RemoveDeadZeroAndOneOperationRector.php

<?php

declare(strict_types=1);

namespace Rector\DeadCode\Rector\Plus;

use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\AssignOp;
use PhpParser\Node\Expr\AssignOp\Div as AssignDiv;
use PhpParser\Node\Expr\AssignOp\Minus as AssignMinus;
use PhpParser\Node\Expr\AssignOp\Mul as AssignMul;
use PhpParser\Node\Expr\AssignOp\Plus as AssignPlus;
use PhpParser\Node\Expr\BinaryOp;
use PhpParser\Node\Expr\BinaryOp\Div;
use PhpParser\Node\Expr\BinaryOp\Minus;
use PhpParser\Node\Expr\BinaryOp\Mul;
use PhpParser\Node\Expr\BinaryOp\Plus;
use PhpParser\Node\Expr\ClassConstFetch;
use PhpParser\Node\Expr\UnaryMinus;
use PhpParser\Node\Scalar\Int_;
use Rector\NodeTypeResolver\Node\AttributeKey;
use Rector\Rector\AbstractRector;
use Rector\RuleDoc\CodeSample\CodeSample;
use Rector\RuleDoc\RuleDefinition;
use Rector\ValueObject\Application\File;

/**
 * @see \Rector\Tests\DeadCode\Rector\Plus\RemoveDeadZeroAndOneOperationRector\RemoveDeadZeroAndOneOperationRectorTest
 */
final class RemoveDeadZeroAndOneOperationRector extends AbstractRector
{
    public function getRuleDefinition(): RuleDefinition
    {
        return new RuleDefinition(
            'Remove operation with 1 and 0, that have no effect on the value',
            [
                new CodeSample(
                    <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $value = 5 * 1;
        $value = 5 + 0;
    }
}
CODE_SAMPLE
                    ,
                    <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $value = 5;
        $value = 5;
    }
}
CODE_SAMPLE
                ),
            ]
        );
    }

    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes(): array
    {
        return [
            Plus::class,
            Minus::class,
            Mul::class,
            Div::class,
            AssignPlus::class,
            AssignMinus::class,
            AssignMul::class,
            AssignDiv::class,
        ];
    }

    /**
     * @param Plus|Minus|Mul|Div|AssignPlus|AssignMinus|AssignMul|AssignDiv $node
     */
    public function refactor(Node $node): ?Node
    {
        if ($node instanceof AssignOp) {
            return $this->processAssignOp($node);
        }

        // -, +
        $result = $this->processBinaryOp($node);
        if (!$result instanceof Expr) {
            return null;
        }

        // the chosen operand can be a same-class operation that still carries a dead 0/1 at its own
        // top level (e.g. 0 + 5 + 0 returns 0 + 5); such a returned node is skip-marked for this rule,
        // so reduce its chain here to finish in a single pass
        while ($result instanceof Plus || $result instanceof Minus || $result instanceof Mul || $result instanceof Div) {
            $reduced = $this->processBinaryOp($result);
            if (!$reduced instanceof Expr || $reduced === $result) {
                break;
            }

            $result = $reduced;
        }

        return $result;
    }

    private function processAssignOp(AssignOp $assignOp): ?Expr
    {
        // +=, -=
        if ($assignOp instanceof AssignPlus || $assignOp instanceof AssignMinus) {
            if (! $this->isLiteralZero($assignOp->expr)) {
                return null;
            }

            // on float, += 0 normalizes negative zero (-0.0) to 0.0, so it is not dead
            if ($assignOp instanceof AssignPlus && ! $this->nodeTypeResolver->getNativeType($assignOp->var)
                ->isInteger()
                ->yes()) {
                return null;
            }

            if ($this->nodeTypeResolver->isNumberType($assignOp->var)) {
                return $assignOp->var;
            }
        }

        // *, /
        if ($assignOp instanceof AssignMul || $assignOp instanceof AssignDiv) {
            if (! $this->isLiteralOne($assignOp->expr)) {
                return null;
            }

            if ($this->nodeTypeResolver->isNumberType($assignOp->var)) {
                return $assignOp->var;
            }
        }

        return null;
    }

    private function processBinaryOp(Node $node): ?Expr
    {
        if ($node instanceof Plus || $node instanceof Minus) {
            return $this->processBinaryPlusAndMinus($node);
        }

        // *, /
        if ($node instanceof Mul) {
            return $this->processBinaryMulAndDiv($node);
        }

        if ($node instanceof Div) {
            return $this->processBinaryMulAndDiv($node);
        }

        return null;
    }

    private function areNumberType(BinaryOp $binaryOp): bool
    {
        if (! $this->nodeTypeResolver->isNumberType($binaryOp->left)) {
            return false;
        }

        return $this->nodeTypeResolver->isNumberType($binaryOp->right);
    }

    private function processBinaryPlusAndMinus(Plus|Minus $binaryOp): ?Expr
    {
        if (! $this->isLiteralZero($binaryOp->left) && ! $this->isLiteralZero($binaryOp->right)) {
            return null;
        }

        if (! $this->areNumberType($binaryOp)) {
            return null;
        }

        if ($this->isLiteralZero($binaryOp->left)) {
            // on float, 0 + $x normalizes negative zero (-0.0) to 0.0 and 0 - $x flips its sign,
            // so the operation is not dead
            if (! $this->nodeTypeResolver->getNativeType($binaryOp->right)
                ->isInteger()
                ->yes()) {
                return null;
            }

            if ($binaryOp instanceof Minus) {
                return new UnaryMinus($binaryOp->right);
            }

            return $binaryOp->right;
        }

        if (! $this->isLiteralZero($binaryOp->right)) {
            return null;
        }

        // on float, $x + 0 normalizes negative zero (-0.0) to 0.0, so it is not dead
        if ($binaryOp instanceof Plus && ! $this->nodeTypeResolver->getNativeType($binaryOp->left)
            ->isInteger()
            ->yes()) {
            return null;
        }

        return $binaryOp->left;
    }

    private function isMulParenthesized(File $file, Mul $mul): bool
    {
        if (! $mul->right instanceof BinaryOp) {
            return false;
        }

        $oldTokens = $file->getOldTokens();
        $endTokenPost = $mul->getEndTokenPos();

        if (isset($oldTokens[$endTokenPost]) && (string) $oldTokens[$endTokenPost] === ')') {
            $startTokenPos = $mul->right->getStartTokenPos();
            $previousEndTokenPost = $mul->left->getEndTokenPos();

            while ($startTokenPos > $previousEndTokenPost) {
                --$startTokenPos;

                if (! isset($oldTokens[$startTokenPos])) {
                    return false;
                }

                // handle space before open parentheses
                if (trim((string) $oldTokens[$startTokenPos]) === '') {
                    continue;
                }

                return (string) $oldTokens[$startTokenPos] === '(';
            }

            return false;
        }

        return false;
    }

    private function processBinaryMulAndDiv(Mul|Div $binaryOp): ?Expr
    {
        if ($binaryOp->left instanceof ClassConstFetch || $binaryOp->right instanceof ClassConstFetch) {
            return null;
        }

        if (! $this->isLiteralOne($binaryOp->left) && ! $this->isLiteralOne($binaryOp->right)) {
            return null;
        }

        if (! $this->areNumberType($binaryOp)) {
            return null;
        }

        if ($binaryOp instanceof Mul && $this->isLiteralOne($binaryOp->left) && $this->nodeTypeResolver->isNumberType(
            $binaryOp->right
        )) {
            if ($this->isMulParenthesized($this->getFile(), $binaryOp)) {
                $binaryOp->right->setAttribute(AttributeKey::WRAPPED_IN_PARENTHESES, true);
            }

            return $binaryOp->right;
        }

        if (! $this->isLiteralOne($binaryOp->right)) {
            return null;
        }

        return $binaryOp->left;
    }

    private function isLiteralOne(Expr $expr): bool
    {
        return $expr instanceof Int_ && $expr->value === 1;
    }

    private function isLiteralZero(Expr $expr): bool
    {
        return $expr instanceof Int_ && $expr->value === 0;
    }
}