The Song class is an abstract class, and the InstrumentalSong and LyricsSong classes inherits it. The Song class contains the the information shared by both its inheriting classes like the title and the tags of the song. Each of the InstrumentalSong and LyricsSong contains additional information relevant to the specific type of the song. If in some time in the future we want to add a new song type, all we need to do is to create a new class represents the new type that inherits the Song class, and it a new type to the enum of song types inside the song class. The Parameters class stores the parameters and the known words from the parameters file. It's parsing the parameters file, extract the data and store it inside its data members. The SortHelper class is used to store the scores of all the songs for some specific words and sort the scores by size. The sort is stable. The sorted scores is used to print the relevant songs of the relevant query in the right order determined by the score size. The MIR class is a driver for the whole MIR system. It stores a vector of pointers to all the Song objects. It initiates the songs vector using methods from the SongsParser file. The class also stores an instance of the Parameters class. It sends a reference to the Parameters object with some query every time to the Song objects to calculate its score. After that, the class prints the songs that gained a positive score for every query in a descended order. The BpmKnownWords file contains a struct used to store the information some bpm known word, and is used by some of the files to store and access the bpm known words from the parameters file.