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 ClassLoader 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 ClassLoader, and based on these observations, apply Extract Interface, too.
1 | <?php |
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43 | class ClassLoader |
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44 | { |
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45 | // PSR-4 |
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46 | private $prefixLengthsPsr4 = array(); |
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47 | private $prefixDirsPsr4 = array(); |
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48 | private $fallbackDirsPsr4 = array(); |
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49 | |||
50 | // PSR-0 |
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51 | private $prefixesPsr0 = array(); |
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52 | private $fallbackDirsPsr0 = array(); |
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53 | |||
54 | private $useIncludePath = false; |
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55 | private $classMap = array(); |
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56 | |||
57 | private $classMapAuthoritative = false; |
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58 | |||
59 | public function getPrefixes() |
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60 | { |
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61 | if (!empty($this->prefixesPsr0)) { |
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62 | return call_user_func_array('array_merge', $this->prefixesPsr0); |
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63 | } |
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64 | |||
65 | return array(); |
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66 | } |
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67 | |||
68 | public function getPrefixesPsr4() |
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69 | { |
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70 | return $this->prefixDirsPsr4; |
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71 | } |
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72 | |||
73 | public function getFallbackDirs() |
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74 | { |
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75 | return $this->fallbackDirsPsr0; |
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76 | } |
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77 | |||
78 | public function getFallbackDirsPsr4() |
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79 | { |
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80 | return $this->fallbackDirsPsr4; |
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81 | } |
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82 | |||
83 | public function getClassMap() |
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84 | { |
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85 | return $this->classMap; |
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86 | } |
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87 | |||
88 | /** |
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89 | * @param array $classMap Class to filename map |
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90 | */ |
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91 | public function addClassMap(array $classMap) |
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92 | { |
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93 | if ($this->classMap) { |
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94 | $this->classMap = array_merge($this->classMap, $classMap); |
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95 | } else { |
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96 | $this->classMap = $classMap; |
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97 | } |
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98 | } |
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99 | |||
100 | /** |
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101 | * Registers a set of PSR-0 directories for a given prefix, either |
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102 | * appending or prepending to the ones previously set for this prefix. |
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103 | * |
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104 | * @param string $prefix The prefix |
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105 | * @param array|string $paths The PSR-0 root directories |
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106 | * @param bool $prepend Whether to prepend the directories |
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107 | */ |
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108 | public function add($prefix, $paths, $prepend = false) |
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109 | { |
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110 | if (!$prefix) { |
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111 | if ($prepend) { |
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112 | $this->fallbackDirsPsr0 = array_merge( |
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113 | (array) $paths, |
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114 | $this->fallbackDirsPsr0 |
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115 | ); |
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116 | } else { |
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117 | $this->fallbackDirsPsr0 = array_merge( |
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118 | $this->fallbackDirsPsr0, |
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119 | (array) $paths |
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120 | ); |
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121 | } |
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122 | |||
123 | return; |
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124 | } |
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125 | |||
126 | $first = $prefix[0]; |
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127 | if (!isset($this->prefixesPsr0[$first][$prefix])) { |
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128 | $this->prefixesPsr0[$first][$prefix] = (array) $paths; |
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129 | |||
130 | return; |
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131 | } |
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132 | if ($prepend) { |
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133 | $this->prefixesPsr0[$first][$prefix] = array_merge( |
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134 | (array) $paths, |
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135 | $this->prefixesPsr0[$first][$prefix] |
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136 | ); |
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137 | } else { |
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138 | $this->prefixesPsr0[$first][$prefix] = array_merge( |
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139 | $this->prefixesPsr0[$first][$prefix], |
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140 | (array) $paths |
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141 | ); |
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142 | } |
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143 | } |
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144 | |||
145 | /** |
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146 | * Registers a set of PSR-4 directories for a given namespace, either |
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147 | * appending or prepending to the ones previously set for this namespace. |
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148 | * |
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149 | * @param string $prefix The prefix/namespace, with trailing '\\' |
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150 | * @param array|string $paths The PSR-0 base directories |
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151 | * @param bool $prepend Whether to prepend the directories |
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152 | * |
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153 | * @throws \InvalidArgumentException |
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154 | */ |
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155 | public function addPsr4($prefix, $paths, $prepend = false) |
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156 | { |
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157 | if (!$prefix) { |
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158 | // Register directories for the root namespace. |
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159 | if ($prepend) { |
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160 | $this->fallbackDirsPsr4 = array_merge( |
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161 | (array) $paths, |
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162 | $this->fallbackDirsPsr4 |
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163 | ); |
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164 | } else { |
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165 | $this->fallbackDirsPsr4 = array_merge( |
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166 | $this->fallbackDirsPsr4, |
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167 | (array) $paths |
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168 | ); |
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169 | } |
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170 | } elseif (!isset($this->prefixDirsPsr4[$prefix])) { |
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171 | // Register directories for a new namespace. |
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172 | $length = strlen($prefix); |
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173 | if ('\\' !== $prefix[$length - 1]) { |
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174 | throw new \InvalidArgumentException("A non-empty PSR-4 prefix must end with a namespace separator."); |
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175 | } |
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176 | $this->prefixLengthsPsr4[$prefix[0]][$prefix] = $length; |
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177 | $this->prefixDirsPsr4[$prefix] = (array) $paths; |
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178 | } elseif ($prepend) { |
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179 | // Prepend directories for an already registered namespace. |
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180 | $this->prefixDirsPsr4[$prefix] = array_merge( |
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181 | (array) $paths, |
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182 | $this->prefixDirsPsr4[$prefix] |
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183 | ); |
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184 | } else { |
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185 | // Append directories for an already registered namespace. |
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186 | $this->prefixDirsPsr4[$prefix] = array_merge( |
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187 | $this->prefixDirsPsr4[$prefix], |
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188 | (array) $paths |
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189 | ); |
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190 | } |
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191 | } |
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192 | |||
193 | /** |
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194 | * Registers a set of PSR-0 directories for a given prefix, |
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195 | * replacing any others previously set for this prefix. |
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196 | * |
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197 | * @param string $prefix The prefix |
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198 | * @param array|string $paths The PSR-0 base directories |
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199 | */ |
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200 | public function set($prefix, $paths) |
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201 | { |
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202 | if (!$prefix) { |
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203 | $this->fallbackDirsPsr0 = (array) $paths; |
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204 | } else { |
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205 | $this->prefixesPsr0[$prefix[0]][$prefix] = (array) $paths; |
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206 | } |
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207 | } |
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208 | |||
209 | /** |
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210 | * Registers a set of PSR-4 directories for a given namespace, |
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211 | * replacing any others previously set for this namespace. |
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212 | * |
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213 | * @param string $prefix The prefix/namespace, with trailing '\\' |
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214 | * @param array|string $paths The PSR-4 base directories |
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215 | * |
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216 | * @throws \InvalidArgumentException |
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217 | */ |
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218 | public function setPsr4($prefix, $paths) |
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219 | { |
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220 | if (!$prefix) { |
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221 | $this->fallbackDirsPsr4 = (array) $paths; |
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222 | } else { |
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223 | $length = strlen($prefix); |
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224 | if ('\\' !== $prefix[$length - 1]) { |
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225 | throw new \InvalidArgumentException("A non-empty PSR-4 prefix must end with a namespace separator."); |
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226 | } |
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227 | $this->prefixLengthsPsr4[$prefix[0]][$prefix] = $length; |
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228 | $this->prefixDirsPsr4[$prefix] = (array) $paths; |
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229 | } |
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230 | } |
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231 | |||
232 | /** |
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233 | * Turns on searching the include path for class files. |
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234 | * |
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235 | * @param bool $useIncludePath |
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236 | */ |
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237 | public function setUseIncludePath($useIncludePath) |
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238 | { |
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239 | $this->useIncludePath = $useIncludePath; |
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240 | } |
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241 | |||
242 | /** |
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243 | * Can be used to check if the autoloader uses the include path to check |
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244 | * for classes. |
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245 | * |
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246 | * @return bool |
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247 | */ |
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248 | public function getUseIncludePath() |
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249 | { |
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250 | return $this->useIncludePath; |
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251 | } |
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252 | |||
253 | /** |
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254 | * Turns off searching the prefix and fallback directories for classes |
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255 | * that have not been registered with the class map. |
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256 | * |
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257 | * @param bool $classMapAuthoritative |
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258 | */ |
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259 | public function setClassMapAuthoritative($classMapAuthoritative) |
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260 | { |
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261 | $this->classMapAuthoritative = $classMapAuthoritative; |
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262 | } |
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263 | |||
264 | /** |
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265 | * Should class lookup fail if not found in the current class map? |
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266 | * |
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267 | * @return bool |
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268 | */ |
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269 | public function isClassMapAuthoritative() |
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270 | { |
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271 | return $this->classMapAuthoritative; |
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272 | } |
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273 | |||
274 | /** |
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275 | * Registers this instance as an autoloader. |
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276 | * |
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277 | * @param bool $prepend Whether to prepend the autoloader or not |
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278 | */ |
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279 | public function register($prepend = false) |
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280 | { |
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281 | spl_autoload_register(array($this, 'loadClass'), true, $prepend); |
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282 | } |
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283 | |||
284 | /** |
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285 | * Unregisters this instance as an autoloader. |
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286 | */ |
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287 | public function unregister() |
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288 | { |
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289 | spl_autoload_unregister(array($this, 'loadClass')); |
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290 | } |
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291 | |||
292 | /** |
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293 | * Loads the given class or interface. |
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294 | * |
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295 | * @param string $class The name of the class |
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296 | * @return bool|null True if loaded, null otherwise |
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297 | */ |
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298 | public function loadClass($class) |
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299 | { |
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300 | if ($file = $this->findFile($class)) { |
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301 | includeFile($file); |
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302 | |||
303 | return true; |
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304 | } |
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305 | } |
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306 | |||
307 | /** |
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308 | * Finds the path to the file where the class is defined. |
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309 | * |
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310 | * @param string $class The name of the class |
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311 | * |
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312 | * @return string|false The path if found, false otherwise |
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313 | */ |
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314 | public function findFile($class) |
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315 | { |
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316 | // work around for PHP 5.3.0 - 5.3.2 https://bugs.php.net/50731 |
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317 | if ('\\' == $class[0]) { |
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318 | $class = substr($class, 1); |
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319 | } |
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320 | |||
321 | // class map lookup |
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322 | if (isset($this->classMap[$class])) { |
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323 | return $this->classMap[$class]; |
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324 | } |
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325 | if ($this->classMapAuthoritative) { |
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326 | return false; |
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327 | } |
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328 | |||
329 | $file = $this->findFileWithExtension($class, '.php'); |
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330 | |||
331 | // Search for Hack files if we are running on HHVM |
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332 | if ($file === null && defined('HHVM_VERSION')) { |
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333 | $file = $this->findFileWithExtension($class, '.hh'); |
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334 | } |
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335 | |||
336 | if ($file === null) { |
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337 | // Remember that this class does not exist. |
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338 | return $this->classMap[$class] = false; |
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339 | } |
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340 | |||
341 | return $file; |
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342 | } |
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343 | |||
344 | private function findFileWithExtension($class, $ext) |
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345 | { |
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346 | // PSR-4 lookup |
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347 | $logicalPathPsr4 = strtr($class, '\\', DIRECTORY_SEPARATOR) . $ext; |
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348 | |||
349 | $first = $class[0]; |
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350 | if (isset($this->prefixLengthsPsr4[$first])) { |
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351 | foreach ($this->prefixLengthsPsr4[$first] as $prefix => $length) { |
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352 | if (0 === strpos($class, $prefix)) { |
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353 | foreach ($this->prefixDirsPsr4[$prefix] as $dir) { |
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354 | if (file_exists($file = $dir . DIRECTORY_SEPARATOR . substr($logicalPathPsr4, $length))) { |
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355 | return $file; |
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356 | } |
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357 | } |
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358 | } |
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359 | } |
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360 | } |
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361 | |||
362 | // PSR-4 fallback dirs |
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363 | foreach ($this->fallbackDirsPsr4 as $dir) { |
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364 | if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr4)) { |
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365 | return $file; |
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366 | } |
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367 | } |
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368 | |||
369 | // PSR-0 lookup |
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370 | if (false !== $pos = strrpos($class, '\\')) { |
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371 | // namespaced class name |
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372 | $logicalPathPsr0 = substr($logicalPathPsr4, 0, $pos + 1) |
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373 | . strtr(substr($logicalPathPsr4, $pos + 1), '_', DIRECTORY_SEPARATOR); |
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374 | } else { |
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375 | // PEAR-like class name |
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376 | $logicalPathPsr0 = strtr($class, '_', DIRECTORY_SEPARATOR) . $ext; |
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377 | } |
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378 | |||
379 | if (isset($this->prefixesPsr0[$first])) { |
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380 | foreach ($this->prefixesPsr0[$first] as $prefix => $dirs) { |
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381 | if (0 === strpos($class, $prefix)) { |
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382 | foreach ($dirs as $dir) { |
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383 | if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) { |
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384 | return $file; |
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385 | } |
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386 | } |
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387 | } |
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388 | } |
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389 | } |
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390 | |||
391 | // PSR-0 fallback dirs |
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392 | foreach ($this->fallbackDirsPsr0 as $dir) { |
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393 | if (file_exists($file = $dir . DIRECTORY_SEPARATOR . $logicalPathPsr0)) { |
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394 | return $file; |
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395 | } |
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396 | } |
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397 | |||
398 | // PSR-0 include paths. |
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399 | if ($this->useIncludePath && $file = stream_resolve_include_path($logicalPathPsr0)) { |
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400 | return $file; |
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401 | } |
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402 | } |
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403 | } |
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404 | |||
414 |