CompilationDatabaseInteface: add all_files_unique()

Author: Sarcasm

compdb/models.py

@@ -68,10 +68,19 @@ def get_compile_commands(self, filepath):
     def get_all_files(self):
         """Return an iterable of path strings.
 
-        A same path can be returned multiple times,
-        store the result in a set if uniqueness is required."""
+        It is ok to return the same path multiple times
+        unless all_files_unique() returns True.
+        """
         raise compdb.NotImplementedError
 
+    def all_files_unique(self):
+        """Whether or not get_all_files() returns unique paths.
+
+        Override this if get_all_files() is guaranteed to return unique paths,
+        this fact can be used for optimization.
+        """
+        return False
+
     def get_all_compile_commands(self):
         """Return an iterable of CompileCommand."""
         raise compdb.NotImplementedError