Add callback request matcher

spec/RequestMatcher/CallbackRequestMatcherSpec.php

@@ -0,0 +1,43 @@
+<?php
+
+namespace spec\Http\Message\RequestMatcher;
+
+use PhpSpec\ObjectBehavior;
+use Prophecy\Argument;
+use Psr\Http\Message\RequestInterface;
+
+class CallbackRequestMatcherSpec extends ObjectBehavior
+{
+    function let()
+    {
+        $this->beConstructedWith(function () {});
+    }
+
+    function it_is_initializable()
+    {
+        $this->shouldHaveType('Http\Message\RequestMatcher\CallbackRequestMatcher');
+    }
+
+    function it_is_a_request_matcher()
+    {
+        $this->shouldImplement('Http\Message\RequestMatcher');
+    }
+
+    function it_matches_a_request(RequestInterface $request)
+    {
+        $callback = function () { return true; };
+
+        $this->beConstructedWith($callback);
+
+        $this->matches($request)->shouldReturn(true);
+    }
+
+    function it_does_not_match_a_request(RequestInterface $request)
+    {
+        $callback = function () { return false; };
+
+        $this->beConstructedWith($callback);
+
+        $this->matches($request)->shouldReturn(false);
+    }
+}

src/RequestMatcher/CallbackRequestMatcher.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace Http\Message\RequestMatcher;
+
+use Http\Message\RequestMatcher;
+use Psr\Http\Message\RequestInterface;
+
+/**
+ * Match a request with a callback.
+ *
+ * @author Márk Sági-Kazár <mark.sagikazar@gmail.com>
+ */
+final class CallbackRequestMatcher implements RequestMatcher
+{
+    /**
+     * @var callable
+     */
+    private $callback;
+
+    /**
+     * @param callable $callback
+     */
+    public function __construct(callable $callback)
+    {
+        $this->callback = $callback;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function matches(RequestInterface $request)
+    {
+        return (bool) call_user_func($this->callback, $request);
+    }
+}