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mod i_min_max;
#[cfg(test)]
mod unit_tests;
use std::{
fmt::Debug,
ops::{Add, Div, Sub},
};
use arith_traits::{IMinMax, IUnaryWrappingOps, IWrappingOps};
use num_traits::{NumOps, One, Zero};
use crate::{
consts::msg,
traits::{IRange, IRangeFrom, IRangeTo, IRangeToInclusive, IRanged},
ErrInt, Error, Result,
};
#[derive(Clone, Copy, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub struct Ranged<TRange>(TRange::ValueType)
where
TRange: IRange;
impl<TRange> Ranged<TRange>
where
TRange: IRange + IRangeFrom + IRangeToInclusive,
ErrInt: From<TRange::ValueType>,
{
/// Constructor
/// This constructor is intended to be called from `const` context. This way, if the value passed in is
/// out of bounds, the compilation will fail. If the code runs, it means the value passed in was within
/// bounds and therefore the function signature is infallible (at runtime). NOTE: Rust does not provide
/// a way to *only* provide a (`const`) method at compile-time, thus, this function can also be called
/// with a runtime value. In such a case, it will panic if the provided value is out of bounds. When writing
/// panic-free code, use the `try_from()` constructor instead.
///
/// # Returns
/// `Self`, if `value` is within `TRange`'s range bounds.
///
/// # Panics
/// If `value` is not within `TRange`'s range bounds:
/// * fails to compile if `value` is `const` (or a literal), or
/// * panics at runtime if `value` is not `const` (prefer `try_from()` constructor instead).
#[must_use]
#[allow(clippy::let_unit_value, clippy::no_effect_underscore_binding)]
pub const fn from(value: TRange::ValueType) -> Self
where
TRange: ~const IRange + ~const IRangeFrom + ~const IRangeTo, {
#[allow(clippy::match_wild_err_arm)]
// TODO: Replace with `const` `expect()` once it exists
match Self::try_from(value) {
Ok(instance) => instance,
// TODO: Note loss of `err` context; restore when `const` `format!` or other solution is found
Err(_err) => panic!("{}", msg::ERR_VALUE_OUT_OF_INCLUSIVE_BOUNDS),
}
}
/// Constructor
/// # Returns
/// Returns `Some(Self)` when `value` is within bounds or `None` otherwise.
#[allow(clippy::let_unit_value, clippy::no_effect_underscore_binding)]
pub const fn try_from(value: TRange::ValueType) -> Result<Self>
where
TRange: ~const IRange + ~const IRangeFrom + ~const IRangeTo, {
let _invariants = TRange::INVARIANTS;
match TRange::contains(&value) {
true => Ok(Self(value)),
false => Err(Error::ValueOutOfInclusiveBounds(
<TRange as IRangeFrom>::start().into(),
<TRange as IRangeTo>::end().into(),
value.into(),
)),
}
}
/// Constructor
/// For orthogonality with this type's other constructors, this constructor may be called from `const` context.
///
/// # Returns
/// `Self`, unconditionally.
///
/// # Safety
/// This constructor is `unsafe` because the value being passed in is not verified to be within the bounds of
/// `TRange`. It is the caller's responsibility to ensure that this contract is upheld--violating it is Undefined
/// Behavior.
#[allow(unsafe_code)]
#[must_use]
pub const unsafe fn unchecked_from(value: TRange::ValueType) -> Self { Self(value) }
}
// TODO: Separate `value()` from `start()` and `end()` methods, since `IRangeFrom` and `IRangeTo(Inclusive)` are not
// required for `value()`, but are for `start()` and `end()`, respectively.
// TODO: Separate `start()` and `end()` methods to accommodate `RangeTo` and `RangeFrom` types, respectively?
// TODO: Reconcile `start()` and `end()` methods with `IMinMax` trait to eliminate redundancy
impl<TRange> const IRanged<TRange> for Ranged<TRange>
where
TRange: ~const IRange + ~const IRangeFrom + ~const IRangeTo + ~const IRangeToInclusive,
{
#[must_use]
fn end(&self) -> TRange::ValueType { TRange::end() }
#[must_use]
fn start(&self) -> TRange::ValueType { TRange::start() }
#[must_use]
fn value(&self) -> &TRange::ValueType { &self.0 }
}
impl<TRangeLhs, TRangeRhs> IWrappingOps<Ranged<TRangeRhs>> for Ranged<TRangeLhs>
where
ErrInt: From<TRangeLhs::ValueType>,
Self: PartialOrd,
TRangeLhs: Clone + IMinMax<TRangeLhs::ValueType> + IRangeFrom + IRangeToInclusive + PartialOrd,
TRangeLhs::ValueType: Debug + PartialOrd + IWrappingOps,
TRangeLhs::WidenedValueType: Add<TRangeRhs::WidenedValueType, Output = TRangeLhs::WidenedValueType>
+ Clone
+ Debug
+ Div<Output = TRangeLhs::WidenedValueType>
+ IWrappingOps<Output = <TRangeLhs as IRange>::WidenedValueType>
+ NumOps<<TRangeLhs as IRange>::WidenedValueType, <TRangeLhs as IRange>::WidenedValueType>
+ One
+ PartialOrd
+ Sub<TRangeRhs::WidenedValueType, Output = TRangeLhs::WidenedValueType>
+ Zero,
TRangeRhs: IRangeFrom + IRangeToInclusive,
{
// TODO: Determine why arithmetic below compiles without having to `#[allow(clippy::integer_arithmetic)]` (!)
fn wrapping_add(self, rhs: Ranged<TRangeRhs>) -> Self::Output {
let sum = TRangeLhs::WidenedValueType::from(self.0) + TRangeRhs::WidenedValueType::from(rhs.0)
- TRangeLhs::WidenedValueType::from(TRangeLhs::MIN);
Self::from(wrapping_total::<TRangeLhs>(TRangeLhs::MIN, TRangeLhs::MAX, sum))
}
fn wrapping_div(self, _rhs: Ranged<TRangeRhs>) -> Self::Output { todo!() }
fn wrapping_div_euclid(self, _rhs: Ranged<TRangeRhs>) -> Self::Output { todo!() }
fn wrapping_mul(self, _rhs: Ranged<TRangeRhs>) -> Self::Output { todo!() }
fn wrapping_rem(self, _rhs: Ranged<TRangeRhs>) -> Self::Output { todo!() }
fn wrapping_rem_euclid(self, _rhs: Ranged<TRangeRhs>) -> Self::Output { todo!() }
fn wrapping_sub(self, rhs: Ranged<TRangeRhs>) -> Self::Output {
let diff = TRangeLhs::WidenedValueType::from(self.0)
- TRangeRhs::WidenedValueType::from(rhs.0)
- TRangeLhs::WidenedValueType::from(TRangeLhs::MIN);
Self::from(wrapping_total::<TRangeLhs>(TRangeLhs::MIN, TRangeLhs::MAX, diff))
}
}
impl<TRangeLhs> IUnaryWrappingOps for Ranged<TRangeLhs>
where
Self: PartialOrd,
TRangeLhs: Clone + IMinMax<TRangeLhs::ValueType> + IRangeFrom + IRangeToInclusive,
TRangeLhs::ValueType: PartialOrd + IWrappingOps,
<TRangeLhs as IRange>::WidenedValueType: IWrappingOps<Output = <TRangeLhs as IRange>::WidenedValueType>
+ Clone
+ NumOps<<TRangeLhs as IRange>::WidenedValueType, <TRangeLhs as IRange>::WidenedValueType>
+ One
+ PartialOrd
+ Zero,
{
type Output = Self;
fn wrapping_abs(self) -> Self::Output {
let (start, end) = (
<TRangeLhs as IRange>::WidenedValueType::from(<TRangeLhs as IRangeFrom>::start()),
<TRangeLhs as IRange>::WidenedValueType::from(<TRangeLhs as IRangeTo>::end()),
);
// `WidenedValueType::from(self.0).abs()` cannot wrap, so `wrapping_abs()` is being used as
// "plain `abs`". Note there is no convenient "plain `abs`" for `ValueType` as (`num::abs<T>(T)` is only
// defined on `T: Signed` (i.e. `f32`, `f64` and `Rational`).
// TODO: Use `abs` or `wrapping_abs`. Attempts to use `WidenedValueType.wrapping_abs()` seem to enter infinite
// recursive loops (resolving `IWrapping`?).
let abs_value = {
let tmp_value = <TRangeLhs as IRange>::WidenedValueType::from(self.0);
match tmp_value >= <TRangeLhs as IRange>::WidenedValueType::zero() {
true => tmp_value,
false => <TRangeLhs as IRange>::WidenedValueType::zero() - tmp_value,
}
};
// If `self.contains(&abs_value)` then return `Ranged(abs_value)`, otherwise
// compute `abs_value`'s wrapped offset into the range and return `Range(wrapped_offset)`.
let working_value = match abs_value <= end {
true => abs_value,
false => {
// Implementation notes and sample walkthrough:
// 0..=255; n(∈) = 256_u8 (boom!)
// 0..=255; Option<n(∈) - 1> = None..=Some(255_u8)
// -128_i8..=127_i8; n(∈) = 256_i8 (boom!)
// -30_i8..=-20_i8; n(∈) = 11_i16 ✅
// |-25| = 25_i16 ✅
// 25_i16 - -20_i16 = 45_i16 ✅
// 45_i16 % 11_i16 = 1_i8 ✅
// -30_i8 + 1_i8 = -29_i8 ✅
// Arithmetic below is safe because span of bounds of `ValueType`
// (`<TRange as IRangeTo>::end() - <TRange as IRangeTo>::start()`) cannot overflow `ValueType`,
// let alone `WidenedValueType`, whose size is at least `2 * size_of::<ValueType>()`.
// `end - start` + 1 (required for inclusive `Range`) _could_ overflow, so `ValueType` has been promoted
// to `WidenedValueType` to ensure overflow cannot happen in this case either.
#[allow(clippy::integer_arithmetic)]
let range_len = end.clone() - start.clone() + <TRangeLhs as IRange>::WidenedValueType::one();
// `abs_value > end` per `match` arm ensures that `abs_value - end` cannot overflow
#[allow(clippy::integer_arithmetic)]
let overflow_magnitude = abs_value - end;
let range_offset = overflow_magnitude % range_len;
start + range_offset
},
};
// `range_offset` calculation above guarantees `working_value` is within `TRange::start()..=TRange::end()`.
// TODO: Since `TryFrom/TryInto` do not require the returned `Result`'s `E` to be `Error` or even `Debug`,
// determine how to output `err` to aid debuggability
Self(working_value.try_into().unwrap_or_else(|_err| unreachable!()))
}
fn wrapping_neg(self) -> Self::Output { todo!() }
fn wrapping_pow(self, _rhs: u32) -> Self::Output { todo!() }
fn wrapping_shl(self, _rhs: u32) -> Self::Output { todo!() }
fn wrapping_shr(self, _rhs: u32) -> Self::Output { todo!() }
}
#[allow(clippy::inline_always)]
#[inline(always)]
fn wrapping_total<TRange>(
start: TRange::ValueType,
end: TRange::ValueType,
total: TRange::WidenedValueType,
) -> TRange::ValueType
where
TRange: IRange,
TRange::WidenedValueType: Add<TRange::WidenedValueType, Output = TRange::WidenedValueType>
+ Clone
+ IUnaryWrappingOps<Output = TRange::WidenedValueType>
+ One
+ Sub<TRange::WidenedValueType, Output = TRange::WidenedValueType>, {
let (start, end) = (TRange::WidenedValueType::from(start), TRange::WidenedValueType::from(end));
// For `Copy` types, `clone()` is `memcpy::copy_*()`; for non-`Copy` types (uncommon), `Clone` bound permits
// ranged type participation
let span = end - start.clone() + <TRange as IRange>::WidenedValueType::one();
let offset = total.wrapping_rem_euclid(span);
// TODO: Since `TryFrom/TryInto` do not require the returned `Result`'s `E` to be `Error` or even `Debug`, determine
// how to output `err` to aid debuggability
(start + offset).try_into().unwrap_or_else(|_err| unreachable!())
}