opensrdk-kernel-method 0.2.5

use std::{
    marker::PhantomData,
    ops::{Add, Mul},
};

use crate::KernelError;

use std::fmt::Debug;

use super::{KernelAdd, KernelMul, PositiveDefiniteKernel};
use opensrdk_symbolic_computation::Expression;

#[derive(Clone)]
pub struct InstantKernel<F>
where
    F: Fn(&Expression, &Expression, &[Expression]) -> Result<Expression, KernelError>
        + Clone
        + Send
        + Sync,
{
    params_len: usize,
    function: F,
    phantom: PhantomData<Expression>,
}

impl<F> Debug for InstantKernel<F>
where
    F: Fn(&Expression, &Expression, &[Expression]) -> Result<Expression, KernelError>
        + Clone
        + Send
        + Sync,
{
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "InstantKernel {{ params_len: {} }}", self.params_len)
    }
}

impl<F> PositiveDefiniteKernel for InstantKernel<F>
where
    F: Fn(&Expression, &Expression, &[Expression]) -> Result<Expression, KernelError>
        + Clone
        + Send
        + Sync,
{
    fn expression(
        &self,
        x: Expression,
        x_prime: Expression,
        params: &[Expression],
    ) -> Result<Expression, KernelError> {
        (self.function)(&x, &x_prime, params)
    }

    fn params_len(&self) -> usize {
        self.params_len
    }
}

impl<R, F> Add<R> for InstantKernel<F>
where
    R: PositiveDefiniteKernel,
    F: Fn(&Expression, &Expression, &[Expression]) -> Result<Expression, KernelError>
        + Clone
        + Send
        + Sync,
{
    type Output = KernelAdd<Self, R>;

    fn add(self, rhs: R) -> Self::Output {
        KernelAdd::new(self, rhs)
    }
}

impl<R, F> Mul<R> for InstantKernel<F>
where
    F: Fn(&Expression, &Expression, &[Expression]) -> Result<Expression, KernelError>
        + Clone
        + Send
        + Sync,
    R: PositiveDefiniteKernel,
{
    type Output = KernelMul<Self, R>;

    fn mul(self, rhs: R) -> Self::Output {
        KernelMul::new(self, rhs)
    }
}

// use super::PositiveDefiniteKernel;
// use crate::KernelError;
// use crate::Value;
// use crate::{KernelAdd, KernelMul};
// use std::marker::PhantomData;
// use std::{fmt::Debug, ops::Add, ops::Mul};

// #[derive(Clone)]
// pub struct InstantKernel<T, F>
// where
//     T: Value,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     params_len: usize,
//     value_function: F,
//     phantom: PhantomData<T>,
// }

// impl<T, F> InstantKernel<T, F>
// where
//     T: Value,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     pub fn new(params_len: usize, value_function: F) -> Self {
//         Self {
//             params_len,
//             value_function,
//             phantom: PhantomData,
//         }
//     }
// }

// impl<T, F> Debug for InstantKernel<T, F>
// where
//     T: Value,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
//         write!(f, "InstantKernel {{ params_len: {} }}", self.params_len)
//     }
// }

// impl<T, F> PositiveDefiniteKernel<T> for InstantKernel<T, F>
// where
//     T: Value,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     fn params_len(&self) -> usize {
//         self.params_len
//     }

//     fn value(&self, params: &[f64], x: &T, xprime: &T) -> Result<f64, KernelError> {
//         (self.value_function)(params, x, xprime)
//     }
// }

// impl<T, R, F> Add<R> for InstantKernel<T, F>
// where
//     T: Value,
//     R: PositiveDefiniteKernel<T>,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     type Output = KernelAdd<Self, R, T>;

//     fn add(self, rhs: R) -> Self::Output {
//         Self::Output::new(self, rhs)
//     }
// }

// impl<T, R, F> Mul<R> for InstantKernel<T, F>
// where
//     T: Value,
//     R: PositiveDefiniteKernel<T>,
//     F: Fn(&[f64], &T, &T) -> Result<f64, KernelError> + Clone + Send + Sync,
// {
//     type Output = KernelMul<Self, R, T>;

//     fn mul(self, rhs: R) -> Self::Output {
//         Self::Output::new(self, rhs)
//     }
// }

// #[cfg(test)]
// mod tests {
//     use crate::*;
//     #[test]
//     fn it_works() {
//         let kernel = RBF + InstantKernel::new(0, |_, _, _| Ok(0.0));

//         //let (func, grad) = kernel
//         //    .value_with_grad(&[1.0, 1.0], &vec![1.0, 2.0, 3.0], &vec![3.0, 2.0, 1.0])
//         //    .unwrap();

//         //println!("{}", func);
//         //println!("{:#?}", grad);

//         let test_value = kernel
//             .value(&[1.0, 1.0], &vec![1.0, 2.0, 3.0], &vec![3.0, 2.0, 1.0])
//             .unwrap();

//         println!("{}", test_value);
//     }
// }