ArrayParser.php

<?php

declare(strict_types=1);

namespace Yiisoft\Db\Pgsql\Data;

use function preg_match;
use function strcspn;
use function stripcslashes;
use function strlen;
use function substr;

/**
 * Array representation to PHP array parser for PostgreSQL Server.
 */
final class ArrayParser
{
    /**
     * Convert an array from PostgresSQL to PHP.
     *
     * @param string $value String to parse.
     *
     * @return (array|string|null)[]|null Parsed value.
     *
     * @psalm-return list<array|string|null>|null
     */
    public function parse(string $value): ?array
    {
        return $value[0] === '{'
            ? $this->parseArray($value)
            : null;
    }

    /**
     * Parse PostgreSQL array encoded in string.
     *
     * @param string $value String to parse.
     * @param int $i parse starting position.
     *
     * @return (array|string|null)[] Parsed value.
     *
     * @psalm-return list<array|string|null>
     */
    private function parseArray(string $value, int &$i = 0): array
    {
        if ($value[++$i] === '}') {
            ++$i;
            return [];
        }

        for ($result = [];; ++$i) {
            $result[] = match ($value[$i]) {
                '{' => $this->parseArray($value, $i),
                ',', '}' => null,
                '"' => $this->parseQuotedString($value, $i),
                default => $this->parseUnquotedString($value, $i),
            };

            if ($value[$i] === '}') {
                ++$i;
                return $result;
            }
        }
    }

    /**
     * Parses quoted string.
     */
    private function parseQuotedString(string $value, int &$i): string
    {
        preg_match('/(?>[^"\\\\]+|\\\\.)*/', $value, $matches, 0, $i + 1);
        $i += strlen($matches[0]) + 2;

        return stripcslashes($matches[0]);
    }

    /**
     * Parses unquoted string.
     */
    private function parseUnquotedString(string $value, int &$i): ?string
    {
        $length = strcspn($value, ',}', $i);
        $result = substr($value, $i, $length);
        $i += $length;

        return $result !== 'NULL' ? $result : null;
    }
}