Regular Expressions 101

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  • Unit Tests (15)

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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

/
/
gxsmJ

Test String

Code Generator

Generated Code

import Foundation // WARNING: You included a flag that Swift doesn't support: J // Wehn this flag is set, it allows duplicated capturing group names. // By default, Swift captures only the last value matched for a repeated capture group. // As an alternative, the pattern can be modified to contain one capturing group per group you want to get in the result. let pattern = ##""" (?:(?<=\n)|(?<=\A)) # Necessarily at the begining of a new line or start of string (?<leading_space>[ ]{0,3}) (?<tag_all> (?: (?<div_open> <(?<tag_name>\S+) (?<tag_attributes>(?&tag_attr))* [^\>]* >\n* ) (?<content>.+?) \n* (?<div_close> (?(<leading_space>) # If leading spaces were found (?: (?<=\n)\g{leading_space} # Either there is a symmetry in leading space for open and closing tag | (?:(?<=\S)[[:blank:]\h]*) # or the closing tag is on the same line with preceding data ) | (?=<\/\g{tag_name}>) # No leading space, so we don't expect anything before the closing tag other than what has already been caught in the 'content' ) <\/\g{tag_name}> ) [[:blank:]\h]*\n ) | (?: <!--[[:blank:]\h\v]*(?<html_comment>.*?)[[:blank:]\h\v]*--> ) | (?: < [[:blank:]\h\v]* (?<tag_name>[a-zA-Z0-9][\w\-]+) (?<tag_attributes>(?&tag_attr))* [[:blank:]\h\v]* \/? [[:blank:]\h\v]* > ) ) (?(DEFINE) (?<tag_attr> (?: [[:blank:]\h]* [\w\-]+ [[:blank:]\h]* = [^\"\'[:blank]\h]+ [[:blank:]\h]* ) | (?: [[:blank:]\h]* [\w\-]+ [[:blank:]\h]* = [[:blank:]\h]* (?<quote>["']) (.*?) \g{quote} [[:blank:]\h]* ) ) ) """## let regex = try! NSRegularExpression(pattern: pattern, options: [.anchorsMatchLines, .allowCommentsAndWhitespace, .dotMatchesLineSeparators]) let testString = ###""" <abbr title="`first backtick!">SB</abbr> <abbr title="`second backtick!">SB</abbr> <table> <tr><td markdown="block">test _emphasis_ (block)</td></tr> </table> ## More complicated <table> <tr><td markdown="1"> * this is _not_ a list item</td></tr> <tr><td markdown="span"> * this is _not_ a list item</td></tr> <tr><td markdown="block"> * this _is_ a list item </td></tr> </table> """### let stringRange = NSRange(location: 0, length: testString.utf16.count) let matches = regex.matches(in: testString, range: stringRange) var result: [[String]] = [] for match in matches { var groups: [String] = [] for rangeIndex in 1 ..< match.numberOfRanges { let nsRange = match.range(at: rangeIndex) guard !NSEqualRanges(nsRange, NSMakeRange(NSNotFound, 0)) else { continue } let string = (testString as NSString).substring(with: nsRange) groups.append(string) } if !groups.isEmpty { result.append(groups) } } 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