Generate C++ function returning the file_identifier of a flatbuffer

Change-Id: I6ee09cf1e86a41b73bb3aa79b68871afb1a4e34f

src/idl_gen_cpp.cpp

@@ -638,21 +638,27 @@ std::string GenerateCPP(const Parser &parser,
               "return verifier.VerifyBuffer<";
       code += parser.root_struct_def->name + ">(); }\n\n";
 
+      if (parser.file_identifier_.length()) {
+        // Return the identifier
+        code += "inline const char *" + parser.root_struct_def->name;
+        code += "Identifier() { return \"" + parser.file_identifier_;
+        code += "\"; }\n\n";
+
+        // Check if a buffer has the identifier.
+        code += "inline bool " + parser.root_struct_def->name;
+        code += "BufferHasIdentifier(const void *buf) { return flatbuffers::";
+        code += "BufferHasIdentifier(buf, ";
+        code += parser.root_struct_def->name + "Identifier()); }\n\n";
+      }
+
       // Finish a buffer with a given root object:
       code += "inline void Finish" + parser.root_struct_def->name;
       code += "Buffer(flatbuffers::FlatBufferBuilder &fbb, flatbuffers::Offset<";
       code += parser.root_struct_def->name + "> root) { fbb.Finish(root";
       if (parser.file_identifier_.length())
-        code += ", \"" + parser.file_identifier_ + "\"";
+        code += ", " + parser.root_struct_def->name + "Identifier()";
       code += "); }\n\n";
 
-      if (parser.file_identifier_.length()) {
-        // Check if a buffer has the identifier.
-        code += "inline bool " + parser.root_struct_def->name;
-        code += "BufferHasIdentifier(const void *buf) { return flatbuffers::";
-        code += "BufferHasIdentifier(buf, \"" + parser.file_identifier_;
-        code += "\"); }\n\n";
-      }
     }
 
     CloseNestedNameSpaces(name_space, &code);

tests/monster_test_generated.h

@@ -240,9 +240,11 @@ inline const Monster *GetMonster(const void *buf) { return flatbuffers::GetRoot<
 
 inline bool VerifyMonsterBuffer(flatbuffers::Verifier &verifier) { return verifier.VerifyBuffer<Monster>(); }
 
-inline void FinishMonsterBuffer(flatbuffers::FlatBufferBuilder &fbb, flatbuffers::Offset<Monster> root) { fbb.Finish(root, "MONS"); }
+inline const char *MonsterIdentifier() { return "MONS"; }
 
-inline bool MonsterBufferHasIdentifier(const void *buf) { return flatbuffers::BufferHasIdentifier(buf, "MONS"); }
+inline bool MonsterBufferHasIdentifier(const void *buf) { return flatbuffers::BufferHasIdentifier(buf, MonsterIdentifier()); }
+
+inline void FinishMonsterBuffer(flatbuffers::FlatBufferBuilder &fbb, flatbuffers::Offset<Monster> root) { fbb.Finish(root, MonsterIdentifier()); }
 
 }  // namespace Example
 }  // namespace MyGame

tests/test.cpp

@@ -117,6 +117,7 @@ void AccessFlatBufferTest(const std::string &flatbuf) {
     flatbuf.length());
   TEST_EQ(VerifyMonsterBuffer(verifier), true);
 
+  TEST_EQ(strcmp(MonsterIdentifier(), "MONS"), 0);
   TEST_EQ(MonsterBufferHasIdentifier(flatbuf.c_str()), true);
 
   // Access the buffer from the root.