Complex classes like Expression 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 Expression, and based on these observations, apply Extract Interface, too.
| 1 | <?php |
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| 21 | class Expression |
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| 22 | { |
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| 23 | /** |
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| 24 | * @var Context |
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| 25 | */ |
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| 26 | protected $context; |
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| 27 | |||
| 28 | /** |
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| 29 | * @var EventManager |
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| 30 | */ |
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| 31 | protected $eventManager; |
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| 32 | |||
| 33 | /** |
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| 34 | * @param Context $context |
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| 35 | */ |
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| 36 | 848 | public function __construct(Context $context, EventManager $eventManager) |
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| 41 | |||
| 42 | /** |
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| 43 | * @param $expr |
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| 44 | * @return ExpressionCompilerInterface|AbstractExpressionCompiler |
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| 45 | */ |
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| 46 | 819 | protected function factory($expr) |
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| 47 | { |
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| 48 | 819 | switch (get_class($expr)) { |
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| 49 | /** |
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| 50 | * Call(s) |
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| 51 | */ |
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| 52 | 819 | case Node\Expr\MethodCall::class: |
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| 53 | return new Expression\MethodCall(); |
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| 54 | 819 | case Node\Expr\FuncCall::class: |
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| 55 | 10 | return new Expression\FunctionCall(); |
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| 56 | 811 | case Node\Expr\StaticCall::class: |
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| 57 | 1 | return new Expression\StaticCall(); |
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| 58 | /** |
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| 59 | * Operators |
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| 60 | */ |
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| 61 | 810 | case Node\Expr\New_::class: |
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| 62 | 2 | return new Expression\Operators\NewOp(); |
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| 63 | 808 | case Node\Expr\Instanceof_::class: |
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| 64 | return new Expression\Operators\InstanceOfOp(); |
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| 65 | /** |
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| 66 | * AssignOp |
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| 67 | */ |
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| 68 | 808 | case Node\Expr\AssignOp\Pow::class: |
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| 69 | 21 | return new Expression\AssignOp\Pow(); |
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| 70 | 787 | case Node\Expr\AssignOp\Plus::class: |
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| 71 | 17 | return new Expression\AssignOp\Plus(); |
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| 72 | 770 | case Node\Expr\AssignOp\Minus::class: |
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| 73 | 20 | return new Expression\AssignOp\Minus(); |
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| 74 | 750 | case Node\Expr\AssignOp\Mul::class: |
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| 75 | 20 | return new Expression\AssignOp\Mul(); |
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| 76 | 730 | case Node\Expr\AssignOp\Div::class: |
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| 77 | 18 | return new Expression\AssignOp\Div(); |
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| 78 | 712 | case Node\Expr\AssignOp\Mod::class: |
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| 79 | 11 | return new Expression\AssignOp\Mod(); |
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| 80 | 701 | case Node\Expr\AssignOp\BitwiseOr::class: |
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| 81 | 12 | return new Expression\AssignOp\BitwiseOr(); |
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| 82 | 689 | case Node\Expr\AssignOp\BitwiseAnd::class: |
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| 83 | 12 | return new Expression\AssignOp\BitwiseAnd(); |
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| 84 | 677 | case Node\Expr\AssignOp\BitwiseXor::class: |
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| 85 | 12 | return new Expression\AssignOp\BitwiseXor(); |
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| 86 | 665 | case Node\Expr\AssignOp\Concat::class: |
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| 87 | 14 | return new Expression\AssignOp\Concat(); |
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| 88 | 651 | case Node\Expr\AssignOp\ShiftLeft::class: |
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| 89 | 12 | return new Expression\AssignOp\ShiftLeft(); |
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| 90 | 639 | case Node\Expr\AssignOp\ShiftRight::class: |
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| 91 | 12 | return new Expression\AssignOp\ShiftRight(); |
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| 92 | |||
| 93 | /** |
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| 94 | * BinaryOp |
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| 95 | */ |
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| 96 | 627 | case Node\Expr\BinaryOp\Identical::class: |
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| 97 | 28 | return new Expression\BinaryOp\Identical(); |
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| 98 | 599 | case Node\Expr\BinaryOp\Concat::class: |
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| 99 | 15 | return new Expression\Operators\Concat(); |
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| 100 | 584 | case Node\Expr\BinaryOp\NotIdentical::class: |
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| 101 | 14 | return new Expression\BinaryOp\NotIdentical(); |
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| 102 | 570 | case Node\Expr\BinaryOp\Equal::class: |
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| 103 | 42 | return new Expression\BinaryOp\Equal(); |
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| 104 | 530 | case Node\Expr\BinaryOp\NotEqual::class: |
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| 105 | 17 | return new Expression\BinaryOp\NotEqual(); |
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| 106 | 513 | case Node\Expr\BinaryOp\Spaceship::class: |
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| 107 | 11 | return new Expression\BinaryOp\SpaceShip(); |
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| 108 | 502 | case Node\Expr\BinaryOp\Coalesce::class: |
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| 109 | 3 | return new Expression\BinaryOp\Coalesce(); |
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| 110 | |||
| 111 | /** |
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| 112 | * @link http://php.net/manual/en/language.operators.increment.php |
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| 113 | */ |
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| 114 | 499 | case Node\Expr\PostInc::class: |
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| 115 | 8 | return new Expression\Operators\PostInc(); |
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| 116 | 491 | case Node\Expr\PostDec::class: |
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| 117 | 8 | return new Expression\Operators\PostDec(); |
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| 118 | 483 | case Node\Expr\PreInc::class: |
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| 119 | 8 | return new Expression\Operators\PreInc(); |
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| 120 | 475 | case Node\Expr\PreDec::class: |
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| 121 | 8 | return new Expression\Operators\PreDec(); |
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| 122 | /** |
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| 123 | * Arithmetical |
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| 124 | */ |
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| 125 | 467 | case Node\Expr\BinaryOp\Div::class: |
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| 126 | 37 | return new Expression\Operators\Arithmetical\Div(); |
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| 127 | 430 | case Node\Expr\BinaryOp\Plus::class: |
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| 128 | 45 | return new Expression\Operators\Arithmetical\Plus(); |
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| 129 | 385 | case Node\Expr\BinaryOp\Minus::class: |
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| 130 | 24 | return new Expression\Operators\Arithmetical\Minus(); |
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| 131 | 361 | case Node\Expr\BinaryOp\Mul::class: |
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| 132 | 35 | return new Expression\Operators\Arithmetical\Mul(); |
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| 133 | 326 | case Node\Expr\BinaryOp\Mod::class: |
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| 134 | 35 | return new Expression\Operators\Arithmetical\Mod(); |
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| 135 | 291 | case Node\Expr\BinaryOp\Pow::class: |
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| 136 | 21 | return new Expression\Operators\Arithmetical\Pow(); |
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| 137 | |||
| 138 | /** |
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| 139 | * Bitwise |
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| 140 | * @link http://php.net/manual/ru/language.operators.bitwise.php |
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| 141 | */ |
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| 142 | 270 | case Node\Expr\BinaryOp\BitwiseOr::class: |
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| 143 | 12 | return new Expression\Operators\Bitwise\BitwiseOr(); |
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| 144 | 258 | case Node\Expr\BinaryOp\BitwiseXor::class: |
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| 145 | 12 | return new Expression\Operators\Bitwise\BitwiseXor(); |
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| 146 | 246 | case Node\Expr\BinaryOp\BitwiseAnd::class: |
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| 147 | 12 | return new Expression\Operators\Bitwise\BitwiseAnd(); |
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| 148 | 234 | case Node\Expr\BinaryOp\ShiftRight::class: |
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| 149 | 12 | return new Expression\Operators\Bitwise\ShiftRight(); |
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| 150 | 222 | case Node\Expr\BinaryOp\ShiftLeft::class: |
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| 151 | 12 | return new Expression\Operators\Bitwise\ShiftLeft(); |
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| 152 | 210 | case Node\Expr\BitwiseNot::class: |
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| 153 | 5 | return new Expression\Operators\Bitwise\BitwiseNot(); |
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| 154 | /** |
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| 155 | * Logical |
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| 156 | */ |
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| 157 | 205 | case Node\Expr\BinaryOp\BooleanOr::class: |
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| 158 | 17 | return new Expression\Operators\Logical\BooleanOr(); |
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| 159 | 188 | case Node\Expr\BinaryOp\BooleanAnd::class: |
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| 160 | 15 | return new Expression\Operators\Logical\BooleanAnd(); |
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| 161 | 173 | case Node\Expr\BooleanNot::class: |
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| 162 | 9 | return new Expression\Operators\Logical\BooleanNot(); |
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| 163 | 164 | case Node\Expr\BinaryOp\LogicalAnd::class: |
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| 164 | 15 | return new Expression\Operators\Logical\LogicalAnd(); |
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| 165 | 149 | case Node\Expr\BinaryOp\LogicalOr::class: |
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| 166 | 17 | return new Expression\Operators\Logical\LogicalOr(); |
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| 167 | 132 | case Node\Expr\BinaryOp\LogicalXor::class: |
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| 168 | 17 | return new Expression\Operators\Logical\LogicalXor(); |
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| 169 | |||
| 170 | /** |
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| 171 | * Comparison |
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| 172 | */ |
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| 173 | 115 | case Node\Expr\BinaryOp\Greater::class: |
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| 174 | 12 | return new Expression\Operators\Comparison\Greater(); |
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| 175 | 103 | case Node\Expr\BinaryOp\GreaterOrEqual::class: |
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| 176 | 12 | return new Expression\Operators\Comparison\GreaterOrEqual(); |
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| 177 | 91 | case Node\Expr\BinaryOp\Smaller::class: |
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| 178 | 12 | return new Expression\Operators\Comparison\Smaller(); |
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| 179 | 79 | case Node\Expr\BinaryOp\SmallerOrEqual::class: |
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| 180 | 12 | return new Expression\Operators\Comparison\SmallerOrEqual(); |
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| 181 | |||
| 182 | /** |
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| 183 | * Casts |
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| 184 | */ |
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| 185 | 67 | case Node\Expr\Cast\Array_::class: |
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| 186 | 3 | return new Expression\Casts\ArrayCast(); |
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| 187 | 65 | case Node\Expr\Cast\Bool_::class: |
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| 188 | 8 | return new Expression\Casts\BoolCast(); |
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| 189 | 58 | case Node\Expr\Cast\Int_::class: |
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| 190 | 8 | return new Expression\Casts\IntCast(); |
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| 191 | 51 | case Node\Expr\Cast\Double::class: |
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| 192 | 8 | return new Expression\Casts\DoubleCast(); |
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| 193 | 44 | case Node\Expr\Cast\Object_::class: |
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| 194 | 2 | return new Expression\Casts\ObjectCast(); |
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| 195 | 43 | case Node\Expr\Cast\String_::class: |
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| 196 | 7 | return new Expression\Casts\StringCast(); |
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| 197 | 37 | case Node\Expr\Cast\Unset_::class: |
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| 198 | 2 | return new Expression\Casts\UnsetCast(); |
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| 199 | |||
| 200 | |||
| 201 | /** |
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| 202 | * Other |
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| 203 | */ |
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| 204 | 35 | case Node\Expr\Closure::class: |
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| 205 | return new Expression\Closure(); |
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| 206 | 35 | case Node\Expr\UnaryMinus::class: |
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| 207 | 9 | return new Expression\Operators\UnaryMinus(); |
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| 208 | 26 | case Node\Expr\UnaryPlus::class: |
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| 209 | 9 | return new Expression\Operators\UnaryPlus(); |
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| 210 | 17 | case Node\Expr\Exit_::class: |
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| 211 | 1 | return new Expression\ExitOp(); |
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| 212 | 16 | case Node\Expr\Isset_::class: |
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| 213 | 3 | return new Expression\IssetOp(); |
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| 214 | 13 | case Node\Expr\Print_::class: |
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| 215 | 2 | return new Expression\PrintOp(); |
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| 216 | 12 | case Node\Expr\Empty_::class: |
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| 217 | 5 | return new Expression\EmptyOp(); |
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| 218 | 7 | case Node\Expr\Eval_::class: |
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| 219 | 2 | return new Expression\EvalOp(); |
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| 220 | 5 | case Node\Expr\ErrorSuppress::class: |
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| 221 | 2 | return new Expression\ErrorSuppress(); |
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| 222 | 3 | case Node\Expr\Clone_::class: |
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| 223 | 1 | return new Expression\CloneOp(); |
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| 224 | 2 | case Node\Expr\Ternary::class: |
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| 225 | 2 | return new Expression\Ternary(); |
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| 226 | } |
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| 227 | |||
| 228 | return false; |
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| 229 | } |
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| 230 | |||
| 231 | /** |
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| 232 | * @param object|string $expr |
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| 233 | * @throws InvalidArgumentException when $expr is not string/object/null |
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| 234 | * @throws RuntimeException when compiler class does not return a CompiledExpression |
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| 235 | * @return CompiledExpression |
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| 236 | */ |
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| 237 | 848 | public function compile($expr) |
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| 321 | |||
| 322 | /** |
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| 323 | * @todo Implement |
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| 324 | * |
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| 325 | * @param Node\Stmt\Property $st |
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| 326 | * @return CompiledExpression |
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| 327 | */ |
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| 328 | public function passProperty(Node\Stmt\Property $st) |
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| 388 | |||
| 389 | /** |
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| 390 | * @param Node\Expr\Variable $expr |
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| 391 | * @param mixed $value |
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| 392 | * @param int $type |
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| 393 | * @return CompiledExpression |
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| 394 | */ |
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| 395 | 1 | public function declareVariable(Node\Expr\Variable $expr, $value = null, $type = CompiledExpression::UNKNOWN) |
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| 405 | |||
| 406 | /** |
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| 407 | * @param Node\Name\FullyQualified $expr |
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| 408 | * @return CompiledExpression |
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| 409 | */ |
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| 410 | public function getFullyQualifiedNodeName(Node\Name\FullyQualified $expr) |
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| 416 | |||
| 417 | /** |
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| 418 | * @param Node\Name $expr |
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| 419 | * @return CompiledExpression |
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| 420 | */ |
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| 421 | 25 | public function getNodeName(Node\Name $expr) |
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| 422 | { |
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| 423 | 25 | $nodeString = $expr->toString(); |
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| 424 | 25 | if ($nodeString === 'null') { |
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| 425 | 1 | return new CompiledExpression(CompiledExpression::NULL); |
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| 426 | } |
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| 427 | |||
| 428 | 24 | if (in_array($nodeString, ['parent'], true)) { |
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| 429 | /** @var ClassDefinition $scope */ |
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| 430 | $scope = $this->context->scope; |
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| 431 | assert($scope instanceof ClassDefinition); |
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| 432 | |||
| 433 | if ($scope->getExtendsClass()) { |
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| 434 | $definition = $scope->getExtendsClassDefinition(); |
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| 435 | if ($definition) { |
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| 436 | return new CompiledExpression(CompiledExpression::OBJECT, $definition); |
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| 437 | } |
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| 438 | } else { |
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| 439 | $this->context->notice( |
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| 440 | 'no-parent', |
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| 441 | 'Cannot access parent:: when current class scope has no parent', |
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| 442 | $expr |
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| 443 | ); |
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| 444 | } |
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| 445 | } |
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| 446 | |||
| 447 | 24 | if (in_array($nodeString, ['self', 'static'], true)) { |
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| 448 | 1 | return CompiledExpression::fromZvalValue($this->context->scope); |
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| 449 | } |
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| 450 | |||
| 451 | 23 | if (defined($nodeString)) { |
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| 452 | 1 | return CompiledExpression::fromZvalValue(constant($expr)); |
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| 453 | } |
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| 454 | |||
| 455 | 23 | return new CompiledExpression(CompiledExpression::STRING, $expr->toString()); |
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| 456 | } |
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| 457 | |||
| 458 | /** |
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| 459 | * @param Node\Expr\PropertyFetch $expr |
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| 460 | * @return CompiledExpression |
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| 461 | */ |
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| 462 | protected function passPropertyFetch(Node\Expr\PropertyFetch $expr) |
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| 503 | |||
| 504 | /** |
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| 505 | * @param Node\Expr\ClassConstFetch $expr |
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| 506 | * @return CompiledExpression |
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| 507 | */ |
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| 508 | protected function passConstFetch(Node\Expr\ClassConstFetch $expr) |
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| 530 | |||
| 531 | /** |
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| 532 | * @param Node\Expr\Assign $expr |
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| 533 | * @return CompiledExpression |
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| 534 | */ |
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| 535 | 29 | protected function passSymbol(Node\Expr\Assign $expr) |
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| 596 | |||
| 597 | 29 | protected function compileVariableDeclaration(CompiledExpression $variableName, CompiledExpression $value) |
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| 627 | |||
| 628 | /** |
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| 629 | * @param Node\Expr\AssignRef $expr |
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| 630 | * @return CompiledExpression |
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| 631 | */ |
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| 632 | 1 | protected function passSymbolByRef(Node\Expr\AssignRef $expr) |
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| 671 | |||
| 672 | /** |
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| 673 | * @param Node\Expr\Variable $expr |
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| 674 | * @return CompiledExpression |
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| 675 | */ |
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| 676 | 12 | protected function passExprVariable(Node\Expr\Variable $expr) |
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| 692 | |||
| 693 | /** |
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| 694 | * Compile Array_ expression to CompiledExpression |
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| 695 | * |
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| 696 | * @param Node\Expr\Array_ $expr |
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| 697 | * @return CompiledExpression |
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| 698 | */ |
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| 699 | 36 | protected function getArray(Node\Expr\Array_ $expr) |
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| 730 | |||
| 731 | /** |
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| 732 | * Convert const fetch expr to CompiledExpression |
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| 733 | * |
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| 734 | * @param Node\Expr\ConstFetch $expr |
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| 735 | * @return CompiledExpression |
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| 736 | */ |
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| 737 | 7 | protected function constFetch(Node\Expr\ConstFetch $expr) |
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| 754 | } |
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| 755 |
The class complexity is the sum of the complexity of all methods. A very high value is usually an indication that your class does not follow the single reponsibility principle and does more than one job.
Some resources for further reading:
You can also find more detailed suggestions for refactoring in the “Code” section of your repository.