1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129

use crate::{
	ConstraintViolation,
	type_math::{ TypeNum, Operator }
};
use std::{
	convert::TryFrom, error::Error, marker::PhantomData,
	ops::{ Deref, DerefMut }
};


/// Implements the conversion traits
macro_rules! impl_conv {
	($type:ty where $($impl_args:tt)*) => {
		impl<$($impl_args)*> $type {
			pub fn len(&self) -> usize {
				self.slice.len()
			}
		}
		impl<$($impl_args)*> Into<&'a[T]> for $type {
			fn into(self) -> &'a[T] {
				self.slice
			}
		}
		impl<$($impl_args)*> Into<&'a mut[T]> for $type {
			fn into(self) -> &'a mut[T] {
				self.slice
			}
		}
		impl<$($impl_args)*> Deref for $type {
			type Target = [T];
			fn deref(&self) -> &Self::Target {
				self.slice
			}
		}
		impl<$($impl_args)*> DerefMut for $type {
			fn deref_mut(&mut self) -> &mut Self::Target {
				self.slice
			}
		}
		impl<$($impl_args)*> AsRef<[T]> for $type {
			fn as_ref(&self) -> &[T] {
				self.slice
			}
		}
		impl<$($impl_args)*> AsMut<[T]> for $type {
			fn as_mut(&mut self) -> &mut[T] {
				self.slice
			}
		}
	};
}


/// An immutable slice with a fixed length as length constraint
#[derive(Debug)]
pub struct FixedMut<'a, T, Val: TypeNum> {
	slice: &'a mut[T],
	constraint: PhantomData<Val>
}
impl<'a, T, Val: TypeNum> TryFrom<&'a mut[T]> for FixedMut<'a, T, Val> {
	type Error = Box<Error + 'static>;
	/// Validates `slice` against the length constraint and creates the constrained slice with it
	fn try_from(slice: &'a mut[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!(FixedMut<'a, T, Val> where 'a, T, Val: TypeNum);


/// An immutable slice with a range as length constraint
#[derive(Debug)]
pub struct RangedMut<'a, T, Start: TypeNum, End: TypeNum> {
	slice: &'a mut[T],
	constraint: PhantomData<(Start, End)>
}
impl<'a, T, Start: TypeNum, End: TypeNum> TryFrom<&'a mut[T]> for RangedMut<'a, T, Start, End> {
	type Error = Box<Error + 'static>;
	/// Validates `slice` against the length constraint and creates the constrained slice with it
	fn try_from(slice: &'a mut[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!(RangedMut<'a, T, Start, End> where 'a, T, Start: TypeNum, End: TypeNum);


/// A mutable slice with a relative length as length constraint
///
/// _Note: Unlike the other constrained slices, this type does not validate the constraint on
/// construction but on deconstruction (`self.try_into()`)_
#[derive(Debug)]
pub struct RelativeMut<'a, T, Op: Operator, By: TypeNum> {
	slice: &'a mut[T],
	constraint: PhantomData<(Op, By)>
}
impl<'a, T, Op: Operator, By: TypeNum> RelativeMut<'a, T, Op, By> {
	/// Validates `slice` against the length constraint and creates the constrained slice with it
	pub fn try_from(slice: &'a mut[T], relative_to: usize) -> Result<Self, Box<Error + 'static>> {
		let expected = Op::r#do(relative_to, By::VALUE)?;
		match slice.len() {
			len if len == expected => Ok(Self::from(slice)),
			len =>
				Err(ConstraintViolation::relative::<Op, By>(len, relative_to))?
		}
	}
	
	/// Computes the expected relative length from `relative_to`, validates the wrapped `slice`
	/// against in and returns it on success
	pub fn get_slice_mut(self, relative_to: usize) -> Result<&'a mut[T], Box<Error + 'static>> {
		let expected = Op::r#do(relative_to, By::VALUE)?;
		match self.slice.len() {
			len if len == expected => Ok(self.slice),
			len =>
				Err(ConstraintViolation::relative::<Op, By>(len, relative_to))?
		}
	}
}
impl<'a, T, Op: Operator, By: TypeNum> From<&'a mut[T]> for RelativeMut<'a, T, Op, By> {
	/// Creates a new relative constrained slice
	fn from(slice: &'a mut[T]) -> Self {
		RelativeMut{ slice, constraint: PhantomData }
	}
}