Regex operator

RegexMatchingOperator.playground

// Playground - noun: a place where people can play

import Cocoa

struct Regex {
    let pattern: String
    let expressionOptions: NSRegularExpressionOptions
    let matchingOptions: NSMatchingOptions
    
    init(pattern: String, expressionOptions: NSRegularExpressionOptions, matchingOptions: NSMatchingOptions) {
        self.pattern = pattern
        self.expressionOptions = expressionOptions
        self.matchingOptions = matchingOptions
    }
    
    init(pattern:String) {
        self.pattern = pattern
        expressionOptions = NSRegularExpressionOptions(0)
        matchingOptions = NSMatchingOptions(0)
    }
}

let r1 = Regex(pattern: "[a-z]")
let r2 = Regex(pattern: "[0-9]", expressionOptions: NSRegularExpressionOptions(0), matchingOptions: NSMatchingOptions(0))

operator infix =~ { associativity left precedence 140 }

func =~(left: String, right: Regex) -> Bool {
    let range: NSRange = NSMakeRange(0, countElements(left))
    if let regex = NSRegularExpression.regularExpressionWithPattern(right.pattern, options: right.expressionOptions, error: nil) {
        let matches: AnyObject[] = regex.matchesInString(left, options: right.matchingOptions, range: range)
        return matches.count > 0
    } else {
        "wat"
    }
    return false
}

func =~(left: String, right: String) -> Bool {
    return left =~ Regex(pattern: right)
}

"a" =~ r1
"2" =~ r1
"a" =~ r2
"2" =~ r2
"2" =~ "[a-z]"
"2" =~ "[0-9]"

Love this so much! We've extended it to be a little more performant if the regex is re-used and added a template replacement operator too: http://www.swift-studies.com/blog/2014/6/12/regex-matching-and-template-replacement-operators-in-swift

Awesome, thank you!
I added this and a "not match" operator (!=~) to SwiftVerbalExpressions: https://github.com/VerbalExpressions/SwiftVerbalExpressions