Macro bitarr
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 keywordconst
, separated from remaining arguments by a space, then the macro expands to aconst
-expression that can be used in any appropriate context (initializing astatic
, aconst
, or passed to aconst fn
). This only works when the bit-ordering argument is either implicit, or one of the three tokens thatbitvec
can recognize. -
$order ,
: When this is one of the three literal tokensLocalBits
,Lsb0
, orMsb0
, then the macro is able to compute the encoded bit-array contents at compile time, including inconst
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
. -
$store ;
: This must be one ofuTYPE
,Cell<uTYPE>
,AtomicUTYPE
, orRadiumUTYPE
whereTYPE
is one of8
,16
,32
,64
, orsize
. The macro recognizes this token textually, and does not have access to the type system resolver, so it will not accept aliases or qualified paths.When not provided, this defaults to
usize
.
The const
argument can be present or absent independently of the
type-parameter pair. The pair must be either both absent or both present
together.
Previous versions of
bitvec
supported$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];