Replace null constant pointer.

Downgrade to C++98.
Replace unordered_map with map.

Downgrade to C++98.
Remove rvalue references.

Downgrade to C++98.
Remove deleted function declarations.

Downgrade to C++98.
Remove constant begin/end container calls.

Downgrade to C++98.
Remove extended initializer lists.

Downgrade to C++98.
Remove automatically detected types.

Downgrade to C++98.
Reduce C++ version

Downgrade to C++98.