js-forth/kernel/stack.js

An implementation of [Forth](https://en.wikipedia.org/wiki/Forth_(programming_language)) in Javascript

function Stack(name) {
    var data = [];

    this.pop = function() {
        if (data.length > 0)
            return data.pop();
        else {
            throw "Stack empty: " + name;
        }
    };

    this.push = function(element) {
        data.push(element);
    };

    this.peek = function(offset) {
        var index = data.length - (offset || 1);
        if (0 <= index && index < data.length)
            return data[index];
        else
            throw "Attempted to peek at invalid stack index " + index + ": " + name;
    };

    this.roll = function(num) {
        if (num === 0) return;

        var index = data.length - num - 1;
        if (0 <= index && index < data.length) {
            var newTop = data.splice(index, 1)[0];
            data.push(newTop);
        } else
            throw "Attempted to roll more elements than in stack " + num + ": " + name;
    };

    this.length = function() {
        return data.length;
    };

    this.clear = function() {
        data.length = 0;
    };

    this.toString = function() {
        return data.toString();
    };
}

module.exports = Stack;