Add support for identityref data type

Change-Id: I369150b83d86a4c22fadf383ee011eee619a4c15
diff --git a/src/yang_schema.hpp b/src/yang_schema.hpp
index e56c853..64e3ac5 100644
--- a/src/yang_schema.hpp
+++ b/src/yang_schema.hpp
@@ -35,10 +35,12 @@
     bool isList(const schemaPath_& location, const ModuleNodePair& node) const override;
     bool isPresenceContainer(const schemaPath_& location, const ModuleNodePair& node) const override;
     bool leafEnumHasValue(const schemaPath_& location, const ModuleNodePair& node, const std::string& value) const override;
+    bool leafIdentityIsValid(const schemaPath_& location, const ModuleNodePair& node, const ModuleValuePair& value) const override;
     bool listHasKey(const schemaPath_& location, const ModuleNodePair& node, const std::string& key) const override;
     bool nodeExists(const std::string& location, const std::string& node) const override;
     const std::set<std::string> listKeys(const schemaPath_& location, const ModuleNodePair& node) const override;
     yang::LeafDataTypes leafType(const schemaPath_& location, const ModuleNodePair& node) const override;
+    const std::set<std::string> validIdentities(const schemaPath_& location, const ModuleNodePair& node, const Prefixes prefixes) const override;
     const std::set<std::string> enumValues(const schemaPath_& location, const ModuleNodePair& node) const override;
     std::set<std::string> childNodes(const schemaPath_& path, const Recursion recursion) const override;