ReadDetector.php

<?php

/**
 * This file is part of the Zephir.
 *
 * (c) Phalcon Team <team@zephir-lang.com>
 *
 * For the full copyright and license information, please view
 * the LICENSE file that was distributed with this source code.
 */

declare(strict_types=1);

namespace Zephir\Detectors;

use Zephir\Variable\Variable;

use function in_array;
use function is_array;
use function strpos;
use function substr;

/**
 * Detects if a variable is used in a given expression context
 * Since zvals are collected between executions to the same section of code
 * We need to ensure that a variable is not contained in the "right-side" expression
 * used to assign the variable, avoiding premature initializations.
 */
class ReadDetector
{
    public function detect($variable, array $expression): bool
    {
        if (!isset($expression['type'])) {
            return false;
        }

        /**
         * Remove branch from variable name.
         */
        $pos = strpos($variable, Variable::BRANCH_MAGIC);
        if ($pos > -1) {
            $variable = substr($variable, 0, $pos);
        }

        if ('variable' === $expression['type'] && $variable === $expression['value']) {
            return true;
        }

        if (in_array($expression['type'], ['fcall', 'mcall', 'scall']) && isset($expression['parameters'])) {
            foreach ($expression['parameters'] as $parameter) {
                if (
                    is_array($parameter['parameter']) &&
                    'variable' === $parameter['parameter']['type'] &&
                    $variable == $parameter['parameter']['value']
                ) {
                    return true;
                }
            }
        }

        return (
                isset($expression['left']) &&
                is_array($expression['left']) &&
                $this->detect($variable, $expression['left'])
            ) || (
                isset($expression['right']) &&
                is_array($expression['right']) &&
                $this->detect($variable, $expression['right'])
            );
    }
}