Crate az

Expand description

Numeric casts

This crate provides casts and checked casts.

Quick examples

``````use az::{Az, OverflowingAs, WrappingAs};
use core::num::Wrapping;

// Panics on overflow with `debug_assertions`, otherwise wraps
assert_eq!(12i32.az::<u32>(), 12u32);

// Always wraps
let wrapped = 1u32.wrapping_neg();
assert_eq!((-1).wrapping_as::<u32>(), wrapped);
assert_eq!((-1).overflowing_as::<u32>(), (wrapped, true));

// Wrapping can also be obtained using `Wrapping`
assert_eq!((-1).az::<Wrapping<u32>>().0, wrapped);``````

Conversions from floating-point to integers are also supported. Numbers are rounded towards zero, but the `Round` wrapper can be used to convert floating-point numbers to integers with rounding to the nearest, with ties rounded to even.

``````use az::{Az, CheckedAs, Round, SaturatingAs};
use core::f32;

assert_eq!(15.7.az::<i32>(), 15);
assert_eq!(Round(15.5).az::<i32>(), 16);
assert_eq!(1.5e20.saturating_as::<i32>(), i32::max_value());
assert_eq!(f32::NAN.checked_as::<i32>(), None);``````

Implementing casts for other types

To provide casts for another type, you should implement the `Cast` trait and if necessary the `CheckedCast`, `SaturatingCast`, `WrappingCast`, `OverflowingCast` and `UnwrappedCast` traits. The `Az`, `CheckedAs`, `SaturatingAs`, `WrappingAs`, `OverflowingAs` and `UnwrappedAs` traits are already implemented for all types using blanket implementations that make use of the former traits.

The cast traits can also be implemented for references. This can be useful for expensive types that are not `Copy`. For example if you have your own integer type that does not implement `Copy`, you could implement casts like in the following example. (The type `I` could be an expensive type, for example a bignum integer, but for the example it is only a wrapped `i32`.)

``````use az::{Az, Cast};
use core::borrow::Borrow;

struct I(i32);
impl Cast<i64> for &'_ I {
fn cast(self) -> i64 { self.0.cast() }
}

let owned = I(12);
assert_eq!((&owned).az::<i64>(), 12);
// borrow can be used if chaining is required
assert_eq!(owned.borrow().az::<i64>(), 12);``````

Using the az crate

The az crate is available on crates.io. To use it in your crate, add it as a dependency inside Cargo.toml:

``````[dependencies]
az = "1.2"``````

The crate requires rustc version 1.31.0 or later.

This crate is free software: you can redistribute it and/or modify it under the terms of either

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache License, Version 2.0, shall be dual licensed as above, without any additional terms or conditions.

Structs

Used to convert floating-point numbers to integers with rounding to the nearest, with ties rounded to even.

Traits

Used to cast values.

Used to cast values.

Used to cast values.

Used for checked casts.

Used for checked casts.

Used for checked casts.

Used for overflowing casts.

Used for overflowing casts.

Used for overflowing casts.

Used to cast into the destination type, saturating if the value does not fit.

Used to cast into the destination type, saturating if the value does not fit.

Used to cast, saturating if the value does not fit.

Used to cast values, panicking if the value does not fit.

Used to cast values, panicking if the value does not fit.

Used to cast values, panicking if the value does not fit.

Wrapping cast.

Wrapping cast.

Wrapping cast.

Functions

Casts the value.

Casts the value, returning `None` if the value does not fit.

Overflowing cast.

Casts the value, saturating if the value does not fit.

Casts the value, panicking if the value does not fit.

Casts the value, wrapping on overflow.