String Parsing (objc.io #9) Swift version

stringparsing.swift

// objc.io Issue #9
// February, 2014
// String Parsing by Chris Eidhof
//
// Swift version by Rob Hudson

import UIKit

// NSTextCheckingResult using NSRange, rather than Range<String.Index>, so we need an NSString, rather than a String
let string: NSString = "backgroundColor = #ff0000"

var error: NSError?
let pattern = "(\\w+) = #(\\p{Hex_Digit}{6})"
let expression = NSRegularExpression(pattern: pattern, options: nil, error: &error)

let result = expression?.firstMatchInString(string as String, options: nil, range: NSMakeRange(0, string.length))
if let result = result {
    let key = string.substringWithRange(result.rangeAtIndex(1))
    let value = string.substringWithRange(result.rangeAtIndex(2))
}

stringparsing4.swift

// objc.io Issue #9
// February, 2014
// String Parsing by Chris Eidhof
//
// Example 4
// Swift version by Rob Hudson

import UIKit

extension UIColor {
    class func colorWithHexString(colorCode: String, alpha: Float = 1.0) -> UIColor {
        var scanner = NSScanner(string:colorCode)
        var color:UInt32 = 0;
        scanner.scanHexInt(&color)
        
        let mask = 0x000000FF
        let r = CGFloat(Float(Int(color >> 16) & mask)/255.0)
        let g = CGFloat(Float(Int(color >> 8) & mask)/255.0)
        let b = CGFloat(Float(Int(color) & mask)/255.0)
        
        return UIColor(red: r, green: g, blue: b, alpha: CGFloat(alpha))
    }
}

let FormatError = 100
let MyErrorDomain = "io.objc.parsing"

let string = "backgroundColor = (189, 23, 95)\ntextColor = #179ac0"
var scanner: NSScanner!

func parse(string: String, inout error: NSError?) -> [String : UIColor]? {
    scanner = NSScanner(string: string)
    scanner.charactersToBeSkipped = NSCharacterSet.whitespaceCharacterSet()
    
    var result = [String : UIColor]()
    let letters = NSCharacterSet.letterCharacterSet()
    while !scanner.atEnd {
        var key: NSString?
        var value: UIColor?
        let didScan = scanner.scanCharactersFromSet(letters, intoString: &key)
        scanner.scanString("=", intoString: nil)
        scanColor(&value)
        if let key = key as? String {
            result[key] = value
        }
        scanner.scanCharactersFromSet(NSCharacterSet.newlineCharacterSet(), intoString: nil) // scan an optional newline
    }
    return result
}

func scanColor(inout color: UIColor?) -> Bool {
    return scanHexColorIntoColor(&color) || scanTupleColorIntoColor(&color)
}

func scanHexColorIntoColor(inout color: UIColor?) -> Bool {
    let hexCharacterSet = NSCharacterSet(charactersInString: "0123456789abcdefABCDEF")
    var colorString: NSString?
    if scanner.scanString("#", intoString: nil) &&
        scanner.scanCharactersFromSet(hexCharacterSet, intoString: &colorString) &&
        colorString?.length == 6 {
            color = UIColor.colorWithHexString(colorString as! String)
            return true
    }
    return false
}

func scanTupleColorIntoColor(inout color: UIColor?) -> Bool {
    var red = 0, green = 0, blue = 0
    let didScan = scanner.scanString("(", intoString: nil) &&
        scanner.scanInteger(&red) &&
        scanner.scanString(",", intoString: nil) &&
        scanner.scanInteger(&green) &&
        scanner.scanString(",", intoString: nil) &&
        scanner.scanInteger(&blue) &&
        scanner.scanString(")", intoString: nil)
    
    if didScan {
        color = UIColor(red: CGFloat(Double(red) / 255.0), green: CGFloat(Double(green) / 255.0), blue: CGFloat(Double(blue) / 255.0), alpha: 1.0)
        return true
    }
    
    return false
}

var error: NSError?
parse(string, &error)

stringparsing5.swift

// objc.io Issue #9
// February, 2014
// String Parsing by Chris Eidhof
//
// Example 5
// Swift version by Rob Hudson

import UIKit

let string = "myView.left = otherView.right * 2 + 10\n" +
"viewController.view.centerX + myConstant <= self.view.centerX"

func tokenize(contents: String) -> [AnyObject] {
    let scanner = NSScanner(string: contents)
    var tokens = [AnyObject]()
    while !scanner.atEnd {
        for token in ["=", "+", "*", ">=", "<=", "."] {
            if scanner.scanString(token, intoString: nil) {
                tokens.append(token)
            }
        }
        var result: NSString?
        if scanner.scanCharactersFromSet(NSCharacterSet.letterCharacterSet(), intoString: &result) {
            if let result = result as? String {
                tokens.append(result)
            }
        }
        var doubleResult = 0.0
        if scanner.scanDouble(&doubleResult) {
            tokens.append(doubleResult)
        }
    }
    return tokens
}

let example = "myConstant = 100\n" +
"myView.left = otherView.right * 2 + 10\n" +
"viewController.view.centerX + myConstant <= self.view.centerX"
let result = tokenize(example)
let expected: [AnyObject] = ["myConstant", "=", 100, "myView", ".", "left", "=", "otherView", ".", "right", "*", 2, "+", 10, "viewController", ".", "view", ".", "centerX", "+", "myConstant", "<=", "self", ".", "view", ".", "centerX"]

// We can't compare AnyObject arrays with == or !=, so we'll use this function
func arraysAreEqual(array1: Array<AnyObject>, array2: Array<AnyObject>) -> Bool {
    if array1.count != array2.count {
        return false
    }
    
    for i in 0..<array1.count {
        if let string1 = array1[i] as? String, string2 = array2[i] as? String {
            if string1 != string2 {
                return false
            }
        } else if let number1 = array1[i] as? NSNumber, number2 = array2[i] as? NSNumber {
            if number1 != number2 {
                return false
            }
        }
    }
    
    return true
}

arraysAreEqual(result, expected) // true