common/helpers/utf8/substr.php - dev - v.bolshakov/AIEcosystem-Testing

common/helpers/utf8/substr.php
67 строк2 KB
Developer
Initial commit
03 авг 2026, 17:43
03 авг 2026, 17:437433917
<?php

use common\helpers\Utf8Helper;

/**
 * Utf8Helper::substr
 */
function _substr($str, $offset, $length = null)
{
    if (Utf8Helper::isAscii($str)) {
        return ($length === null) ? substr($str, $offset) : substr($str, $offset, $length);
    }

    // Normalize params
    $str = (string)$str;
    $strlen = Utf8Helper::strlen($str);
    $offset = (int)($offset < 0) ? max(0, $strlen + $offset) : $offset; // Normalize to positive offset
    $length = ($length === null) ? null : (int)$length;

    // Impossible
    if ($length === 0 or $offset >= $strlen or ($length < 0 and $length <= $offset - $strlen)) {
        return '';
    }

    // Whole string
    if ($offset == 0 and ($length === null or $length >= $strlen)) {
        return $str;
    }

    // Build regex
    $regex = '^';

    // Create an offset expression
    if ($offset > 0) {
        // PCRE repeating quantifiers must be less than 65536, so repeat when necessary
        $x = (int)($offset / 65535);
        $y = (int)($offset % 65535);
        $regex .= ($x == 0) ? '' : ('(?:.{65535}){' . $x . '}');
        $regex .= ($y == 0) ? '' : ('.{' . $y . '}');
    }

    // Create a length expression
    if ($length === null) {
        $regex .= '(.*)'; // No length set, grab it all
    } // Find length from the left (positive length)
    elseif ($length > 0) {
        // Reduce length so that it can't go beyond the end of the string
        $length = min($strlen - $offset, $length);

        $x = (int)($length / 65535);
        $y = (int)($length % 65535);
        $regex .= '(';
        $regex .= ($x == 0) ? '' : ('(?:.{65535}){' . $x . '}');
        $regex .= '.{' . $y . '})';
    } // Find length from the right (negative length)
    else {
        $x = (int)(-$length / 65535);
        $y = (int)(-$length % 65535);
        $regex .= '(.*)';
        $regex .= ($x == 0) ? '' : ('(?:.{65535}){' . $x . '}');
        $regex .= '.{' . $y . '}';
    }

    preg_match('/' . $regex . '/us', $str, $matches);

    return $matches[1];
}