Complex classes like ControlFlowGraph 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 ControlFlowGraph, and based on these observations, apply Extract Interface, too.
| 1 | <?php  | 
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| 11 | class ControlFlowGraph  | 
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| 12 | { | 
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| 13 | /**  | 
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| 14 | * @var int  | 
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| 15 | */  | 
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| 16 | protected $lastBlockId = 1;  | 
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| 17 | |||
| 18 | /**  | 
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| 19 | * @var Block  | 
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| 20 | */  | 
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| 21 | protected $root;  | 
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| 22 | |||
| 23 | /**  | 
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| 24 | * @var Block[]  | 
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| 25 | */  | 
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| 26 | protected $labels;  | 
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| 27 | |||
| 28 | /**  | 
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| 29 | * @todo  | 
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| 30 | *  | 
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| 31 | * @var \PhpParser\Node\Stmt\Goto_[]  | 
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| 32 | */  | 
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| 33 | protected $unresolvedGotos;  | 
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| 34 | |||
| 35 | /**  | 
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| 36 | * @param $statement  | 
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| 37 | */  | 
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| 38 | 6 | public function __construct($statement)  | 
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| 48 | |||
| 49 | /**  | 
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| 50 | * @param \PhpParser\Node[] $nodes  | 
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| 51 | * @param Block $block  | 
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| 52 | */  | 
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| 53 | 5 | protected function passNodes(array $nodes, Block $block)  | 
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| 107 | |||
| 108 | /**  | 
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| 109 | * If current block is not empty, lets create a new one  | 
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| 110 | *  | 
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| 111 | * @param Block $block  | 
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| 112 | * @return Block  | 
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| 113 | */  | 
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| 114 | protected function createNewBlockIfNeeded(Block $block)  | 
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| 124 | |||
| 125 | /**  | 
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| 126 | * @param \PhpParser\Node\Expr $expr  | 
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| 127 | * @return Node\AbstractNode  | 
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| 128 | */  | 
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| 129 | 4 | protected function passExpr(\PhpParser\Node\Expr $expr)  | 
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| 165 | |||
| 166 | /**  | 
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| 167 | * @param \PhpParser\Node\Stmt\If_ $if  | 
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| 168 | * @param Block $block  | 
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| 169 | * @return Block  | 
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| 170 | */  | 
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| 171 | protected function passIf(\PhpParser\Node\Stmt\If_ $if, Block $block)  | 
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| 202 | |||
| 203 | /**  | 
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| 204 | * @param \PhpParser\Node\Stmt\For_ $for  | 
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| 205 | * @param Block $block  | 
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| 206 | * @return Block  | 
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| 207 | */  | 
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| 208 | protected function passFor(\PhpParser\Node\Stmt\For_ $for, Block $block)  | 
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| 222 | |||
| 223 | /**  | 
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| 224 | * @param \PhpParser\Node\Stmt\Do_ $do  | 
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| 225 | * @param Block $block  | 
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| 226 | * @return Block  | 
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| 227 | */  | 
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| 228 | protected function passDo(\PhpParser\Node\Stmt\Do_ $do, Block $block)  | 
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| 246 | |||
| 247 | /**  | 
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| 248 | * @param \PhpParser\Node\Stmt\While_ $while  | 
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| 249 | * @param Block $block  | 
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| 250 | * @return Block  | 
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| 251 | */  | 
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| 252 | protected function passWhile(\PhpParser\Node\Stmt\While_ $while, Block $block)  | 
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| 274 | |||
| 275 | /**  | 
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| 276 | * @param \PhpParser\Node\Stmt\Throw_ $throw_  | 
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| 277 | * @param Block $block  | 
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| 278 | */  | 
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| 279 | protected function passThrow(\PhpParser\Node\Stmt\Throw_ $throw_, Block $block)  | 
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| 283 | |||
| 284 | /**  | 
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| 285 | * @param \PhpParser\Node\Expr\Assign $assign  | 
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| 286 | * @param Block $block  | 
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| 287 | */  | 
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| 288 | protected function passAssign(\PhpParser\Node\Expr\Assign $assign, Block $block)  | 
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| 292 | |||
| 293 | /**  | 
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| 294 | * @param \PhpParser\Node\Stmt\Return_ $return  | 
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| 295 | * @param Block $block  | 
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| 296 | */  | 
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| 297 | 4 | protected function passReturn(\PhpParser\Node\Stmt\Return_ $return, Block $block)  | 
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| 313 | |||
| 314 | /**  | 
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| 315 | * @param \PhpParser\Node\Stmt\TryCatch $stmt  | 
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| 316 | * @param Block $block  | 
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| 317 | * @return Block  | 
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| 318 | */  | 
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| 319 | protected function passTryCatch(\PhpParser\Node\Stmt\TryCatch $stmt, Block $block)  | 
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| 336 | |||
| 337 | /**  | 
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| 338 | * @return Block  | 
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| 339 | */  | 
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| 340 | public function getRoot()  | 
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| 344 | }  | 
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| 345 | 
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.