rector/rules/CodeQuality/Rector/Foreach_/UnusedForeachValueToArrayKeysRector.php

<?php

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

use PhpParser\Node;
use PhpParser\Node\Expr;
use PhpParser\Node\Expr\Array_;
use PhpParser\Node\Expr\ArrayItem;
use PhpParser\Node\Expr\Variable;
use PhpParser\Node\Stmt\Foreach_;
use PHPStan\Type\ObjectType;
use Rector\DeadCode\NodeAnalyzer\ExprUsedInNodeAnalyzer;
use Rector\PhpParser\Node\BetterNodeFinder;
use Rector\Rector\AbstractRector;
use Symplify\RuleDocGenerator\ValueObject\CodeSample\CodeSample;
use Symplify\RuleDocGenerator\ValueObject\RuleDefinition;
/**
 * @see \Rector\Tests\CodeQuality\Rector\Foreach_\UnusedForeachValueToArrayKeysRector\UnusedForeachValueToArrayKeysRectorTest
 */
final class UnusedForeachValueToArrayKeysRector extends AbstractRector
{
    /**
     * @readonly
     * @var \Rector\DeadCode\NodeAnalyzer\ExprUsedInNodeAnalyzer
     */
    private $exprUsedInNodeAnalyzer;
    /**
     * @readonly
     * @var \Rector\PhpParser\Node\BetterNodeFinder
     */
    private $betterNodeFinder;
    public function __construct(ExprUsedInNodeAnalyzer $exprUsedInNodeAnalyzer, BetterNodeFinder $betterNodeFinder)
    {
        $this->exprUsedInNodeAnalyzer = $exprUsedInNodeAnalyzer;
        $this->betterNodeFinder = $betterNodeFinder;
    }
    public function getRuleDefinition() : RuleDefinition
    {
        return new RuleDefinition('Change foreach with unused $value but only $key, to array_keys()', [new CodeSample(<<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $items = [];
        foreach ($values as $key => $value) {
            $items[$key] = null;
        }
    }
}
CODE_SAMPLE
, <<<'CODE_SAMPLE'
class SomeClass
{
    public function run()
    {
        $items = [];
        foreach (array_keys($values) as $key) {
            $items[$key] = null;
        }
    }
}
CODE_SAMPLE
)]);
    }
    /**
     * @return array<class-string<Node>>
     */
    public function getNodeTypes() : array
    {
        return [Foreach_::class];
    }
    /**
     * @param Foreach_ $node
     */
    public function refactor(Node $node) : ?Node
    {
        if (!$node->keyVar instanceof Expr) {
            return null;
        }
        // special case of nested array items
        if ($node->valueVar instanceof Array_) {
            $valueArray = $this->refactorArrayForeachValue($node->valueVar, $node);
            if ($valueArray instanceof Array_) {
                $node->valueVar = $valueArray;
            }
            // not sure what does this mean :)
            if ($node->valueVar->items !== []) {
                return null;
            }
        } elseif ($node->valueVar instanceof Variable) {
            if ($this->isVariableUsedInForeach($node->valueVar, $node)) {
                return null;
            }
        } else {
            return null;
        }
        if (!$this->isArrayType($node->expr)) {
            return null;
        }
        $this->removeForeachValueAndUseArrayKeys($node, $node->keyVar);
        return $node;
    }
    /**
     * @param int[] $removedKeys
     */
    private function isArrayItemsRemovalWithoutChangingOrder(Array_ $array, array $removedKeys) : bool
    {
        $hasRemovingStarted = \false;
        foreach (\array_keys($array->items) as $key) {
            if (\in_array($key, $removedKeys, \true)) {
                $hasRemovingStarted = \true;
            } elseif ($hasRemovingStarted) {
                // we cannot remove the previous item, and not remove the next one, because that would change the order
                return \false;
            }
        }
        return \true;
    }
    private function refactorArrayForeachValue(Array_ $array, Foreach_ $foreach) : ?Array_
    {
        // only last items can be removed, without changing the order
        $removedKeys = [];
        foreach ($array->items as $key => $arrayItem) {
            if (!$arrayItem instanceof ArrayItem) {
                // only known values can be processes
                return null;
            }
            $value = $arrayItem->value;
            if (!$value instanceof Variable) {
                // only variables can be processed
                return null;
            }
            if ($this->isVariableUsedInForeach($value, $foreach)) {
                continue;
            }
            $removedKeys[] = $key;
        }
        if (!$this->isArrayItemsRemovalWithoutChangingOrder($array, $removedKeys)) {
            return null;
        }
        // clear removed items
        foreach ($removedKeys as $removedKey) {
            unset($array->items[$removedKey]);
        }
        return $array;
    }
    private function isVariableUsedInForeach(Variable $variable, Foreach_ $foreach) : bool
    {
        return (bool) $this->betterNodeFinder->findFirst($foreach->stmts, function (Node $node) use($variable) : bool {
            return $this->exprUsedInNodeAnalyzer->isUsed($node, $variable);
        });
    }
    private function removeForeachValueAndUseArrayKeys(Foreach_ $foreach, Expr $keyVarExpr) : void
    {
        // remove key value
        $foreach->valueVar = $keyVarExpr;
        $foreach->keyVar = null;
        $foreach->expr = $this->nodeFactory->createFuncCall('array_keys', [$foreach->expr]);
    }
    private function isArrayType(Expr $expr) : bool
    {
        $exprType = $this->getType($expr);
        if ($exprType instanceof ObjectType) {
            return \false;
        }
        return $exprType->isArray()->yes();
    }
}