diff options
author | Florian Dold <florian.dold@gmail.com> | 2017-05-03 15:35:00 +0200 |
---|---|---|
committer | Florian Dold <florian.dold@gmail.com> | 2017-05-03 15:35:00 +0200 |
commit | de98e0b232509d5f40c135d540a70e415272ff85 (patch) | |
tree | a79222a5b58484ab3b80d18efcaaa7ccc4769b33 /node_modules/async/memoize.js | |
parent | e0c9d480a73fa629c1e4a47d3e721f1d2d345406 (diff) |
node_modules
Diffstat (limited to 'node_modules/async/memoize.js')
-rw-r--r-- | node_modules/async/memoize.js | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/node_modules/async/memoize.js b/node_modules/async/memoize.js new file mode 100644 index 000000000..4942eb8a2 --- /dev/null +++ b/node_modules/async/memoize.js @@ -0,0 +1,100 @@ +'use strict'; + +Object.defineProperty(exports, "__esModule", { + value: true +}); +exports.default = memoize; + +var _identity = require('lodash/identity'); + +var _identity2 = _interopRequireDefault(_identity); + +var _rest = require('./internal/rest'); + +var _rest2 = _interopRequireDefault(_rest); + +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((0, _rest2.default)(function (args) { + 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'];
\ No newline at end of file |