refactor!: unwrap BasicBlock enum (#781)

BREAKING_CHANGES: `BasicBlock::{DFB, Exit}` are now standalone structs
`DataflowBlock, ExitBlock`. A level of nesting in serialization is also
removed for these operations.

---------

Co-authored-by: Alan Lawrence <alan.lawrence@quantinuum.com>

src/builder/cfg.rs

@@ -5,7 +5,7 @@ use super::{
     BasicBlockID, BuildError, CfgID, Container, Dataflow, HugrBuilder, Wire,
 };
 
-use crate::ops::{self, BasicBlock, OpType};
+use crate::ops::{self, DataflowBlock, ExitBlock, OpType};
 use crate::{
     extension::{ExtensionRegistry, ExtensionSet},
     types::FunctionType,
@@ -86,7 +86,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         output: TypeRow,
     ) -> Result<Self, BuildError> {
         let n_out_wires = output.len();
-        let exit_block_type = OpType::BasicBlock(BasicBlock::Exit {
+        let exit_block_type = OpType::ExitBlock(ExitBlock {
             cfg_outputs: output,
         });
         let exit_node = base
@@ -102,7 +102,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         })
     }
 
-    /// Return a builder for a non-entry [`BasicBlock::DFB`] child graph with `inputs`
+    /// Return a builder for a non-entry [`DataflowBlock`] child graph with `inputs`
     /// and `outputs` and the variants of the branching TupleSum value
     /// specified by `tuple_sum_rows`.
     ///
@@ -134,7 +134,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         entry: bool,
     ) -> Result<BlockBuilder<&mut Hugr>, BuildError> {
         let tuple_sum_rows: Vec<_> = tuple_sum_rows.into_iter().collect();
-        let op = OpType::BasicBlock(BasicBlock::DFB {
+        let op = OpType::DataflowBlock(DataflowBlock {
             inputs: inputs.clone(),
             other_outputs: other_outputs.clone(),
             tuple_sum_rows: tuple_sum_rows.clone(),
@@ -159,7 +159,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         )
     }
 
-    /// Return a builder for a non-entry [`BasicBlock::DFB`] child graph with `inputs`
+    /// Return a builder for a non-entry [`DataflowBlock`] child graph with `inputs`
     /// and `outputs` and a UnitSum type: a Sum of `n_cases` unit types.
     ///
     /// # Errors
@@ -178,7 +178,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         )
     }
 
-    /// Return a builder for the entry [`BasicBlock::DFB`] child graph with `inputs`
+    /// Return a builder for the entry [`DataflowBlock`] child graph with `inputs`
     /// and `outputs` and the variants of the branching TupleSum value
     /// specified by `tuple_sum_rows`.
     ///
@@ -198,7 +198,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
         self.any_block_builder(inputs, tuple_sum_rows, other_outputs, extension_delta, true)
     }
 
-    /// Return a builder for the entry [`BasicBlock::DFB`] child graph with `inputs`
+    /// Return a builder for the entry [`DataflowBlock`] child graph with `inputs`
     /// and `outputs` and a UnitSum type: a Sum of `n_cases` unit types.
     ///
     /// # Errors
@@ -235,7 +235,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> CFGBuilder<B> {
     }
 }
 
-/// Builder for a [`BasicBlock::DFB`] child graph.
+/// Builder for a [`DataflowBlock`] child graph.
 pub type BlockBuilder<B> = DFGWrapper<B, BasicBlockID>;
 
 impl<B: AsMut<Hugr> + AsRef<Hugr>> BlockBuilder<B> {
@@ -248,6 +248,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> BlockBuilder<B> {
     ) -> Result<(), BuildError> {
         Dataflow::set_outputs(self, [branch_wire].into_iter().chain(outputs))
     }
+
     fn create(
         base: B,
         block_n: Node,
@@ -284,7 +285,7 @@ impl<B: AsMut<Hugr> + AsRef<Hugr>> BlockBuilder<B> {
 }
 
 impl BlockBuilder<Hugr> {
-    /// Initialize a [`BasicBlock::DFB`] rooted HUGR builder
+    /// Initialize a [`DataflowBlock`] rooted HUGR builder
     pub fn new(
         inputs: impl Into<TypeRow>,
         input_extensions: impl Into<Option<ExtensionSet>>,
@@ -295,7 +296,7 @@ impl BlockBuilder<Hugr> {
         let inputs = inputs.into();
         let tuple_sum_rows: Vec<_> = tuple_sum_rows.into_iter().collect();
         let other_outputs = other_outputs.into();
-        let op = BasicBlock::DFB {
+        let op = DataflowBlock {
             inputs: inputs.clone(),
             other_outputs: other_outputs.clone(),
             tuple_sum_rows: tuple_sum_rows.clone(),

src/extension/infer/test.rs

@@ -461,7 +461,7 @@ fn make_block(
     let tuple_sum_type = Type::new_tuple_sum(tuple_sum_rows.clone());
     let dfb_sig = FunctionType::new(inputs.clone(), vec![tuple_sum_type])
         .with_extension_delta(&extension_delta.clone());
-    let dfb = ops::BasicBlock::DFB {
+    let dfb = ops::DataflowBlock {
         inputs,
         other_outputs: type_row![],
         tuple_sum_rows,
@@ -496,7 +496,7 @@ fn create_entry_exit(
     exit_types: impl Into<TypeRow>,
 ) -> Result<([Node; 3], Node), Box<dyn Error>> {
     let entry_tuple_sum = Type::new_tuple_sum(entry_variants.clone());
-    let dfb = ops::BasicBlock::DFB {
+    let dfb = ops::DataflowBlock {
         inputs: inputs.clone(),
         other_outputs: type_row![],
         tuple_sum_rows: entry_variants,
@@ -505,7 +505,7 @@ fn create_entry_exit(
 
     let exit = hugr.add_node_with_parent(
         root,
-        ops::BasicBlock::Exit {
+        ops::ExitBlock {
             cfg_outputs: exit_types.into(),
         },
     )?;

src/hugr/rewrite/outline_cfg.rs

@@ -12,9 +12,10 @@ use crate::hugr::rewrite::Rewrite;
 use crate::hugr::views::sibling::SiblingMut;
 use crate::hugr::{HugrMut, HugrView};
 use crate::ops;
+use crate::ops::controlflow::BasicBlock;
 use crate::ops::dataflow::DataflowOpTrait;
 use crate::ops::handle::{BasicBlockID, CfgID, NodeHandle};
-use crate::ops::{BasicBlock, OpType};
+use crate::ops::{DataflowBlock, OpType};
 use crate::PortIndex;
 use crate::{type_row, Node};
 
@@ -114,12 +115,13 @@ impl Rewrite for OutlineCfg {
             self.compute_entry_exit_outside_extensions(h)?;
         // 1. Compute signature
         // These panic()s only happen if the Hugr would not have passed validate()
-        let OpType::BasicBlock(BasicBlock::DFB { inputs, .. }) = h.get_optype(entry) else {
+        let OpType::DataflowBlock(DataflowBlock { inputs, .. }) = h.get_optype(entry) else {
             panic!("Entry node is not a basic block")
         };
         let inputs = inputs.clone();
         let outputs = match h.get_optype(outside) {
-            OpType::BasicBlock(b) => b.dataflow_input().clone(),
+            OpType::DataflowBlock(dfb) => dfb.dataflow_input().clone(),
+            OpType::ExitBlock(exit) => exit.dataflow_input().clone(),
             _ => panic!("External successor not a basic block"),
         };
         let outer_cfg = h.get_parent(entry).unwrap();
@@ -265,7 +267,6 @@ mod test {
     use crate::hugr::views::sibling::SiblingMut;
     use crate::hugr::HugrMut;
     use crate::ops::handle::{BasicBlockID, CfgID, NodeHandle};
-    use crate::ops::{BasicBlock, OpType};
     use crate::types::FunctionType;
     use crate::{type_row, HugrView, Node};
     use cool_asserts::assert_matches;
@@ -348,12 +349,9 @@ mod test {
             h.output_neighbours(tail).take(2).collect::<HashSet<Node>>(),
             HashSet::from([exit, new_block])
         );
-        assert_matches!(
-            h.get_optype(new_block),
-            OpType::BasicBlock(BasicBlock::DFB { .. })
-        );
+        assert!(h.get_optype(new_block).is_dataflow_block());
         assert_eq!(h.base_hugr().get_parent(new_cfg), Some(new_block));
-        assert_matches!(h.base_hugr().get_optype(new_cfg), OpType::CFG(_));
+        assert!(h.base_hugr().get_optype(new_cfg).is_cfg());
     }
 
     #[test]
@@ -409,12 +407,9 @@ mod test {
             .unwrap();
         h.update_validate(&PRELUDE_REGISTRY).unwrap();
         assert_eq!(new_block, h.children(h.root()).next().unwrap());
-        assert_matches!(
-            h.get_optype(new_block),
-            OpType::BasicBlock(BasicBlock::DFB { .. })
-        );
+        assert!(h.get_optype(new_block).is_dataflow_block());
         assert_eq!(h.get_parent(new_cfg), Some(new_block));
-        assert_matches!(h.get_optype(new_cfg), OpType::CFG(_));
+        assert!(h.get_optype(new_cfg).is_cfg());
         for n in other_blocks {
             assert_eq!(depth(&h, n), 1);
         }

src/hugr/rewrite/replace.rs

@@ -449,7 +449,7 @@ mod test {
     use crate::ops::custom::{ExternalOp, OpaqueOp};
     use crate::ops::dataflow::DataflowOpTrait;
     use crate::ops::handle::{BasicBlockID, ConstID, NodeHandle};
-    use crate::ops::{self, BasicBlock, Case, LeafOp, OpTag, OpType, DFG};
+    use crate::ops::{self, Case, DataflowBlock, LeafOp, OpTag, OpType, DFG};
     use crate::std_extensions::collections;
     use crate::types::{FunctionType, Type, TypeArg, TypeRow};
     use crate::{type_row, Direction, Hugr, HugrView, OutgoingPort};
@@ -504,14 +504,8 @@ mod test {
             let popp = h.get_parent(pop).unwrap();
             let pushp = h.get_parent(push).unwrap();
             assert_ne!(popp, pushp); // Two different BBs
-            assert!(matches!(
-                h.get_optype(popp),
-                OpType::BasicBlock(BasicBlock::DFB { .. })
-            ));
-            assert!(matches!(
-                h.get_optype(pushp),
-                OpType::BasicBlock(BasicBlock::DFB { .. })
-            ));
+            assert!(h.get_optype(popp).is_dataflow_block());
+            assert!(h.get_optype(pushp).is_dataflow_block());
 
             assert_eq!(h.get_parent(popp).unwrap(), h.get_parent(pushp).unwrap());
         }
@@ -523,7 +517,7 @@ mod test {
         }));
         let r_bb = replacement.add_node_with_parent(
             replacement.root(),
-            BasicBlock::DFB {
+            DataflowBlock {
                 inputs: vec![listy.clone()].into(),
                 tuple_sum_rows: vec![type_row![]],
                 other_outputs: vec![listy.clone()].into(),
@@ -596,10 +590,7 @@ mod test {
 
             let grandp = h.get_parent(popp).unwrap();
             assert_eq!(grandp, h.get_parent(pushp).unwrap());
-            assert!(matches!(
-                h.get_optype(grandp),
-                OpType::BasicBlock(BasicBlock::DFB { .. })
-            ));
+            assert!(h.get_optype(grandp).is_dataflow_block());
         }
 
         Ok(())

src/hugr/validate/test.rs

@@ -289,7 +289,7 @@ fn cfg_children_restrictions() {
     let block = b
         .add_node_with_parent(
             cfg,
-            ops::BasicBlock::DFB {
+            ops::DataflowBlock {
                 inputs: type_row![BOOL_T],
                 tuple_sum_rows: vec![type_row![]],
                 other_outputs: type_row![BOOL_T],
@@ -301,7 +301,7 @@ fn cfg_children_restrictions() {
     let exit = b
         .add_node_with_parent(
             cfg,
-            ops::BasicBlock::Exit {
+            ops::ExitBlock {
                 cfg_outputs: type_row![BOOL_T],
             },
         )
@@ -315,7 +315,7 @@ fn cfg_children_restrictions() {
     let exit2 = b
         .add_node_after(
             exit,
-            ops::BasicBlock::Exit {
+            ops::ExitBlock {
                 cfg_outputs: type_row![BOOL_T],
             },
         )
@@ -330,7 +330,7 @@ fn cfg_children_restrictions() {
     // Change the types in the BasicBlock node to work on qubits instead of bits
     b.replace_op(
         block,
-        NodeType::new_pure(ops::BasicBlock::DFB {
+        NodeType::new_pure(ops::DataflowBlock {
             inputs: type_row![Q],
             tuple_sum_rows: vec![type_row![]],
             other_outputs: type_row![Q],

src/hugr/views/root_checked.rs

@@ -74,7 +74,7 @@ mod test {
     use crate::hugr::hugrmut::sealed::HugrMutInternals;
     use crate::hugr::{HugrError, HugrMut, NodeType};
     use crate::ops::handle::{BasicBlockID, CfgID, DataflowParentID, DfgID};
-    use crate::ops::{BasicBlock, LeafOp, OpTag};
+    use crate::ops::{DataflowBlock, LeafOp, OpTag};
     use crate::{ops, type_row, types::FunctionType, Hugr, HugrView};
 
     #[test]
@@ -94,7 +94,7 @@ mod test {
         let mut dfg_v = RootChecked::<&mut Hugr, DfgID>::try_new(&mut h).unwrap();
         // That is a HugrMutInternal, so we can try:
         let root = dfg_v.root();
-        let bb = NodeType::new_pure(BasicBlock::DFB {
+        let bb = NodeType::new_pure(DataflowBlock {
             inputs: type_row![],
             other_outputs: type_row![],
             tuple_sum_rows: vec![type_row![]],

src/ops.rs

@@ -21,7 +21,7 @@ use smol_str::SmolStr;
 use enum_dispatch::enum_dispatch;
 
 pub use constant::Const;
-pub use controlflow::{BasicBlock, Case, Conditional, TailLoop, CFG};
+pub use controlflow::{Case, Conditional, DataflowBlock, ExitBlock, TailLoop, CFG};
 pub use dataflow::{Call, CallIndirect, Input, LoadConstant, Output, DFG};
 pub use leaf::LeafOp;
 pub use module::{AliasDecl, AliasDefn, FuncDecl, FuncDefn, Module};
@@ -48,7 +48,8 @@ pub enum OpType {
     LoadConstant,
     DFG,
     LeafOp,
-    BasicBlock,
+    DataflowBlock,
+    ExitBlock,
     TailLoop,
     CFG,
     Conditional,
@@ -93,7 +94,8 @@ impl_op_ref_try_into!(CallIndirect);
 impl_op_ref_try_into!(LoadConstant);
 impl_op_ref_try_into!(DFG, dfg);
 impl_op_ref_try_into!(LeafOp);
-impl_op_ref_try_into!(BasicBlock);
+impl_op_ref_try_into!(DataflowBlock);
+impl_op_ref_try_into!(ExitBlock);
 impl_op_ref_try_into!(TailLoop);
 impl_op_ref_try_into!(CFG, cfg);
 impl_op_ref_try_into!(Conditional);