tree-tools-php

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<?php
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declare(strict_types=1);
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namespace Smoren\TreeTools;
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use Smoren\TypeTools\MapAccess;
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use stdClass;
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class TreeBuilder
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{
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    /**
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     * Builds a tree from given flat collection of items with relations.
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     *
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     * @param iterable<mixed> $collection
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     * @param string $idField
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     * @param string $parentIdField
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     * @param string $childrenContainerField
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     * @param string $itemContainerField
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     *
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     * @return array<mixed>
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     */
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    public static function build(
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        iterable $collection,
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        string $idField = 'id',
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        string $parentIdField = 'parent_id',
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        string $childrenContainerField = 'children',
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        string $itemContainerField = 'item'
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    ): array {
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        $result = [];
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        $map = [];
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        foreach($collection as $item) {
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            $map[MapAccess::get($item, $idField)] = static::wrapItem(
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                $item,
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                $childrenContainerField,
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                $itemContainerField
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            );
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        }
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        foreach($map as &$item) {
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            if(($parentId = static::getParentId($item, $parentIdField, $itemContainerField)) !== null) {
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                $childrenContainer = &static::getChildrenContainer($map[$parentId], $childrenContainerField);
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                $childrenContainer[] = &$item;
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            } else {
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                $result[] = &$item;
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            }
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        }
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        return $result;
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    }
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    /**
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     * Returns value of parent relation.
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     *
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     * @param mixed $item
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     * @param string $parentIdField
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     * @param string $itemContainerField
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     *
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     * @return scalar|null
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     */
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    protected static function getParentId($item, string $parentIdField, string $itemContainerField)
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    {
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        /** @var scalar|null $parentId */
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        $parentId = MapAccess::get($item, $parentIdField);
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        if($parentId !== null) {
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            return $parentId;
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        }
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        return MapAccess::get(MapAccess::get($item, $itemContainerField), $parentIdField);
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    }
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    /**
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     * Returns children container of given item.
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     *
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     * @param mixed $item
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     * @param string $childrenContainerField
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     *
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     * @return array<mixed>
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     */
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    protected static function &getChildrenContainer(&$item, string $childrenContainerField): array
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    {
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        if(is_array($item)) {
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            return $item[$childrenContainerField];
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        }
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        return $item->{$childrenContainerField};
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    }
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    /**
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     * Wraps collection item for tree representation.
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     *
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     * @param mixed $item
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     * @param string $childrenContainerField
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     * @param string $itemContainerField
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     *
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     * @return array<mixed>|stdClass
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     */
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    protected static function wrapItem($item, string $childrenContainerField, string $itemContainerField)
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    {
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        if(is_array($item)) {
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            $item[$childrenContainerField] = [];
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            return $item;
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        }
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        if($item instanceof stdClass) {
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            $item->{$childrenContainerField} = [];
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            return $item;
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        }
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        return [$itemContainerField => &$item, $childrenContainerField => []];
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    }
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}
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