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use std::array::IntoIter;
use std::mem::MaybeUninit;
use crate::{Iterable, Consumer, Producer, GrowableProducer};
impl<T, const N: usize> Iterable for [T; N] {
type C = Vec<T>;
type CC<U> = Vec<U>;
type F = [T; N];
type CF<U> = [U; N];
type CR<'a> where T: 'a= Vec<&'a T>;
type FR<'a> where T: 'a = [&'a T; N];
fn unzip<A, B>(self) -> (Self::CF<A>, Self::CF<B>)
where
Self: Sized,
Self: Iterable<Item=(A, B)>,
{
let mut l: [MaybeUninit<A>; N] = MaybeUninit::uninit_array();
let mut r: [MaybeUninit<B>; N] = MaybeUninit::uninit_array();
for (i, (a, b)) in self.into_iter().enumerate() {
l[i] = MaybeUninit::new(a);
r[i] = MaybeUninit::new(b);
}
unsafe { (transmute(l), transmute(r)) }
}
}
impl<T, const N: usize> Consumer for [T; N] {
type Item = T;
type IntoIter = IntoIter<T, N>;
fn into_iter(self) -> Self::IntoIter {
IntoIter::new(self)
}
}
impl<T, const N: usize> Producer<T> for [T; N] {
fn from_iter<IT>(iter: IT) -> Self
where
IT: IntoIterator<Item = T>
{
let mut arr: [MaybeUninit<T>; N] = MaybeUninit::uninit_array();
let mut count = 0;
for (i, t) in iter.into_iter().enumerate() {
if i >= N {
panic!("iter's length greater then array's length")
}
arr[i] = MaybeUninit::new(t);
count += 1;
}
if count < N {
panic!("iter's length less than array's length")
}
unsafe { transmute(arr) }
}
}
impl<T, const N: usize> GrowableProducer<T> for [T; N] {
fn empty() -> Self {
panic!("can not create empty array!")
}
fn add_one(&mut self, _: T) {
panic!("can not add element to an array!")
}
}
#[inline]
unsafe fn transmute<T, U, const N: usize>(mut arr: [MaybeUninit<T>; N]) -> U {
let ptr = &mut arr as *mut _ as *mut U;
let res = ptr.read();
core::mem::forget(arr);
res
}
delegate_into_iterator!(&'a [T; N], impl <'a, T: 'a, const N: usize>);
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn test_c() {
let v = [1, 2, 3];
let res = v.filter(|i| i > &1);
assert_eq!(res, vec![2, 3]);
}
#[test]
fn test_cc() {
let v = [1, 2, 3];
let res = v.flat_map(|i| vec![i, 1]);
assert_eq!(res, vec![1, 1, 2, 1, 3, 1]);
}
fn assert_array<T, const N: usize>(_: &[T; N]) {}
#[test]
fn test_f() {
let v = [1, 2, 3];
let res = v.rev();
assert_array(&res);
assert_eq!(res, [3, 2, 1]);
}
#[test]
fn test_cf() {
let v = [1, 2, 3];
let res = Iterable::map(v, |i| i.to_string());
assert_array(&res);
assert_eq!(res, ["1".to_string(), "2".to_string(), "3".to_string()]);
let v = [(1,2), (3, 4), (5,6)];
let (a, b) = v.unzip();
assert_array(&a);
assert_array(&b);
assert_eq!(a, [1, 3, 5]);
assert_eq!(b, [2, 4, 6]);
}
#[test]
fn test_c_r() {
let v = [1, 2, 3];
let res = (&v).filter(|i| i > &&1);
assert_eq!(res, [&2, &3]);
}
#[test]
fn test_cc_r() {
let v = [1, 2, 3];
let res = (&v).flat_map(|i| vec![*i, 1]);
assert_eq!(res, vec![1, 1, 2, 1, 3, 1]);
}
#[test]
fn test_f_r() {
let v = [1, 2, 3];
let res = (&v).rev();
assert_array(&res);
assert_eq!(res, [&3, &2, &1]);
}
#[test]
fn test_cf_r() {
let v = [1, 2, 3];
let res = Iterable::map(&v, |i| i.to_string());
assert_array(&res);
assert_eq!(res, ["1".to_string(), "2".to_string(), "3".to_string()]);
}
#[test]
#[should_panic]
fn test_producer1() {
let v = vec![1, 2, 3];
<[i32; 4]>::from_iter(v);
}
#[test]
#[should_panic]
fn test_producer2() {
let v = vec![1, 2, 3, 4, 5];
<[i32; 4]>::from_iter(v);
}
#[test]
#[should_panic]
fn test_growable_producer_empty() {
<[i32; 10] as GrowableProducer<i32>>::empty();
}
#[test]
#[should_panic]
fn test_growable_producer_add_one() {
let a = &mut [1,2,3];
<[i32; 3] as GrowableProducer<i32>>::add_one(a, 1);
}
}