1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
/**
Collects an iterator constant into an array
# Iterator methods
This macro supports emulating iterator methods by expanding to equivalent code.
The supported iterator methods are documented in the [`iterator_dsl`] module,
because they are also supported by other `konst::iter` macros.
# Syntax
The syntax of this macro is:
```text
collect_const!(
$Item:ty => $into_iterator:expr
$(, $iterator_method:ident ($($method_args:tt)*) )*
$(,)?
)
```
Where `$Item` is the type of the elements that'll be collected into an array.
Where `$into_iterator` is any type that can be converted into a const iterator, with
[`konst::iter::into_iter`](crate::iter::into_iter).
Where `$iterator_method` is any of the supported methods described in
the [`iterator_dsl`] module.
# Examples
### Iterating over a range
```rust
use konst::iter;
const ARR: [u64; 8] = iter::collect_const!(u64 =>
10..,
filter(|n| *n % 2 == 0),
skip(5),
take(8),
);
assert_eq!(ARR, [20, 22, 24, 26, 28, 30, 32, 34]);
```
### Iterating over an array
```rust
use konst::iter;
const ARR: [u8; 6] = iter::collect_const!(u8 =>
// the `&` is required here,
// because by-value iteration over arrays is not supported.
&[10, 20, 30],
flat_map(|&n| {
// To allow returning references to arrays, the macro extends
// the lifetime of borrows to temporaries in return position.
// The lifetime of the array is extended to the entire iterator chain.
&[n - 1, n + 1]
}),
copied()
);
assert_eq!(ARR, [9, 11, 19, 21, 29, 31]);
```
[`iterator_dsl`]: crate::iter::iterator_dsl
*/
pub use iter_collect_const as collect_const;