulation functions |
2 | ;;;; | |
1011dac0 | 3 | ;;;; Copyright (C) 1995, 1996, 1997, 1999 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 | |
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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. | |
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43 | ;;;; |
44 | \f | |
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45 | (define-module (ice-9 string-fun)) |
46 | ||
47 | ;;;; | |
48 | ;;; | |
49 | ;;; Various string funcitons, particularly those that take | |
50 | ;;; advantage of the "shared substring" capability. | |
51 | ;;; | |
52 | \f | |
53 | ;;; {String Fun: Dividing Strings Into Fields} | |
54 | ;;; | |
55 | ;;; The names of these functions are very regular. | |
56 | ;;; Here is a grammar of a call to one of these: | |
57 | ;;; | |
58 | ;;; <string-function-invocation> | |
59 | ;;; := (<action>-<seperator-disposition>-<seperator-determination> <seperator-param> <str> <ret>) | |
60 | ;;; | |
61 | ;;; <str> = the string | |
62 | ;;; | |
63 | ;;; <ret> = The continuation. String functions generally return | |
64 | ;;; multiple values by passing them to this procedure. | |
65 | ;;; | |
66 | ;;; <action> = split | |
67 | ;;; | separate-fields | |
68 | ;;; | |
69 | ;;; "split" means to divide a string into two parts. | |
70 | ;;; <ret> will be called with two arguments. | |
71 | ;;; | |
72 | ;;; "separate-fields" means to divide a string into as many | |
73 | ;;; parts as possible. <ret> will be called with | |
74 | ;;; however many fields are found. | |
75 | ;;; | |
76 | ;;; <seperator-disposition> = before | |
77 | ;;; | after | |
78 | ;;; | discarding | |
79 | ;;; | |
80 | ;;; "before" means to leave the seperator attached to | |
81 | ;;; the beginning of the field to its right. | |
82 | ;;; "after" means to leave the seperator attached to | |
83 | ;;; the end of the field to its left. | |
84 | ;;; "discarding" means to discard seperators. | |
85 | ;;; | |
86 | ;;; Other dispositions might be handy. For example, "isolate" | |
87 | ;;; could mean to treat the separator as a field unto itself. | |
88 | ;;; | |
89 | ;;; <seperator-determination> = char | |
90 | ;;; | predicate | |
91 | ;;; | |
92 | ;;; "char" means to use a particular character as field seperator. | |
93 | ;;; "predicate" means to check each character using a particular predicate. | |
94 | ;;; | |
95 | ;;; Other determinations might be handy. For example, "character-set-member". | |
96 | ;;; | |
97 | ;;; <seperator-param> = A parameter that completes the meaning of the determinations. | |
98 | ;;; For example, if the determination is "char", then this parameter | |
99 | ;;; says which character. If it is "predicate", the parameter is the | |
100 | ;;; predicate. | |
101 | ;;; | |
102 | ;;; | |
103 | ;;; For example: | |
104 | ;;; | |
105 | ;;; (separate-fields-discarding-char #\, "foo, bar, baz, , bat" list) | |
106 | ;;; => ("foo" " bar" " baz" " " " bat") | |
107 | ;;; | |
108 | ;;; (split-after-char #\- 'an-example-of-split list) | |
109 | ;;; => ("an-" "example-of-split") | |
110 | ;;; | |
111 | ;;; As an alternative to using a determination "predicate", or to trying to do anything | |
112 | ;;; complicated with these functions, consider using regular expressions. | |
113 | ;;; | |
114 | ||
115 | (define-public (split-after-char char str ret) | |
116 | (let ((end (cond | |
117 | ((string-index str char) => 1+) | |
118 | (else (string-length str))))) | |
4e15fee8 DH |
119 | (ret (substring str 0 end) |
120 | (substring str end)))) | |
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121 | |
122 | (define-public (split-before-char char str ret) | |
123 | (let ((end (or (string-index str char) | |
124 | (string-length str)))) | |
4e15fee8 DH |
125 | (ret (substring str 0 end) |
126 | (substring str end)))) | |
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127 | |
128 | (define-public (split-discarding-char char str ret) | |
129 | (let ((end (string-index str char))) | |
130 | (if (not end) | |
131 | (ret str "") | |
4e15fee8 DH |
132 | (ret (substring str 0 end) |
133 | (substring str (1+ end)))))) | |
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134 | |
135 | (define-public (split-after-char-last char str ret) | |
136 | (let ((end (cond | |
137 | ((string-rindex str char) => 1+) | |
138 | (else 0)))) | |
4e15fee8 DH |
139 | (ret (substring str 0 end) |
140 | (substring str end)))) | |
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141 | |
142 | (define-public (split-before-char-last char str ret) | |
143 | (let ((end (or (string-rindex str char) 0))) | |
4e15fee8 DH |
144 | (ret (substring str 0 end) |
145 | (substring str end)))) | |
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146 | |
147 | (define-public (split-discarding-char-last char str ret) | |
148 | (let ((end (string-rindex str char))) | |
149 | (if (not end) | |
150 | (ret str "") | |
4e15fee8 DH |
151 | (ret (substring str 0 end) |
152 | (substring str (1+ end)))))) | |
a6401ee0 | 153 | |
1011dac0 | 154 | (define-public (split-before-predicate pred str ret) |
a6401ee0 JB |
155 | (let loop ((n 0)) |
156 | (cond | |
157 | ((= n (string-length str)) (ret str "")) | |
158 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
4e15fee8 DH |
159 | (else (ret (substring str 0 n) |
160 | (substring str n)))))) | |
1011dac0 | 161 | (define-public (split-after-predicate pred str ret) |
a6401ee0 JB |
162 | (let loop ((n 0)) |
163 | (cond | |
164 | ((= n (string-length str)) (ret str "")) | |
165 | ((not (pred (string-ref str n))) (loop (1+ n))) | |
4e15fee8 DH |
166 | (else (ret (substring str 0 (1+ n)) |
167 | (substring str (1+ n))))))) | |
a6401ee0 | 168 | |
1011dac0 | 169 | (define-public (split-discarding-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 n) |
175 | (substring str (1+ n))))))) | |
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176 | |
177 | (define-public (separate-fields-discarding-char ch str ret) | |
178 | (let loop ((fields '()) | |
179 | (str str)) | |
180 | (cond | |
181 | ((string-rindex str ch) | |
4e15fee8 DH |
182 | => (lambda (w) (loop (cons (substring str (+ 1 w)) fields) |
183 | (substring str 0 w)))) | |
a6401ee0 JB |
184 | (else (apply ret str fields))))) |
185 | ||
186 | (define-public (separate-fields-after-char ch str ret) | |
187 | (reverse | |
188 | (let loop ((fields '()) | |
189 | (str str)) | |
190 | (cond | |
191 | ((string-index str ch) | |
4e15fee8 DH |
192 | => (lambda (w) (loop (cons (substring str 0 (+ 1 w)) fields) |
193 | (substring str (+ 1 w))))) | |
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194 | (else (apply ret str fields)))))) |
195 | ||
196 | (define-public (separate-fields-before-char ch str ret) | |
197 | (let loop ((fields '()) | |
198 | (str str)) | |
199 | (cond | |
200 | ((string-rindex str ch) | |
4e15fee8 DH |
201 | => (lambda (w) (loop (cons (substring str w) fields) |
202 | (substring str 0 w)))) | |
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203 | (else (apply ret str fields))))) |
204 | ||
205 | \f | |
206 | ;;; {String Fun: String Prefix Predicates} | |
207 | ;;; | |
208 | ;;; Very simple: | |
209 | ;;; | |
210 | ;;; (define-public ((string-prefix-predicate pred?) prefix str) | |
211 | ;;; (and (<= (string-length prefix) (string-length str)) | |
4e15fee8 | 212 | ;;; (pred? prefix (substring str 0 (string-length prefix))))) |
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213 | ;;; |
214 | ;;; (define-public string-prefix=? (string-prefix-predicate string=?)) | |
215 | ;;; | |
216 | ||
217 | (define-public ((string-prefix-predicate pred?) prefix str) | |
218 | (and (<= (string-length prefix) (string-length str)) | |
4e15fee8 | 219 | (pred? prefix (substring str 0 (string-length prefix))))) |
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220 | |
221 | (define-public string-prefix=? (string-prefix-predicate string=?)) | |
222 | ||
223 | \f | |
224 | ;;; {String Fun: Strippers} | |
225 | ;;; | |
226 | ;;; <stripper> = sans-<removable-part> | |
227 | ;;; | |
228 | ;;; <removable-part> = surrounding-whitespace | |
229 | ;;; | trailing-whitespace | |
230 | ;;; | leading-whitespace | |
231 | ;;; | final-newline | |
232 | ;;; | |
233 | ||
234 | (define-public (sans-surrounding-whitespace s) | |
235 | (let ((st 0) | |
236 | (end (string-length s))) | |
237 | (while (and (< st (string-length s)) | |
238 | (char-whitespace? (string-ref s st))) | |
239 | (set! st (1+ st))) | |
240 | (while (and (< 0 end) | |
241 | (char-whitespace? (string-ref s (1- end)))) | |
242 | (set! end (1- end))) | |
243 | (if (< end st) | |
244 | "" | |
4e15fee8 | 245 | (substring s st end)))) |
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246 | |
247 | (define-public (sans-trailing-whitespace s) | |
248 | (let ((st 0) | |
249 | (end (string-length s))) | |
250 | (while (and (< 0 end) | |
251 | (char-whitespace? (string-ref s (1- end)))) | |
252 | (set! end (1- end))) | |
253 | (if (< end st) | |
254 | "" | |
4e15fee8 | 255 | (substring s st end)))) |
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256 | |
257 | (define-public (sans-leading-whitespace s) | |
258 | (let ((st 0) | |
259 | (end (string-length s))) | |
260 | (while (and (< st (string-length s)) | |
261 | (char-whitespace? (string-ref s st))) | |
262 | (set! st (1+ st))) | |
263 | (if (< end st) | |
264 | "" | |
4e15fee8 | 265 | (substring s st end)))) |
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266 | |
267 | (define-public (sans-final-newline str) | |
268 | (cond | |
269 | ((= 0 (string-length str)) | |
270 | str) | |
271 | ||
272 | ((char=? #\nl (string-ref str (1- (string-length str)))) | |
4e15fee8 | 273 | (substring str 0 (1- (string-length str)))) |
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274 | |
275 | (else str))) | |
276 | \f | |
277 | ;;; {String Fun: has-trailing-newline?} | |
278 | ;;; | |
279 | ||
280 | (define-public (has-trailing-newline? str) | |
281 | (and (< 0 (string-length str)) | |
282 | (char=? #\nl (string-ref str (1- (string-length str)))))) | |
283 | ||
284 | ||
285 | \f | |
286 | ;;; {String Fun: with-regexp-parts} | |
287 | ||
288 | ;;; This relies on the older, hairier regexp interface, which we don't | |
289 | ;;; particularly want to implement, and it's not used anywhere, so | |
290 | ;;; we're just going to drop it for now. | |
291 | ;;; (define-public (with-regexp-parts regexp fields str return fail) | |
292 | ;;; (let ((parts (regexec regexp str fields))) | |
293 | ;;; (if (number? parts) | |
294 | ;;; (fail parts) | |
295 | ;;; (apply return parts)))) | |
296 |