[feature] add rzz qasm output support

pytket/pytket/qasm/qasm.py

@@ -144,9 +144,9 @@
     ),
 }
 included_gates["hqslib1"] = included_gates["qelib1"].copy()
-included_gates["hqslib1"].update(("U1q", "rz", "ZZ"))
+included_gates["hqslib1"].update(("U1q", "rz", "ZZ", "RZZ"))
 included_gates["hqslib1"].difference_update(
-    ("crx", "cry", "sx", "sxdg", "csx", "swap", "cswap")
+    ("crx", "cry", "sx", "sxdg", "csx", "swap", "cswap", "rzz")
 )
 _tk_to_qasm_noparams = dict(((item[1], item[0]) for item in NOPARAM_COMMANDS.items()))
 _tk_to_qasm_noparams[OpType.CX] = "cx"  # prefer "cx" to "CX"
@@ -580,7 +580,11 @@ def circuit_to_qasm_io(
                 f"{args[-1]} = {args[0]} {_classical_gatestr_map[opstr]} {args[1]};\n"
             )
             continue
-        if optype in _tk_to_qasm_noparams:
+        if header == "hqslib1" and optype == OpType.ZZPhase:
+            # special handling for zzphase
+            opstr = "RZZ"
+            params = op.params
+        elif optype in _tk_to_qasm_noparams:
             opstr = _tk_to_qasm_noparams[optype]
         elif optype in _tk_to_qasm_params:
             opstr = _tk_to_qasm_params[optype]

pytket/tests/qasm_test.py

@@ -343,6 +343,13 @@ def test_new_qelib1_aliases() -> None:
     assert "U3(0, 0, 0) q[0]" in commands_str
 
 
+def test_h1_rzz() -> None:
+    c = Circuit(2)
+    c.add_gate(OpType.ZZPhase, [0.1], [0, 1])
+    assert "rzz" in circuit_to_qasm_str(c, header="qelib1")
+    assert "RZZ" in circuit_to_qasm_str(c, header="hqslib1")
+
+
 if __name__ == "__main__":
     test_qasm_correct()
     test_qasm_qubit()