p2s/src/utils/TupleDictionary.js

A JavaScript 2D physics engine.

var Utils = require('./Utils');

module.exports = TupleDictionary;

/**
 * @class TupleDictionary
 * @constructor
 */
function TupleDictionary() {

    /**
     * The data storage
     * @property data
     * @type {Object}
     */
    this.data = {};

    /**
     * Keys that are currently used.
     * @property {Array} keys
     */
    this.keys = [];
}

/**
 * Generate a key given two integers
 * @method getKey
 * @param  {number} i
 * @param  {number} j
 * @return {string}
 */
TupleDictionary.prototype.getKey = function(id1, id2) {
    id1 = id1|0;
    id2 = id2|0;

    if ( (id1|0) === (id2|0) ){
        return -1;
    }

    // valid for values < 2^16
    return ((id1|0) > (id2|0) ?
        (id1 << 16) | (id2 & 0xFFFF) :
        (id2 << 16) | (id1 & 0xFFFF))|0
        ;
};

/**
 * @method getByKey
 * @param  {Number} key
 * @return {Object}
 */
TupleDictionary.prototype.getByKey = function(key) {
    key = key|0;
    return this.data[key];
};

/**
 * @method get
 * @param  {Number} i
 * @param  {Number} j
 * @return {Number}
 */
TupleDictionary.prototype.get = function(i, j) {
    return this.data[this.getKey(i, j)];
};

/**
 * Set a value.
 * @method set
 * @param  {Number} i
 * @param  {Number} j
 * @param {Number} value
 */
TupleDictionary.prototype.set = function(i, j, value) {
    if(!value){
        throw new Error("No data!");
    }

    var key = this.getKey(i, j);

    // Check if key already exists
    if(!this.data[key]){
        this.keys.push(key);
    }

    this.data[key] = value;

    return key;
};

/**
 * Remove all data.
 * @method reset
 */
TupleDictionary.prototype.reset = function() {
    var data = this.data,
        keys = this.keys;

    var l = keys.length;
    while(l--) {
        delete data[keys[l]];
    }

    keys.length = 0;
};

/**
 * Copy another TupleDictionary. Note that all data in this dictionary will be removed.
 * @method copy
 * @param {TupleDictionary} dict The TupleDictionary to copy into this one.
 */
TupleDictionary.prototype.copy = function(dict) {
    this.reset();
    Utils.appendArray(this.keys, dict.keys);
    var l = dict.keys.length;
    while(l--){
        var key = dict.keys[l];
        this.data[key] = dict.data[key];
    }
};