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{# retoor < retoor @ molodetz . nl > #}
{% extends 'page.html' %}
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{% set page_title = "regex" %}
{% set breadcrumb = [{"url": "api/index.html", "title": "API Reference"}, {"title": "regex"}] %}
{% set prev_page = {"url": "api/base64.html", "title": "base64"} %}
{% set next_page = {"url": "api/jinja.html", "title": "jinja"} %}
{% block article %}
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< h1 > regex</ h1 >
< p > The < code > regex</ code > module provides regular expression matching, replacement, and splitting using PCRE-compatible patterns.</ p >
< pre >< code > import "regex" for Regex, Match</ code ></ pre >
< div class = "toc" >
< h4 > On This Page</ h4 >
< ul >
< li >< a href = "#regex-class" > Regex Class</ a ></ li >
< li >< a href = "#match-class" > Match Class</ a ></ li >
< li >< a href = "#pattern-syntax" > Pattern Syntax</ a ></ li >
< li >< a href = "#examples" > Examples</ a ></ li >
</ ul >
</ div >
< h2 id = "regex-class" > Regex Class</ h2 >
< div class = "class-header" >
< h3 > Regex</ h3 >
< p > Regular expression pattern</ p >
</ div >
< h3 > Constructors</ h3 >
< div class = "method-signature" >
< span class = "method-name" > Regex.new</ span > (< span class = "param" > pattern</ span > ) → < span class = "type" > Regex</ span >
</ div >
< p > Creates a new regex from a pattern string.</ p >
< pre >< code > var re = Regex.new("\\d+") // Match digits</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > Regex.new</ span > (< span class = "param" > pattern</ span > , < span class = "param" > flags</ span > ) → < span class = "type" > Regex</ span >
</ div >
< p > Creates a regex with flags.</ p >
< ul class = "param-list" >
< li >< span class = "param-name" > pattern</ span > < span class = "param-type" > (String)</ span > - Regex pattern</ li >
< li >< span class = "param-name" > flags</ span > < span class = "param-type" > (String)</ span > - Flags: "i" (case-insensitive), "m" (multiline), "s" (dotall)</ li >
</ ul >
< pre >< code > var re = Regex.new("hello", "i") // Case-insensitive</ code ></ pre >
< h3 > Properties</ h3 >
< div class = "method-signature" >
< span class = "method-name" > pattern</ span > → < span class = "type" > String</ span >
</ div >
< p > The pattern string.</ p >
< div class = "method-signature" >
< span class = "method-name" > flags</ span > → < span class = "type" > String</ span >
</ div >
< p > The flags string.</ p >
< h3 > Methods</ h3 >
< div class = "method-signature" >
< span class = "method-name" > test</ span > (< span class = "param" > string</ span > ) → < span class = "type" > Bool</ span >
</ div >
< p > Tests if the pattern matches anywhere in the string.</ p >
< pre >< code > var re = Regex.new("\\d+")
System.print(re.test("abc123")) // true
System.print(re.test("abc")) // false</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > match</ span > (< span class = "param" > string</ span > ) → < span class = "type" > Match|null</ span >
</ div >
< p > Finds the first match in the string.</ p >
< pre >< code > var re = Regex.new("(\\w+)@(\\w+\\.\\w+)")
var m = re.match("email: alice@example.com")
if (m != null) {
System.print(m.text) // alice@example.com
System.print(m.group(1)) // alice
System.print(m.group(2)) // example.com
}</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > matchAll</ span > (< span class = "param" > string</ span > ) → < span class = "type" > List</ span >
</ div >
< p > Finds all matches in the string.</ p >
< pre >< code > var re = Regex.new("\\d+")
var matches = re.matchAll("a1 b22 c333")
for (m in matches) {
System.print(m.text) // 1, 22, 333
}</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > replace</ span > (< span class = "param" > string</ span > , < span class = "param" > replacement</ span > ) → < span class = "type" > String</ span >
</ div >
< p > Replaces the first match with the replacement string.</ p >
< pre >< code > var re = Regex.new("\\d+")
System.print(re.replace("a1b2c3", "X")) // aXb2c3</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > replaceAll</ span > (< span class = "param" > string</ span > , < span class = "param" > replacement</ span > ) → < span class = "type" > String</ span >
</ div >
< p > Replaces all matches with the replacement string.</ p >
< pre >< code > var re = Regex.new("\\d+")
System.print(re.replaceAll("a1b2c3", "X")) // aXbXcX</ code ></ pre >
< div class = "method-signature" >
< span class = "method-name" > split</ span > (< span class = "param" > string</ span > ) → < span class = "type" > List</ span >
</ div >
< p > Splits the string by the pattern.</ p >
< pre >< code > var re = Regex.new("[,;\\s]+")
var parts = re.split("a, b; c d")
System.print(parts) // [a, b, c, d]</ code ></ pre >
< h2 id = "match-class" > Match Class</ h2 >
< div class = "class-header" >
< h3 > Match</ h3 >
< p > Regex match result</ p >
</ div >
< h3 > Properties</ h3 >
< table >
< tr >
< th > Property</ th >
< th > Type</ th >
< th > Description</ th >
</ tr >
< tr >
< td >< code > text</ code ></ td >
< td > String</ td >
< td > The matched text</ td >
</ tr >
< tr >
< td >< code > start</ code ></ td >
< td > Num</ td >
< td > Start index in the original string</ td >
</ tr >
< tr >
< td >< code > end</ code ></ td >
< td > Num</ td >
< td > End index in the original string</ td >
</ tr >
< tr >
< td >< code > groups</ code ></ td >
< td > List</ td >
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< td > List where index 0 is the entire match, index 1+ are capture groups</ td >
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</ tr >
</ table >
< h3 > Methods</ h3 >
< div class = "method-signature" >
< span class = "method-name" > group</ span > (< span class = "param" > index</ span > ) → < span class = "type" > String|null</ span >
</ div >
< p > Gets a captured group by index. Group 0 is the entire match.</ p >
< pre >< code > var re = Regex.new("(\\w+)-(\\d+)")
var m = re.match("item-42")
System.print(m.group(0)) // item-42
System.print(m.group(1)) // item
System.print(m.group(2)) // 42</ code ></ pre >
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< div class = "admonition note" >
< div class = "admonition-title" > Note</ div >
< p > The < code > groups</ code > list uses 0-based indexing where < code > groups[0]</ code > is the entire match (same as < code > text</ code > ), and < code > groups[1]</ code > , < code > groups[2]</ code > , etc. are the captured groups. This is consistent with < code > group(0)</ code > , < code > group(1)</ code > , etc.</ p >
</ div >
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< h2 id = "pattern-syntax" > Pattern Syntax</ h2 >
< h3 > Character Classes</ h3 >
< table >
< tr >< th > Pattern</ th >< th > Matches</ th ></ tr >
< tr >< td >< code > .</ code ></ td >< td > Any character (except newline)</ td ></ tr >
< tr >< td >< code > \d</ code ></ td >< td > Digit (0-9)</ td ></ tr >
< tr >< td >< code > \D</ code ></ td >< td > Non-digit</ td ></ tr >
< tr >< td >< code > \w</ code ></ td >< td > Word character (a-z, A-Z, 0-9, _)</ td ></ tr >
< tr >< td >< code > \W</ code ></ td >< td > Non-word character</ td ></ tr >
< tr >< td >< code > \s</ code ></ td >< td > Whitespace</ td ></ tr >
< tr >< td >< code > \S</ code ></ td >< td > Non-whitespace</ td ></ tr >
< tr >< td >< code > [abc]</ code ></ td >< td > Any of a, b, or c</ td ></ tr >
< tr >< td >< code > [^abc]</ code ></ td >< td > Not a, b, or c</ td ></ tr >
< tr >< td >< code > [a-z]</ code ></ td >< td > Range a through z</ td ></ tr >
</ table >
< h3 > Quantifiers</ h3 >
< table >
< tr >< th > Pattern</ th >< th > Matches</ th ></ tr >
< tr >< td >< code > *</ code ></ td >< td > 0 or more</ td ></ tr >
< tr >< td >< code > +</ code ></ td >< td > 1 or more</ td ></ tr >
< tr >< td >< code > ?</ code ></ td >< td > 0 or 1</ td ></ tr >
< tr >< td >< code > {n}</ code ></ td >< td > Exactly n times</ td ></ tr >
< tr >< td >< code > {n,}</ code ></ td >< td > n or more times</ td ></ tr >
< tr >< td >< code > {n,m}</ code ></ td >< td > Between n and m times</ td ></ tr >
</ table >
< h3 > Anchors</ h3 >
< table >
< tr >< th > Pattern</ th >< th > Matches</ th ></ tr >
< tr >< td >< code > ^</ code ></ td >< td > Start of string/line</ td ></ tr >
< tr >< td >< code > $</ code ></ td >< td > End of string/line</ td ></ tr >
< tr >< td >< code > \b</ code ></ td >< td > Word boundary</ td ></ tr >
< tr >< td >< code > \B</ code ></ td >< td > Non-word boundary</ td ></ tr >
</ table >
< h3 > Groups</ h3 >
< table >
< tr >< th > Pattern</ th >< th > Description</ th ></ tr >
< tr >< td >< code > (abc)</ code ></ td >< td > Capturing group</ td ></ tr >
< tr >< td >< code > (?:abc)</ code ></ td >< td > Non-capturing group</ td ></ tr >
< tr >< td >< code > a|b</ code ></ td >< td > Alternation (a or b)</ td ></ tr >
</ table >
< h2 id = "examples" > Examples</ h2 >
< h3 > Email Validation</ h3 >
< pre >< code > import "regex" for Regex
var emailRe = Regex.new("^[\\w.+-]+@[\\w-]+\\.[\\w.-]+$")
var emails = ["alice@example.com", "invalid", "bob@test.org"]
for (email in emails) {
if (emailRe.test(email)) {
System.print("%(email) is valid")
} else {
System.print("%(email) is invalid")
}
}</ code ></ pre >
< h3 > Extracting Data</ h3 >
< pre >< code > import "regex" for Regex
var logRe = Regex.new("(\\d{4}-\\d{2}-\\d{2}) (\\w+): (.+)")
var log = "2024-01-15 ERROR: Connection failed"
var m = logRe.match(log)
if (m != null) {
System.print("Date: %(m.group(1))") // 2024-01-15
System.print("Level: %(m.group(2))") // ERROR
System.print("Message: %(m.group(3))") // Connection failed
}</ code ></ pre >
< h3 > Find and Replace</ h3 >
< pre >< code > import "regex" for Regex
var text = "Call 555-1234 or 555-5678"
var phoneRe = Regex.new("\\d{3}-\\d{4}")
var redacted = phoneRe.replaceAll(text, "XXX-XXXX")
System.print(redacted) // Call XXX-XXXX or XXX-XXXX</ code ></ pre >
< h3 > Parsing URLs</ h3 >
< pre >< code > import "regex" for Regex
var urlRe = Regex.new("(https?)://([^/]+)(/.*)?")
var url = "https://example.com/path/to/page"
var m = urlRe.match(url)
System.print("Scheme: %(m.group(1))") // https
System.print("Host: %(m.group(2))") // example.com
System.print("Path: %(m.group(3))") // /path/to/page</ code ></ pre >
< div class = "admonition note" >
< div class = "admonition-title" > Note</ div >
< p > Remember to escape backslashes in Wren strings. Use < code > \\d</ code > instead of < code > \d</ code > .</ p >
</ div >
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{% endblock %}
