From 7ab21172779f4baadbfe070d8348e1debebc9fbe Mon Sep 17 00:00:00 2001
From: Kartik Singhal <kartik.singhal@quantinuum.com>
Date: Tue, 10 Sep 2024 15:58:09 -0500
Subject: [PATCH] fix: generate nested multi-bit conditions for pecos support

---
 pytket/phir/phirgen.py | 30 +++++++++++++++++++++---------
 requirements.txt       |  2 +-
 tests/test_phirgen.py  |  4 ++--
 3 files changed, 24 insertions(+), 12 deletions(-)

diff --git a/pytket/phir/phirgen.py b/pytket/phir/phirgen.py
index 5cfb4e0..1d6eca7 100644
--- a/pytket/phir/phirgen.py
+++ b/pytket/phir/phirgen.py
@@ -11,6 +11,7 @@
 import json
 import logging
 import sys
+from collections import deque
 from copy import deepcopy
 from importlib.metadata import version
 from typing import TYPE_CHECKING, Any, TypeAlias
@@ -356,15 +357,26 @@ def convert_classicalevalop(op: tk.ClassicalEvalOp, cmd: tk.Command) -> JsonDict
 
 def multi_bit_condition(args: "list[UnitID]", value: int) -> JsonDict:
     """Construct bitwise condition."""
-    return {
-        "cop": "&",
-        "args": [
-            {"cop": "==", "args": [arg_to_bit(arg), bval]}
-            for (arg, bval) in zip(
-                args[::-1], map(int, f"{value:0{len(args)}b}"), strict=True
-            )
-        ],
-    }
+    val_bits = deque(map(int, f"{value:0{len(args)}b}"))
+
+    def nested_cop(cop: str, args: "deque[UnitID]", val_bits: deque[int]) -> JsonDict:
+        if len(args) == 2:  # noqa: PLR2004
+            return {
+                "cop": cop,
+                "args": [
+                    {"cop": "==", "args": [arg_to_bit(args.popleft()), val_bits.pop()]},
+                    {"cop": "==", "args": [arg_to_bit(args.popleft()), val_bits.pop()]},
+                ],
+            }
+        return {
+            "cop": cop,
+            "args": [
+                {"cop": "==", "args": [arg_to_bit(args.popleft()), val_bits.pop()]},
+                nested_cop(cop, args, val_bits),
+            ],
+        }
+
+    return nested_cop("&", deque(args), val_bits)
 
 
 def convert_subcmd(op: tk.Op, cmd: tk.Command) -> JsonDict | None:  # noqa: PLR0912
diff --git a/requirements.txt b/requirements.txt
index 5d083f1..48fe235 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,7 +6,7 @@ pre-commit==3.8.0
 pydata_sphinx_theme==0.15.4
 pytest==8.3.3
 pytket==1.32.0
-quantum-pecos==v0.6.0.dev4
+quantum-pecos[simulators]==v0.6.0.dev4
 ruff==0.6.4
 setuptools_scm==8.1.0
 sphinx==8.0.2
diff --git a/tests/test_phirgen.py b/tests/test_phirgen.py
index 75d9d93..c7a33c2 100644
--- a/tests/test_phirgen.py
+++ b/tests/test_phirgen.py
@@ -96,8 +96,8 @@ def test_pytket_classical_only() -> None:
         "condition": {
             "cop": "&",
             "args": [
-                {"cop": "==", "args": [["b", 2], 1]},
                 {"cop": "==", "args": [["b", 1], 0]},
+                {"cop": "==", "args": [["b", 2], 1]},
             ],
         },
         "true_branch": [
@@ -179,8 +179,8 @@ def test_conditional_barrier() -> None:
         "condition": {
             "cop": "&",
             "args": [
-                {"cop": "==", "args": [["m", 1], 0]},
                 {"cop": "==", "args": [["m", 0], 0]},
+                {"cop": "==", "args": [["m", 1], 0]},
             ],
         },
         "true_branch": [{"meta": "barrier", "args": [["q", 0], ["q", 1]]}],