<?php

/*
 * This file is part of Psy Shell.
 *
 * (c) 2012-2023 Justin Hileman
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Psy\Util;

/**
 * String utility methods.
 *
 * @author ju1ius
 */
class Str
{
    const UNVIS_RX = <<<'EOS'
/
    \\(?:
        ((?:040)|s)
        | (240)
        | (?: M-(.) )
        | (?: M\^(.) )
        | (?: \^(.) )
    )
/xS
EOS;

    /**
     * Decodes a string encoded by libsd's strvis.
     *
     * From `man 3 vis`:
     *
     * Use an ‘M’ to represent meta characters (characters with the 8th bit set),
     * and use a caret ‘^’ to represent control characters (see iscntrl(3)).
     * The following formats are used:
     *
     *      \040    Represents ASCII space.
     *
     *      \240    Represents Meta-space (&nbsp in HTML).
     *
     *      \M-C    Represents character ‘C’ with the 8th bit set.
     *              Spans characters ‘\241’ through ‘\376’.
     *
     *      \M^C    Represents control character ‘C’ with the 8th bit set.
     *              Spans characters ‘\200’ through ‘\237’, and ‘\377’ (as ‘\M^?’).
     *
     *      \^C     Represents the control character ‘C’.
     *              Spans characters ‘\000’ through ‘\037’, and ‘\177’ (as ‘\^?’).
     *
     * The other formats are supported by PHP's stripcslashes,
     * except for the \s sequence (ASCII space).
     *
     * @param string $input The string to decode
     */
    public static function unvis(string $input): string
    {
        $output = \preg_replace_callback(self::UNVIS_RX, [self::class, 'unvisReplace'], $input);

        // other escapes & octal are handled by stripcslashes
        return \stripcslashes($output);
    }

    /**
     * Callback for Str::unvis.
     *
     * @param array $match The matches passed by preg_replace_callback
     */
    protected static function unvisReplace(array $match): string
    {
        // \040, \s
        if (!empty($match[1])) {
            return "\x20";
        }
        // \240
        if (!empty($match[2])) {
            return "\xa0";
        }
        // \M-(.)
        if (isset($match[3]) && $match[3] !== '') {
            $chr = $match[3];
            // unvis S_META1
            $cp = 0200;
            $cp |= \ord($chr);

            return \chr($cp);
        }
        // \M^(.)
        if (isset($match[4]) && $match[4] !== '') {
            $chr = $match[4];
            // unvis S_META | S_CTRL
            $cp = 0200;
            $cp |= ($chr === '?') ? 0177 : \ord($chr) & 037;

            return \chr($cp);
        }
        // \^(.)
        if (isset($match[5]) && $match[5] !== '') {
            $chr = $match[5];
            // unvis S_CTRL
            $cp = 0;
            $cp |= ($chr === '?') ? 0177 : \ord($chr) & 037;

            return \chr($cp);
        }
    }
}

• [F] Docblock.php
  Delete
• [F] Json.php
  Delete
• [F] Mirror.php
  Delete
• [F] Str.php
  Delete

Blog Section

Discover the Latest in Digital Payments and NFC Technology

Dive into our blog to explore the cutting-edge trends in digital payments and NFC technology. Stay updated on the innovations that are revolutionizing transactions, boosting security, and making payments quicker and more convenient. Learn how these advancements are shaping the future of financial interactions and driving the global transition towards a cashless world.

The Rise of Contactless Payments:...

In recent years, contactless payments have surged in popularity, driven...

Visit Blog

March 27, 2024

Enhancing Payment Security: The Role...

As digital transactions proliferate, ensuring robust payment security is more critical than ever. Two foundational...

Visit Blog

March 27, 2024

The Future of Digital Wallets:...

Digital wallets have fundamentally transformed how we manage money, offering a streamlined, secure, and highly...

Visit Blog

March 27, 2024