tenebrous-dicebot/api/node_modules/async/memoize.js

101 lines
3.2 KiB
JavaScript

'use strict';
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = memoize;
var _identity = require('lodash/identity');
var _identity2 = _interopRequireDefault(_identity);
var _slice = require('./internal/slice');
var _slice2 = _interopRequireDefault(_slice);
var _setImmediate = require('./internal/setImmediate');
var _setImmediate2 = _interopRequireDefault(_setImmediate);
var _initialParams = require('./internal/initialParams');
var _initialParams2 = _interopRequireDefault(_initialParams);
var _wrapAsync = require('./internal/wrapAsync');
var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
function has(obj, key) {
return key in obj;
}
/**
* Caches the results of an async function. When creating a hash to store
* function results against, the callback is omitted from the hash and an
* optional hash function can be used.
*
* If no hash function is specified, the first argument is used as a hash key,
* which may work reasonably if it is a string or a data type that converts to a
* distinct string. Note that objects and arrays will not behave reasonably.
* Neither will cases where the other arguments are significant. In such cases,
* specify your own hash function.
*
* The cache of results is exposed as the `memo` property of the function
* returned by `memoize`.
*
* @name memoize
* @static
* @memberOf module:Utils
* @method
* @category Util
* @param {AsyncFunction} fn - The async function to proxy and cache results from.
* @param {Function} hasher - An optional function for generating a custom hash
* for storing results. It has all the arguments applied to it apart from the
* callback, and must be synchronous.
* @returns {AsyncFunction} a memoized version of `fn`
* @example
*
* var slow_fn = function(name, callback) {
* // do something
* callback(null, result);
* };
* var fn = async.memoize(slow_fn);
*
* // fn can now be used as if it were slow_fn
* fn('some name', function() {
* // callback
* });
*/
function memoize(fn, hasher) {
var memo = Object.create(null);
var queues = Object.create(null);
hasher = hasher || _identity2.default;
var _fn = (0, _wrapAsync2.default)(fn);
var memoized = (0, _initialParams2.default)(function memoized(args, callback) {
var key = hasher.apply(null, args);
if (has(memo, key)) {
(0, _setImmediate2.default)(function () {
callback.apply(null, memo[key]);
});
} else if (has(queues, key)) {
queues[key].push(callback);
} else {
queues[key] = [callback];
_fn.apply(null, args.concat(function () /*args*/{
var args = (0, _slice2.default)(arguments);
memo[key] = args;
var q = queues[key];
delete queues[key];
for (var i = 0, l = q.length; i < l; i++) {
q[i].apply(null, args);
}
}));
}
});
memoized.memo = memo;
memoized.unmemoized = fn;
return memoized;
}
module.exports = exports['default'];