Burrows-Wheeler Transform by JSX

bwt.jsx

class _BWEntry {
    static var LAST_CHAR = String.fromCharCode(1);

    var last: string;
    var key: string;
    var _index: number;
    function constructor(str: string, index: number) {
        this.key = str.slice(index);
        this._index = index;
        if (index == 0)
        {
            this.last = _BWEntry.LAST_CHAR;
        }
        else
        {
            this.last = str.slice(index - 1, index);
        }
    }
}

class _BWDecodeEntry {
    var ch: string;
    var index: number;
    function constructor(input: string, index: number) {
        this.index = index;
        this.ch = input.slice(index, index + 1);
    }
}

class BurrowsWheeler {
    static var LAST_CHAR = String.fromCharCode(1);

    static function encode(input : string) : string
    {
        var S : string = input + BurrowsWheeler.LAST_CHAR;
        var Si = [] : _BWEntry[];
        for (var i = 0; i < S.length; i++)
        {
            Si.push(new _BWEntry(S, i));
        }
        //log Si;
        Si.sort(function (a : _BWEntry, b : _BWEntry) : number {
            if (a.key < b.key)
            {
                return -1;
            }
            else if (a.key > b.key)
            {
                return 1;
            }
            return 0;
        });
        //log Si;
        var temp = [] : string[];
        Si.forEach(function (entry : _BWEntry) {
            temp.push(entry.last);
        });
        return temp.join("");
    }

    static function decode(input : string) : string
    {
        var Si = [] : _BWDecodeEntry[];
        for (var i = 0; i < input.length; i++)
        {
            Si.push(new _BWDecodeEntry(input, i));
        }
        //log Si;
        Si.sort(function (a : _BWDecodeEntry, b : _BWDecodeEntry) : number {
            if (a.ch < b.ch)
            {
                return -1;
            }
            else if (a.ch > b.ch)
            {
                return 1;
            }
            return a.index - b.index;
        });
        //log Si;
        var result = [] : string[];
        var nextIndex = 0;
        for (var j in Si)
        {
            var nextEntry = Si[nextIndex];
            //log nextEntry;
            result.push(nextEntry.ch);
            nextIndex = nextEntry.index;
        }
        return result.slice(1).join('');
    }

    static function escape(input: string) : string
    {
        return input.replace(BurrowsWheeler.LAST_CHAR, "$");
    }
}

class _Main {
    static function main (args: string[]) : void {

        var teststr : string = "abracadabra";
        var encoded_string = BurrowsWheeler.encode(teststr);
        log "encoded: ", BurrowsWheeler.escape(encoded_string);
        var decoded_string = BurrowsWheeler.decode(encoded_string);
        log "decoded: ", decoded_string;
    }
}