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✏️ Editing: SimplifyIfNullableReturnRector.php

<?php

declare (strict_types=1);
namespace Rector\CodeQuality\Rector\If_;

use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\BooleanNot;
use PhpParser\Node\Expr\Instanceof_;
use PhpParser\Node\Name;
use PhpParser\Node\Stmt;
use PhpParser\Node\Stmt\Expression;
use PhpParser\Node\Stmt\If_;
use PhpParser\Node\Stmt\Return_;
use PHPStan\Type\NullType;
use PHPStan\Type\ObjectType;
use PHPStan\Type\Type;
use PHPStan\Type\UnionType;
use Rector\CodeQuality\TypeResolver\AssignVariableTypeResolver;
use Rector\Contract\PhpParser\Node\StmtsAwareInterface;
use Rector\DeadCode\PhpDoc\TagRemover\VarTagRemover;
use Rector\NodeManipulator\IfManipulator;
use Rector\PhpParser\Node\Value\ValueResolver;
use Rector\Rector\AbstractRector;
use Rector\StaticTypeMapper\ValueObject\Type\FullyQualifiedObjectType;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
/**
 * @see \Rector\Tests\CodeQuality\Rector\If_\SimplifyIfNullableReturnRector\SimplifyIfNullableReturnRectorTest
 */
final class SimplifyIfNullableReturnRector extends AbstractRector
{
    /**
     * @readonly
     * @var \Rector\NodeManipulator\IfManipulator
     */
    private $ifManipulator;
    /**
     * @readonly
     * @var \Rector\CodeQuality\TypeResolver\AssignVariableTypeResolver
     */
    private $assignVariableTypeResolver;
    /**
     * @readonly
     * @var \Rector\DeadCode\PhpDoc\TagRemover\VarTagRemover
     */
    private $varTagRemover;
    /**
     * @readonly
     * @var \Rector\PhpParser\Node\Value\ValueResolver
     */
    private $valueResolver;
    public function __construct(IfManipulator $ifManipulator, AssignVariableTypeResolver $assignVariableTypeResolver, VarTagRemover $varTagRemover, ValueResolver $valueResolver)
    {
        $this->ifManipulator = $ifManipulator;
        $this->assignVariableTypeResolver = $assignVariableTypeResolver;
        $this->varTagRemover = $varTagRemover;
        $this->valueResolver = $valueResolver;
    }
    public function getRuleDefinition() : RuleDefinition
    {
        return new RuleDefinition('Direct return on if nullable check before return', [new CodeSample(<<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $value = $this->get();
        if (! $value instanceof \stdClass) {
            return null;
        }

return $value;
    }

public function get(): ?stdClass {
    }
}
CODE_SAMPLE
, <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        return $this->get();
    }

public function get(): ?stdClass {
    }
}
CODE_SAMPLE
)]);
    }
    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes() : array
    {
        return [StmtsAwareInterface::class];
    }
    /**
     * @param StmtsAwareInterface $node
     */
    public function refactor(Node $node) : ?Node
    {
        if ($node->stmts === null) {
            return null;
        }
        foreach ($node->stmts as $key => $stmt) {
            if (!$stmt instanceof Return_) {
                continue;
            }
            $previousStmt = $node->stmts[$key - 1] ?? null;
            if (!$previousStmt instanceof If_) {
                continue;
            }
            $if = $previousStmt;
            if ($this->shouldSkip($if, $stmt)) {
                continue;
            }
            /** @var BooleanNot|Instanceof_ $cond */
            $cond = $if->cond;
            /** @var Instanceof_ $instanceof */
            $instanceof = $cond instanceof BooleanNot ? $cond->expr : $cond;
            // @todo allow property as well
            $variable = $instanceof->expr;
            $class = $instanceof->class;
            if (!$class instanceof Name) {
                continue;
            }
            /** @var Return_ $returnIfStmt */
            $returnIfStmt = $if->stmts[0];
            if ($this->isIfStmtReturnIncorrect($cond, $variable, $returnIfStmt)) {
                continue;
            }
            $previousPreviousStmt = $node->stmts[$key - 2] ?? null;
            if (!$previousPreviousStmt instanceof Expression) {
                continue;
            }
            if (!$previousPreviousStmt->expr instanceof Assign) {
                continue;
            }
            $previousPreviousAssign = $previousPreviousStmt->expr;
            if (!$this->nodeComparator->areNodesEqual($previousPreviousAssign->var, $variable)) {
                continue;
            }
            if ($this->isNextReturnIncorrect($cond, $variable, $stmt)) {
                continue;
            }
            $variableType = $this->assignVariableTypeResolver->resolve($previousPreviousAssign);
            if (!$variableType instanceof UnionType) {
                continue;
            }
            $className = $class->toString();
            $types = $variableType->getTypes();
            $directReturn = $this->processSimplifyNullableReturn($variableType, $types, $className, $previousPreviousStmt, $previousPreviousAssign->expr);
            if (!$directReturn instanceof Return_) {
                continue;
            }
            // unset previous assign
            unset($node->stmts[$key - 2]);
            // unset previous if
            unset($node->stmts[$key - 1]);
            $node->stmts[$key] = $directReturn;
            return $node;
        }
        return null;
    }
    /**
     * @param \PhpParser\Node\Expr\BooleanNot|\PhpParser\Node\Expr\Instanceof_ $expr
     */
    private function isIfStmtReturnIncorrect($expr, Expr $variable, Return_ $return) : bool
    {
        if (!$return->expr instanceof Expr) {
            return \true;
        }
        if ($expr instanceof BooleanNot && !$this->valueResolver->isNull($return->expr)) {
            return \true;
        }
        return $expr instanceof Instanceof_ && !$this->nodeComparator->areNodesEqual($variable, $return->expr);
    }
    /**
     * @param \PhpParser\Node\Expr\BooleanNot|\PhpParser\Node\Expr\Instanceof_ $expr
     */
    private function isNextReturnIncorrect($expr, Expr $variable, Return_ $return) : bool
    {
        if (!$return->expr instanceof Expr) {
            return \true;
        }
        if ($expr instanceof BooleanNot && !$this->nodeComparator->areNodesEqual($return->expr, $variable)) {
            return \true;
        }
        return $expr instanceof Instanceof_ && !$this->valueResolver->isNull($return->expr);
    }
    /**
     * @param Type[] $types
     */
    private function processSimplifyNullableReturn(UnionType $unionType, array $types, string $className, Expression $expression, Expr $expr) : ?Return_
    {
        if (\count($types) > 2) {
            return null;
        }
        if ($types[0] instanceof FullyQualifiedObjectType && $types[1] instanceof NullType && $className === $types[0]->getClassName()) {
            return $this->createDirectReturn($expression, $expr, $unionType);
        }
        if ($types[0] instanceof NullType && $types[1] instanceof FullyQualifiedObjectType && $className === $types[1]->getClassName()) {
            return $this->createDirectReturn($expression, $expr, $unionType);
        }
        if ($this->isNotTypedNullable($types, $className)) {
            return null;
        }
        return $this->createDirectReturn($expression, $expr, $unionType);
    }
    /**
     * @param Type[] $types
     */
    private function isNotTypedNullable(array $types, string $className) : bool
    {
        if (!$types[0] instanceof ObjectType) {
            return \true;
        }
        if (!$types[1] instanceof NullType) {
            return \true;
        }
        return $className !== $types[0]->getClassName();
    }
    private function createDirectReturn(Expression $expression, Expr $expr, UnionType $unionType) : Return_
    {
        $exprReturn = new Return_($expr);
        $this->varTagRemover->removeVarPhpTagValueNodeIfNotComment($expression, $unionType);
        $this->mirrorComments($exprReturn, $expression);
        return $exprReturn;
    }
    private function shouldSkip(If_ $if, Stmt $stmt) : bool
    {
        if (!$this->ifManipulator->isIfWithOnly($if, Return_::class)) {
            return \true;
        }
        if (!$stmt instanceof Return_) {
            return \true;
        }
        $cond = $if->cond;
        if (!$cond instanceof BooleanNot) {
            return !$cond instanceof Instanceof_;
        }
        return !$cond->expr instanceof Instanceof_;
    }
}

MR SKB