CakePHP ListExpression

ListExpression.php

<?php
declare(strict_types=1);

namespace App\Database\Expression;

use Cake\Database\ExpressionInterface;
use Cake\Database\ValueBinder;
use Closure;

class ListExpression implements ExpressionInterface
{
    /**
     * Holds the identifier string
     *
     * @var array
     */
    protected $_items;

    /**
     * Constructor
     *
     * @param array $items list items
     */
    public function __construct(array $items)
    {
        $this->setItems($items);
    }

    /**
     * Sets the items this expression represents
     *
     * @param array $items The items.
     * @return void
     */
    public function setItems(array $items): void
    {
        $this->_items = $items;
    }

    /**
     * Returns the items this expression represents
     *
     * @return array
     */
    public function getItems(): array
    {
        return $this->_items;
    }

    /**
     * Converts the expression to its string representation
     *
     * @param \Cake\Database\ValueBinder $generator Placeholder generator object
     * @return string
     */
    public function sql(ValueBinder $generator): string
    {
        $result = '';
        foreach ($this->_items as $item) {
            if ($result !== '') {
                $result .= ' ';
            }
            if (is_string($item)) {
                $result .= $item;
            } elseif ($item instanceof ExpressionInterface) {
                $result .= $item->sql($generator);
            }
        }

        return $result;
    }

    /**
     * This method is a no-op, this is a leaf type of expression,
     * hence there is nothing to traverse
     *
     * @param \Closure $visitor The callable to traverse with.
     * @return $this
     */
    public function traverse(Closure $visitor)
    {
        foreach ($this->_items as $v) {
            if ($v instanceof ExpressionInterface) {
                $visitor($v);
                $v->traverse($visitor);
            }
            if (!is_array($v)) {
                continue;
            }
            foreach ($v as $field) {
                if ($field instanceof ExpressionInterface) {
                    $visitor($field);
                    $field->traverse($visitor);
                }
            }
        }

        return $this;
    }
}