RemoveDoubleAssignRector.php

<?php

declare (strict_types=1);
namespace Rector\DeadCode\Rector\Assign;

use PhpParser\Node;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\PropertyFetch;
use PhpParser\Node\Expr\StaticPropertyFetch;
use PhpParser\Node\Expr\Variable;
use PhpParser\Node\Stmt\Expression;
use Rector\Contract\PhpParser\Node\StmtsAwareInterface;
use Rector\DeadCode\SideEffect\SideEffectNodeDetector;
use Rector\PhpParser\Node\BetterNodeFinder;
use Rector\PHPStan\ScopeFetcher;
use Rector\Rector\AbstractRector;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
/**
 * @see \Rector\Tests\DeadCode\Rector\Assign\RemoveDoubleAssignRector\RemoveDoubleAssignRectorTest
 */
final class RemoveDoubleAssignRector extends AbstractRector
{
    /**
     * @readonly
     */
    private SideEffectNodeDetector $sideEffectNodeDetector;
    /**
     * @readonly
     */
    private BetterNodeFinder $betterNodeFinder;
    public function __construct(SideEffectNodeDetector $sideEffectNodeDetector, BetterNodeFinder $betterNodeFinder)
    {
        $this->sideEffectNodeDetector = $sideEffectNodeDetector;
        $this->betterNodeFinder = $betterNodeFinder;
    }
    public function getRuleDefinition() : RuleDefinition
    {
        return new RuleDefinition('Simplify useless double assigns', [new CodeSample(<<<'CODE_SAMPLE'
$value = 1;
$value = 1;
CODE_SAMPLE
, '$value = 1;')]);
    }
    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes() : array
    {
        return [StmtsAwareInterface::class];
    }
    /**
     * @param StmtsAwareInterface $node
     */
    public function refactor(Node $node) : ?Node
    {
        $scope = ScopeFetcher::fetch($node);
        $stmts = $node->stmts;
        if ($stmts === null) {
            return null;
        }
        $hasChanged = \false;
        foreach ($stmts as $key => $stmt) {
            if (!isset($stmts[$key + 1])) {
                continue;
            }
            if (!$stmt instanceof Expression) {
                continue;
            }
            $nextStmt = $stmts[$key + 1];
            if (!$nextStmt instanceof Expression) {
                continue;
            }
            if (!$stmt->expr instanceof Assign) {
                continue;
            }
            if (!$nextStmt->expr instanceof Assign) {
                continue;
            }
            $nextAssign = $nextStmt->expr;
            if (!$this->nodeComparator->areNodesEqual($nextAssign->var, $stmt->expr->var)) {
                continue;
            }
            // early check self referencing, ensure that variable not re-used
            if ($this->isSelfReferencing($nextAssign)) {
                continue;
            }
            // detect call expression has side effect
            // no calls on right, could hide e.g. array_pop()|array_shift()
            if ($this->sideEffectNodeDetector->detectCallExpr($stmt->expr->expr, $scope)) {
                continue;
            }
            // next stmts can have side effect as well
            if (($nextAssign->var instanceof PropertyFetch || $nextAssign->var instanceof StaticPropertyFetch) && $this->sideEffectNodeDetector->detectCallExpr($nextAssign->expr, $scope)) {
                continue;
            }
            if (!$stmt->expr->var instanceof Variable && !$stmt->expr->var instanceof PropertyFetch && !$stmt->expr->var instanceof StaticPropertyFetch) {
                continue;
            }
            // remove current Stmt if will be overriden in next stmt
            unset($node->stmts[$key]);
            $hasChanged = \true;
        }
        if (!$hasChanged) {
            return null;
        }
        return $node;
    }
    private function isSelfReferencing(Assign $assign) : bool
    {
        return (bool) $this->betterNodeFinder->findFirst($assign->expr, fn(Node $subNode): bool => $this->nodeComparator->areNodesEqual($assign->var, $subNode));
    }
}