Adds generateInheritanceHierarchy to hidl-gen.

Bug: 118016875
Test: Added 'interface' lines to an init_rc file and observed errors
when misspelled or missing entire inheritance hierarchy.
Change-Id: Ia18a4000753a1133148f1e2bc340f4ec083824d7
diff --git a/generateInheritanceHierarchy.cpp b/generateInheritanceHierarchy.cpp
new file mode 100644
index 0000000..38d1a5d
--- /dev/null
+++ b/generateInheritanceHierarchy.cpp
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#include "AST.h"
+
+#include <android-base/logging.h>
+#include <hidl-util/Formatter.h>
+#include <json/json.h>
+#include <string>
+#include <vector>
+
+#include "Interface.h"
+
+namespace android {
+
+void AST::generateInheritanceHierarchy(Formatter& out) const {
+    const Interface* callingIface = mRootScope.getInterface();
+    CHECK(callingIface != nullptr);
+
+    Json::Value root;
+    root["interface"] = callingIface->fqName().string();
+    if (callingIface->superType()) {
+        Json::Value inheritedInterfaces(Json::arrayValue);
+        for (const Interface* iface : mRootScope.getInterface()->superTypeChain()) {
+            if (iface->isIBase()) break;
+            inheritedInterfaces.append(iface->fqName().string());
+        }
+        root["inheritedInterfaces"] = inheritedInterfaces;
+    }
+    Json::StyledWriter writer;
+    out << writer.write(root);
+}
+
+}  // namespace android