feat: add angle type to tket2 extension

moved from hugr

tket2/src/extension.rs

@@ -19,6 +19,9 @@ use hugr::{type_row, Extension};
 use lazy_static::lazy_static;
 use smol_str::SmolStr;
 
+/// Definition for Angle ops and types.
+pub mod angle;
+
 /// The ID of the TKET1 extension.
 pub const TKET1_EXTENSION_ID: ExtensionId = IdentList::new_unchecked("TKET1");
 
@@ -163,6 +166,7 @@ pub static ref TKET2_EXTENSION: Extension = {
     )
     .unwrap();
 
+    angle::add_to_extension(&mut e);
     e
 };
 }

tket2/src/extension/angle.rs

@@ -0,0 +1,281 @@
+use std::{cmp::max, num::NonZeroU64};
+
+use hugr::{
+    extension::{prelude::ERROR_TYPE, SignatureError},
+    types::{
+        type_param::{TypeArgError, TypeParam},
+        ConstTypeError, CustomCheckFailure, CustomType, FunctionType, Type, TypeArg, TypeBound,
+    },
+    values::CustomConst,
+    Extension,
+};
+use itertools::Itertools;
+use smol_str::SmolStr;
+use std::f64::consts::TAU;
+
+use super::TKET2_EXTENSION_ID;
+
+/// Identifier for the angle type.
+const ANGLE_TYPE_ID: SmolStr = SmolStr::new_inline("angle");
+
+fn angle_custom_type(log_denom_arg: TypeArg) -> CustomType {
+    CustomType::new(
+        ANGLE_TYPE_ID,
+        [log_denom_arg],
+        TKET2_EXTENSION_ID,
+        TypeBound::Eq,
+    )
+}
+
+/// Angle type with a given log-denominator (specified by the TypeArg).
+///
+/// This type is capable of representing angles that are multiples of 2π / 2^N where N is the
+/// log-denominator.
+pub(super) fn angle_type(log_denom_arg: TypeArg) -> Type {
+    Type::new_extension(angle_custom_type(log_denom_arg))
+}
+
+/// The largest permitted log-denominator.
+pub const LOG_DENOM_MAX: u8 = 53;
+
+const fn is_valid_log_denom(n: u8) -> bool {
+    n <= LOG_DENOM_MAX
+}
+
+/// Type parameter for the log-denominator of an angle.
+pub const LOG_DENOM_TYPE_PARAM: TypeParam =
+    TypeParam::bounded_nat(NonZeroU64::MIN.saturating_add(LOG_DENOM_MAX as u64));
+
+/// Get the log-denominator of the specified type argument or error if the argument is invalid.
+pub(super) fn get_log_denom(arg: &TypeArg) -> Result<u8, TypeArgError> {
+    match arg {
+        TypeArg::BoundedNat { n } if is_valid_log_denom(*n as u8) => Ok(*n as u8),
+        _ => Err(TypeArgError::TypeMismatch {
+            arg: arg.clone(),
+            param: LOG_DENOM_TYPE_PARAM,
+        }),
+    }
+}
+
+pub(super) const fn type_arg(log_denom: u8) -> TypeArg {
+    TypeArg::BoundedNat {
+        n: log_denom as u64,
+    }
+}
+
+/// An angle
+#[derive(Clone, Debug, Eq, PartialEq, serde::Serialize, serde::Deserialize)]
+pub struct ConstAngle {
+    log_denom: u8,
+    value: u64,
+}
+
+impl ConstAngle {
+    /// Create a new [`ConstAngle`] from a log-denominator and a numerator
+    pub fn new(log_denom: u8, value: u64) -> Result<Self, ConstTypeError> {
+        if !is_valid_log_denom(log_denom) {
+            return Err(ConstTypeError::CustomCheckFail(
+                hugr::types::CustomCheckFailure::Message(
+                    "Invalid angle log-denominator.".to_owned(),
+                ),
+            ));
+        }
+        if value >= (1u64 << log_denom) {
+            return Err(ConstTypeError::CustomCheckFail(
+                hugr::types::CustomCheckFailure::Message(
+                    "Invalid unsigned integer value.".to_owned(),
+                ),
+            ));
+        }
+        Ok(Self { log_denom, value })
+    }
+
+    /// Create a new [`ConstAngle`] from a log-denominator and a floating-point value in radians,
+    /// rounding to the nearest corresponding value. (Ties round away from zero.)
+    pub fn from_radians_rounding(log_denom: u8, theta: f64) -> Result<Self, ConstTypeError> {
+        if !is_valid_log_denom(log_denom) {
+            return Err(ConstTypeError::CustomCheckFail(
+                hugr::types::CustomCheckFailure::Message(
+                    "Invalid angle log-denominator.".to_owned(),
+                ),
+            ));
+        }
+        let a = (((1u64 << log_denom) as f64) * theta / TAU).round() as i64;
+        Ok(Self {
+            log_denom,
+            value: a.rem_euclid(1i64 << log_denom) as u64,
+        })
+    }
+
+    /// Returns the value of the constant
+    pub fn value(&self) -> u64 {
+        self.value
+    }
+
+    /// Returns the log-denominator of the constant
+    pub fn log_denom(&self) -> u8 {
+        self.log_denom
+    }
+}
+
+#[typetag::serde]
+impl CustomConst for ConstAngle {
+    fn name(&self) -> SmolStr {
+        format!("a(2π*{}/2^{})", self.value, self.log_denom).into()
+    }
+    fn check_custom_type(&self, typ: &CustomType) -> Result<(), CustomCheckFailure> {
+        if typ.clone() == angle_custom_type(type_arg(self.log_denom)) {
+            Ok(())
+        } else {
+            Err(CustomCheckFailure::Message(
+                "Angle constant type mismatch.".into(),
+            ))
+        }
+    }
+    fn equal_consts(&self, other: &dyn CustomConst) -> bool {
+        hugr::values::downcast_equal_consts(self, other)
+    }
+}
+/// Collect a vector into an array.
+fn collect_array<const N: usize, T: std::fmt::Debug>(arr: &[T]) -> [&T; N] {
+    arr.iter().collect_vec().try_into().unwrap()
+}
+
+fn atrunc_sig(arg_values: &[TypeArg]) -> Result<FunctionType, SignatureError> {
+    let [arg0, arg1] = collect_array(arg_values);
+    let m: u8 = get_log_denom(arg0)?;
+    let n: u8 = get_log_denom(arg1)?;
+    if m < n {
+        return Err(SignatureError::InvalidTypeArgs);
+    }
+    Ok(FunctionType::new(
+        vec![angle_type(arg0.clone())],
+        vec![angle_type(arg1.clone())],
+    ))
+}
+
+fn aconvert_sig(arg_values: &[TypeArg]) -> Result<FunctionType, SignatureError> {
+    let [arg0, arg1] = collect_array(arg_values);
+    Ok(FunctionType::new(
+        vec![angle_type(arg0.clone())],
+        vec![Type::new_sum(vec![angle_type(arg1.clone()), ERROR_TYPE])],
+    ))
+}
+
+fn abinop_sig(arg_values: &[TypeArg]) -> Result<FunctionType, SignatureError> {
+    let [arg0, arg1] = collect_array(arg_values);
+    let m: u8 = get_log_denom(arg0)?;
+    let n: u8 = get_log_denom(arg1)?;
+    let l: u8 = max(m, n);
+    Ok(FunctionType::new(
+        vec![
+            angle_type(TypeArg::BoundedNat { n: m as u64 }),
+            angle_type(TypeArg::BoundedNat { n: n as u64 }),
+        ],
+        vec![angle_type(TypeArg::BoundedNat { n: l as u64 })],
+    ))
+}
+
+fn aunop_sig(arg_values: &[TypeArg]) -> Result<FunctionType, SignatureError> {
+    let [arg] = collect_array(arg_values);
+    Ok(FunctionType::new_linear(vec![angle_type(arg.clone())]))
+}
+
+pub(super) fn add_to_extension(extension: &mut Extension) {
+    extension
+        .add_type(
+            ANGLE_TYPE_ID,
+            vec![LOG_DENOM_TYPE_PARAM],
+            "angle value with a given log-denominator".to_owned(),
+            TypeBound::Eq.into(),
+        )
+        .unwrap();
+
+    extension
+        .add_op_custom_sig_simple(
+            "atrunc".into(),
+            "truncate an angle to one with a lower log-denominator with the same value, rounding \
+            down in [0, 2π) if necessary"
+                .to_owned(),
+            vec![LOG_DENOM_TYPE_PARAM, LOG_DENOM_TYPE_PARAM],
+            atrunc_sig,
+        )
+        .unwrap();
+
+    extension
+        .add_op_custom_sig_simple(
+            "aconvert".into(),
+            "convert an angle to one with another log-denominator having the same value, if \
+            possible, otherwise return an error"
+                .to_owned(),
+            vec![LOG_DENOM_TYPE_PARAM, LOG_DENOM_TYPE_PARAM],
+            aconvert_sig,
+        )
+        .unwrap();
+
+    extension
+        .add_op_custom_sig_simple(
+            "aadd".into(),
+            "addition of angles".to_owned(),
+            vec![LOG_DENOM_TYPE_PARAM],
+            abinop_sig,
+        )
+        .unwrap();
+
+    extension
+        .add_op_custom_sig_simple(
+            "asub".into(),
+            "subtraction of the second angle from the first".to_owned(),
+            vec![LOG_DENOM_TYPE_PARAM],
+            abinop_sig,
+        )
+        .unwrap();
+
+    extension
+        .add_op_custom_sig_simple(
+            "aneg".into(),
+            "negation of an angle".to_owned(),
+            vec![LOG_DENOM_TYPE_PARAM],
+            aunop_sig,
+        )
+        .unwrap();
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use hugr::types::TypeArg;
+
+    #[test]
+    fn test_angle_log_denoms() {
+        let type_arg_53 = TypeArg::BoundedNat { n: 53 };
+        assert_eq!(get_log_denom(&type_arg_53).unwrap(), 53);
+
+        let type_arg_54 = TypeArg::BoundedNat { n: 54 };
+        assert!(matches!(
+            get_log_denom(&type_arg_54),
+            Err(TypeArgError::TypeMismatch { .. })
+        ));
+    }
+
+    #[test]
+    fn test_angle_consts() {
+        let const_a32_7 = ConstAngle::new(5, 7).unwrap();
+        let const_a33_7 = ConstAngle::new(6, 7).unwrap();
+        let const_a32_8 = ConstAngle::new(6, 8).unwrap();
+        assert_ne!(const_a32_7, const_a33_7);
+        assert_ne!(const_a32_7, const_a32_8);
+        assert_eq!(const_a32_7, ConstAngle::new(5, 7).unwrap());
+        assert!(matches!(
+            ConstAngle::new(3, 256),
+            Err(ConstTypeError::CustomCheckFail(_))
+        ));
+        assert!(matches!(
+            ConstAngle::new(54, 256),
+            Err(ConstTypeError::CustomCheckFail(_))
+        ));
+        let const_af1 = ConstAngle::from_radians_rounding(5, 0.21874 * TAU).unwrap();
+        assert_eq!(const_af1.value(), 7);
+        assert_eq!(const_af1.log_denom(), 5);
+    }
+}