myBrainfuck; Javascript Brainfuck Interpreter

myBrainfuck.js

/**
 * myBrainfuck; Javascript Brainfuck Interpreter
 *  http://actinium.org/ <Lianol>
 *  Usage:
 *      var interpreter = new MyBrainfuck();
 *      var result = interpreter.execute(source);
 *      alert(result.stdout);
 */
(function () {
    var myBrainfuck = function (option) {
        var defaults = {
            command: {
                next:   '>',
                prev:   '<',
                inc:    '+',
                dec:    '-',
                put:    '.',
                get:    ',',
                do:     '[',
                done:   ']',
            },
            memsize: Math.pow(2, 15),
        };
        this.setting = this.extend(defaults, option);
    };
    
    myBrainfuck.prototype.extend = function () {
        var target = arguments[0] || {};
        for (var i = 1; i < arguments.length; i++) {
            for (var j in arguments[i]) {
                if (typeof arguments[i][j] === 'object') {
                    target[j] = this.extend(target[j], arguments[i][j]);
                } else {
                    target[j] = arguments[i][j];
                }
            }
        }
        return target;
    };
    
    myBrainfuck.prototype.decodeSource = function (source) {
        // sort command by length DESC
        var commandName = Object.keys(this.setting.command)
            .sort(function (a, b) { return this.setting.command[b].length - this.setting.command[a].length; }.bind(this)),
            temp = [];
    
        // decode
        while (source.length > 0) {
            var notfound = true;
            for (var i = 0; i < commandName.length; i++) {
                var command = this.setting.command[commandName[i]];
                if (source.indexOf(command) === 0) {
                    temp.push(commandName[i]);
                    source = source.replace(command, '');
                    notfound = false;
                }
            }
            if (notfound) {
                source = source.substr(1);
            }
        }
        return temp;
    };
    
    myBrainfuck.prototype.execute = function (source, stdin) {
        // initialize
        var commandLine = this.decodeSource(source),
            stdin = stdin.split(''),
            stdout = '',
            memory = [],
            pointer = 0;
        for (var i = 0; i < this.setting.memsize; i++) {
            memory[i] = 0;
        }
        
        // run
        for (var i = 0; i < commandLine.length; i++) {
            // execute command
            switch (commandLine[i]) {
                case 'next':
                    if (pointer++ === this.setting.memsize) {
                        pointer = 0;
                    }
                    break;
                case 'prev':
                    if (pointer-- === -1) {
                        pointer += this.setting.memsize;
                    }
                    break;
                case 'inc':
                    if (memory[pointer]++ === 128) {
                        memory[pointer] = -128;
                    }
                    break;
                case 'dec':
                    if (memory[pointer]-- === -129) {
                        memory[pointer] = 127;
                    }
                    break;
                case 'put':
                    stdout += String.fromCharCode(memory[pointer]);
                    break;
                case 'get':
                    memory[pointer] = stdin.pop().charCodeAt(0);
                    break;
                case 'do':
                    if (memory[pointer] === 0) {
                        for (var o = i; o < commandLine.length; o++) {
                            if (commandLine[o] === 'done') {
                                i = o;
                                break;
                            }
                        }
                    }
                    break;
                case 'done':
                    for (var o = i; o >= 0; o--) {
                        if (commandLine[o] === 'do') {
                            i = o - 1;
                            break;
                        }
                    }
                    break;
            }
        }
        
        return {stdout: stdout, source: commandLine};
    };
    
    window.myBrainfuck = myBrainfuck;
})();