Macro bitvec::prelude::bitarr

source ·
macro_rules! bitarr {
    (const Cell<$store:ident>, $order:ident; $($val:expr),* $(,)?) => { ... };
    (const $store:ident, $order:ident; $($val:expr),* $(,)?) => { ... };
    (const $store:ty, $order:ty; $val:expr; $len:expr) => { ... };
    (const $val:expr; $len:expr) => { ... };
    (const $($val:expr),* $(,)?) => { ... };
    (Cell<$store:ident>, $order:ident; $($val:expr),* $(,)?) => { ... };
    (Cell<$store:ident>, $order:path; $($val:expr),* $(,)?) => { ... };
    ($store:ident, $order:ident; $($val:expr),* $(,)?) => { ... };
    ($store:ident, $order:path; $($val:expr),* $(,)?) => { ... };
    ($store:ty, $order:ty; $val:expr; $len:expr) => { ... };
    ($val:expr; $len:expr) => { ... };
    ($($val:expr),* $(,)?) => { ... };
}
Expand description

Bit-Array Value Constructor

This macro provides a bit-initializer syntax for BitArray values. It takes a superset of the vec! arguments, and is capable of producing bit-arrays in const contexts (for known type parameters).

Like vec!, it can accept a sequence of comma-separated bit values, or a semicolon-separated pair of a bit value and a repetition counter. Bit values may be any integer or name of a const integer, but should only be 0 or 1.

Argument Syntax

It accepts zero, one, or three prefix arguments:

  • const: If the first argument to the macro is the keyword const, separated from remaining arguments by a space, then the macro expands to a const-expression that can be used in any appropriate context (initializing a static, a const, or passed to a const fn). This only works when the bit-ordering argument is either implicit, or one of the three tokens that bitvec can recognize.

  • $order ,: When this is one of the three literal tokens LocalBits, Lsb0, or Msb0, then the macro is able to compute the encoded bit-array contents at compile time, including in const contexts. When it is anything else, the encoding must take place at runtime. The name or path chosen must be in scope at the macro invocation site.

    When not provided, this defaults to Lbs0.

  • $store ;: This must be one of uTYPE, Cell<uTYPE>, AtomicUTYPE, or RadiumUTYPE where TYPE is one of 8, 16, 32, 64, or size. The macro recognizes this token textually, and does not have access to the type system resolver, so it will not accept aliases or qualified paths.

    When not provided, this defaults to usize.

The const argument can be present or absent independently of the type-parameter pair. The pair must be either both absent or both present together.

Previous versions of bitvec supported $order-only arguments. This has been removed for clarity of use and ease of implementation.

Examples

use bitvec::prelude::*;
use core::{cell::Cell, mem};
use radium::types::*;

let a: BitArray = bitarr![0, 1, 0, 0, 1];

let b: BitArray = bitarr![1; 5];
assert_eq!(b.len(), mem::size_of::<usize>() * 8);

let c = bitarr![u16, Lsb0; 0, 1, 0, 0, 1];
let d = bitarr![Cell<u16>, Msb0; 1; 10];
const E: BitArray<[u32; 1], LocalBits> = bitarr![u32, LocalBits; 1; 15];
let f = bitarr![RadiumU32, Msb0; 1; 20];