Allow parsing RAML files with model extensions

Add constructor so that the RamlDocumentBuilder can also parse custom
sub-classes of Raml. In this way, the RAML model can be extended.

src/main/java/org/raml/parser/visitor/RamlDocumentBuilder.java

@@ -49,9 +49,19 @@ public RamlDocumentBuilder()
         this(new DefaultResourceLoader());
     }
 
+    public RamlDocumentBuilder(Class<? extends Raml> documentClass)
+    {
+        this(documentClass, new DefaultResourceLoader());
+    }
+
     public RamlDocumentBuilder(ResourceLoader resourceLoader, TagResolver... tagResolvers)
     {
-        super(Raml.class, resourceLoader, defaultResolver(tagResolvers));
+        this(Raml.class, resourceLoader, tagResolvers);
+    }
+
+    public RamlDocumentBuilder(Class<? extends Raml> documentClass, ResourceLoader resourceLoader, TagResolver... tagResolvers)
+    {
+        super(documentClass, resourceLoader, defaultResolver(tagResolvers));
     }
 
     private static TagResolver[] defaultResolver(TagResolver[] tagResolvers)

src/main/java/org/raml/parser/visitor/YamlDocumentBuilder.java

@@ -56,7 +56,7 @@
 public class YamlDocumentBuilder<T> implements NodeHandler, ContextPathAware
 {
 
-    private Class<T> documentClass;
+    private Class<? extends T> documentClass;
     private T documentObject;
     private Stack<NodeBuilder<?>> builderContext = new Stack<NodeBuilder<?>>();
     private Stack<Object> documentContext = new Stack<Object>();
@@ -65,7 +65,7 @@ public class YamlDocumentBuilder<T> implements NodeHandler, ContextPathAware
     private TagResolver[] tagResolvers;
     private ContextPath contextPath;
 
-    public YamlDocumentBuilder(Class<T> documentClass, ResourceLoader resourceLoader, TagResolver... tagResolvers)
+    public YamlDocumentBuilder(Class<? extends T> documentClass, ResourceLoader resourceLoader, TagResolver... tagResolvers)
     {
         this.documentClass = documentClass;
         this.resourceLoader = resourceLoader;

src/test/java/org/raml/parser/visitor/RamlDocumentBuilderTestCase.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2015 (c) SAP SE
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+ * either express or implied. See the License for the specific
+ * language governing permissions and limitations under the License.
+ */
+package org.raml.parser.visitor;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.assertThat;
+
+import org.junit.Test;
+import org.raml.model.Raml;
+import org.raml.parser.annotation.Scalar;
+import org.raml.parser.builder.AbstractRamlTestCase;
+
+public class RamlDocumentBuilderTestCase extends AbstractRamlTestCase
+{
+
+    @Test
+    public void parseExtendedModel()
+    {
+        RamlExt raml = (RamlExt) new RamlDocumentBuilder(RamlExt.class).build("org/raml/parser/visitor/extended.yaml");
+        assertThat(raml.getTitle(), is("extended model")); // standard property
+        assertThat(raml.getExtension(), is("additional data")); // non-standard property
+    }
+
+    public static class RamlExt extends Raml
+    {
+        private static final long serialVersionUID = 533345138584973337L;
+
+        @Scalar
+        private String extension;
+
+        public String getExtension() {
+            return extension;
+        }
+
+        public void setExtension(String extension) {
+            this.extension = extension;
+        }
+    }
+}

src/test/resources/org/raml/parser/visitor/extended.yaml

@@ -0,0 +1,3 @@
+#%RAML 0.8
+title: extended model
+extension: additional data