score-set 3.0.0

A Rust library for building static weighted scoring operator sets
Documentation 
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use alloc::boxed::Box;

use witnessed::Witnessed;

/// Witness attached to values known to be valid for the normalized `[0, 1]`
/// scoring boundary.
pub struct V01;

/// Error returned when a value cannot be proven to be in the normalized
/// `[0, 1]` range.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct V01Error;

/// Proves that an `f32` value is in the normalized `[0, 1]` range.
///
/// This function is suitable for use with [`witnessed::Witnessing::by`]:
///
/// ```
/// use score_set::traits::{prove_v01_f32, V01};
/// use witnessed::{WitnessExt, Witnessed};
///
/// let score: Witnessed<f32, V01> = 0.75_f32.witness().by(prove_v01_f32).unwrap();
/// assert_eq!(*score, 0.75);
/// ```
///
/// Values such as `NaN` are rejected because neither range comparison
/// succeeds for them.
pub fn prove_v01_f32(value: &f32) -> Result<V01, V01Error> {
    (0.0..=1.0).contains(value).then_some(V01).ok_or(V01Error)
}

/// Proves that an `f64` value is in the normalized `[0, 1]` range.
///
/// Values such as `NaN` are rejected because neither range comparison
/// succeeds for them.
pub fn prove_v01_f64(value: &f64) -> Result<V01, V01Error> {
    (0.0..=1.0).contains(value).then_some(V01).ok_or(V01Error)
}

/// Measures a context and returns a value chosen by the implementation.
///
/// `Output` is the value consumed by a corresponding `Map01F32` or `Map01F64`
/// implementation.
pub trait Measure<Ctx: ?Sized>: Send + Sync {
    /// The value produced by [`Measure::measure`].
    type Output;

    /// Extracts a measurable value from `ctx`.
    fn measure(&self, ctx: &Ctx) -> Self::Output;
}

/// Maps a measurement into the `[0, 1]` range.
///
/// `Input` is associated with the mapper rather than fixed in the trait, so a
/// mapper can consume any measurement type. The normalized result carries the
/// [`V01`] witness.
pub trait Map01F32: Send + Sync {
    /// The value accepted by [`Map01F32::map`].
    type Input;

    /// Converts `value` into a normalized score.
    fn map(&self, value: Self::Input) -> Witnessed<f32, V01>;
}

/// Maps a measurement into the `[0, 1]` range.
///
/// `Input` is associated with the mapper rather than fixed in the trait, so a
/// mapper can consume any measurement type. The normalized result carries the
/// [`V01`] witness.
pub trait Map01F64: Send + Sync {
    /// The value accepted by [`Map01F64::map`].
    type Input;

    /// Converts `value` into a normalized score.
    fn map(&self, value: Self::Input) -> Witnessed<f64, V01>;
}

/// Evaluates a context into an `f64` score.
pub trait EvalF64<Ctx: ?Sized>: Send + Sync {
    /// Computes a score from `ctx`.
    fn eval(&self, ctx: &Ctx) -> f64;
}

impl<Ctx, E> EvalF64<Ctx> for Box<E>
where
    Ctx: ?Sized,
    E: EvalF64<Ctx> + ?Sized,
{
    #[inline]
    fn eval(&self, ctx: &Ctx) -> f64 {
        self.as_ref().eval(ctx)
    }
}

/// Evaluates a context into an `f32` score.
pub trait EvalF32<Ctx: ?Sized>: Send + Sync {
    /// Computes a score from `ctx`.
    fn eval(&self, ctx: &Ctx) -> f32;
}

impl<Ctx, E> EvalF32<Ctx> for Box<E>
where
    Ctx: ?Sized,
    E: EvalF32<Ctx> + ?Sized,
{
    #[inline]
    fn eval(&self, ctx: &Ctx) -> f32 {
        self.as_ref().eval(ctx)
    }
}