When set to true it means that no other completion source should activate when this one activates,
WHen set to true it means that this Completion source can work without an AST, for example when the file is syntactically invalid.
Obtains the part of the included path the user has already entered
the ast to search
the location where the user is typing
the part of the included path the user has already entered
Determines whether we are in a include<> or use<> statement
FilenameCompletionProvider provides completions to the include<> and use<> statements.