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Implement vec! macro #40

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May 27, 2025
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5 changes: 4 additions & 1 deletion src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,9 @@
#![deny(missing_docs)]
#![doc = include_str!("../README.md")]

#[macro_use]
mod macros;

use core::mem::MaybeUninit;
use core::{cmp, error, fmt, slice};

Expand Down Expand Up @@ -60,7 +63,7 @@ impl<T, const CAPACITY: usize> Vec<T, CAPACITY> {
pub const fn new() -> Self {
assert!(CAPACITY > 0, "CAPACITY must be greater than 0");

// SAFETY: The elements in the array are not accessed before beign initialized.
// SAFETY: The elements in the array are not accessed before being initialized.
let data = unsafe { MaybeUninit::<[MaybeUninit<T>; CAPACITY]>::uninit().assume_init() };
Self { data, length: 0 }
}
Expand Down
56 changes: 56 additions & 0 deletions src/macros.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,56 @@
/// Creates new vector.
///
/// # Forms
///
/// - `vec![T; CAPACITY]`: Creates a new empty `Vec<T, CAPACITY>` with maximum `CAPACITY` elements of type `T`.
/// - `vec![x, y, z]`: Creates a `Vec` initialized with the given values. The capacity is inferred from the number of elements.
///
/// # Examples
///
/// Create an empty vector with capacity:
///
/// ```rust
/// let vec = static_vector::vec![i32; 10];
/// assert!(vec.is_empty());
/// ```
///
/// Create a vector from elements:
///
/// ```rust
/// let vec = static_vector::vec![1, 2, 3];
/// assert_eq!(vec.as_slice(), &[1, 2, 3]);
/// ```
#[macro_export]
macro_rules! vec {
($type:ty; $capacity:literal) => {
$crate::Vec::<$type, $capacity>::new()
};

($($value:expr),+ $(,)?) => {
{
let mut vec = $crate::Vec::<_, { [$($value),+].len() }>::new();
// It's safe to call unwrap because we are initializing the vector with a known number of elements
// (which is also the capacity).
vec.extend_from_slice(&[$($value),+]).unwrap();
vec
}
};
}

#[cfg(test)]
mod tests {
#[test]
fn vec_with_type_and_capacity() {
let vec = vec![i32; 10];
assert_eq!(vec.capacity(), 10);
assert!(vec.is_empty());
}

#[test]
fn vec_with_elements() {
let vec = vec![1, 2, 3];
assert_eq!(vec.capacity(), 3);
assert_eq!(vec.len(), 3);
assert_eq!(vec.as_slice(), &[1, 2, 3]);
}
}