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
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
<?php
/**
* @link http://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
namespace yii\di;
use Yii;
use Closure;
use yii\base\Component;
use yii\base\InvalidConfigException;
/**
* ServiceLocator implements a [service locator](http://en.wikipedia.org/wiki/Service_locator_pattern).
*
* To use ServiceLocator, you first need to register component IDs with the corresponding component
* definitions with the locator by calling [[set()]] or [[setComponents()]].
* You can then call [[get()]] to retrieve a component with the specified ID. The locator will automatically
* instantiate and configure the component according to the definition.
*
* For example,
*
* ```php
* $locator = new \yii\di\ServiceLocator;
* $locator->setComponents([
* 'db' => [
* 'class' => 'yii\db\Connection',
* 'dsn' => 'sqlite:path/to/file.db',
* ],
* 'cache' => [
* 'class' => 'yii\caching\DbCache',
* 'db' => 'db',
* ],
* ]);
*
* $db = $locator->get('db'); // or $locator->db
* $cache = $locator->get('cache'); // or $locator->cache
* ```
*
* Because [[\yii\base\Module]] extends from ServiceLocator, modules and the application are all service locators.
*
* @property array $components The list of the component definitions or the loaded component instances (ID =>
* definition or instance).
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @since 2.0
*/
class ServiceLocator extends Component
{
/**
* @var array shared component instances indexed by their IDs
*/
private $_components = [];
/**
* @var array component definitions indexed by their IDs
*/
private $_definitions = [];
/**
* Getter magic method.
* This method is overridden to support accessing components like reading properties.
* @param string $name component or property name
* @return mixed the named property value
*/
public function __get($name)
{
if ($this->has($name)) {
return $this->get($name);
} else {
return parent::__get($name);
}
}
/**
* Checks if a property value is null.
* This method overrides the parent implementation by checking if the named component is loaded.
* @param string $name the property name or the event name
* @return boolean whether the property value is null
*/
public function __isset($name)
{
if ($this->has($name, true)) {
return true;
} else {
return parent::__isset($name);
}
}
/**
* Returns a value indicating whether the locator has the specified component definition or has instantiated the component.
* This method may return different results depending on the value of `$checkInstance`.
*
* - If `$checkInstance` is false (default), the method will return a value indicating whether the locator has the specified
* component definition.
* - If `$checkInstance` is true, the method will return a value indicating whether the locator has
* instantiated the specified component.
*
* @param string $id component ID (e.g. `db`).
* @param boolean $checkInstance whether the method should check if the component is shared and instantiated.
* @return boolean whether the locator has the specified component definition or has instantiated the component.
* @see set()
*/
public function has($id, $checkInstance = false)
{
return $checkInstance ? isset($this->_components[$id]) : isset($this->_definitions[$id]);
}
/**
* Returns the component instance with the specified ID.
*
* @param string $id component ID (e.g. `db`).
* @param boolean $throwException whether to throw an exception if `$id` is not registered with the locator before.
* @return object|null the component of the specified ID. If `$throwException` is false and `$id`
* is not registered before, null will be returned.
* @throws InvalidConfigException if `$id` refers to a nonexistent component ID
* @see has()
* @see set()
*/
public function get($id, $throwException = true)
{
if (isset($this->_components[$id])) {
return $this->_components[$id];
}
if (isset($this->_definitions[$id])) {
$definition = $this->_definitions[$id];
if (is_object($definition) && !$definition instanceof Closure) {
return $this->_components[$id] = $definition;
} else {
return $this->_components[$id] = Yii::createObject($definition);
}
} elseif ($throwException) {
throw new InvalidConfigException("Unknown component ID: $id");
} else {
return null;
}
}
/**
* Registers a component definition with this locator.
*
* For example,
*
* ```php
* // a class name
* $locator->set('cache', 'yii\caching\FileCache');
*
* // a configuration array
* $locator->set('db', [
* 'class' => 'yii\db\Connection',
* 'dsn' => 'mysql:host=127.0.0.1;dbname=demo',
* 'username' => 'root',
* 'password' => '',
* 'charset' => 'utf8',
* ]);
*
* // an anonymous function
* $locator->set('cache', function ($params) {
* return new \yii\caching\FileCache;
* });
*
* // an instance
* $locator->set('cache', new \yii\caching\FileCache);
* ```
*
* If a component definition with the same ID already exists, it will be overwritten.
*
* @param string $id component ID (e.g. `db`).
* @param mixed $definition the component definition to be registered with this locator.
* It can be one of the followings:
*
* - a class name
* - a configuration array: the array contains name-value pairs that will be used to
* initialize the property values of the newly created object when [[get()]] is called.
* The `class` element is required and stands for the the class of the object to be created.
* - a PHP callable: either an anonymous function or an array representing a class method (e.g. `['Foo', 'bar']`).
* The callable will be called by [[get()]] to return an object associated with the specified component ID.
* - an object: When [[get()]] is called, this object will be returned.
*
* @throws InvalidConfigException if the definition is an invalid configuration array
*/
public function set($id, $definition)
{
if ($definition === null) {
unset($this->_components[$id], $this->_definitions[$id]);
return;
}
unset($this->_components[$id]);
if (is_object($definition) || is_callable($definition, true)) {
// an object, a class name, or a PHP callable
$this->_definitions[$id] = $definition;
} elseif (is_array($definition)) {
// a configuration array
if (isset($definition['class'])) {
$this->_definitions[$id] = $definition;
} else {
throw new InvalidConfigException("The configuration for the \"$id\" component must contain a \"class\" element.");
}
} else {
throw new InvalidConfigException("Unexpected configuration type for the \"$id\" component: " . gettype($definition));
}
}
/**
* Removes the component from the locator.
* @param string $id the component ID
*/
public function clear($id)
{
unset($this->_definitions[$id], $this->_components[$id]);
}
/**
* Returns the list of the component definitions or the loaded component instances.
* @param boolean $returnDefinitions whether to return component definitions instead of the loaded component instances.
* @return array the list of the component definitions or the loaded component instances (ID => definition or instance).
*/
public function getComponents($returnDefinitions = true)
{
return $returnDefinitions ? $this->_definitions : $this->_components;
}
/**
* Registers a set of component definitions in this locator.
*
* This is the bulk version of [[set()]]. The parameter should be an array
* whose keys are component IDs and values the corresponding component definitions.
*
* For more details on how to specify component IDs and definitions, please refer to [[set()]].
*
* If a component definition with the same ID already exists, it will be overwritten.
*
* The following is an example for registering two component definitions:
*
* ```php
* [
* 'db' => [
* 'class' => 'yii\db\Connection',
* 'dsn' => 'sqlite:path/to/file.db',
* ],
* 'cache' => [
* 'class' => 'yii\caching\DbCache',
* 'db' => 'db',
* ],
* ]
* ```
*
* @param array $components component definitions or instances
*/
public function setComponents($components)
{
foreach ($components as $id => $component) {
$this->set($id, $component);
}
}
}