86bf3ce859
Add 'core::array::from_fn' and 'core::array::try_from_fn'
These auxiliary methods fill uninitialized arrays in a safe way and are particularly useful for elements that don't implement `Default`.
```rust
// Foo doesn't implement Default
struct Foo(usize);
let _array = core::array::from_fn::<_, _, 2>(|idx| Foo(idx));
```
Different from `FromIterator`, it is guaranteed that the array will be fully filled and no error regarding uninitialized state will be throw. In certain scenarios, however, the creation of an **element** can fail and that is why the `try_from_fn` function is also provided.
```rust
#[derive(Debug, PartialEq)]
enum SomeError {
Foo,
}
let array = core::array::try_from_fn(|i| Ok::<_, SomeError>(i));
assert_eq!(array, Ok([0, 1, 2, 3, 4]));
let another_array = core::array::try_from_fn(|_| Err(SomeError::Foo));
assert_eq!(another_array, Err(SomeError::Foo));
```
111 lines
2.5 KiB
Rust
111 lines
2.5 KiB
Rust
#![feature(alloc_layout_extra)]
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#![feature(array_chunks)]
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#![feature(array_methods)]
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#![feature(array_windows)]
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#![feature(bool_to_option)]
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#![feature(box_syntax)]
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#![feature(cell_update)]
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#![feature(cfg_panic)]
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#![feature(cfg_target_has_atomic)]
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#![feature(const_assume)]
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#![feature(const_cell_into_inner)]
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#![feature(const_maybe_uninit_assume_init)]
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#![feature(const_ptr_read)]
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#![feature(const_ptr_write)]
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#![feature(const_ptr_offset)]
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#![feature(const_trait_impl)]
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#![feature(const_num_from_num)]
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#![feature(core_intrinsics)]
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#![feature(core_private_bignum)]
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#![feature(core_private_diy_float)]
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#![feature(dec2flt)]
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#![feature(div_duration)]
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#![feature(duration_consts_2)]
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#![feature(duration_constants)]
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#![feature(exact_size_is_empty)]
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#![feature(extern_types)]
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#![feature(flt2dec)]
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#![feature(fmt_internals)]
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#![feature(array_from_fn)]
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#![feature(hashmap_internals)]
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#![feature(try_find)]
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#![feature(is_sorted)]
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#![feature(pattern)]
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#![feature(sort_internals)]
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#![feature(slice_partition_at_index)]
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#![feature(maybe_uninit_uninit_array)]
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#![feature(maybe_uninit_array_assume_init)]
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#![feature(maybe_uninit_extra)]
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#![feature(maybe_uninit_write_slice)]
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#![feature(min_specialization)]
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#![feature(numfmt)]
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#![feature(step_trait)]
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#![feature(str_internals)]
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#![feature(test)]
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#![feature(trusted_len)]
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#![feature(try_trait_v2)]
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#![feature(slice_internals)]
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#![feature(slice_partition_dedup)]
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#![feature(int_log)]
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#![feature(iter_advance_by)]
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#![feature(iter_partition_in_place)]
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#![feature(iter_intersperse)]
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#![feature(iter_is_partitioned)]
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#![feature(iter_order_by)]
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#![feature(const_mut_refs)]
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#![feature(const_pin)]
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#![feature(const_slice_from_raw_parts)]
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#![feature(const_raw_ptr_deref)]
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#![feature(never_type)]
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#![feature(unwrap_infallible)]
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#![feature(option_result_unwrap_unchecked)]
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#![feature(result_into_ok_or_err)]
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#![feature(ptr_metadata)]
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#![feature(once_cell)]
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#![feature(unsized_tuple_coercion)]
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#![feature(const_option)]
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#![feature(integer_atomics)]
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#![feature(int_roundings)]
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#![feature(slice_group_by)]
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#![feature(trusted_random_access)]
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#![feature(unsize)]
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#![feature(unzip_option)]
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#![deny(unsafe_op_in_unsafe_fn)]
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extern crate test;
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mod alloc;
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mod any;
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mod array;
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mod ascii;
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mod atomic;
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mod bool;
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mod cell;
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mod char;
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mod clone;
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mod cmp;
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mod const_ptr;
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mod fmt;
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mod hash;
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mod intrinsics;
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mod iter;
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mod lazy;
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mod macros;
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mod manually_drop;
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mod mem;
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mod nonzero;
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mod num;
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mod ops;
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mod option;
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mod pattern;
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mod pin;
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mod ptr;
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mod result;
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mod slice;
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mod str;
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mod str_lossy;
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mod task;
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mod time;
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mod tuple;
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mod unicode;
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