feat(phirgen): add support for ZERO/ONE nullary ops (#180)

Closes: #178

.pre-commit-config.yaml

@@ -25,7 +25,7 @@ repos:
         - black==23.10.1
 
   - repo: https://github.com/astral-sh/ruff-pre-commit
-    rev: v0.4.4
+    rev: v0.4.5
     hooks:
       - id: ruff
         args: [--fix, --exit-non-zero-on-fix]

pytket/phir/phirgen.py

@@ -99,9 +99,14 @@ def assign_cop(
     }
 
 
-def classical_op(exp: LogicExp, *, bitwise: bool = False) -> JsonDict:
+def classical_op(exp: LogicExp, *, bitwise: bool = False) -> JsonDict | int:
     """PHIR for classical register operations."""
     match exp.op:
+        # Nullary
+        case BitWiseOp.ZERO:
+            return 0
+        case BitWiseOp.ONE:
+            return 1
         # Bitwise
         case RegWiseOp.AND | BitWiseOp.AND:
             cop = "&"

pytket/phir/phirgen_parallel.py

@@ -62,7 +62,7 @@ def process_sub_commands(
     rz_group_number = -3  # set to 0 when first RZ gate is assigned (-3 + 3 = 0)
     r1xy_group_number = -2  # set to 1 when first R1XY gate is assigned (-2 + 3 = 1)
     other_group_number = -1  # set to 2 when first other gate is assigned (-1 + 3 = 2)
-    num_scs_per_qubit: dict["UnitID", int] = {}
+    num_scs_per_qubit: dict[UnitID, int] = {}
     group_exec_order: list[int] = []
 
     for qubit, cmds in sub_commands.items():
@@ -131,14 +131,14 @@ def process_sub_commands(
 def groups2qops(groups: dict[int, list[tk.Command]], ops: list["JsonDict"]) -> None:  # noqa: PLR0912
     """Convert the groups of parallel ops to properly formatted PHIR."""
     for group in groups.values():
-        angles2qops: dict[tuple[sympy.Expr | float, ...], "JsonDict"] = {}
+        angles2qops: dict[tuple[sympy.Expr | float, ...], JsonDict] = {}
         for qop in group:
             if not qop.op.is_gate():
                 append_cmd(qop, ops)
             else:
                 angles = qop.op.params
                 if tuple(angles) not in angles2qops:
-                    fmt_qop: "JsonDict" = {
+                    fmt_qop: JsonDict = {
                         "qop": tket_gate_to_phir[qop.op.type],
                         "angles": [angles, "pi"],
                     }
@@ -159,7 +159,7 @@ def groups2qops(groups: dict[int, list[tk.Command]], ops: list["JsonDict"]) -> N
         # this branch is skipped because non-gate sub-commands
         # are always the only member of their group (see process_sub_commands)
         if len(angles2qops) > 1:
-            pll_block: "JsonDict" = {"block": "qparallel", "ops": []}
+            pll_block: JsonDict = {"block": "qparallel", "ops": []}
             for phir_qop in angles2qops.values():
                 pll_block["ops"].append(phir_qop)
             comment = {"//": f"Parallel {tket_gate_to_phir[qop.op.type]}"}
@@ -256,7 +256,7 @@ def format_and_add_primary_commands(
                     append_cmd(shard.primary_command, ops)
             # for measure, format and include "returns"
             elif gate_type == "Measure":
-                fmt_measure: "JsonDict" = {
+                fmt_measure: JsonDict = {
                     "qop": "Measure",
                     "args": [],
                     "returns": [],
@@ -268,7 +268,7 @@ def format_and_add_primary_commands(
                 ops.append(fmt_measure)
             # all other gates, treat as standard qops
             else:
-                fmt_qop: "JsonDict" = {"qop": gate_type, "args": []}
+                fmt_qop: JsonDict = {"qop": gate_type, "args": []}
                 for shard in group:
                     pc = shard.primary_command
                     fmt_qop["args"].append(arg_to_bit(pc.args[0]))
@@ -325,7 +325,7 @@ def genphir_parallel(
 
     phir = PHIR_HEADER
     phir["metadata"]["strict_parallelism"] = True
-    ops: list["JsonDict"] = []
+    ops: list[JsonDict] = []
 
     qbits = set()
     cbits = set()

pytket/phir/sharding/shards2ops.py

@@ -25,7 +25,7 @@ def parse_shards_naive(
     scheduled: set[int] = set()
     num_shards: int = len(shards)
     qid_count: int = 0
-    qubits2ids: dict["UnitID", int] = {}
+    qubits2ids: dict[UnitID, int] = {}
 
     while len(scheduled) < num_shards:
         layer: Layer = []

requirements.txt

@@ -4,11 +4,11 @@ networkx==2.8.8
 phir==0.3.3
 pre-commit==3.7.1
 pydata_sphinx_theme==0.15.2
-pytest==8.2.0
+pytest==8.2.1
 pytest-order==1.2.1
-pytket==1.27.0
-ruff==0.4.4
+pytket==1.28.0
+ruff==0.4.5
 setuptools_scm==8.1.0
 sphinx==7.3.7
-wasmtime==20.0.0
+wasmtime==21.0.0
 wheel==0.43.0

tests/test_phirgen.py

@@ -11,6 +11,7 @@
 import json
 
 from pytket.circuit import Bit, Circuit
+from pytket.circuit.logic_exp import BitWiseOp, create_bit_logic_exp
 from pytket.phir.api import pytket_to_phir
 from pytket.qasm.qasm import circuit_from_qasm_str
 from pytket.unit_id import BitRegister
@@ -431,3 +432,33 @@ def test_irregular_multibit_ops() -> None:
             },
         ],
     }
+
+
+def test_nullary_ops() -> None:
+    """From https://github.com/CQCL/pytket-phir/issues/178 ."""
+    c = Circuit(1, 1)
+    exp1 = create_bit_logic_exp(BitWiseOp.ONE, [])
+    c.H(0, condition=exp1)
+    exp0 = create_bit_logic_exp(BitWiseOp.ZERO, [])
+    c.H(0, condition=exp0)
+    c.measure_all()
+    phir = json.loads(pytket_to_phir(c))
+
+    assert phir["ops"][4] == {
+        "cop": "=",
+        "returns": [["tk_SCRATCH_BIT", 0]],
+        "args": [1],
+    }
+    assert phir["ops"][6] == {
+        "cop": "=",
+        "returns": [["tk_SCRATCH_BIT", 1]],
+        "args": [0],
+    }
+    assert phir["ops"][8]["condition"] == {
+        "cop": "==",
+        "args": [["tk_SCRATCH_BIT", 0], 1],
+    }
+    assert phir["ops"][10]["condition"] == {
+        "cop": "==",
+        "args": [["tk_SCRATCH_BIT", 1], 1],  # evals to False
+    }