Here is a list of all files with brief descriptions:

build
src
libyang.h	The main libyang public header
src
dict.h	Libyang dictionary
extensions.h	Libyang support for YANG extension implementations
tree_data.h	Libyang representation of data trees
tree_schema.h	Libyang representation of data model trees
user_types.h	Libyang support for user YANG type implementations
xml.h	Public API of libyang XML parser
swig
cpp
src
Libyang.cpp	Implementation of header Libyang.hpp
Libyang.hpp	Class implementation for libyang C header libyang.h
Tree_Data.cpp	Implementation of header Tree_Data.hpp
Tree_Data.hpp	Class implementation for libyang C header tree_data.h
Tree_Schema.cpp	Implementation of header Tree_Schema.hpp
Tree_Schema.hpp	Class implementation for libyang C header tree_schema.h
Xml.cpp	Implementation of header Xml.hpp
Xml.hpp	Class implementation for libyang C header xml.h