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    <h3>Editing: ByteString.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\String;

use Symfony\Component\String\Exception\ExceptionInterface;
use Symfony\Component\String\Exception\InvalidArgumentException;
use Symfony\Component\String\Exception\RuntimeException;

/**
 * Represents a binary-safe string of bytes.
 *
 * @author Nicolas Grekas &lt;p@tchwork.com&gt;
 * @author Hugo Hamon &lt;hugohamon@neuf.fr&gt;
 *
 * @throws ExceptionInterface
 */
class ByteString extends AbstractString
{
    private const ALPHABET_ALPHANUMERIC = '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

    public function __construct(string $string = '')
    {
        $this-&gt;string = $string;
    }

    /*
     * The following method was derived from code of the Hack Standard Library (v4.40 - 2020-05-03)
     *
     * https://github.com/hhvm/hsl/blob/80a42c02f036f72a42f0415e80d6b847f4bf62d5/src/random/private.php#L16
     *
     * Code subject to the MIT license (https://github.com/hhvm/hsl/blob/master/LICENSE).
     *
     * Copyright (c) 2004-2020, Facebook, Inc. (https://www.facebook.com/)
     */

    public static function fromRandom(int $length = 16, string $alphabet = null): self
    {
        if ($length &lt;= 0) {
            throw new InvalidArgumentException(sprintf('A strictly positive length is expected, &quot;%d&quot; given.', $length));
        }

        $alphabet ??= self::ALPHABET_ALPHANUMERIC;
        $alphabetSize = \strlen($alphabet);
        $bits = (int) ceil(log($alphabetSize, 2.0));
        if ($bits &lt;= 0 || $bits &gt; 56) {
            throw new InvalidArgumentException('The length of the alphabet must in the [2^1, 2^56] range.');
        }

        $ret = '';
        while ($length &gt; 0) {
            $urandomLength = (int) ceil(2 * $length * $bits / 8.0);
            $data = random_bytes($urandomLength);
            $unpackedData = 0;
            $unpackedBits = 0;
            for ($i = 0; $i &lt; $urandomLength &amp;&amp; $length &gt; 0; ++$i) {
                // Unpack 8 bits
                $unpackedData = ($unpackedData &lt;&lt; 8) | \ord($data[$i]);
                $unpackedBits += 8;

                // While we have enough bits to select a character from the alphabet, keep
                // consuming the random data
                for (; $unpackedBits &gt;= $bits &amp;&amp; $length &gt; 0; $unpackedBits -= $bits) {
                    $index = ($unpackedData &amp; ((1 &lt;&lt; $bits) - 1));
                    $unpackedData &gt;&gt;= $bits;
                    // Unfortunately, the alphabet size is not necessarily a power of two.
                    // Worst case, it is 2^k + 1, which means we need (k+1) bits and we
                    // have around a 50% chance of missing as k gets larger
                    if ($index &lt; $alphabetSize) {
                        $ret .= $alphabet[$index];
                        --$length;
                    }
                }
            }
        }

        return new static($ret);
    }

    public function bytesAt(int $offset): array
    {
        $str = $this-&gt;string[$offset] ?? '';

        return '' === $str ? [] : [\ord($str)];
    }

    public function append(string ...$suffix): static
    {
        $str = clone $this;
        $str-&gt;string .= 1 &gt;= \count($suffix) ? ($suffix[0] ?? '') : implode('', $suffix);

        return $str;
    }

    public function camel(): static
    {
        $str = clone $this;

        $parts = explode(' ', trim(ucwords(preg_replace('/[^a-zA-Z0-9\x7f-\xff]++/', ' ', $this-&gt;string))));
        $parts[0] = 1 !== \strlen($parts[0]) &amp;&amp; ctype_upper($parts[0]) ? $parts[0] : lcfirst($parts[0]);
        $str-&gt;string = implode('', $parts);

        return $str;
    }

    public function chunk(int $length = 1): array
    {
        if (1 &gt; $length) {
            throw new InvalidArgumentException('The chunk length must be greater than zero.');
        }

        if ('' === $this-&gt;string) {
            return [];
        }

        $str = clone $this;
        $chunks = [];

        foreach (str_split($this-&gt;string, $length) as $chunk) {
            $str-&gt;string = $chunk;
            $chunks[] = clone $str;
        }

        return $chunks;
    }

    public function endsWith(string|iterable|AbstractString $suffix): bool
    {
        if ($suffix instanceof AbstractString) {
            $suffix = $suffix-&gt;string;
        } elseif (!\is_string($suffix)) {
            return parent::endsWith($suffix);
        }

        return '' !== $suffix &amp;&amp; \strlen($this-&gt;string) &gt;= \strlen($suffix) &amp;&amp; 0 === substr_compare($this-&gt;string, $suffix, -\strlen($suffix), null, $this-&gt;ignoreCase);
    }

    public function equalsTo(string|iterable|AbstractString $string): bool
    {
        if ($string instanceof AbstractString) {
            $string = $string-&gt;string;
        } elseif (!\is_string($string)) {
            return parent::equalsTo($string);
        }

        if ('' !== $string &amp;&amp; $this-&gt;ignoreCase) {
            return 0 === strcasecmp($string, $this-&gt;string);
        }

        return $string === $this-&gt;string;
    }

    public function folded(): static
    {
        $str = clone $this;
        $str-&gt;string = strtolower($str-&gt;string);

        return $str;
    }

    public function indexOf(string|iterable|AbstractString $needle, int $offset = 0): ?int
    {
        if ($needle instanceof AbstractString) {
            $needle = $needle-&gt;string;
        } elseif (!\is_string($needle)) {
            return parent::indexOf($needle, $offset);
        }

        if ('' === $needle) {
            return null;
        }

        $i = $this-&gt;ignoreCase ? stripos($this-&gt;string, $needle, $offset) : strpos($this-&gt;string, $needle, $offset);

        return false === $i ? null : $i;
    }

    public function indexOfLast(string|iterable|AbstractString $needle, int $offset = 0): ?int
    {
        if ($needle instanceof AbstractString) {
            $needle = $needle-&gt;string;
        } elseif (!\is_string($needle)) {
            return parent::indexOfLast($needle, $offset);
        }

        if ('' === $needle) {
            return null;
        }

        $i = $this-&gt;ignoreCase ? strripos($this-&gt;string, $needle, $offset) : strrpos($this-&gt;string, $needle, $offset);

        return false === $i ? null : $i;
    }

    public function isUtf8(): bool
    {
        return '' === $this-&gt;string || preg_match('//u', $this-&gt;string);
    }

    public function join(array $strings, string $lastGlue = null): static
    {
        $str = clone $this;

        $tail = null !== $lastGlue &amp;&amp; 1 &lt; \count($strings) ? $lastGlue.array_pop($strings) : '';
        $str-&gt;string = implode($this-&gt;string, $strings).$tail;

        return $str;
    }

    public function length(): int
    {
        return \strlen($this-&gt;string);
    }

    public function lower(): static
    {
        $str = clone $this;
        $str-&gt;string = strtolower($str-&gt;string);

        return $str;
    }

    public function match(string $regexp, int $flags = 0, int $offset = 0): array
    {
        $match = ((\PREG_PATTERN_ORDER | \PREG_SET_ORDER) &amp; $flags) ? 'preg_match_all' : 'preg_match';

        if ($this-&gt;ignoreCase) {
            $regexp .= 'i';
        }

        set_error_handler(static function ($t, $m) { throw new InvalidArgumentException($m); });

        try {
            if (false === $match($regexp, $this-&gt;string, $matches, $flags | \PREG_UNMATCHED_AS_NULL, $offset)) {
                throw new RuntimeException('Matching failed with error: '.preg_last_error_msg());
            }
        } finally {
            restore_error_handler();
        }

        return $matches;
    }

    public function padBoth(int $length, string $padStr = ' '): static
    {
        $str = clone $this;
        $str-&gt;string = str_pad($this-&gt;string, $length, $padStr, \STR_PAD_BOTH);

        return $str;
    }

    public function padEnd(int $length, string $padStr = ' '): static
    {
        $str = clone $this;
        $str-&gt;string = str_pad($this-&gt;string, $length, $padStr, \STR_PAD_RIGHT);

        return $str;
    }

    public function padStart(int $length, string $padStr = ' '): static
    {
        $str = clone $this;
        $str-&gt;string = str_pad($this-&gt;string, $length, $padStr, \STR_PAD_LEFT);

        return $str;
    }

    public function prepend(string ...$prefix): static
    {
        $str = clone $this;
        $str-&gt;string = (1 &gt;= \count($prefix) ? ($prefix[0] ?? '') : implode('', $prefix)).$str-&gt;string;

        return $str;
    }

    public function replace(string $from, string $to): static
    {
        $str = clone $this;

        if ('' !== $from) {
            $str-&gt;string = $this-&gt;ignoreCase ? str_ireplace($from, $to, $this-&gt;string) : str_replace($from, $to, $this-&gt;string);
        }

        return $str;
    }

    public function replaceMatches(string $fromRegexp, string|callable $to): static
    {
        if ($this-&gt;ignoreCase) {
            $fromRegexp .= 'i';
        }

        $replace = \is_array($to) || $to instanceof \Closure ? 'preg_replace_callback' : 'preg_replace';

        set_error_handler(static function ($t, $m) { throw new InvalidArgumentException($m); });

        try {
            if (null === $string = $replace($fromRegexp, $to, $this-&gt;string)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k =&gt; $v) {
                    if ($lastError === $v &amp;&amp; str_ends_with($k, '_ERROR')) {
                        throw new RuntimeException('Matching failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Matching failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }

        $str = clone $this;
        $str-&gt;string = $string;

        return $str;
    }

    public function reverse(): static
    {
        $str = clone $this;
        $str-&gt;string = strrev($str-&gt;string);

        return $str;
    }

    public function slice(int $start = 0, int $length = null): static
    {
        $str = clone $this;
        $str-&gt;string = (string) substr($this-&gt;string, $start, $length ?? \PHP_INT_MAX);

        return $str;
    }

    public function snake(): static
    {
        $str = $this-&gt;camel();
        $str-&gt;string = strtolower(preg_replace(['/([A-Z]+)([A-Z][a-z])/', '/([a-z\d])([A-Z])/'], '\1_\2', $str-&gt;string));

        return $str;
    }

    public function splice(string $replacement, int $start = 0, int $length = null): static
    {
        $str = clone $this;
        $str-&gt;string = substr_replace($this-&gt;string, $replacement, $start, $length ?? \PHP_INT_MAX);

        return $str;
    }

    public function split(string $delimiter, int $limit = null, int $flags = null): array
    {
        if (1 &gt; $limit ??= \PHP_INT_MAX) {
            throw new InvalidArgumentException('Split limit must be a positive integer.');
        }

        if ('' === $delimiter) {
            throw new InvalidArgumentException('Split delimiter is empty.');
        }

        if (null !== $flags) {
            return parent::split($delimiter, $limit, $flags);
        }

        $str = clone $this;
        $chunks = $this-&gt;ignoreCase
            ? preg_split('{'.preg_quote($delimiter).'}iD', $this-&gt;string, $limit)
            : explode($delimiter, $this-&gt;string, $limit);

        foreach ($chunks as &amp;$chunk) {
            $str-&gt;string = $chunk;
            $chunk = clone $str;
        }

        return $chunks;
    }

    public function startsWith(string|iterable|AbstractString $prefix): bool
    {
        if ($prefix instanceof AbstractString) {
            $prefix = $prefix-&gt;string;
        } elseif (!\is_string($prefix)) {
            return parent::startsWith($prefix);
        }

        return '' !== $prefix &amp;&amp; 0 === ($this-&gt;ignoreCase ? strncasecmp($this-&gt;string, $prefix, \strlen($prefix)) : strncmp($this-&gt;string, $prefix, \strlen($prefix)));
    }

    public function title(bool $allWords = false): static
    {
        $str = clone $this;
        $str-&gt;string = $allWords ? ucwords($str-&gt;string) : ucfirst($str-&gt;string);

        return $str;
    }

    public function toUnicodeString(string $fromEncoding = null): UnicodeString
    {
        return new UnicodeString($this-&gt;toCodePointString($fromEncoding)-&gt;string);
    }

    public function toCodePointString(string $fromEncoding = null): CodePointString
    {
        $u = new CodePointString();

        if (\in_array($fromEncoding, [null, 'utf8', 'utf-8', 'UTF8', 'UTF-8'], true) &amp;&amp; preg_match('//u', $this-&gt;string)) {
            $u-&gt;string = $this-&gt;string;

            return $u;
        }

        set_error_handler(static function ($t, $m) { throw new InvalidArgumentException($m); });

        try {
            try {
                $validEncoding = false !== mb_detect_encoding($this-&gt;string, $fromEncoding ?? 'Windows-1252', true);
            } catch (InvalidArgumentException $e) {
                if (!\function_exists('iconv')) {
                    throw $e;
                }

                $u-&gt;string = iconv($fromEncoding ?? 'Windows-1252', 'UTF-8', $this-&gt;string);

                return $u;
            }
        } finally {
            restore_error_handler();
        }

        if (!$validEncoding) {
            throw new InvalidArgumentException(sprintf('Invalid &quot;%s&quot; string.', $fromEncoding ?? 'Windows-1252'));
        }

        $u-&gt;string = mb_convert_encoding($this-&gt;string, 'UTF-8', $fromEncoding ?? 'Windows-1252');

        return $u;
    }

    public function trim(string $chars = &quot; \t\n\r\0\x0B\x0C&quot;): static
    {
        $str = clone $this;
        $str-&gt;string = trim($str-&gt;string, $chars);

        return $str;
    }

    public function trimEnd(string $chars = &quot; \t\n\r\0\x0B\x0C&quot;): static
    {
        $str = clone $this;
        $str-&gt;string = rtrim($str-&gt;string, $chars);

        return $str;
    }

    public function trimStart(string $chars = &quot; \t\n\r\0\x0B\x0C&quot;): static
    {
        $str = clone $this;
        $str-&gt;string = ltrim($str-&gt;string, $chars);

        return $str;
    }

    public function upper(): static
    {
        $str = clone $this;
        $str-&gt;string = strtoupper($str-&gt;string);

        return $str;
    }

    public function width(bool $ignoreAnsiDecoration = true): int
    {
        $string = preg_match('//u', $this-&gt;string) ? $this-&gt;string : preg_replace('/[\x80-\xFF]/', '?', $this-&gt;string);

        return (new CodePointString($string))-&gt;width($ignoreAnsiDecoration);
    }
}
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