nonzero_lit

A small macro crate providing safe, easy, and fully zero-cost way to construct constant or literal instances of the NonZero* types from core::num.

Features

• Crate fully supports no_std.

• All NonZero types are supported:

  • core::num::NonZeroUsize via the nonzero_lit::usize! macro.
  • core::num::NonZeroIsize via the nonzero_lit::isize! macro.
  • core::num::NonZeroU128 via the nonzero_lit::u128! macro.
  • core::num::NonZeroI128 via the nonzero_lit::i128! macro.
  • core::num::NonZeroU64 via the nonzero_lit::u64! macro.
  • core::num::NonZeroI64 via the nonzero_lit::i64! macro.
  • core::num::NonZeroU32 via the nonzero_lit::u32! macro.
  • core::num::NonZeroI32 via the nonzero_lit::i32! macro.
  • core::num::NonZeroU16 via the nonzero_lit::u16! macro.
  • core::num::NonZeroI16 via the nonzero_lit::i16! macro.
  • core::num::NonZeroU8 via the nonzero_lit::u8! macro.
  • core::num::NonZeroI8 via the nonzero_lit::i8! macro.

• Fully zero cost, even for debug builds — we always evaluate the constant as a const, even when the result is used as part of a non-const expression.

• Input to the macros can be arbitrary constant expressions. This includes const fn calls, which would be more difficult to verify the result as non-zero by hand.

• Misuse (trying to make a NonZero$Int with a zero value) is always detected at compile time, even when the macro is not being used to initialize a constant.

• No unsafe code.

Usage

Add this to your Cargo.toml:

[dependencies]
nonzero_lit = "0.1"

Examples

let x = nonzero_lit::i32!(4);
assert_eq!(x.get(), 4);

const FERRIS: core::num::NonZeroU32 = nonzero_lit::u32!(0xf34415);
assert_eq!(FERRIS.get(), 0xf34415);

use core::num::NonZeroU64;
const MASK: NonZeroU64 = nonzero_lit::u64!(0xffff_00ff_00ff_0f0f);
const MASKEE: NonZeroU64 = nonzero_lit::u64!(0xaabb_ccdd_eeff_1122);
const MASKED: NonZeroU64 = nonzero_lit::u64!(MASK.get() & MASKEE.get());
assert_eq!(MASKED.get(), 0xaabb_00dd_00ff_0102_u64);

License

Public domain, as explained here. If that's unacceptable, it's also available under either the Apache-2.0 or MIT licenses, at your option.