1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
|
// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
var nativeDeepCopy = requireNative('utils').deepCopy;
/**
* An object forEach. Calls |f| with each (key, value) pair of |obj|, using
* |self| as the target.
* @param {Object} obj The object to iterate over.
* @param {function} f The function to call in each iteration.
* @param {Object} self The object to use as |this| in each function call.
*/
function forEach(obj, f, self) {
for (var key in obj) {
if ($Object.hasOwnProperty(obj, key))
$Function.call(f, self, key, obj[key]);
}
}
/**
* Assuming |array_of_dictionaries| is structured like this:
* [{id: 1, ... }, {id: 2, ...}, ...], you can use
* lookup(array_of_dictionaries, 'id', 2) to get the dictionary with id == 2.
* @param {Array<Object<?>>} array_of_dictionaries
* @param {string} field
* @param {?} value
*/
function lookup(array_of_dictionaries, field, value) {
var filter = function (dict) {return dict[field] == value;};
var matches = $Array.filter(array_of_dictionaries, filter);
if (matches.length == 0) {
return undefined;
} else if (matches.length == 1) {
return matches[0]
} else {
throw new Error("Failed lookup of field '" + field + "' with value '" +
value + "'");
}
}
/**
* Sets a property |value| on |obj| with property name |key|. Like
*
* obj[key] = value;
*
* but without triggering setters.
*/
function defineProperty(obj, key, value) {
$Object.defineProperty(obj, key, {
__proto__: null,
configurable: true,
enumerable: true,
writable: true,
value: value,
});
}
/**
* Takes a private class implementation |privateClass| and exposes a subset of
* its methods |functions| and properties |properties| and |readonly| to a
* public wrapper class that should be passed in. Within bindings code, you can
* access the implementation from an instance of the wrapper class using
* privates(instance).impl, and from the implementation class you can access
* the wrapper using this.wrapper (or implInstance.wrapper if you have another
* instance of the implementation class).
*
* |publicClass| should be a constructor that calls constructPrivate() like so:
*
* privates(publicClass).constructPrivate(this, arguments);
*
* @param {function} publicClass The publicly exposed wrapper class. This must
* be a named function, and the name appears in stack traces.
* @param {Object} privateClass The class implementation.
* @param {{superclass: ?Function,
* functions: ?Array<string>,
* properties: ?Array<string>,
* readonly: ?Array<string>}} exposed The names of properties on the
* implementation class to be exposed. |superclass| represents the
* constructor of the class to be used as the superclass of the exposed
* class; |functions| represents the names of functions which should be
* delegated to the implementation; |properties| are gettable/settable
* properties and |readonly| are read-only properties.
*/
function expose(publicClass, privateClass, exposed) {
$Object.setPrototypeOf(exposed, null);
// This should be called by publicClass.
privates(publicClass).constructPrivate = function(self, args) {
if (!(self instanceof publicClass)) {
throw new Error('Please use "new ' + publicClass.name + '"');
}
// The "instanceof publicClass" check can easily be spoofed, so we check
// whether the private impl is already set before continuing.
var privateSelf = privates(self);
if ('impl' in privateSelf) {
throw new Error('Object ' + publicClass.name + ' is already constructed');
}
var privateObj = $Object.create(privateClass.prototype);
$Function.apply(privateClass, privateObj, args);
privateObj.wrapper = self;
privateSelf.impl = privateObj;
};
function getPrivateImpl(self) {
var impl = privates(self).impl;
if (!(impl instanceof privateClass)) {
// Either the object is not constructed, or the property descriptor is
// used on a target that is not an instance of publicClass.
throw new Error('impl is not an instance of ' + privateClass.name);
}
return impl;
}
var publicClassPrototype = {
// The final prototype will be assigned at the end of this method.
__proto__: null,
constructor: publicClass,
};
if ('functions' in exposed) {
$Array.forEach(exposed.functions, function(func) {
publicClassPrototype[func] = function() {
var impl = getPrivateImpl(this);
return $Function.apply(impl[func], impl, arguments);
};
});
}
if ('properties' in exposed) {
$Array.forEach(exposed.properties, function(prop) {
$Object.defineProperty(publicClassPrototype, prop, {
__proto__: null,
enumerable: true,
get: function() {
return getPrivateImpl(this)[prop];
},
set: function(value) {
var impl = getPrivateImpl(this);
delete impl[prop];
impl[prop] = value;
}
});
});
}
if ('readonly' in exposed) {
$Array.forEach(exposed.readonly, function(readonly) {
$Object.defineProperty(publicClassPrototype, readonly, {
__proto__: null,
enumerable: true,
get: function() {
return getPrivateImpl(this)[readonly];
},
});
});
}
// The prototype properties have been installed. Now we can safely assign an
// unsafe prototype and export the class to the public.
var superclass = exposed.superclass || $Object.self;
$Object.setPrototypeOf(publicClassPrototype, superclass.prototype);
publicClass.prototype = publicClassPrototype;
return publicClass;
}
/**
* Returns a deep copy of |value|. The copy will have no references to nested
* values of |value|.
*/
function deepCopy(value) {
return nativeDeepCopy(value);
}
exports.$set('forEach', forEach);
exports.$set('lookup', lookup);
exports.$set('defineProperty', defineProperty);
exports.$set('expose', expose);
exports.$set('deepCopy', deepCopy);
|
