[[tags: egg]] [[toc:]] == regex === Introduction This extension provides the regular expression API that used to be available in CHICKEN releases before version ''4.6.1''. It is a thin wrapper around the [[/man/4/Unit irregex|irregex]} procedures and only intended to keep old code working. === Usage (require-extension regex) === Documentation ==== grep (grep REGEX LIST [ACCESSOR]) Returns all items of {{LIST}} that match the regular expression {{REGEX}}. This procedure could be defined as follows: (define (grep regex lst) (filter (lambda (x) (string-search regex x)) lst) ) {{ACCESSOR}} is an optional accessor-procedure applied to each element before doing the match. It should take a single argument and return a string that will then be used in the regular expression matching. {{ACCESSOR}} defaults to the identity function. ==== glob->regexp (glob->regexp PATTERN [SRE?]) Converts the file-pattern {{PATTERN}} into a regular expression. (glob->regexp "foo.*") => "foo\..*" {{PATTERN}} should follow "glob" syntax. Allowed wildcards are * [C...] [C1-C2] [-C...] ? {{glob->regexp}} returns a regular expression object if the optional argument {{SRE?}} is false or not given, otherwise the SRE of the computed regular expression is returned. ==== regexp (regexp STRING [IGNORECASE [IGNORESPACE [UTF8]]]) Returns a precompiled regular expression object for {{string}}. The optional arguments {{IGNORECASE}}, {{IGNORESPACE}} and {{UTF8}} specify whether the regular expression should be matched with case- or whitespace-differences ignored, or whether the string should be treated as containing UTF-8 encoded characters, respectively. Note that code that uses regular expressions heavily should always use them in precompiled form, which is likely to be much faster than passing strings to any of the regular-expression routines described below. ==== regexp? (regexp? X) Returns {{#t}} if {{X}} is a precompiled regular expression, or {{#f}} otherwise. ==== string-match ==== string-match-positions (string-match REGEXP STRING)
(string-match-positions REGEXP STRING) Matches the regular expression in {{REGEXP}} (a string or a precompiled regular expression) with {{STRING}} and returns either {{#f}} if the match failed, or a list of matching groups, where the first element is the complete match. For each matching group the result-list contains either: {{#f}} for a non-matching but optional group; a list of start- and end-position of the match in {{STRING}} (in the case of {{string-match-positions}}); or the matching substring (in the case of {{string-match}}). Note that the exact string is matched. For searching a pattern inside a string, see below. Note also that {{string-match}} is implemented by calling {{string-search}} with the regular expression wrapped in {{^ ... $}}. If invoked with a precompiled regular expression argument (by using {{regexp}}), {{string-match}} is identical to {{string-search}}. ==== string-search ==== string-search-positions (string-search REGEXP STRING [START [RANGE]])
(string-search-positions REGEXP STRING [START [RANGE]]) Searches for the first match of the regular expression in {{REGEXP}} with {{STRING}}. The search can be limited to {{RANGE}} characters. ==== string-split-fields (string-split-fields REGEXP STRING [MODE [START]]) Splits {{STRING}} into a list of fields according to {{MODE}}, where {{MODE}} can be the keyword {{#:infix}} ({{REGEXP}} matches field separator), the keyword {{#:suffix}} ({{REGEXP}} matches field terminator) or {{#t}} ({{REGEXP}} matches field), which is the default. (define s "this is a string 1, 2, 3,") (string-split-fields "[^ ]+" s) => ("this" "is" "a" "string" "1," "2," "3,") (string-split-fields " " s #:infix) => ("this" "is" "a" "string" "1," "2," "3,") (string-split-fields "," s #:suffix) => ("this is a string 1" " 2" " 3") ==== string-substitute (string-substitute REGEXP SUBST STRING [MODE]) Searches substrings in {{STRING}} that match {{REGEXP}} and substitutes them with the string {{SUBST}}. The substitution can contain references to subexpressions in {{REGEXP}} with the {{\NUM}} notation, where {{NUM}} refers to the NUMth parenthesized expression. The optional argument {{MODE}} defaults to 1 and specifies the number of the match to be substituted. Any non-numeric index specifies that all matches are to be substituted. (string-substitute "([0-9]+) (eggs|chicks)" "\\2 (\\1)" "99 eggs or 99 chicks" 2) => "99 eggs or chicks (99)" Note that a regular expression that matches an empty string will signal an error. ==== string-substitute* (string-substitute* STRING SMAP [MODE]) Substitutes elements of {{STRING}} with {{string-substitute}} according to {{SMAP}}. {{SMAP}} should be an association-list where each element of the list is a pair of the form {{(MATCH . REPLACEMENT)}}. Every occurrence of the regular expression {{MATCH}} in {{STRING}} will be replaced by the string {{REPLACEMENT}} (string-substitute* "

Hello, world!

" '(("<[/A-Za-z0-9]+>" . ""))) => "Hello, world!" ==== regexp-escape (regexp-escape STRING) Escapes all special characters in {{STRING}} with {{\}}, so that the string can be embedded into a regular expression. (regexp-escape "^[0-9]+:.*$") => "\\^\\[0-9\\]\\+:.\n.\\*\\$" === Author [[felix winkelmann]] === License Copyright (c) 2010, Felix L. Winkelmann All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. The name of the authors may not be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. === Version History ; 0.1 : initial release