<?php

/*
 * This file is part of PHP CS Fixer.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *     Dariusz Rumiński <dariusz.ruminski@gmail.com>
 *
 * This source file is subject to the MIT license that is bundled
 * with this source code in the file LICENSE.
 */

namespace PhpCsFixer\Tokenizer\Analyzer;

use PhpCsFixer\Tokenizer\CT;
use PhpCsFixer\Tokenizer\Tokens;

/**
 * @author Kuba Werłos <werlos@gmail.com>
 *
 * @internal
 */
final class ReferenceAnalyzer
{
    /**
     * @param int $index
     *
     * @return bool
     */
    public function isReference(Tokens $tokens, $index)
    {
        if ($tokens[$index]->isGivenKind(CT::T_RETURN_REF)) {
            return true;
        }

        if (!$tokens[$index]->equals('&')) {
            return false;
        }

        /** @var int $index */
        $index = $tokens->getPrevMeaningfulToken($index);
        if ($tokens[$index]->equalsAny(['=', [T_AS], [T_CALLABLE], [T_DOUBLE_ARROW], [CT::T_ARRAY_TYPEHINT]])) {
            return true;
        }

        if ($tokens[$index]->isGivenKind(T_STRING)) {
            $index = $tokens->getPrevMeaningfulToken($index);
        }

        return $tokens[$index]->equalsAny(['(', ',', [T_NS_SEPARATOR], [CT::T_NULLABLE_TYPE]]);
    }
}
