RosettaCodeData/Task/Run-length-encoding/Elena/run-length-encoding.elena

import system'text;
import system'routines;
import extensions;
import extensions'text;

singleton compressor
{
    string compress(string s)
    {
        auto  tb := new TextBuilder();
        int count := 0;
        char current := s[0];
        s.forEach:(ch)
        {
            if (ch == current)
            {
                count += 1
            }
            else
            {
                tb.writeFormatted("{0}{1}",count,current);
                count := 1;
                current := ch
            }
        };

        tb.writeFormatted("{0}{1}",count,current);

        ^ tb
    }

    string decompress(string s)
    {
        auto tb := new TextBuilder();
        char current := $0;
        var a := new StringWriter();
        s.forEach:(ch)
        {
            current := ch;
            if (current.isDigit())
            {
                a.append(ch)
            }
            else
            {
                int count := a.toInt();
                a.clear();

                tb.fill(current,count)
            }
        };

        ^ tb
    }
}

public program()
{
    var s := "WWWWWWWWWWWWBWWWWWWWWWWWWBBBWWWWWWWWWWWWWWWWWWWWWWWWBWWWWWWWWWWWWWW";

    s := compressor.compress(s);
    console.printLine(s);

    s := compressor.decompress(s);
    console.printLine(s)
}