RemoveDefaultValueFromAssignedPropertyRector.php

<?php

declare(strict_types=1);

namespace Rector\DeadCode\Rector\Property;

use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\ArrayDimFetch;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Stmt\Class_;
use PhpParser\Node\Stmt\ClassMethod;
use Rector\NodeAnalyzer\AlwaysInitializedPropertyAnalyzer;
use Rector\NodeAnalyzer\PropertyFetchAnalyzer;
use Rector\PhpParser\Node\BetterNodeFinder;
use Rector\Rector\AbstractRector;
use Rector\TypeDeclaration\AlreadyAssignDetector\ConstructorAssignDetector;
use Rector\ValueObject\MethodName;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;

/**
 * @see \Rector\Tests\DeadCode\Rector\Property\RemoveDefaultValueFromAssignedPropertyRector\RemoveDefaultValueFromAssignedPropertyRectorTest
 */
final class RemoveDefaultValueFromAssignedPropertyRector extends AbstractRector
{
    public function __construct(
        private readonly ConstructorAssignDetector $constructorAssignDetector,
        private readonly BetterNodeFinder $betterNodeFinder,
        private readonly PropertyFetchAnalyzer $propertyFetchAnalyzer,
        private readonly AlwaysInitializedPropertyAnalyzer $alwaysInitializedPropertyAnalyzer
    ) {
    }

    public function getRuleDefinition(): RuleDefinition
    {
        return new RuleDefinition(
            'Remove redundant default value from property that is always assigned in the constructor',
            [
                new CodeSample(
                    <<<'CODE_SAMPLE'
class SomeClass
{
    private ?SomeType $someType = null;

    public function __construct(SomeType $someType)
    {
        $this->someType = $someType;
    }
}
CODE_SAMPLE
                    ,
                    <<<'CODE_SAMPLE'
class SomeClass
{
    private ?SomeType $someType;

    public function __construct(SomeType $someType)
    {
        $this->someType = $someType;
    }
}
CODE_SAMPLE
                ),
            ]
        );
    }

    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [Class_::class];
    }

    /**
     * @param Class_ $node
     */
    public function refactor(Node $node): ?Node
    {
        $constructClassMethod = $node->getMethod(MethodName::CONSTRUCT);
        if (! $constructClassMethod instanceof ClassMethod) {
            return null;
        }

        $hasChanged = false;

        foreach ($node->getProperties() as $property) {
            // untyped properties are handled by RemoveNullPropertyInitializationRector
            if (! $property->type instanceof Node) {
                continue;
            }

            if ($property->hooks !== []) {
                continue;
            }

            foreach ($property->props as $propertyProperty) {
                if (! $propertyProperty->default instanceof Expr) {
                    continue;
                }

                $propertyName = $this->getName($propertyProperty);

                // guards against an assign that reads the default value first, e.g. $this->value = $this->value + 1
                if (! $this->constructorAssignDetector->isPropertyAssignedConditionally($node, $propertyName)) {
                    continue;
                }

                // the property must be initialized on every path out of the constructor,
                // otherwise removing the default value leaves it uninitialized
                if (! $this->alwaysInitializedPropertyAnalyzer->isAlwaysInitialized(
                    $constructClassMethod,
                    $propertyName
                )) {
                    continue;
                }

                // $this->value['key'] = ... writes to the default value, it does not replace it
                if ($this->isAssignedViaOffsetAccess($constructClassMethod, $propertyName)) {
                    continue;
                }

                $propertyProperty->default = null;
                $hasChanged = true;
            }
        }

        if ($hasChanged) {
            return $node;
        }

        return null;
    }

    private function isAssignedViaOffsetAccess(ClassMethod $constructClassMethod, string $propertyName): bool
    {
        $assign = $this->betterNodeFinder->findFirstInFunctionLikeScoped(
            $constructClassMethod,
            function (Node $node) use ($propertyName): bool {
                if (! $node instanceof Assign) {
                    return false;
                }

                $assignVar = $node->var;
                if (! $assignVar instanceof ArrayDimFetch) {
                    return false;
                }

                while ($assignVar instanceof ArrayDimFetch) {
                    $assignVar = $assignVar->var;
                }

                return $this->propertyFetchAnalyzer->isLocalPropertyFetchName($assignVar, $propertyName);
            }
        );

        return $assign instanceof Assign;
    }
}