— typedef: map<unsigned int, music_node*> BellNodeMap;

This map is used to form the structure of the tree. The branches are stored in the structure, with the unsigned int being an index by bell number. Index 0 is for matching any bell. Note, where a node of the tree has no branches coming off of it (because it is the end, or there is nothing else to match against) the map will be empty.

— typedef: BellNodeMap::iterator BellNodeMapIterator;

This type definition is used to provide a shorter type name to iterate the map described above.

— typedef: vector<unsigned int> DetailsVector;

This type definition defines the vector that is used to store the id of the music_details expressions that end at this node.

— typedef: DetailsVector::iterator DetailsVectorIterator;

This type definition is used to provide a shorter type name to iterate the details vector defined above.