BF runtime

bf.js

(function(g) {
var cur = 0,
    p = 0,
    mem = [0],
    ret = [],
    slen = -1,
    pos = [],
    unlimit_loop = 5000,
    tmp = "",
    ptype = Object.prototype.toString,
run = function(str) {
    slen = str.length;
    while(cur < slen) {
        tmp = str.charAt(cur);
        switch(str.charAt(cur)) {
        case ">":
            if(p < mem.length - 1) p++;
            else (p = mem.push(undefined) - 1);
            break;
        case "<":
            if(p > 0) p--;
            break;
        case "+":
            if(ptype.apply(mem[p]) == "[object Number]") mem[p]++;
            else throw new Error("wrong data type");
            break;
        case "-":
            if(ptype.apply(mem[p]) == "[object Number]") mem[p]--;
            else throw new Error("wrong data type");
            break;
        case ",":
            if(ptype.apply(mem[p]) != "[object Number]") mem[p] = 0;
            while((tmp = str.charAt(++cur)).charAt() - 48 < 10) {
                mem[p] = mem[p] * 10 + (tmp|0);
            }
            cur--;
            break;
        case ".":
            if(ptype.apply(mem[p]) == "[object Number]") ret.push(mem[p]) && (mem[p] = undefined);
            else throw new Error("wrong data type");
            break;
        case "[":
            pos.push(cur);
            if(unlimit_loop-- == 0) throw new Error("unlimit loop");
            break;
        case "]":
            if(mem[p] > 0) cur = pos.pop() - 1;
            else pos.pop();
            break;
        default:
            console.log("你真调皮");
        }
        cur++;
    }
    return ret;
};
g.bf = function(str) {
    cur = 0,
    p = 0,
    mem = [],
    ret = [],
    pos = [],
    slen = -1, tmp="";
    return run(str);
};
})(window);

bf.test.js

//base on Qunit
module("Logic");

test("bf", function() {
    deepEqual(bf(",45+>,5-<.>."), [46, 4]);
    deepEqual(bf(",356."), [356]);
    deepEqual(bf(",1>,2>,3>,4>,5>,6.<.<.<.<.<."), [6, 5, 4, 3, 2, 1]);
    deepEqual(bf(",3>,2[<+>-]<."), [5]);
    deepEqual(bf(",0>,10[>,10[>,10[<<<<+>>>-]<-]<-]<."), [1000]);
});