ArrayMergeFromArraySpreadFactory.php

<?php

declare(strict_types=1);

namespace Rector\DowngradePhp81\NodeFactory;

use PhpParser\Node\Arg;
use PhpParser\Node\ArrayItem;
use PhpParser\Node\Expr\Array_;
use PhpParser\Node\Expr\FuncCall;
use PhpParser\Node\Expr\Ternary;
use PhpParser\Node\Name;
use PHPStan\Analyser\MutatingScope;
use PHPStan\Type\IterableType;
use PHPStan\Type\ObjectType;
use PHPStan\Type\Type;

final readonly class ArrayMergeFromArraySpreadFactory
{
    public function createFromArray(Array_ $array, MutatingScope $mutatingScope): FuncCall
    {
        $newArrayItems = $this->dissolveArrayItems($array);
        return $this->createArrayMergeFuncCall($newArrayItems, $mutatingScope);
    }

    /**
     * Iterate all array items:
     *
     * 1. If they use the spread, remove it
     * 2. If not, make the item part of an accumulating array,
     *    to be added once the next spread is found, or at the end
     * @return ArrayItem[]
     */
    private function dissolveArrayItems(Array_ $array): array
    {
        $newItems = [];

        $accumulatedItems = [];
        foreach ($array->items as $item) {
            if ($item instanceof ArrayItem && $item->unpack) {
                if ($accumulatedItems !== []) {
                    // If previous items were in the new array, add them first
                    $newItems[] = $this->createArrayItemFromArray($accumulatedItems);
                    // Reset the accumulated items
                    $accumulatedItems = [];
                }

                // Add the current item, still with "unpack = true" (it will be removed later on)
                $newItems[] = $item;
                continue;
            }

            // Normal item, it goes into the accumulated array
            $accumulatedItems[] = $item;
        }

        // Add the remaining accumulated items
        if ($accumulatedItems !== []) {
            $newItems[] = $this->createArrayItemFromArray($accumulatedItems);
        }

        return $newItems;
    }

    /**
     * @param ArrayItem[] $arrayItems
     */
    private function createArrayMergeFuncCall(array $arrayItems, MutatingScope $mutatingScope): FuncCall
    {
        $args = array_map(function (ArrayItem $arrayItem) use ($mutatingScope): Arg {
            if ($arrayItem->unpack) {
                // Do not unpack anymore
                $arrayItem->unpack = false;
                return $this->createArgFromSpreadArrayItem($mutatingScope, $arrayItem);
            }

            return new Arg($arrayItem->value);
        }, $arrayItems);

        return new FuncCall(new Name('array_merge'), $args);
    }

    /**
     * @param array<ArrayItem> $items
     */
    private function createArrayItemFromArray(array $items): ArrayItem
    {
        $array = new Array_($items);
        return new ArrayItem($array);
    }

    private function createArgFromSpreadArrayItem(MutatingScope $mutatingScope, ArrayItem $arrayItem): Arg
    {
        $type = $mutatingScope->getType($arrayItem->value);

        $iteratorToArrayFuncCall = new FuncCall(new Name('iterator_to_array'), [new Arg($arrayItem->value)]);

        // If we know it is an array, then print it directly
        // Otherwise PHPStan throws an error:
        // "Else branch is unreachable because ternary operator condition is always true."
        if ($type->isArray()->yes()) {
            return new Arg($arrayItem->value);
        }

        // If it is iterable, then directly return `iterator_to_array`
        if ($this->isIterableType($type)) {
            return new Arg($iteratorToArrayFuncCall);
        }

        // Print a ternary, handling either an array or an iterator
        $inArrayFuncCall = new FuncCall(new Name('is_array'), [new Arg($arrayItem->value)]);
        return new Arg(new Ternary($inArrayFuncCall, $arrayItem->value, $iteratorToArrayFuncCall));
    }

    /**
     * Iterables: objects declaring the interface Traversable,
     * For "iterable" type, it can be array
     */
    private function isIterableType(Type $type): bool
    {
        if ($type instanceof IterableType) {
            return false;
        }

        $traversableObjectType = new ObjectType('Traversable');
        return $traversableObjectType->isSuperTypeOf($type)
            ->yes();
    }
}