1 | ;
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2 |
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3 | Object.defineProperty(exports, "__esModule", {
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4 | value: true
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5 | });
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6 | exports.default = memoize;
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7 |
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8 | var _setImmediate = require('./internal/setImmediate.js');
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9 |
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10 | var _setImmediate2 = _interopRequireDefault(_setImmediate);
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11 |
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12 | var _initialParams = require('./internal/initialParams.js');
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13 |
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14 | var _initialParams2 = _interopRequireDefault(_initialParams);
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15 |
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16 | var _wrapAsync = require('./internal/wrapAsync.js');
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17 |
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18 | var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
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19 |
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20 | function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
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21 |
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22 | /**
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23 | * Caches the results of an async function. When creating a hash to store
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24 | * function results against, the callback is omitted from the hash and an
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25 | * optional hash function can be used.
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26 | *
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27 | * **Note: if the async function errs, the result will not be cached and
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28 | * subsequent calls will call the wrapped function.**
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29 | *
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30 | * If no hash function is specified, the first argument is used as a hash key,
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31 | * which may work reasonably if it is a string or a data type that converts to a
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32 | * distinct string. Note that objects and arrays will not behave reasonably.
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33 | * Neither will cases where the other arguments are significant. In such cases,
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34 | * specify your own hash function.
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35 | *
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36 | * The cache of results is exposed as the `memo` property of the function
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37 | * returned by `memoize`.
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38 | *
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39 | * @name memoize
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40 | * @static
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41 | * @memberOf module:Utils
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42 | * @method
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43 | * @category Util
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44 | * @param {AsyncFunction} fn - The async function to proxy and cache results from.
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45 | * @param {Function} hasher - An optional function for generating a custom hash
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46 | * for storing results. It has all the arguments applied to it apart from the
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47 | * callback, and must be synchronous.
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48 | * @returns {AsyncFunction} a memoized version of `fn`
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49 | * @example
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50 | *
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51 | * var slow_fn = function(name, callback) {
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52 | * // do something
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53 | * callback(null, result);
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54 | * };
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55 | * var fn = async.memoize(slow_fn);
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56 | *
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57 | * // fn can now be used as if it were slow_fn
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58 | * fn('some name', function() {
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59 | * // callback
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60 | * });
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61 | */
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62 | function memoize(fn, hasher = v => v) {
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63 | var memo = Object.create(null);
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64 | var queues = Object.create(null);
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65 | var _fn = (0, _wrapAsync2.default)(fn);
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66 | var memoized = (0, _initialParams2.default)((args, callback) => {
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67 | var key = hasher(...args);
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68 | if (key in memo) {
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69 | (0, _setImmediate2.default)(() => callback(null, ...memo[key]));
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70 | } else if (key in queues) {
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71 | queues[key].push(callback);
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72 | } else {
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73 | queues[key] = [callback];
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74 | _fn(...args, (err, ...resultArgs) => {
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75 | // #1465 don't memoize if an error occurred
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76 | if (!err) {
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77 | memo[key] = resultArgs;
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78 | }
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79 | var q = queues[key];
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80 | delete queues[key];
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81 | for (var i = 0, l = q.length; i < l; i++) {
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82 | q[i](err, ...resultArgs);
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83 | }
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84 | });
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85 | }
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86 | });
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87 | memoized.memo = memo;
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88 | memoized.unmemoized = fn;
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89 | return memoized;
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90 | }
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91 | module.exports = exports.default; |
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