source: ps/trunk/binaries/data/mods/public/simulation/helpers/WeightedList.js@ 19270

var WeightedList = function()
{
    this.elements = [ ];
    this.totalWeight = 0;
};

WeightedList.prototype.length = function()
{
    return this.elements.length;
};

WeightedList.prototype.push = function(item, weight)
{
    if (weight === undefined)
        weight = 1;
    this.totalWeight += weight;
    this.elements.push({ "item": item, "weight": weight });
};

WeightedList.prototype.removeAt = function(index)
{
    var element = this.elements.splice(index, 1)[0];
    if (element)
        this.totalWeight -= element.weight;
};

WeightedList.prototype.itemAt = function(index)
{
    var element = this.elements[index];
    return element ? element.item : null;
};

WeightedList.prototype.randomIndex = function() {
    var element;
    var targetWeight = randFloat(0, this.totalWeight);
    var cumulativeWeight = 0;
    for (var index = 0; index < this.elements.length; index++)
    {
        element = this.elements[index];
        cumulativeWeight += element.weight;
        if (cumulativeWeight >= targetWeight)
            return index;
    }
    return -1;
};

Engine.RegisterGlobal("WeightedList", WeightedList);