Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
Complex classes like Enum often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Enum, and based on these observations, apply Extract Interface, too.
1 | <?php |
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16 | abstract class Enum |
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17 | { |
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18 | /** |
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19 | * The selected enumerator value |
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20 | * |
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21 | * @var null|bool|int|float|string |
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22 | */ |
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23 | private $value; |
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24 | |||
25 | /** |
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26 | * The ordinal number of the enumerator |
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27 | * |
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28 | * @var null|int |
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29 | */ |
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30 | private $ordinal; |
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31 | |||
32 | /** |
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33 | * An array of available constants by class |
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34 | * |
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35 | * @var array ["$class" => ["$name" => $value, ...], ...] |
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36 | */ |
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37 | private static $constants = array(); |
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38 | |||
39 | /** |
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40 | * Already instantiated enumerators |
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41 | * |
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42 | * @var array ["$class" => ["$name" => $instance, ...], ...] |
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43 | */ |
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44 | private static $instances = array(); |
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45 | |||
46 | /** |
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47 | * Constructor |
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48 | * |
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49 | * @param null|bool|int|float|string $value The value of the enumerator |
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50 | * @param int|null $ordinal The ordinal number of the enumerator |
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51 | */ |
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52 | 32 | final private function __construct($value, $ordinal = null) |
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57 | |||
58 | /** |
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59 | * Get the name of the enumerator |
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60 | * |
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61 | * @return string |
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62 | * @see getName() |
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63 | */ |
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64 | 1 | public function __toString() |
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68 | |||
69 | /** |
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70 | * @throws LogicException Enums are not cloneable |
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71 | * because instances are implemented as singletons |
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72 | */ |
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73 | 1 | final private function __clone() |
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77 | |||
78 | /** |
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79 | * @throws LogicException Enums are not serializable |
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80 | * because instances are implemented as singletons |
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81 | */ |
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82 | 1 | final public function __sleep() |
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86 | |||
87 | /** |
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88 | * @throws LogicException Enums are not serializable |
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89 | * because instances are implemented as singletons |
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90 | */ |
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91 | 1 | final public function __wakeup() |
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95 | |||
96 | /** |
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97 | * Get the value of the enumerator |
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98 | * |
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99 | * @return null|bool|int|float|string |
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100 | */ |
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101 | 22 | final public function getValue() |
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105 | |||
106 | /** |
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107 | * Get the name of the enumerator |
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108 | * |
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109 | * @return string |
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110 | */ |
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111 | 8 | final public function getName() |
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115 | |||
116 | /** |
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117 | * Get the ordinal number of the enumerator |
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118 | * |
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119 | * @return int |
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120 | */ |
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121 | 44 | final public function getOrdinal() |
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140 | |||
141 | /** |
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142 | * Compare this enumerator against another and check if it's the same. |
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143 | * |
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144 | * @param mixed $enumerator |
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145 | * @return bool |
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146 | */ |
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147 | 2 | final public function is($enumerator) |
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148 | { |
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149 | 2 | return $this === $enumerator || $this->value === $enumerator |
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150 | |||
151 | // The following additional conditions are required only because of the issue of serializable singletons |
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152 | 2 | || ($enumerator instanceof static |
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153 | 2 | && get_class($enumerator) === get_called_class() |
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154 | 2 | && $enumerator->value === $this->value |
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155 | ); |
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156 | } |
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157 | |||
158 | /** |
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159 | * Get an enumerator instance of the given value or instance |
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160 | * |
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161 | * @param static|null|bool|int|float|string $value |
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162 | * @return static |
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163 | * @throws InvalidArgumentException On an unknwon or invalid value |
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164 | * @throws LogicException On ambiguous constant values |
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165 | */ |
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166 | 67 | final public static function get($value) |
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167 | { |
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168 | 67 | if ($value instanceof static && get_class($value) === get_called_class()) { |
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169 | 26 | return $value; |
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170 | } |
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171 | |||
172 | 48 | $class = get_called_class(); |
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173 | 48 | $constants = self::detectConstants($class); |
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174 | 46 | $name = array_search($value, $constants, true); |
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175 | 46 | View Code Duplication | if ($name === false) { |
176 | 7 | $message = is_scalar($value) |
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177 | 3 | ? 'Unknown value ' . var_export($value, true) |
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178 | 7 | : 'Invalid value of type ' . (is_object($value) ? get_class($value) : gettype($value)); |
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179 | 7 | throw new InvalidArgumentException($message); |
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180 | } |
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181 | |||
182 | 40 | if (!isset(self::$instances[$class][$name])) { |
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183 | 16 | self::$instances[$class][$name] = new $class($constants[$name]); |
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184 | } |
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185 | |||
186 | 40 | return self::$instances[$class][$name]; |
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187 | } |
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188 | |||
189 | /** |
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190 | * Get an enumerator instance by the given name |
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191 | * |
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192 | * @param string $name The name of the enumerator |
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193 | * @return static |
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194 | * @throws InvalidArgumentException On an invalid or unknown name |
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195 | * @throws LogicException On ambiguous values |
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196 | */ |
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197 | 37 | final public static function getByName($name) |
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212 | |||
213 | /** |
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214 | * Get an enumeration instance by the given ordinal number |
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215 | * |
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216 | * @param int $ordinal The ordinal number or the enumerator |
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217 | * @return static |
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218 | * @throws InvalidArgumentException On an invalid ordinal number |
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219 | * @throws LogicException On ambiguous values |
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220 | */ |
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221 | 19 | final public static function getByOrdinal($ordinal) |
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222 | { |
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223 | 19 | $ordinal = (int) $ordinal; |
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224 | 19 | $class = get_called_class(); |
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225 | 19 | $constants = self::detectConstants($class); |
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226 | 19 | $item = array_slice($constants, $ordinal, 1, true); |
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227 | 19 | if (empty($item)) { |
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228 | 1 | throw new InvalidArgumentException(sprintf( |
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229 | 1 | 'Invalid ordinal number, must between 0 and %s', |
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230 | 1 | count($constants) - 1 |
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231 | )); |
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232 | } |
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233 | |||
234 | 18 | $name = key($item); |
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235 | 18 | if (isset(self::$instances[$class][$name])) { |
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236 | 16 | return self::$instances[$class][$name]; |
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237 | } |
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238 | |||
239 | 3 | return self::$instances[$class][$name] = new $class(current($item), $ordinal); |
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240 | } |
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241 | |||
242 | /** |
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243 | * Clear all instantiated enumerators of the called class |
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244 | * |
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245 | * NOTE: This can break singleton behavior ... use it with caution! |
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246 | * |
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247 | * @return void |
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248 | */ |
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249 | 32 | final public static function clear() |
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254 | |||
255 | /** |
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256 | * Get a list of enumerator instances ordered by ordinal number |
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257 | * |
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258 | * @return static[] |
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259 | */ |
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260 | 13 | final public static function getEnumerators() |
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264 | |||
265 | /** |
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266 | * Get all available constants of the called class |
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267 | * |
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268 | * @return array |
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269 | * @throws LogicException On ambiguous constant values |
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270 | */ |
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271 | 59 | final public static function getConstants() |
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275 | |||
276 | /** |
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277 | * Is the given enumerator part of this enumeration |
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278 | * |
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279 | * @param static|null|bool|int|float|string $value |
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280 | * @return bool |
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281 | */ |
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282 | 1 | final public static function has($value) |
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293 | |||
294 | /** |
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295 | * Detect all available constants by the given class |
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296 | * |
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297 | * @param string $class |
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298 | * @return array |
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299 | * @throws LogicException On ambiguous constant values |
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300 | */ |
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301 | 79 | private static function detectConstants($class) |
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302 | { |
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303 | 79 | if (!isset(self::$constants[$class])) { |
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304 | 29 | $reflection = new ReflectionClass($class); |
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305 | 29 | $constants = array(); |
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306 | |||
307 | do { |
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308 | 29 | $scopeConstants = array(); |
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309 | 29 | if (PHP_VERSION_ID >= 70100) { |
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310 | // Since PHP-7.1 visibility modifiers are allowed for class constants |
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311 | // for enumerations we are only interested in public once. |
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312 | foreach ($reflection->getReflectionConstants() as $reflConstant) { |
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313 | if ($reflConstant->isPublic()) { |
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314 | $scopeConstants[ $reflConstant->getName() ] = $reflConstant->getValue(); |
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315 | } |
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316 | } |
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317 | } else { |
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318 | // In PHP < 7.1 all class constants were public by definition |
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319 | 29 | $scopeConstants = $reflection->getConstants(); |
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320 | } |
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321 | |||
322 | 29 | $constants = $scopeConstants + $constants; |
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323 | 29 | } while (($reflection = $reflection->getParentClass()) && $reflection->name !== __CLASS__); |
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324 | |||
325 | // Detect ambiguous values and report names |
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326 | 29 | $ambiguous = array(); |
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327 | 29 | foreach ($constants as $value) { |
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328 | 28 | $names = array_keys($constants, $value, true); |
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329 | 28 | if (count($names) > 1) { |
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330 | 28 | $ambiguous[var_export($value, true)] = $names; |
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331 | } |
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332 | } |
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333 | 29 | if (!empty($ambiguous)) { |
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334 | 2 | throw new LogicException( |
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335 | 'All possible values needs to be unique. The following are ambiguous: ' |
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336 | 2 | . implode(', ', array_map(function ($names) use ($constants) { |
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337 | 2 | return implode('/', $names) . '=' . var_export($constants[$names[0]], true); |
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338 | 2 | }, $ambiguous)) |
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339 | ); |
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340 | } |
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341 | |||
342 | 27 | self::$constants[$class] = $constants; |
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343 | } |
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344 | |||
345 | 77 | return self::$constants[$class]; |
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346 | } |
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347 | |||
348 | /** |
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349 | * Get an enumerator instance by the given name. |
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350 | * |
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351 | * This will be called automatically on calling a method |
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352 | * with the same name of a defined enumerator. |
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353 | * |
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354 | * @param string $method The name of the enumeraotr (called as method) |
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355 | * @param array $args There should be no arguments |
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356 | * @return static |
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357 | * @throws InvalidArgumentException On an invalid or unknown name |
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358 | * @throws LogicException On ambiguous constant values |
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359 | */ |
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360 | 22 | final public static function __callStatic($method, array $args) |
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364 | } |
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365 |