Fix parsing all comment types (#1290)

* Fix parsing all comment types

* style

pyquil/_parser/grammar.lark

@@ -1,6 +1,7 @@
 quil : (all_instr _NEWLINE?)*
 
-?all_instr : def_gate
+?all_instr : COMMENT
+           | def_gate
            | def_circuit
            | def_frame
            | def_waveform
@@ -41,6 +42,8 @@ quil : (all_instr _NEWLINE?)*
        | classical_comparison
        | include
 
+COMMENT : "#" /[^\n]*/ NEWLINE
+
 def_gate : "DEFGATE" name [ variables ] ":" matrix -> def_gate_matrix
          | "DEFGATE" name "AS" "MATRIX" [ variables ] ":" matrix -> def_gate_matrix
          | "DEFGATE" name "AS" "PERMUTATION" ":" _NEWLINE_TAB matrix_row -> def_gate_as_permutation

pyquil/tests/test_parser.py

@@ -18,6 +18,7 @@
 import numpy as np
 import pytest
 
+from pyquil import Program
 from pyquil.gates import (
     ADD,
     AND,
@@ -668,3 +669,30 @@ def test_parse_defgate_as_pauli():
         parse("DEFGATE RY(%theta) 0 AS PAULI-SUM:\n    Y(-%theta/2) q")
 
     assert excp.value.token == Token("INT", "0")
+
+
+@pytest.mark.parametrize(
+    "program",
+    [
+        """# comment on first line
+H 0
+""",
+        """H 0 # mid-line comment on first line
+H 0
+""",
+        """H 0
+# comment on second line
+H 0
+""",
+        """H 0
+H 0 # mid-line comment on second line
+""",
+        """H 0
+# comment on last line with newline
+""",
+        """H 0
+# comment on last line without newline""",
+    ],
+)
+def test_parse_comments(program):
+    Program(program)