Regex

Advanced regular expressions for Swift

Goals

Regex library was mainly introduced to fulfill the needs of Swift Express - web application server side framework for Swift.

Still we hope it will be useful for everybody else.

Happy regexing ;)

Features

• Deep Integration with Swift
  • =~ operator support
  • Swift Pattern Matching (aka switch operator) support
• Named groups
• Match checking
• Extraction/Search functions
• Replace functions
  • With a pattern
  • With custom replacing function
• Splitting with a Regular Expression
  • Simple
  • With groups
• String extensions
• Supports grapheme clusters 👨‍👩‍👧

Extra

Path to Regex converter is available as a separate library here: PathToRegex

This one allows using path patterns like /folder/*/:file.txt or /route/:one/:two to be converted to Regular Expressions and matched against strings.

Getting started

Installation

Package Manager

Add the following dependency to your Package.swift:

.Package(url: "https://github.com/crossroadlabs/Regex.git", majorVersion: 1)

Run swift build and build your app.

CocoaPods

Add the following to your Podfile:

pod 'CrossroadRegex'

Make sure that you are integrating your dependencies using frameworks: add use_frameworks! to your Podfile. Then run pod install.

Carthage

Add the following to your Cartfile:

github "crossroadlabs/Regex"

Run carthage update and follow the steps as described in Carthage’s README.

Manually

1. Download and drop /Regex folder in your project.
2. Congratulations!

Examples

Hello Regex:

All the lines below are identical and represent simple matching. All operators and matches function return Bool

//operator way, can match either regex or string containing pattern
"l321321alala" =~ "(.+?)([123]*)(.*)".r
"l321321alala" =~ "(.+?)([123]*)(.*)"

//similar function
"(.+?)([123]*)(.*)".r!.matches("l321321alala")

Operator !~ returns true if expression does NOT match:

"l321321alala" !~ "(.+?)([123]*)(.*)".r
"l321321alala" !~ "(.+?)([123]*)(.*)"
//both return false

Swift Pattern Matching (aka switch keyword)

Regex provides very deep integration with Swift and can be used with the switch keyword in the following way:

let letter = "a"
let digit = "1"
let other = "!"

//you just put your string is a regular Swift's switch to match to regular expressions
switch letter {
    //note .r after the string literal of the pattern
    case "\d".r: print("digit")
    case "[a-z]".r: print("letter")
    default: print("bizarre symbol")
}

switch digit {
    case "\d".r: print("digit")
    case "[a-z]".r: print("letter")
    default: print("bizarre symbol")
}

switch other {
    //note .r after the string literal of the pattern
    case "\d".r: print("digit")
    case "[a-z]".r: print("letter")
    default: print("bizarre symbol")
}

The output of the code above will be:

letter
digit
bizarre symbol

Accessing groups:

// strings can be converted to regex in Scala style .r property of a string
let digits = "(.+?)([123]*)(.*)".r?.findFirst(in: "l321321alala")?.group(at: 2)
// digits is "321321" here

Named groups:

let regex:RegexType = try Regex(pattern:"(.+?)([123]*)(.*)",
                                        groupNames:"letter", "digits", "rest")
let match = regex.findFirst(in: "l321321alala")
if let match = match {
    let letter = match.group(named: "letter")
    let digits = match.group(named: "digits")
    let rest = match.group(named: "rest")
    //do something with extracted data
}

Replace:

let replaced = "(.+?)([123]*)(.*)".r?.replaceAll(in: "l321321alala", with: "$1-$2-$3")
//replaced is "l-321321-alala"

Replace with custom replacer function:

let replaced = "(.+?)([123]+)(.+?)".r?.replaceAll(in: "l321321la321a") { match in
    if match.group(at: 1) == "l" {
        return nil
    } else {
        return match.matched.uppercaseString
    }
}
//replaced is "l321321lA321A"

Split:

In the following example, split() looks for 0 or more spaces followed by a semicolon followed by 0 or more spaces and, when found, removes the spaces from the string. nameList is the array returned as a result of split().

let names = "Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand"
let nameList = names.split(using: "\s*;\s*".r)
//name list contains ["Harry Trump", "Fred Barney", "Helen Rigby", "Bill Abel", "Chris Hand"]

Split with groups:

If separator contains capturing parentheses, matched results are returned in the array.

let myString = "Hello 1 word. Sentence number 2."
let splits = myString.split(using: "(\d)".r)
//splits contains ["Hello ", "1", " word. Sentence number ", "2", "."]

Changelog

You can view the CHANGELOG as a separate document here.

Contributing

To get started, sign the Contributor License Agreement.

by Crossroad Labs