Support braces in types for @return

In this change, I have introduced a miniature automaton-light to parse
the type from the @return body. This will prevent issues with people
using generics and other unsupported forms of types.

This change does _not_ allow for the use of Generics or similar; the
TypeResolver will still fail to resolve this type. This will remove a
breaking issue in consuming applications where a runtime exception used
to be thrown.

Please note that this change is only for @return; other tags still need
to be done. This will resolve issue #186

src/DocBlock/Tags/Return_.php

@@ -50,11 +50,10 @@ final class Return_ extends BaseTag implements Factory\StaticMethod
         Assert::notNull($typeResolver);
         Assert::notNull($descriptionFactory);
 
-        $parts = preg_split('/\s+/Su', $body, 2);
-        Assert::isArray($parts);
+        list($type, $description) = self::splitBodyIntoTypeAndTheRest($body);
 
-        $type        = $typeResolver->resolve($parts[0] ?? '', $context);
-        $description = $descriptionFactory->create($parts[1] ?? '', $context);
+        $type = $typeResolver->resolve($type, $context);
+        $description = $descriptionFactory->create($description, $context);
 
         return new static($type, $description);
     }
@@ -71,4 +70,29 @@ final class Return_ extends BaseTag implements Factory\StaticMethod
     {
         return $this->type . ' ' . (string) $this->description;
     }
+
+    private static function splitBodyIntoTypeAndTheRest(string $body) : array
+    {
+        $type = '';
+        $nestingLevel = 0;
+        for ($i = 0; $i < strlen($body); $i++) {
+            $character = $body[$i];
+
+            if (trim($character) === '' && $nestingLevel === 0) {
+                break;
+            }
+
+            $type .= $character;
+            if (in_array($character, ['<', '(', '[', '{'])) {
+                $nestingLevel++;
+            }
+            if (in_array($character, ['>', ')', ']', '}'])) {
+                $nestingLevel--;
+            }
+        }
+
+        $description = trim(substr($body, strlen($type)));
+
+        return [$type, $description];
+    }
 }

tests/unit/DocBlock/Tags/ReturnTest.php

@@ -148,6 +148,41 @@ class ReturnTest extends TestCase
         $this->assertSame($description, $fixture->getDescription());
     }
 
+    /**
+     * This test checks whether a braces in a Type are allowed.
+     *
+     * The advent of generics poses a few issues, one of them is that spaces can now be part of a type. In the past we
+     * could purely rely on spaces to split the individual parts of the body of a tag; but when there is a type in play
+     * we now need to check for braces.
+     *
+     * This test tests whether an error occurs demonstrating that the braces were taken into account; this test is still
+     * expected to produce an exception because the TypeResolver does not support generics.
+     *
+     * @covers ::create
+     * @uses \phpDocumentor\Reflection\DocBlock\Tags\Return_::<public>
+     * @uses \phpDocumentor\Reflection\DocBlock\DescriptionFactory
+     * @uses \phpDocumentor\Reflection\TypeResolver
+     * @uses \phpDocumentor\Reflection\DocBlock\Description
+     * @uses \phpDocumentor\Reflection\Types\String_
+     * @uses \phpDocumentor\Reflection\Types\Context
+     */
+    public function testFactoryMethodWithGenericWithSpace()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        $this->expectExceptionMessage('"\array😁<string,😁 😁string>" is not a valid Fqsen.');
+
+        $descriptionFactory = m::mock(DescriptionFactory::class);
+        $resolver = new TypeResolver();
+        $context = new Context('');
+
+        $description = new Description('My Description');
+        $descriptionFactory->shouldReceive('create')
+            ->with('My Description', $context)
+            ->andReturn($description);
+
+        Return_::create('array😁<string,😁 string> My Description', $resolver, $descriptionFactory, $context);
+    }
+
     /**
      * @covers ::create
      */