pass down foreach

bqskit/passes/control/foreach.py

@@ -38,6 +38,11 @@ class ForEachBlockPass(BasePass):
     pass_down_key_prefix = 'ForEachBlockPass_pass_down_'
     """If a key exists in the pass data with this prefix, pass it to blocks."""
 
+    pass_down_block_specific_key_prefix = (
+        'ForEachBlockPass_specific_pass_down_'
+    )
+    """Key for injecting a block specific pass data."""
+
     def __init__(
         self,
         loop_body: WorkflowLike,
@@ -197,6 +202,10 @@ async def run(self, circuit: Circuit, data: PassData) -> None:
             for key in data:
                 if key.startswith(self.pass_down_key_prefix):
                     block_data[key] = data[key]
+                elif key.startswith(
+                    self.pass_down_block_specific_key_prefix,
+                ) and i in data[key]:
+                    block_data[key] = data[key][i]
             block_data.seed = data.seed
 
             subcircuits.append(subcircuit)

tests/passes/control/test_foreachblock.py

@@ -5,15 +5,20 @@
 from bqskit.compiler.basepass import BasePass
 from bqskit.compiler.compiler import Compiler
 from bqskit.compiler.passdata import PassData
+from bqskit.compiler.workflow import Workflow
 from bqskit.ir.circuit import Circuit
 from bqskit.ir.gates import CircuitGate
+from bqskit.ir.gates import CNOTGate
 from bqskit.ir.gates import HGate
 from bqskit.ir.gates import XGate
 from bqskit.ir.gates import YGate
 from bqskit.ir.gates import ZGate
 from bqskit.ir.operation import Operation
 from bqskit.passes import UnfoldPass
 from bqskit.passes.control.foreach import ForEachBlockPass
+from bqskit.passes.partitioning.quick import QuickPartitioner
+from bqskit.passes.synthesis.qsearch import QSearchSynthesisPass
+from bqskit.passes.util.update import UpdateDataPass
 
 
 @pytest.fixture
@@ -130,3 +135,31 @@ def test_no_hang_on_empty_collection(compiler: Compiler) -> None:
     circuit.append_gate(XGate(), 0)
     feb_pass = ForEachBlockPass(RemoveXGatePass(), collection_filter=empty_coll)
     compiler.compile(circuit, feb_pass)
+
+
+def test_pass_down_seeds(compiler: Compiler) -> None:
+    circuit = Circuit(3)
+    circuit.append_gate(CNOTGate(), (0, 1))
+    circuit.append_gate(CNOTGate(), (1, 2))
+
+    seed = Circuit(3)
+    seed.append_gate(CNOTGate(), (0, 1))
+    seed.append_gate(CNOTGate(), (1, 2))
+
+    # Manually sed seed for block 0
+    seeds = {0: [seed]}
+
+    key = 'ForEachBlockPass_specific_pass_down_seed_circuits'
+
+    partitioner = QuickPartitioner()
+    updater = UpdateDataPass(key, seeds)
+    qsearch = QSearchSynthesisPass()
+    foreach = ForEachBlockPass(qsearch)
+    unfolder = UnfoldPass()
+    workflow = Workflow([partitioner, updater, foreach, unfolder])
+    compiled, data = compiler.compile(
+        circuit, workflow, request_data=True,
+    )
+    dist = compiled.get_unitary().get_distance_from(circuit.get_unitary())
+    assert dist <= 1e-5
+    assert key in data