From cced76a7266723439554b46350bb28cc11264782 Mon Sep 17 00:00:00 2001
From: Agustin Borgna <agustin.borgna@quantinuum.com>
Date: Wed, 5 Jun 2024 17:40:24 +0100
Subject: [PATCH] feat: CircuitBuilder::add_constant

---
 hugr-core/src/builder.rs         |  4 +++-
 hugr-core/src/builder/circuit.rs | 22 +++++++++++++++++++---
 hugr-core/src/hugr.rs            |  2 +-
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/hugr-core/src/builder.rs b/hugr-core/src/builder.rs
index c186b57cd..787decc07 100644
--- a/hugr-core/src/builder.rs
+++ b/hugr-core/src/builder.rs
@@ -222,6 +222,7 @@ pub(crate) mod test {
 
     use crate::hugr::{views::HugrView, HugrMut, NodeType};
     use crate::ops;
+    use crate::std_extensions::arithmetic::float_ops::FLOAT_OPS_REGISTRY;
     use crate::types::{FunctionType, PolyFuncType, Type};
     use crate::{type_row, Hugr};
 
@@ -252,7 +253,8 @@ pub(crate) mod test {
         let f_builder = module_builder.define_function("main", signature)?;
 
         f(f_builder)?;
-        Ok(module_builder.finish_prelude_hugr()?)
+
+        Ok(module_builder.finish_hugr(&FLOAT_OPS_REGISTRY)?)
     }
 
     #[fixture]
diff --git a/hugr-core/src/builder/circuit.rs b/hugr-core/src/builder/circuit.rs
index d59098776..2fecff49d 100644
--- a/hugr-core/src/builder/circuit.rs
+++ b/hugr-core/src/builder/circuit.rs
@@ -3,7 +3,7 @@ use std::mem;
 
 use thiserror::Error;
 
-use crate::ops::{NamedOp, OpType};
+use crate::ops::{NamedOp, OpType, Value};
 use crate::utils::collect_array;
 
 use super::{BuildError, Dataflow};
@@ -199,6 +199,11 @@ impl<'a, T: Dataflow + ?Sized> CircuitBuilder<'a, T> {
         Ok(collect_array(outputs))
     }
 
+    /// Adds a constant value to the circuit and loads it into a wire.
+    pub fn add_constant(&mut self, value: impl Into<Value>) -> Wire {
+        self.builder.add_load_value(value)
+    }
+
     /// Add a wire to the list of tracked wires.
     ///
     /// Returns the new unit index.
@@ -237,7 +242,10 @@ mod test {
     use super::*;
     use cool_asserts::assert_matches;
 
-    use crate::utils::test_quantum_extension::{cx_gate, h_gate, measure, q_alloc, q_discard};
+    use crate::std_extensions::arithmetic::float_types::{self, ConstF64};
+    use crate::utils::test_quantum_extension::{
+        cx_gate, h_gate, measure, q_alloc, q_discard, rz_f64,
+    };
     use crate::{
         builder::{
             test::{build_main, NAT, QB},
@@ -252,7 +260,9 @@ mod test {
     #[test]
     fn simple_linear() {
         let build_res = build_main(
-            FunctionType::new(type_row![QB, QB], type_row![QB, QB]).into(),
+            FunctionType::new(type_row![QB, QB], type_row![QB, QB])
+                .with_extension_delta(float_types::EXTENSION_ID)
+                .into(),
             |mut f_build| {
                 let wires = f_build.input_wires().map(Some).collect();
 
@@ -268,6 +278,12 @@ mod test {
                     .append(cx_gate(), [0, 1])?
                     .append(cx_gate(), [1, 0])?;
 
+                let angle = linear.add_constant(ConstF64::new(0.5));
+                linear.append_and_consume(
+                    rz_f64(),
+                    [CircuitUnit::Linear(0), CircuitUnit::Wire(angle)],
+                )?;
+
                 let outs = linear.finish();
                 f_build.finish_with_outputs(outs)
             },
diff --git a/hugr-core/src/hugr.rs b/hugr-core/src/hugr.rs
index 875bd8ddc..d3e8f6959 100644
--- a/hugr-core/src/hugr.rs
+++ b/hugr-core/src/hugr.rs
@@ -201,7 +201,7 @@ impl Hugr {
     }
 
     /// Leaving this here as in the future we plan for it to infer deltas
-    /// of container nodes e.g. [DFG]. For the moment it does nothing.
+    /// of container nodes e.g. DFG. For the moment it does nothing.
     pub fn infer_extensions(&mut self) -> Result<(), ExtensionError> {
         Ok(())
     }