feat: Add lazify-measure pass (#482)

Co-authored-by: Alec Edgington <54802828+cqc-alec@users.noreply.github.com>
Co-authored-by: Mark Koch <48097969+mark-koch@users.noreply.github.com>

Author: 3 people

.github/change-filters.yml

@@ -8,6 +8,7 @@ rust-core: &rust-core
 
 rust:
   - *rust-core
+  - "tket2-hseries/**"
   - "badger-optimiser/**"
   - "compile-rewriter/**"
 

tket2-hseries/src/extension.rs

@@ -1,3 +1,3 @@
 //! This module defines the Hugr extensions used by tket2-hseries.
-
 pub mod futures;
+pub mod quantum_lazy;

tket2-hseries/src/extension/quantum_lazy.rs

@@ -0,0 +1,161 @@
+//! This module defines the Hugr extension used to represent Lazy Quantum
+//! Operations.
+//!
+//! Lazyness is represented by returning `tket2.futures.Future` classical
+//! values. Qubits are never lazy.
+use hugr::{
+    builder::{BuildError, Dataflow},
+    extension::{
+        prelude::{BOOL_T, QB_T},
+        simple_op::{try_from_name, MakeExtensionOp, MakeOpDef, MakeRegisteredOp},
+        ExtensionId, ExtensionRegistry, OpDef, SignatureFunc, PRELUDE,
+    },
+    ops::{CustomOp, OpType},
+    types::FunctionType,
+    Extension, Wire,
+};
+
+use lazy_static::lazy_static;
+use strum_macros::{EnumIter, EnumString, IntoStaticStr};
+
+use crate::extension::futures;
+
+use super::futures::future_type;
+
+/// The "tket2.quantum.lazy" extension id.
+pub const EXTENSION_ID: ExtensionId = ExtensionId::new_unchecked("tket2.quantum.lazy");
+
+lazy_static! {
+    /// The "tket2.quantum.lazy" extension.
+    pub static ref EXTENSION: Extension = {
+        let mut ext = Extension::new(EXTENSION_ID);
+        LazyQuantumOp::load_all_ops(&mut ext).unwrap();
+        ext
+    };
+
+    /// Extension registry including the "tket2.quantum.lazy" extension and
+    /// dependencies.
+    pub static ref REGISTRY: ExtensionRegistry = ExtensionRegistry::try_new([
+        futures::EXTENSION.to_owned(),
+        PRELUDE.to_owned(),
+        EXTENSION.to_owned()
+    ]).unwrap();
+}
+
+#[derive(
+    Clone,
+    Copy,
+    Debug,
+    serde::Serialize,
+    serde::Deserialize,
+    Hash,
+    PartialEq,
+    Eq,
+    PartialOrd,
+    Ord,
+    EnumIter,
+    IntoStaticStr,
+    EnumString,
+)]
+#[allow(missing_docs)]
+#[non_exhaustive]
+pub enum LazyQuantumOp {
+    Measure,
+}
+
+impl MakeOpDef for LazyQuantumOp {
+    fn signature(&self) -> SignatureFunc {
+        match self {
+            Self::Measure => FunctionType::new(QB_T, vec![QB_T, future_type(BOOL_T)]).into(),
+        }
+    }
+
+    fn from_def(op_def: &OpDef) -> Result<Self, hugr::extension::simple_op::OpLoadError> {
+        try_from_name(op_def.name(), &EXTENSION_ID)
+    }
+
+    fn extension(&self) -> ExtensionId {
+        EXTENSION_ID
+    }
+}
+
+impl MakeRegisteredOp for LazyQuantumOp {
+    fn extension_id(&self) -> ExtensionId {
+        EXTENSION_ID
+    }
+
+    fn registry<'s, 'r: 's>(&'s self) -> &'r ExtensionRegistry {
+        &REGISTRY
+    }
+}
+
+impl TryFrom<&OpType> for LazyQuantumOp {
+    type Error = ();
+    fn try_from(value: &OpType) -> Result<Self, Self::Error> {
+        let Some(custom_op) = value.as_custom_op() else {
+            Err(())?
+        };
+        match custom_op {
+            CustomOp::Extension(ext) => Self::from_extension_op(ext).ok(),
+            CustomOp::Opaque(opaque) => try_from_name(opaque.name(), &EXTENSION_ID).ok(),
+        }
+        .ok_or(())
+    }
+}
+
+/// An extension trait for [Dataflow] providing methods to add
+/// "tket2.quantum.lazy" operations.
+pub trait LazyQuantumOpBuilder: Dataflow {
+    /// Add a "tket2.quantum.lazy.Measure" op.
+    fn add_lazy_measure(&mut self, qb: Wire) -> Result<[Wire; 2], BuildError> {
+        Ok(self
+            .add_dataflow_op(LazyQuantumOp::Measure, [qb])?
+            .outputs_arr())
+    }
+}
+
+impl<D: Dataflow> LazyQuantumOpBuilder for D {}
+
+#[cfg(test)]
+mod test {
+    use std::sync::Arc;
+
+    use cool_asserts::assert_matches;
+    use futures::FutureOpBuilder as _;
+    use hugr::{
+        builder::{DataflowHugr, FunctionBuilder},
+        ops::NamedOp,
+    };
+    use strum::IntoEnumIterator as _;
+
+    use super::*;
+
+    fn get_opdef(op: impl NamedOp) -> Option<&'static Arc<OpDef>> {
+        EXTENSION.get_op(&op.name())
+    }
+
+    #[test]
+    fn create_extension() {
+        assert_eq!(EXTENSION.name(), &EXTENSION_ID);
+
+        for o in LazyQuantumOp::iter() {
+            assert_eq!(LazyQuantumOp::from_def(get_opdef(o).unwrap()), Ok(o));
+        }
+    }
+
+    #[test]
+    fn circuit() {
+        let hugr = {
+            let mut func_builder =
+                FunctionBuilder::new("circuit", FunctionType::new(QB_T, vec![QB_T, BOOL_T]))
+                    .unwrap();
+            let [qb] = func_builder.input_wires_arr();
+            let [qb, lazy_b] = func_builder.add_lazy_measure(qb).unwrap();
+            let [b] = func_builder.add_read(lazy_b, BOOL_T).unwrap();
+            func_builder
+                .finish_hugr_with_outputs([qb, b], &REGISTRY)
+                .unwrap()
+        };
+        assert_matches!(hugr.validate(&REGISTRY), Ok(_));
+    }
+}