oxjs/source/Ox/js/Function.js
2012-05-28 15:52:27 +02:00

79 lines
2.2 KiB
JavaScript

'use strict';
/*@
Ox.cache <f> Memoize a function
<script>
Ox.test.fn = Ox.cache(function(n) { return n * Math.random(); });
</script>
> Ox.test.fn(10) == Ox.test.fn(10);
true
> Ox.test.fn(10) == Ox.test.fn.clear()(10);
false
@*/
Ox.cache = function(fn, options) {
options = Ox.extend({
async: false,
key: JSON.stringify
}, options || {})
var cache = {},
ret = function() {
var args = Ox.toArray(arguments),
callback,
key = options.key(args);
function callback() {
// cache all arguments passed to callback
cache[key] = Ox.toArray(arguments);
// call the original callback
Ox.last(args).apply(this, arguments);
}
if (options.async) {
if (!(key in cache)) {
// call function with patched callback
fn.apply(this, args.slice(0, -1).concat(callback));
} else {
// call callback with cached arguments
callback.apply(this, cache[key])
}
} else {
if (!(key in cache)) {
cache[key] = fn.apply(this, args);
}
return cache[key];
}
};
ret.clear = function() {
if (arguments.length == 0) {
cache = {};
} else {
Ox.makeArray(arguments).forEach(function(key) {
delete cache[key];
});
}
return ret;
}
return ret;
};
/*@
Ox.identity <f> Returns its first argument
This can be used as a default iterator
> Ox.identity(Infinity)
Infinity
@*/
Ox.identity = function(value) {
return value;
};
/*@
Ox.noop <f> Returns undefined and calls optional callback without arguments
This can be used as a default iterator in an asynchronous loop, or to
combine a synchronous and an asynchronous code path.
> Ox.noop(1, 2, 3)
undefined
> Ox.noop(1, 2, 3, function() { Ox.test(arguments.length, 0); })
undefined
@*/
Ox.noop = function() {
var callback = Ox.last(arguments);
Ox.isFunction(callback) && callback();
};