Disallow tags_to_ignore in tag_transformers

Author: babacry

cirq-core/cirq/transformers/tag_transformers.py

@@ -26,7 +26,7 @@ def index_tags(
     circuit: 'cirq.AbstractCircuit',
     *,
     context: Optional['cirq.TransformerContext'] = None,
-    target_tags: Optional[set[Hashable]] = None,
+    target_tags: set[Hashable],
 ) -> 'cirq.Circuit':
     """Indexes tags in target_tags as tag_0, tag_1, ... per tag.
 
@@ -38,7 +38,10 @@ def index_tags(
     Returns:
         Copy of the transformed input circuit.
     """
-    target_tags = target_tags or set()
+    if context and context.tags_to_ignore:
+        raise ValueError("index_tags doesn't support tags_to_ignore, use function args instead.")
+    if not target_tags:
+        return circuit
     tag_iter_by_tags = {tag: itertools.count(start=0, step=1) for tag in target_tags}
 
     def _map_func(op: 'cirq.Operation', _) -> 'cirq.OP_TREE':
@@ -51,10 +54,7 @@ def _map_func(op: 'cirq.Operation', _) -> 'cirq.OP_TREE':
         return op.untagged.with_tags(*tag_set)
 
     return transformer_primitives.map_operations(
-        circuit,
-        _map_func,
-        deep=context.deep if context else False,
-        tags_to_ignore=context.tags_to_ignore if context else [],
+        circuit, _map_func, deep=context.deep if context else False
     ).unfreeze(copy=False)
 
 
@@ -68,8 +68,6 @@ def remove_tags(
 ) -> 'cirq.Circuit':
     """Removes tags from the operations based on the input args.
 
-    Note: context.tags_to_ignore has higher priority than target_tags and remove_if.
-
     Args:
         circuit: Input circuit to apply the transformations on. The input circuit is not mutated.
         context: `cirq.TransformerContext` storing common configurable options for transformers.
@@ -80,6 +78,8 @@ def remove_tags(
     Returns:
         Copy of the transformed input circuit.
     """
+    if context and context.tags_to_ignore:
+        raise ValueError("remove_tags doesn't support tags_to_ignore, use function args instead.")
     target_tags = target_tags or set()
 
     def _map_func(op: 'cirq.Operation', _) -> 'cirq.OP_TREE':
@@ -91,8 +91,5 @@ def _map_func(op: 'cirq.Operation', _) -> 'cirq.OP_TREE':
         return op.untagged.with_tags(*remaing_tags)
 
     return transformer_primitives.map_operations(
-        circuit,
-        _map_func,
-        deep=context.deep if context else False,
-        tags_to_ignore=context.tags_to_ignore if context else [],
+        circuit, _map_func, deep=context.deep if context else False
     ).unfreeze(copy=False)

cirq-core/cirq/transformers/tag_transformers_test.py

@@ -12,6 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pytest
+
 import cirq
 
 
@@ -38,6 +40,18 @@ def test_index_tags():
     )
 
 
+def test_index_tags_empty_target_tags():
+    q0, q1 = cirq.LineQubit.range(2)
+    input_circuit = cirq.Circuit(
+        cirq.X(q0).with_tags("tag1", "tag2"),
+        cirq.Y(q1).with_tags("tag1"),
+        cirq.CZ(q0, q1).with_tags("tag2"),
+    )
+    check_same_circuit_with_same_tag_sets(
+        cirq.index_tags(input_circuit, target_tags={}), input_circuit
+    )
+
+
 def test_remove_tags():
     q0, q1 = cirq.LineQubit.range(2)
     input_circuit = cirq.Circuit(
@@ -67,21 +81,21 @@ def test_remove_tags_via_remove_if():
     )
 
 
+def test_index_tags_with_tags_to_ignore():
+    with pytest.raises(
+        ValueError, match="index_tags doesn't support tags_to_ignore, use function args instead."
+    ):
+        cirq.index_tags(
+            circuit=cirq.Circuit(),
+            target_tags={"tag0"},
+            context=cirq.TransformerContext(tags_to_ignore=["tag0"]),
+        )
+
+
 def test_remove_tags_with_tags_to_ignore():
-    q0, q1 = cirq.LineQubit.range(2)
-    input_circuit = cirq.Circuit(
-        cirq.X(q0).with_tags("tag1", "tag0"),
-        cirq.Y(q1).with_tags("not_tag1"),
-        cirq.CZ(q0, q1).with_tags("tag2"),
-    )
-    expected_circuit = cirq.Circuit(
-        cirq.X(q0).with_tags("tag1", "tag0"), cirq.Y(q1).with_tags("not_tag1"), cirq.CZ(q0, q1)
-    )
-    check_same_circuit_with_same_tag_sets(
+    with pytest.raises(
+        ValueError, match="remove_tags doesn't support tags_to_ignore, use function args instead."
+    ):
         cirq.remove_tags(
-            input_circuit,
-            remove_if=lambda tag: tag.startswith("tag"),
-            context=cirq.TransformerContext(tags_to_ignore=["tag0"]),
-        ),
-        expected_circuit,
-    )
+            circuit=cirq.Circuit(), context=cirq.TransformerContext(tags_to_ignore=["tag0"])
+        )