function Cache(loader) {
	this.loader = loader;
	this.loaded = {};
	this.loading = {};
}

Cache.prototype.get = function(key) {
	return function(f) {
		if(this.loaded[key] != undefined) {
			f(this.loaded[key]);
		} else {
			this.startLoading(key);
			this.loading[key].push(f);
			this.loader(key)(this.store(key));
		}
	}.bind(this);
};

Cache.prototype.warmUp = function(key) {
	if(this.loaded[key] == undefined) {
		this.startLoading(key);
		this.loader(key)(this.store(key));
	}
};

Cache.prototype.startLoading = function(key) {
	if(this.loading[key] == undefined) {
		this.loading[key] = [];
	}
};

Cache.prototype.store = function(key) {
	return function(value) {
		this.loaded[key] = value;
		for(var i = 0; i < this.loading[key].length; i++) {
			this.loading[key][i](value);
		}
		this.loading[key] = null;
	}.bind(this);
};

return {
	make: make
};

function make(loader) {
	var cache = new Cache(loader);
	return {
		get: cache.get.bind(cache),
		warmUp: cache.warmUp.bind(cache)
	};
}