main: enable using files as input

compiler/__main__.py

@@ -33,6 +33,7 @@ def main():
     valid_mock_inputs = list(filter(lambda x: x[0] != "_", dir(mock)))
     parser.add_argument("--mock-input", dest="mock_input", type=str, choices=valid_mock_inputs, default="legacy_mock",
                         help="Specify mock input")
+    parser.add_argument(dest="sources", metavar="SOURCE_FILES", help="Input files", type=Path, nargs="*")
 
     args = parser.parse_args()
 
@@ -43,6 +44,10 @@ def main():
         print("Source:\n", data)
         _input_stream = io.StringIO(data)
 
+    if len(args.sources):
+        assert len(args.sources) == 1
+        _input_stream = io.open(args.sources[0])
+
     input_stream = TextIOWithMemory(_input_stream)
 
     tokens = \