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use crate::{
ConstraintViolation,
type_math::{ TypeNum, Operator }
};
use std::{
convert::TryFrom, error::Error, marker::PhantomData, slice::SliceIndex,
ops::{ Deref, Index }
};
macro_rules! impl_conv {
($type:ty where $($impl_args:tt)*) => {
impl<$($impl_args)*> $type {
pub fn len(&self) -> usize {
self.slice.len()
}
pub fn slice(&self) -> &[T] {
self.slice
}
}
impl<$($impl_args)*> Into<&'a[T]> for $type {
fn into(self) -> &'a[T] {
self.slice
}
}
impl<$($impl_args)*> Deref for $type {
type Target = [T];
fn deref(&self) -> &Self::Target {
self.slice
}
}
impl<$($impl_args)*> AsRef<[T]> for $type {
fn as_ref(&self) -> &[T] {
self.slice
}
}
impl<$($impl_args)*, I: SliceIndex<[T]>> Index<I> for $type {
type Output = I::Output;
fn index(&self, index: I) -> &Self::Output {
&self.slice[index]
}
}
};
}
#[derive(Debug, Copy, Clone)]
pub struct Fixed<'a, T, Val: TypeNum> {
slice: &'a[T],
constraint: PhantomData<Val>
}
impl<'a, T, Val: TypeNum> TryFrom<&'a[T]> for Fixed<'a, T, Val> {
type Error = Box<Error + 'static>;
fn try_from(slice: &'a[T]) -> Result<Self, Self::Error> {
match slice.len() {
len if len == Val::VALUE => Ok(Self{ slice, constraint: PhantomData }),
len => Err(ConstraintViolation::fixed::<Val>(len))?
}
}
}
impl_conv!(Fixed<'a, T, Val> where 'a, T, Val: TypeNum);
#[derive(Debug, Copy, Clone)]
pub struct Ranged<'a, T, Start: TypeNum, End: TypeNum> {
slice: &'a[T],
constraint: PhantomData<(Start, End)>
}
impl<'a, T, Start: TypeNum, End: TypeNum> TryFrom<&'a[T]> for Ranged<'a, T, Start, End> {
type Error = Box<Error + 'static>;
fn try_from(slice: &'a[T]) -> Result<Self, Self::Error> {
match slice.len() {
len if len >= Start::VALUE && len < End::VALUE =>
Ok(Self{ slice, constraint: PhantomData }),
len => Err(ConstraintViolation::ranged::<Start, End>(len))?
}
}
}
impl_conv!(Ranged<'a, T, Start, End> where 'a, T, Start: TypeNum, End: TypeNum);
#[derive(Debug, Copy, Clone)]
pub struct Relative<'a, T, Op: Operator, By: TypeNum> {
slice: &'a[T],
constraint: PhantomData<(Op, By)>
}
impl<'a, T, Op: Operator, By: TypeNum> Relative<'a, T, Op, By> {
pub fn try_from(slice: &'a[T], relative_to: usize) -> Result<Self, Box<Error + 'static>> {
Self::validate(slice.len(), relative_to)?;
Ok(Self::from(slice))
}
pub fn slice(self, relative_to: usize) -> Result<&'a[T], Box<Error + 'static>> {
Self::validate(self.slice.len(), relative_to)?;
Ok(self.slice)
}
fn validate(len: usize, relative_to: usize) -> Result<(), Box<Error + 'static>> {
let expected = Op::r#do(relative_to, By::VALUE)?;
match len == expected {
true => Ok(()),
false => Err(ConstraintViolation::relative::<Op, By>(len, relative_to))?
}
}
}
impl<'a, T, Op: Operator, By: TypeNum> From<&'a[T]> for Relative<'a, T, Op, By> {
fn from(slice: &'a[T]) -> Self {
Relative{ slice, constraint: PhantomData }
}
}