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//! Utilities used throughout the library.
use alloc::{alloc::Allocator, collections::TryReserveError, vec::Vec};
#[cfg(feature = "core-fmt")]
use core::fmt;
#[cfg(feature = "core-error")]
use core::error;
/// Extension trait for handling OOM conditions better with a [`Vec`].
pub trait VecMemoryExt<T> {
/// Appends an element to the back of the vector.
///
/// # Errors
///
/// This method errors if the capacity overflows or if the allocator
/// reports a failure.
fn try_push(&mut self, value: T) -> Result<(), TryReserveError>;
}
impl<T, A> VecMemoryExt<T> for Vec<T, A>
where
A: Allocator,
{
fn try_push(&mut self, value: T) -> Result<(), TryReserveError> {
self.try_reserve(1)?;
//SAFETY: we just reserved space for this element
unsafe { self.push_within_capacity(value).unwrap_unchecked() };
Ok(())
}
}
/// Extension trait for wrapping arithmetic.
pub const trait WrappingArithmeticExt {
/// Wrapping integer increment.
fn wrapping_increment(self) -> Self;
/// Mutable wrapping integer increment.
fn wrapping_increment_mut(&mut self);
/// Wrapping integer decrement.
fn wrapping_decrement(self) -> Self;
/// Mutable wrapping integer decrement.
fn wrapping_decrement_mut(&mut self);
}
macro_rules! wrapping_arithmetic_ext_impl {
($t:ty) => {
impl const WrappingArithmeticExt for $t {
fn wrapping_increment(self) -> Self {
self.wrapping_add(1)
}
fn wrapping_increment_mut(&mut self) {
*self = self.wrapping_add(1);
}
fn wrapping_decrement(self) -> Self {
self.wrapping_sub(1)
}
fn wrapping_decrement_mut(&mut self) {
*self = self.wrapping_sub(1);
}
}
};
}
wrapping_arithmetic_ext_impl!(usize);
wrapping_arithmetic_ext_impl!(u64);
wrapping_arithmetic_ext_impl!(u32);
wrapping_arithmetic_ext_impl!(u16);
wrapping_arithmetic_ext_impl!(u8);
wrapping_arithmetic_ext_impl!(isize);
wrapping_arithmetic_ext_impl!(i64);
wrapping_arithmetic_ext_impl!(i32);
wrapping_arithmetic_ext_impl!(i16);
wrapping_arithmetic_ext_impl!(i8);
/// Extension trait for checked arithmetic that turns the output into a
/// [`Result`].
pub const trait CheckedArithmeticExt: Sized {
/// Checked integer addition.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_add(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
/// Checked integer decrement.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_decrement(self) -> Result<Self, IntegerOverflowError>;
/// Checked integer division.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_div(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
/// Checked integer increment.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_increment(self) -> Result<Self, IntegerOverflowError>;
/// Checked integer multiplication.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_mul(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
/// Checked integer remainder.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_rem(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
/// Checked integer subtraction.
///
/// # Errors
///
/// Returns an error if the result would have overflowed.
fn errored_sub(self, rhs: Self) -> Result<Self, IntegerOverflowError>;
}
macro_rules! checked_arithmetic_ext_impl {
($t:ty) => {
impl const CheckedArithmeticExt for $t {
fn errored_add(
self,
rhs: Self,
) -> Result<Self, IntegerOverflowError> {
self.checked_add(rhs).ok_or(IntegerOverflowError)
}
fn errored_decrement(self) -> Result<Self, IntegerOverflowError> {
self.errored_sub(1)
}
fn errored_div(
self,
rhs: Self,
) -> Result<Self, IntegerOverflowError> {
self.checked_div(rhs).ok_or(IntegerOverflowError)
}
fn errored_increment(self) -> Result<Self, IntegerOverflowError> {
self.errored_add(1)
}
fn errored_mul(
self,
rhs: Self,
) -> Result<Self, IntegerOverflowError> {
self.checked_mul(rhs).ok_or(IntegerOverflowError)
}
fn errored_rem(
self,
rhs: Self,
) -> Result<Self, IntegerOverflowError> {
self.checked_rem(rhs).ok_or(IntegerOverflowError)
}
fn errored_sub(
self,
rhs: Self,
) -> Result<Self, IntegerOverflowError> {
self.checked_sub(rhs).ok_or(IntegerOverflowError)
}
}
};
}
checked_arithmetic_ext_impl!(usize);
checked_arithmetic_ext_impl!(u64);
checked_arithmetic_ext_impl!(u32);
checked_arithmetic_ext_impl!(u16);
checked_arithmetic_ext_impl!(u8);
checked_arithmetic_ext_impl!(isize);
checked_arithmetic_ext_impl!(i64);
checked_arithmetic_ext_impl!(i32);
checked_arithmetic_ext_impl!(i16);
checked_arithmetic_ext_impl!(i8);
/// Representation of an integer overflow error.
#[derive(Copy, Clone, PartialEq, Eq)]
#[cfg_attr(feature = "core-fmt", derive(Debug))]
pub struct IntegerOverflowError;
#[cfg(feature = "core-fmt")]
impl fmt::Display for IntegerOverflowError {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.write_str("integer overflow")
}
}
#[cfg(feature = "core-error")]
impl error::Error for IntegerOverflowError {}
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