File Core/SafeDisplay.php | Nexus MCP SDK (1.x-dev) API

1:	<?php
2:
3:	declare(strict_types=1);
4:
5:	/**
6:	* This file is part of the Nexus MCP SDK package.
7:	*
8:	* (c) 2026 John Paul E. Balandan, CPA <paulbalandan@gmail.com>
9:	*
10:	* For the full copyright and license information, please view
11:	* the LICENSE file that was distributed with this source code.
12:	*/
13:
14:	namespace Nexus\Mcp\Core;
15:
16:	/**
17:	* Renderer for the peer-derived strings appearing in log lines, exception messages, and JSON-RPC error payloads.
18:	*
19:	* Never un-escape the result, since a backslash is not itself escaped.
20:	*/
21:	final class SafeDisplay
22:	{
23:	private const int MAX_LENGTH = 80;
24:	private const int MAX_CAUSE_LENGTH = 256;
25:
26:	/**
27:	* Escapes every byte outside printable ASCII as `\xNN` and caps a short identifier at `MAX_LENGTH`.
28:	*/
29:	public static function sanitise(string $value): string
30:	{
31:	return self::render($value, self::MAX_LENGTH);
32:	}
33:
34:	/**
35:	* The same at `MAX_CAUSE_LENGTH`, for a composed message or a URI.
36:	*/
37:	public static function sanitiseCause(string $message): string
38:	{
39:	return self::render($message, self::MAX_CAUSE_LENGTH);
40:	}
41:
42:	/**
43:	* The same for a string request id, passing an int one through unchanged.
44:	*/
45:	public static function sanitiseId(int\|string $id): int\|string
46:	{
47:	return \is_string($id) ? self::render($id, self::MAX_LENGTH) : $id;
48:	}
49:
50:	private static function render(string $value, int $maxLength): string
51:	{
52:	$escaped = preg_replace_callback(
53:	'/[^\x20-\x7E]/',
54:	static fn(array $matches): string => \sprintf('\\x%02x', \ord($matches[0])),
55:	$value,
56:	) ?? '';
57:
58:	if ($maxLength < \strlen($escaped)) {
59:	return substr($escaped, 0, $maxLength - 3).'...';
60:	}
61:
62:	return $escaped;
63:	}
64:	}
65:

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