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[EDIT] FILE: TypeNormalizer.php

<?php

declare (strict_types=1);
namespace Rector\TypeDeclaration;

use PHPStan\Type\ArrayType;
use PHPStan\Type\Constant\ConstantArrayType;
use PHPStan\Type\MixedType;
use PHPStan\Type\NeverType;
use PHPStan\Type\Type;
use PHPStan\Type\TypeTraverser;
use PHPStan\Type\UnionType;
use Rector\TypeDeclaration\ValueObject\NestedArrayType;
use Rector\Util\Reflection\PrivatesAccessor;
/**
 * @see \Rector\Tests\TypeDeclaration\TypeNormalizerTest
 */
final class TypeNormalizer
{
    /**
     * @readonly
     * @var \Rector\Util\Reflection\PrivatesAccessor
     */
    private $privatesAccessor;
    /**
     * @var NestedArrayType[]
     */
    private $collectedNestedArrayTypes = [];
    public function __construct(PrivatesAccessor $privatesAccessor)
    {
        $this->privatesAccessor = $privatesAccessor;
    }
    /**
     * @api
     *
     * Turn nested array union types to unique ones:
     * e.g. int[]|string[][]|bool[][]|string[][]
     * ↓
     * int[]|string[][]|bool[][]
     */
    public function normalizeArrayOfUnionToUnionArray(Type $type, int $arrayNesting = 1) : Type
    {
        if (!$type instanceof ArrayType) {
            return $type;
        }
        if ($type instanceof ConstantArrayType && $arrayNesting === 1) {
            return $type;
        }
        // first collection of types
        if ($arrayNesting === 1) {
            $this->collectedNestedArrayTypes = [];
        }
        if ($type->getItemType() instanceof ArrayType) {
            ++$arrayNesting;
            $this->normalizeArrayOfUnionToUnionArray($type->getItemType(), $arrayNesting);
        } elseif ($type->getItemType() instanceof UnionType) {
            $this->collectNestedArrayTypeFromUnionType($type->getItemType(), $arrayNesting);
        } else {
            $this->collectedNestedArrayTypes[] = new NestedArrayType($type->getItemType(), $arrayNesting, $type->getKeyType());
        }
        return $this->createUnionedTypesFromArrayTypes($this->collectedNestedArrayTypes);
    }
    /**
     * From "string[]|mixed[]" based on empty array to to "string[]"
     */
    public function normalizeArrayTypeAndArrayNever(Type $type) : Type
    {
        return TypeTraverser::map($type, function (Type $traversedType, callable $traverserCallable) : Type {
            if ($this->isConstantArrayNever($traversedType)) {
                \assert($traversedType instanceof ConstantArrayType);
                // not sure why, but with direct new node everything gets nulled to MixedType
                $this->privatesAccessor->setPrivateProperty($traversedType, 'keyType', new MixedType());
                $this->privatesAccessor->setPrivateProperty($traversedType, 'itemType', new MixedType());
                return $traversedType;
            }
            if ($traversedType instanceof NeverType) {
                return new MixedType();
            }
            return $traverserCallable($traversedType, $traverserCallable);
        });
    }
    private function isConstantArrayNever(Type $type) : bool
    {
        return $type instanceof ConstantArrayType && $type->getKeyType() instanceof NeverType && $type->getItemType() instanceof NeverType;
    }
    private function collectNestedArrayTypeFromUnionType(UnionType $unionType, int $arrayNesting) : void
    {
        foreach ($unionType->getTypes() as $unionedType) {
            if ($unionedType->isArray()->yes()) {
                ++$arrayNesting;
                $this->normalizeArrayOfUnionToUnionArray($unionedType, $arrayNesting);
            } else {
                $this->collectedNestedArrayTypes[] = new NestedArrayType($unionedType, $arrayNesting);
            }
        }
    }
    /**
     * @param NestedArrayType[] $collectedNestedArrayTypes
     * @return \PHPStan\Type\UnionType|\PHPStan\Type\ArrayType
     */
    private function createUnionedTypesFromArrayTypes(array $collectedNestedArrayTypes)
    {
        $unionedTypes = [];
        foreach ($collectedNestedArrayTypes as $collectedNestedArrayType) {
            $arrayType = $collectedNestedArrayType->getType();
            for ($i = 0; $i < $collectedNestedArrayType->getArrayNestingLevel(); ++$i) {
                $arrayType = new ArrayType($collectedNestedArrayType->getKeyType(), $arrayType);
            }
            /** @var ArrayType $arrayType */
            $unionedTypes[] = $arrayType;
        }
        if (\count($unionedTypes) > 1) {
            return new UnionType($unionedTypes);
        }
        return $unionedTypes[0];
    }
}

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