Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

/
/
gm

Test String

Substitution

Processing...

Code Generator

Language

Generated Code

import Foundation let pattern = #"<ref\s+((?:group|follow|extends)\s*=(?:(?!name\s*=)[\s\S])*)?name\s*=\s*(?:"\s*([^"](?:(?!\s*\/>|\s*"\s*>|\s+(?:group|follow|extends)).)*?)\s*"|'\s*([^'"](?:(?!\s*\/>|\s*'>|\s+(?:group|follow|extends)).)*?)\s*'|([^"](?:(?!\s*\/>|\s*>|\s+(?:group|follow|extends)).)*))(\s+(?:group|follow|extends)\s*=(?:(?!\s*\/>|"\s*>|'\s*>)[\s\S])*)*\s*(?:(\/)|)>"# let regex = try! NSRegularExpression(pattern: pattern, options: .anchorsMatchLines) let testString = #""" <ref name=Test1 /><ref name=Test2 /> <ref name=Bad 1 /><ref name=Bad 2 /> <ref name="Test 3"/> <ref name="Test 4" /> <ref name=Test5>Foo</ref> <ref name="Test 6">Foo</ref> <ref name=Test7>Foo </ref> <ref name = Test8 > Foo </ref> <ref name = Test9 > Foo </ref> <ref name="Test 10">Foo </ref> <ref name = "Test 11" > Foo </ref> <ref name = Test12 > Foo </ref> <ref name = Test13 /> <ref name = "Test 14" /> <ref name = Test15 /> <ref name = "Test 16" /> <ref name = Test17 /> <ref name = "Test 18" /> <ref name="Test/19" /> ==A heading== <ref name = "Test/20" /> <ref name = "Test 21"/> <ref name = "Test / 22"/> <ref name = "Test > 23"/> <ref name="Te>st/ 23.1"/> <ref name =" Test 24 "/> <ref name='Test/ 25' /> <ref name='Test/ 26'> Foo </ref> <ref name='Te>st/ 27' /> <ref name = " Test 28 " >Foo</ref> <ref name='Test "29"' /> - This one is expected to produce invalid XML "'Test "29"'"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: "'Test "2 9"'" <ref name = "Test 30" > <ref name = "Test 31"> <ref name = "Test 32" /> <ref name = "Test 33"/> <ref name = Test34 > <ref name = Test35> <ref name = Test36 /> <ref name = Test37/> <ref name = " Test 38 "/> <ref name = " Test 39 " /> <ref name='Test 40'/> <ref name=AAA/> <ref name="BBB AAA BBB" /> <ref name="This "isjustnot" valid"/> - This one is expected to produce invalid XML "This "isjustnot" valid"; surprisingly, MW can parse it anyway for a case this simple, but not if there's a space within the interior-most quotes: "This "is just not" valid". <ref name="This 'actually is' valid"/> <ref name='But this "is also" a problem' /> (or will be after our " substitution) <ref name=apostrophe's /> <ref name="more apostrophe's" /> <ref name='this's bad, but we can fix it!' /> <ref name='this is okay'/> <ref name="'this is dumb'"/> <ref name="this is 'less' dumb" /> <ref name="what about 'this case'"/> <ref name="'or this' one" /> <ref name="foo" group="bar"/> <ref name="foo" group="bar" /> <ref group="bar" name="foo" /> <ref name='foo' group='bar'/> <ref name='foo' group='bar' /> <ref group='bar' name='foo' /> <ref name=foo group=bar/> <ref name=foo group=bar /> <ref group=bar name=foo/> <ref name="foo" follow="bar" /> <ref name='foo' follow='bar'/> <ref name=foo follow=bar/> <ref name="foo" extends="bar" /> <ref name='foo' extends='bar'/> <ref name=foo extends=bar/> <ref name='foo' group="bar" extends=baz follow="quux quux" /> <ref group="bar" name='foo' extends=baz follow="quux quux" /> <ref group="bar" extends=baz name='foo' follow="quux quux" /> <ref group="bar" extends=baz follow="quux quux" name='foo' /> <ref group="bar" extends=baz name=foo follow="quux quux" /> <ref group="bar" extends=baz name="foo's foo" follow="quux quux" /> <ref group="bar's > / bar" extends=baz name='foos > / foo' follow="quux quux" /> <ref group= "bar's > / bar" extends= baz name= ' foos > / foo ' follow= "quux > quux" /> <ref name="foos > / foo" group="bar's > / bar" extends=baz follow="quux quux"/> <ref name = ' foos > / foo ' group = "bar's > / bar" extends =baz follow =" quux quux " /> <ref name="foos > / foo" group="bar's > / bar" extends=baz follow='quux quux'/> """# let stringRange = NSRange(location: 0, length: testString.utf16.count) let substitutionString = #"<ref $1name="$2$3$4"$5${6:+ /:}>"# let result = regex.stringByReplacingMatches(in: testString, range: stringRange, withTemplate: substitutionString) print(result)

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Swift 5.2, please visit: https://developer.apple.com/documentation/foundation/nsregularexpression