Fix QASM lexer when identifiers start with keywords (quantumlib#7018)

* Fix QASM lexer when identifiers start with keywords

* improve test

* Change use of `reserved` to be more standard

* more tests

* rollback mypy change

* reorder tests, remove redundant pi test

* mypy

* mypy

* dedupe test

cirq-core/cirq/contrib/acquaintance/gates.py

@@ -316,10 +316,12 @@ def _decompose_(self, qubits: Sequence['cirq.Qid']) -> Iterator['cirq.OP_TREE']:
                 parts_qubits = list(left_part + right_part)
                 parts[i] = parts_qubits[: len(right_part)]
                 parts[i + 1] = parts_qubits[len(right_part) :]
-            layers.prior_interstitial.sort(key=op_sort_key)  # type: ignore[arg-type]
+            if op_sort_key is not None:
+                layers.prior_interstitial.sort(key=op_sort_key)
             for l in ('prior_interstitial', 'pre', 'intra', 'post'):
                 yield getattr(layers, l)
-        layers.posterior_interstitial.sort(key=op_sort_key)  # type: ignore[arg-type]
+        if op_sort_key is not None:
+            layers.posterior_interstitial.sort(key=op_sort_key)
         yield layers.posterior_interstitial
 
         assert list(

cirq-core/cirq/contrib/qasm_import/_lexer.py

@@ -14,7 +14,6 @@
 
 import re
 from typing import Optional
-import numpy as np
 import ply.lex as lex
 
 from cirq.contrib.qasm_import.exception import QasmException
@@ -35,8 +34,7 @@ def __init__(self):
         'reset': 'RESET',
         'gate': 'GATE',
         'if': 'IF',
-        '->': 'ARROW',
-        '==': 'EQ',
+        'pi': 'PI',
     }
 
     tokens = [
@@ -46,7 +44,8 @@ def __init__(self):
         'STDGATESINC',
         'QELIBINC',
         'ID',
-        'PI',
+        'ARROW',
+        'EQ',
     ] + list(reserved.values())
 
     def t_newline(self, t):
@@ -55,11 +54,6 @@ def t_newline(self, t):
 
     t_ignore = ' \t'
 
-    def t_PI(self, t):
-        r"""pi"""
-        t.value = np.pi
-        return t
-
     # all numbers except NATURAL_NUMBERs:
     # it's useful to have this separation to be able to handle indices
     # separately. In case of the parameter expressions, we are "OR"-ing
@@ -97,38 +91,6 @@ def t_STDGATESINC(self, t):
         r"""include(\s+)"stdgates.inc";"""
         return t
 
-    def t_QREG(self, t):
-        r"""qreg"""
-        return t
-
-    def t_QUBIT(self, t):
-        r"""qubit"""
-        return t
-
-    def t_CREG(self, t):
-        r"""creg"""
-        return t
-
-    def t_BIT(self, t):
-        r"""bit"""
-        return t
-
-    def t_MEASURE(self, t):
-        r"""measure"""
-        return t
-
-    def t_RESET(self, t):
-        r"""reset"""
-        return t
-
-    def t_GATE(self, t):
-        r"""gate"""
-        return t
-
-    def t_IF(self, t):
-        r"""if"""
-        return t
-
     def t_ARROW(self, t):
         """->"""
         return t
@@ -139,6 +101,8 @@ def t_EQ(self, t):
 
     def t_ID(self, t):
         r"""[a-zA-Z][a-zA-Z\d_]*"""
+        if t.value in QasmLexer.reserved:
+            t.type = QasmLexer.reserved[t.value]
         return t
 
     def t_COMMENT(self, t):

cirq-core/cirq/contrib/qasm_import/_lexer_test.py

@@ -13,7 +13,6 @@
 # limitations under the License.
 
 import pytest
-import numpy as np
 from cirq.contrib.qasm_import import QasmException
 from cirq.contrib.qasm_import._lexer import QasmLexer
 
@@ -103,12 +102,28 @@ def test_numbers(number: str):
     assert token.value == float(number)
 
 
-def test_pi():
+@pytest.mark.parametrize('token', QasmLexer.reserved.keys())
+def test_keywords(token):
     lexer = QasmLexer()
-    lexer.input('pi')
-    token = lexer.token()
-    assert token.type == "PI"
-    assert token.value == np.pi
+    identifier = f'{token} {token}'
+    lexer.input(identifier)
+    t = lexer.token()
+    assert t.type == QasmLexer.reserved[token]
+    assert t.value == token
+    t2 = lexer.token()
+    assert t2.type == QasmLexer.reserved[token]
+    assert t2.value == token
+
+
+@pytest.mark.parametrize('token', QasmLexer.reserved.keys())
+@pytest.mark.parametrize('separator', ['', '_'])
+def test_identifier_starts_or_ends_with_keyword(token, separator):
+    lexer = QasmLexer()
+    identifier = f'{token}{separator}{token}'
+    lexer.input(identifier)
+    t = lexer.token()
+    assert t.type == "ID"
+    assert t.value == identifier
 
 
 def test_qreg():

cirq-core/cirq/contrib/qasm_import/_parser.py

@@ -510,10 +510,13 @@ def p_expr_binary(self, p):
 
     def p_term(self, p):
         """term : NUMBER
-        | NATURAL_NUMBER
-        | PI"""
+        | NATURAL_NUMBER"""
         p[0] = p[1]
 
+    def p_pi(self, p):
+        """term : PI"""
+        p[0] = np.pi
+
     # qargs : qarg ',' qargs
     #      | qarg ';'
 

cirq-core/cirq/contrib/qasm_import/_parser_test.py

@@ -1499,3 +1499,22 @@ def _test_parse_exception(qasm: str, cirq_err: str, qiskit_err: str | None):
             "Skipped _test_qiskit_parse_exception because "
             "qiskit isn't installed to verify against."
         )
+
+
+def test_nested_custom_gate_has_keyword_in_name():
+    qasm = """OPENQASM 2.0;
+     include "qelib1.inc";
+     qreg q[1];
+     gate gateGate qb { x qb; }
+     gate qregGate qa { gateGate qa; }
+     qregGate q;
+    """
+    qb = cirq.NamedQubit('qb')
+    inner = cirq.FrozenCircuit(cirq.X(qb))
+    qa = cirq.NamedQubit('qa')
+    middle = cirq.FrozenCircuit(cirq.CircuitOperation(inner, qubit_map={qb: qa}))
+    q_0 = cirq.NamedQubit('q_0')
+    expected = cirq.Circuit(cirq.CircuitOperation(middle, qubit_map={qa: q_0}))
+    parser = QasmParser()
+    parsed_qasm = parser.parse(qasm)
+    assert parsed_qasm.circuit == expected

cirq-web/cirq_web/circuits/circuit.py

@@ -57,7 +57,9 @@ def get_client_code(self) -> str:
             <button id="camera-reset">Reset Camera</button>
             <button id="camera-toggle">Toggle Camera Type</button>
             <script>
-            let viz_{stripped_id} = createGridCircuit({self.serialized_circuit}, {moments}, "{self.id}", {self.padding_factor});
+            let viz_{stripped_id} = createGridCircuit(
+                {self.serialized_circuit}, {moments}, "{self.id}", {self.padding_factor}
+            );
 
             document.getElementById("camera-reset").addEventListener('click', ()  => {{
             viz_{stripped_id}.scene.setCameraAndControls(viz_{stripped_id}.circuit);

cirq-web/cirq_web/circuits/circuit_test.py

@@ -51,7 +51,9 @@ def test_circuit_client_code(qubit):
         <button id="camera-reset">Reset Camera</button>
         <button id="camera-toggle">Toggle Camera Type</button>
         <script>
-        let viz_{stripped_id} = createGridCircuit({str(circuit_obj)}, {str(moments)}, "{circuit.id}", {circuit.padding_factor});
+        let viz_{stripped_id} = createGridCircuit(
+            {str(circuit_obj)}, {str(moments)}, "{circuit.id}", {circuit.padding_factor}
+        );
 
         document.getElementById("camera-reset").addEventListener('click', ()  => {{
         viz_{stripped_id}.scene.setCameraAndControls(viz_{stripped_id}.circuit);