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 single character of: a, b, c or d
    [[ab][cd]]
  • 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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

"
"

Test String

Code Generator

Language

Generated Code

import Foundation let pattern = #"export\s+async\s+function\s+generateMetadata\s*\(\s*\{[\s\S]*?\}\s*\):\s*Promise<Metadata>\s*{\s*const\s*\{\s*t\s*\}\s*=\s*await\s*translationServer\s*\(\s*locale\s*,\s*'projectTitles'\s*\);\s*return\s*\{\s*title\s*:\s*translate\s*\}?\s*}"# let regex = try! NSRegularExpression(pattern: pattern) let testString = #""" import { Metadata } from 'next'; import CreateEnactment from './_components'; import { translationServer } from 'i18n'; import { hasPermissionServerSide } from 'utils'; const CreateEnactmentPage = async () => { await hasPermissionServerSide({ branchRoles: ['ADMIN', 'OPERATOR'] }); return <CreateEnactment />; }; export async function generateMetadata({ params: { locale, enactmentId } }: { params: Params }): Promise<Metadata> { const { t } = await translationServer(locale, 'projectTitles'); const translate = enactmentId === 'new-enactment' ? t('newEnactment') : t('viewEnactment'); // to meta tag return { title: translate }; } export default CreateEnactmentPage; """# let stringRange = NSRange(location: 0, length: testString.utf16.count) if let firstMatch = regex.firstMatch(in: testString, range: stringRange) { let result: [String] = (1 ..< firstMatch.numberOfRanges).map { (testString as NSString).substring(with: firstMatch.range(at: $0)) } print(result) } else { print("No matches were found.") }

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