Book a Demo!
CoCalc Logo Icon
StoreFeaturesDocsShareSupportNewsAboutPoliciesSign UpSign In
seleniumhq
GitHub Repository: seleniumhq/selenium
Path: blob/trunk/third_party/closure/goog/memoize/memoize.js
2868 views
1
// Copyright 2008 The Closure Library Authors. All Rights Reserved.
2
//
3
// Licensed under the Apache License, Version 2.0 (the "License");
4
// you may not use this file except in compliance with the License.
5
// You may obtain a copy of the License at
6
//
7
// http://www.apache.org/licenses/LICENSE-2.0
8
//
9
// Unless required by applicable law or agreed to in writing, software
10
// distributed under the License is distributed on an "AS-IS" BASIS,
11
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12
// See the License for the specific language governing permissions and
13
// limitations under the License.
14
15
/**
16
* @fileoverview Tool for caching the result of expensive deterministic
17
* functions.
18
*
19
* @see http://en.wikipedia.org/wiki/Memoization
20
*
21
*/
22
23
goog.provide('goog.memoize');
24
25
26
/**
27
* Decorator around functions that caches the inner function's return values.
28
*
29
* To cache parameterless functions, see goog.functions.cacheReturnValue.
30
*
31
* @param {Function} f The function to wrap. Its return value may only depend
32
* on its arguments and 'this' context. There may be further restrictions
33
* on the arguments depending on the capabilities of the serializer used.
34
* @param {function(number, Object): string=} opt_serializer A function to
35
* serialize f's arguments. It must have the same signature as
36
* goog.memoize.simpleSerializer. It defaults to that function.
37
* @this {Object} The object whose function is being wrapped.
38
* @return {!Function} The wrapped function.
39
*/
40
goog.memoize = function(f, opt_serializer) {
41
var serializer = opt_serializer || goog.memoize.simpleSerializer;
42
43
return function() {
44
if (goog.memoize.ENABLE_MEMOIZE) {
45
// In the strict mode, when this function is called as a global function,
46
// the value of 'this' is undefined instead of a global object. See:
47
// https://developer.mozilla.org/en/JavaScript/Strict_mode
48
var thisOrGlobal = this || goog.global;
49
// Maps the serialized list of args to the corresponding return value.
50
var cache = thisOrGlobal[goog.memoize.CACHE_PROPERTY_] ||
51
(thisOrGlobal[goog.memoize.CACHE_PROPERTY_] = {});
52
var key = serializer(goog.getUid(f), arguments);
53
return cache.hasOwnProperty(key) ?
54
cache[key] :
55
(cache[key] = f.apply(this, arguments));
56
} else {
57
return f.apply(this, arguments);
58
}
59
};
60
};
61
62
63
/**
64
* @define {boolean} Flag to disable memoization in unit tests.
65
*/
66
goog.define('goog.memoize.ENABLE_MEMOIZE', true);
67
68
69
/**
70
* Clears the memoization cache on the given object.
71
* @param {Object} cacheOwner The owner of the cache. This is the {@code this}
72
* context of the memoized function.
73
*/
74
goog.memoize.clearCache = function(cacheOwner) {
75
cacheOwner[goog.memoize.CACHE_PROPERTY_] = {};
76
};
77
78
79
/**
80
* Name of the property used by goog.memoize as cache.
81
* @type {string}
82
* @private
83
*/
84
goog.memoize.CACHE_PROPERTY_ = 'closure_memoize_cache_';
85
86
87
/**
88
* Simple and fast argument serializer function for goog.memoize.
89
* Supports string, number, boolean, null and undefined arguments. Doesn't
90
* support \x0B characters in the strings.
91
* @param {number} functionUid Unique identifier of the function whose result
92
* is cached.
93
* @param {?{length:number}} args The arguments that the function to memoize is
94
* called with. Note: it is an array-like object, because supports indexing
95
* and has the length property.
96
* @return {string} The list of arguments with type information concatenated
97
* with the functionUid argument, serialized as \x0B-separated string.
98
*/
99
goog.memoize.simpleSerializer = function(functionUid, args) {
100
var context = [functionUid];
101
for (var i = args.length - 1; i >= 0; --i) {
102
context.push(typeof args[i], args[i]);
103
}
104
return context.join('\x0B');
105
};
106
107