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];
+    }
 }