swifter/Sources/String+Misc.swift

//
//  String+Misc.swift
//  Swifter
//
//  Copyright (c) 2014-2016 Damian Kołakowski. All rights reserved.
//

import Foundation

extension String {

    public func split(separator: Character) -> [String] {
        return self.characters.split { $0 == separator }.map(String.init)
    }
    
    public func split(maxSplit: Int = Int.max, separator: Character) -> [String] {
        return self.characters.split(maxSplit) { $0 == separator }.map(String.init)
    }
    
    public func replace(old: Character, new: Character) -> String {
        var buffer = [Character]()
        self.characters.forEach { buffer.append($0 == old ? new : $0) }
        return String(buffer)
    }
    
    public func unquote() -> String {
        var scalars = self.unicodeScalars;
        if scalars.first == "\"" && scalars.last == "\"" && scalars.count >= 2 {
            scalars.removeFirst();
            scalars.removeLast();
            return String(scalars)
        }
        return self
    }
    
    public func trim() -> String {
        var scalars = self.unicodeScalars
        while let _ = unicodeScalarToUInt32Whitespace(scalars.first) { scalars.removeFirst() }
        while let _ = unicodeScalarToUInt32Whitespace(scalars.last) { scalars.removeLast() }
        return String(scalars)
    }
    
    public static func fromUInt8(array: [UInt8]) -> String {
        return String(data: NSData(bytes: array, length: array.count), encoding: NSUTF8StringEncoding) ?? ""
    }
    
    public func removePercentEncoding() -> String {
        var scalars = self.unicodeScalars
        var output = ""
        var bytesBuffer = [UInt8]()
        while let scalar = scalars.popFirst() {
            if scalar == "%" {
                let first = scalars.popFirst()
                let secon = scalars.popFirst()
                if let first = unicodeScalarToUInt32Hex(first), secon = unicodeScalarToUInt32Hex(secon) {
                    bytesBuffer.append(first*16+secon)
                } else {
                    if !bytesBuffer.isEmpty {
                        output.appendContentsOf(String.fromUInt8(bytesBuffer))
                        bytesBuffer.removeAll()
                    }
                    if let first = first { output.append(Character(first)) }
                    if let secon = secon { output.append(Character(secon)) }
                }
            } else {
                if !bytesBuffer.isEmpty {
                    output.appendContentsOf(String.fromUInt8(bytesBuffer))
                    bytesBuffer.removeAll()
                }
                output.append(Character(scalar))
            }
        }
        if !bytesBuffer.isEmpty {
            output.appendContentsOf(String.fromUInt8(bytesBuffer))
            bytesBuffer.removeAll()
        }
        return output
    }
    
    private func unicodeScalarToUInt32Whitespace(x: UnicodeScalar?) -> UInt8? {
        if let x = x {
            if x.value >= 9 && x.value <= 13 {
                return UInt8(x.value)
            }
            if x.value == 32 {
                return UInt8(x.value)
            }
        }
        return nil
    }
    
    private func unicodeScalarToUInt32Hex(x: UnicodeScalar?) -> UInt8? {
        if let x = x {
            if x.value >= 48 && x.value <= 57 {
                return UInt8(x.value) - 48
            }
            if x.value >= 97 && x.value <= 102 {
                return UInt8(x.value) - 87
            }
            if x.value >= 65 && x.value <= 70 {
                return UInt8(x.value) - 55
            }
        }
        return nil
    }
}