Emit warning when HERA-C boilerplate is detected

Resolves #19

hera/parser.py

@@ -18,6 +18,10 @@
 class TreeToOplist(Transformer):
     """Transform Lark's parse tree into a list of HERA ops."""
 
+    def cpp_program(self, matches):
+        emit_warning("void HERA_main() { ... } is not necessary")
+        return matches
+
     def op(self, matches):
         return Op(matches[0], matches[1:])
 
@@ -115,8 +119,10 @@ def parse(text):
 
     if isinstance(tree, Tree):
         return tree.children
-    else:
+    elif isinstance(tree, Op):
         return [tree]
+    else:
+        return tree
 
 
 def replace_escapes(s):

test/test_main.py

@@ -21,7 +21,7 @@ def test_program_to_string():
 
 
 def test_dump_state(capsys):
-    dump_state(VirtualMachine())
+    dump_state(VirtualMachine(), verbose=True)
 
     captured = capsys.readouterr()
     assert "R1  = 0x0000 = 0" in captured.err

test/test_parser.py

@@ -1,4 +1,5 @@
 import pytest
+from unittest.mock import patch
 
 from hera.parser import Op, parse, replace_escapes
 from hera.utils import HERAError
@@ -97,6 +98,15 @@ def test_parse_hera_boilerplate_no_includes():
     assert parse("void HERA_main() {SETLO(R1, 42)}") == [Op("SETLO", ["R1", 42])]
 
 
+def test_parse_hera_boilerplate_gives_warning():
+    with patch("hera.utils._emit_msg") as mock_emit_warning:
+        parse("void HERA_main() {SETLO(R1, 42)}")
+        assert mock_emit_warning.call_count == 1
+        assert "Warning" in mock_emit_warning.call_args[0][0]
+        assert "HERA_main" in mock_emit_warning.call_args[0][0]
+        assert "not necessary" in mock_emit_warning.call_args[0][0]
+
+
 def test_parse_another_single_line_comments():
     program = """\
 // Single-line comment