Dice Parser

function ParseAndRollDice(dice) {
    var output = [];
    var trainyard = [];
    var value = -1;
    for(var i=0; i<dice.length;i++) {
        var exp = dice[i];
        if(exp == ' ') continue;
        if(exp>='0' && exp<='9') {
            if(value == -1) value = 0;
            value = value*10+parseInt(exp.toString());
            continue;
        }
        else if(value != -1) {
            output.push(value);
            value = -1;
        }
        switch(exp) {
            case '{':
            case '(':
                output.push(exp);
            case '+':
            case '-':
            case '*':
            case '/':
            case 'd':
            case 'p':
            case 's':
            case 'h':
            case 'l':
            case '<':
            case '>':
            case ',':
                while(trainyard.length > 0 && trainyard[trainyard.length-1] != '(' && GetPrecedence(exp) < GetPrecedence(trainyard[trainyard.length-1])) {
                    var pp = trainyard.pop();
                    output.push(pp);
                }
                trainyard.push(exp);
                break;
            case '}':
                while(trainyard.length > 0) {
                    var c = trainyard.pop();
                    if(c == '{') break;
                    if(c == '(') {
                        state.message = "Unpaired (!";
                        return 0;
                    }
                    output.push(c);
                }
                output.push(exp);
                break;
            case ')':
                while(trainyard.length > 0) {
                    var c = trainyard.pop();
                    if(c == '(') break;
                    if(c == '{') {
                        state.message = "Unpaired {!";
                        return 0;
                    }
                    output.push(c);
                }
                output.push(exp);
                break;
            default:
                if(!(exp>='0' && exp<='9')) {
                    state.message = "Unrecognized dice operation: " + exp;
                    return 0;
                }
                break;
        }
    }
    if(value > 0) {
        output.push(value);
    }
    while(trainyard.length > 0) {
        output.push(trainyard.pop());
    }
    var ops = [];
    var v1=0;
    var v2=0;
    var collapse = 0;
    var retreat = [];
    while(output.length > 0) {
        exp = output.shift();
        switch(exp) {
            case '+':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(v2+v1);
                break;
            case '-':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(v2-v1);
                break;
            case '*':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(v2*v1);
                break;
            case '/':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(Math.floor(v2/v1));
                break;
            case 'd':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                var r = [];
                for(var n=0; n < v2; n++) {
                    r.push(Math.floor(Math.random()*v1)+1);
                }
                if(collapse == 0) {
                    ops.push(ParseArray(r));
                }
                else {
                    ops.push(r);
                }
                break;
            case 'p':
            case 's':
                v1 = ParseArray(ops.pop());
                v2 = ops.pop();
                if(!Array.isArray(v2)) {
                    state.message = "Unrecognized dice operation: " + exp + "\nValue " + v2 + " was not a collection.";
                    return 0;
                }
                if(v2.length < v1) {
                    state.message = "Invalid dice operation: " + exp + "\nValue " + v1 + " was larger than the size of the collection " + v2 + ".";
                    return 0;
                }
                var r = [];
                for(var h=0;h<v1;h++) {
                    var i = Math.floor(Math.random()*v2.length);
                    r.push(v2[i]);
                    if(exp == 'p')
                        v2.splice(i,1);
                }
                if(collapse == 0) {
                    ops.push(ParseArray(r));
                }
                else {
                    ops.push(r);
                }
                break;
            case 'h':
                v1 = ParseArray(ops.pop());
                v2 = ops.pop();
                if(!Array.isArray(v2)) {
                    state.message = "Unrecognized dice operation: " + exp + "\nValue " + v2 + " was not a collection.";
                    return 0;
                }
                v2.sort(function(a, b){return a - b});
                v2.reverse();
                var r = [];
                for(var h=0;h<v1;h++) {
                    r.push(v2[h]);
                }
                ops.push(r);
                break;
            case 'l':
                v1 = ParseArray(ops.pop());
                v2 = ops.pop();
                if(!Array.isArray(v2)) {
                    state.message = "Unrecognized dice operation: " + exp + "\nValue " + v2 + " was not a collection.";
                    return 0;
                }
                v2.sort(function(a, b){return a - b});
                var r = [];
                for(var h=0;h<v1;h++) {
                    r.push(v2[h]);
                }
                ops.push(r);
                break;
            case '<':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(v2 <= v1);
                break;
                break;
            case '>':
                v1 = ParseArray(ops.pop());
                v2 = ParseArray(ops.pop());
                ops.push(v2 >= v1);
                break;
            case '{':
                collapse++;
                break;
            case '}':
                collapse--;
                break;
            case '(':
                if(collapse > 0) {
                    retreat.push(collapse);
                    collapse = 0;
                }
                break;
            case ')':
                if(retreat.length > 0) {
                    collapse = retreat.pop();
                }
                break;
            case ',':
                v1 = ops.pop();
                v2 = ops.pop();
                var p = [];
                if(collapse > 0) {
                    if(Array.isArray(v2)) {
                        p = v2.concat(v1);
                    }
                    else if(Array.isArray(v1)) {
                        var v3 = [];
                        v3.push(v2);
                        p = v3.concat(v1);
                    }
                    else {
                        p = [v2, v1];
                    }
                    ops.push(p);
                }
                else {
                    state.message = "Invalid operation: " + exp + "\nTo create a collection, use {a,b}.";
                    return 0;
                }
                break;
            default:
                if(collapse > 0) {
                    ops.push([exp]);
                }
                else {
                    ops.push(exp);
                }
                break;
        }
    }
    var ret = ops.pop();
    if(ret === true) {
        return "[Success!]";
    }
    else if(ret === false) {
        return "[Failed!]";
    }
    if(Array.isArray(ret)) {
        return "(" + ret + ")";
    }
    return ParseArray(ret);
}

function GetPrecedence(op) {
    if(op == '(') return 999;
    if(op == 'd') return 50;
    if(op == 'p') return 40;
    if(op == 's') return 40;
    if(op == '*') return 20;
    if(op == '/') return 20;
    if(op == 'h') return 10;
    if(op == 'l') return 10;
    if(op == '+') return 5;
    if(op == '-') return 5;
    if(op == '<') return 1;
    if(op == '>') return 1;
    if(op == ',') return 1;
    return 0;
}

function ParseArray(val) {
    if(Array.isArray(val)) {
        var r = 0;
        for(var i = 0; i < val.length; i++) {
            r+=val[i];
        }
        return r;
    }
    else
        return val;
}