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    <h3>Editing: TraceableUrlMatcher.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\Routing\Matcher;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\Routing\Exception\ExceptionInterface;
use Symfony\Component\Routing\Route;
use Symfony\Component\Routing\RouteCollection;

/**
 * TraceableUrlMatcher helps debug path info matching by tracing the match.
 *
 * @author Fabien Potencier &lt;fabien@symfony.com&gt;
 */
class TraceableUrlMatcher extends UrlMatcher
{
    public const ROUTE_DOES_NOT_MATCH = 0;
    public const ROUTE_ALMOST_MATCHES = 1;
    public const ROUTE_MATCHES = 2;

    protected $traces;

    public function getTraces(string $pathinfo)
    {
        $this-&gt;traces = [];

        try {
            $this-&gt;match($pathinfo);
        } catch (ExceptionInterface $e) {
        }

        return $this-&gt;traces;
    }

    public function getTracesForRequest(Request $request)
    {
        $this-&gt;request = $request;
        $traces = $this-&gt;getTraces($request-&gt;getPathInfo());
        $this-&gt;request = null;

        return $traces;
    }

    protected function matchCollection(string $pathinfo, RouteCollection $routes)
    {
        // HEAD and GET are equivalent as per RFC
        if ('HEAD' === $method = $this-&gt;context-&gt;getMethod()) {
            $method = 'GET';
        }
        $supportsTrailingSlash = 'GET' === $method &amp;&amp; $this instanceof RedirectableUrlMatcherInterface;
        $trimmedPathinfo = rtrim($pathinfo, '/') ?: '/';

        foreach ($routes as $name =&gt; $route) {
            $compiledRoute = $route-&gt;compile();
            $staticPrefix = rtrim($compiledRoute-&gt;getStaticPrefix(), '/');
            $requiredMethods = $route-&gt;getMethods();

            // check the static prefix of the URL first. Only use the more expensive preg_match when it matches
            if ('' !== $staticPrefix &amp;&amp; !str_starts_with($trimmedPathinfo, $staticPrefix)) {
                $this-&gt;addTrace(sprintf('Path &quot;%s&quot; does not match', $route-&gt;getPath()), self::ROUTE_DOES_NOT_MATCH, $name, $route);
                continue;
            }
            $regex = $compiledRoute-&gt;getRegex();

            $pos = strrpos($regex, '$');
            $hasTrailingSlash = '/' === $regex[$pos - 1];
            $regex = substr_replace($regex, '/?$', $pos - $hasTrailingSlash, 1 + $hasTrailingSlash);

            if (!preg_match($regex, $pathinfo, $matches)) {
                // does it match without any requirements?
                $r = new Route($route-&gt;getPath(), $route-&gt;getDefaults(), [], $route-&gt;getOptions());
                $cr = $r-&gt;compile();
                if (!preg_match($cr-&gt;getRegex(), $pathinfo)) {
                    $this-&gt;addTrace(sprintf('Path &quot;%s&quot; does not match', $route-&gt;getPath()), self::ROUTE_DOES_NOT_MATCH, $name, $route);

                    continue;
                }

                foreach ($route-&gt;getRequirements() as $n =&gt; $regex) {
                    $r = new Route($route-&gt;getPath(), $route-&gt;getDefaults(), [$n =&gt; $regex], $route-&gt;getOptions());
                    $cr = $r-&gt;compile();

                    if (\in_array($n, $cr-&gt;getVariables()) &amp;&amp; !preg_match($cr-&gt;getRegex(), $pathinfo)) {
                        $this-&gt;addTrace(sprintf('Requirement for &quot;%s&quot; does not match (%s)', $n, $regex), self::ROUTE_ALMOST_MATCHES, $name, $route);

                        continue 2;
                    }
                }

                continue;
            }

            $hasTrailingVar = $trimmedPathinfo !== $pathinfo &amp;&amp; preg_match('#\{\w+\}/?$#', $route-&gt;getPath());

            if ($hasTrailingVar &amp;&amp; ($hasTrailingSlash || (null === $m = $matches[\count($compiledRoute-&gt;getPathVariables())] ?? null) || '/' !== ($m[-1] ?? '/')) &amp;&amp; preg_match($regex, $trimmedPathinfo, $m)) {
                if ($hasTrailingSlash) {
                    $matches = $m;
                } else {
                    $hasTrailingVar = false;
                }
            }

            $hostMatches = [];
            if ($compiledRoute-&gt;getHostRegex() &amp;&amp; !preg_match($compiledRoute-&gt;getHostRegex(), $this-&gt;context-&gt;getHost(), $hostMatches)) {
                $this-&gt;addTrace(sprintf('Host &quot;%s&quot; does not match the requirement (&quot;%s&quot;)', $this-&gt;context-&gt;getHost(), $route-&gt;getHost()), self::ROUTE_ALMOST_MATCHES, $name, $route);
                continue;
            }

            $status = $this-&gt;handleRouteRequirements($pathinfo, $name, $route);

            if (self::REQUIREMENT_MISMATCH === $status[0]) {
                $this-&gt;addTrace(sprintf('Condition &quot;%s&quot; does not evaluate to &quot;true&quot;', $route-&gt;getCondition()), self::ROUTE_ALMOST_MATCHES, $name, $route);
                continue;
            }

            if ('/' !== $pathinfo &amp;&amp; !$hasTrailingVar &amp;&amp; $hasTrailingSlash === ($trimmedPathinfo === $pathinfo)) {
                if ($supportsTrailingSlash &amp;&amp; (!$requiredMethods || \in_array('GET', $requiredMethods))) {
                    $this-&gt;addTrace('Route matches!', self::ROUTE_MATCHES, $name, $route);

                    return $this-&gt;allow = $this-&gt;allowSchemes = [];
                }
                $this-&gt;addTrace(sprintf('Path &quot;%s&quot; does not match', $route-&gt;getPath()), self::ROUTE_DOES_NOT_MATCH, $name, $route);
                continue;
            }

            if ($route-&gt;getSchemes() &amp;&amp; !$route-&gt;hasScheme($this-&gt;context-&gt;getScheme())) {
                $this-&gt;allowSchemes = array_merge($this-&gt;allowSchemes, $route-&gt;getSchemes());
                $this-&gt;addTrace(sprintf('Scheme &quot;%s&quot; does not match any of the required schemes (%s)', $this-&gt;context-&gt;getScheme(), implode(', ', $route-&gt;getSchemes())), self::ROUTE_ALMOST_MATCHES, $name, $route);
                continue;
            }

            if ($requiredMethods &amp;&amp; !\in_array($method, $requiredMethods)) {
                $this-&gt;allow = array_merge($this-&gt;allow, $requiredMethods);
                $this-&gt;addTrace(sprintf('Method &quot;%s&quot; does not match any of the required methods (%s)', $this-&gt;context-&gt;getMethod(), implode(', ', $requiredMethods)), self::ROUTE_ALMOST_MATCHES, $name, $route);
                continue;
            }

            $this-&gt;addTrace('Route matches!', self::ROUTE_MATCHES, $name, $route);

            return $this-&gt;getAttributes($route, $name, array_replace($matches, $hostMatches, $status[1] ?? []));
        }

        return [];
    }

    private function addTrace(string $log, int $level = self::ROUTE_DOES_NOT_MATCH, ?string $name = null, ?Route $route = null)
    {
        $this-&gt;traces[] = [
            'log' =&gt; $log,
            'name' =&gt; $name,
            'level' =&gt; $level,
            'path' =&gt; null !== $route ? $route-&gt;getPath() : null,
        ];
    }
}
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