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

/**
 * A Readline interface implementation for GNU Readline.
 *
 * This is by far the coolest way to do it, if you can.
 *
 * Oh well.
 */
class GNUReadline implements Readline
{
    /** @var string|false */
    protected $historyFile;
    /** @var int */
    protected $historySize;
    /** @var bool */
    protected $eraseDups;

    /**
     * GNU Readline is supported iff `readline_list_history` is defined. PHP
     * decided it would be awesome to swap out GNU Readline for Libedit, but
     * they ended up shipping an incomplete implementation. So we've got this.
     *
     * NOTE: As of PHP 7.4, PHP sometimes has history support in the Libedit
     * wrapper, so that will use the GNUReadline implementation as well!
     */
    public static function isSupported(): bool
    {
        return \function_exists('readline') &amp;&amp; \function_exists('readline_list_history');
    }

    /**
     * Check whether this readline implementation supports bracketed paste.
     *
     * Currently, the GNU readline implementation does, but the libedit wrapper does not.
     */
    public static function supportsBracketedPaste(): bool
    {
        return self::isSupported() &amp;&amp; \stripos(\readline_info('library_version') ?: '', 'editline') === false;
    }

    public function __construct($historyFile = null, $historySize = 0, $eraseDups = false)
    {
        $this-&gt;historyFile = ($historyFile !== null) ? $historyFile : false;
        $this-&gt;historySize = $historySize;
        $this-&gt;eraseDups = $eraseDups;

        \readline_info('readline_name', 'psysh');
    }

    /**
     * {@inheritdoc}
     */
    public function addHistory(string $line): bool
    {
        if ($res = \readline_add_history($line)) {
            $this-&gt;writeHistory();
        }

        return $res;
    }

    /**
     * {@inheritdoc}
     */
    public function clearHistory(): bool
    {
        if ($res = \readline_clear_history()) {
            $this-&gt;writeHistory();
        }

        return $res;
    }

    /**
     * {@inheritdoc}
     */
    public function listHistory(): array
    {
        return \readline_list_history();
    }

    /**
     * {@inheritdoc}
     */
    public function readHistory(): bool
    {
        \readline_read_history();
        \readline_clear_history();

        return \readline_read_history($this-&gt;historyFile);
    }

    /**
     * {@inheritdoc}
     */
    public function readline(?string $prompt = null)
    {
        return \readline($prompt);
    }

    /**
     * {@inheritdoc}
     */
    public function redisplay()
    {
        \readline_redisplay();
    }

    /**
     * {@inheritdoc}
     */
    public function writeHistory(): bool
    {
        // We have to write history first, since it is used
        // by Libedit to list history
        if ($this-&gt;historyFile !== false) {
            $res = \readline_write_history($this-&gt;historyFile);
        } else {
            $res = true;
        }

        if (!$res || !$this-&gt;eraseDups &amp;&amp; !$this-&gt;historySize &gt; 0) {
            return $res;
        }

        $hist = $this-&gt;listHistory();
        if (!$hist) {
            return true;
        }

        if ($this-&gt;eraseDups) {
            // flip-flip technique: removes duplicates, latest entries win.
            $hist = \array_flip(\array_flip($hist));
            // sort on keys to get the order back
            \ksort($hist);
        }

        if ($this-&gt;historySize &gt; 0) {
            $histsize = \count($hist);
            if ($histsize &gt; $this-&gt;historySize) {
                $hist = \array_slice($hist, $histsize - $this-&gt;historySize);
            }
        }

        \readline_clear_history();
        foreach ($hist as $line) {
            \readline_add_history($line);
        }

        if ($this-&gt;historyFile !== false) {
            return \readline_write_history($this-&gt;historyFile);
        }

        return true;
    }
}
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