box_iter/
lib.rs

1#![no_std]
2#![feature(layout_for_ptr, allocator_api)]
3
4pub(crate) extern crate alloc;
5
6mod r#trait;
7use alloc::alloc::Global;
8pub use r#trait::*;
9use core::{alloc::{Allocator, Layout}, ptr::NonNull, ops::Range, mem::needs_drop, iter::{FusedIterator}};
10
11pub struct IntoIter<T, A: Allocator = Global> {
12    pub(crate) ptr: NonNull<[T]>,
13    pub(crate) range: Range<*mut T>,
14    pub(crate) alloc: A
15}
16
17impl<T, A: Allocator> Iterator for IntoIter<T, A> {
18    type Item = T;
19
20    #[inline(always)]
21    fn next (&mut self) -> Option<Self::Item> {
22        self.nth(0)
23    }
24
25    #[inline(always)]
26    fn size_hint(&self) -> (usize, Option<usize>) {
27        let len = self.len();
28        (len, Some(len))
29    }
30
31    #[inline(always)]
32    fn count(self) -> usize where Self: Sized {
33        self.len()
34    }
35
36    #[inline]
37    fn last(mut self) -> Option<Self::Item> where Self: Sized {
38        if self.range.end <= self.range.start {
39            return None
40        }
41
42        let v = unsafe { core::ptr::read(self.range.end.sub(1)) };
43        self.range.end = self.range.start;
44        Some(v)
45    }
46
47    #[inline]
48    fn nth(&mut self, n: usize) -> Option<Self::Item> {
49        unsafe {
50            let ptr = self.range.start.add(n);
51
52            if ptr >= self.range.end {
53                self.range.start = self.range.end;
54                return None
55            }
56    
57            self.range.start = ptr.add(1);
58            debug_assert!(!ptr.is_null());
59            Some(core::ptr::read(ptr))
60        }
61    }
62}
63
64impl<T, A: Allocator> DoubleEndedIterator for IntoIter<T, A> {
65    #[inline(always)]
66    fn next_back(&mut self) -> Option<Self::Item> {
67        self.nth_back(0)
68    }
69
70    #[inline]
71    fn nth_back(&mut self, n: usize) -> Option<Self::Item> {
72        unsafe {
73            self.range.end = self.range.end.sub(n + 1);
74            let ptr = self.range.end;
75
76            if ptr < self.range.start {
77                self.range.end = self.range.start;
78                return None
79            }
80    
81            debug_assert!(!ptr.is_null());
82            Some(core::ptr::read(ptr))
83        }
84    }
85}
86
87impl<T, A: Allocator> ExactSizeIterator for IntoIter<T, A> {
88    #[inline(always)]
89    fn len(&self) -> usize {
90        ((self.range.end as usize) - (self.range.start as usize)) / core::mem::size_of::<T>()
91    }
92}
93
94impl<T, A: Allocator> FusedIterator for IntoIter<T, A> {}
95
96impl<T, A: Allocator> Drop for IntoIter<T, A> {
97    #[inline]
98    fn drop(&mut self) {
99        if needs_drop::<T>() {
100            let mut ptr = self.range.start;
101
102            while ptr < self.range.end {
103                unsafe {
104                    core::ptr::drop_in_place(ptr);
105                    ptr = ptr.add(1);
106                }
107            }
108        }
109
110        unsafe {
111            let layout = Layout::for_value_raw(self.ptr.as_ptr());
112            self.alloc.deallocate(self.ptr.cast(), layout);
113        }
114    }
115}
116
117unsafe impl<T: Send, A: Allocator + Send> Send for IntoIter<T, A> {}
118unsafe impl<T: Sync, A: Allocator + Sync> Sync for IntoIter<T, A> {}
119
120#[cfg(test)]
121mod test {
122    extern crate std;
123    use std::{prelude::rust_2021::*, println};
124
125    use alloc::vec;
126    use crate::BoxIntoIter;
127
128    #[test]
129    fn test () {
130        let array = vec!["hello".to_string(), "world".to_string()].into_boxed_slice().into_iter();
131        println!("{:?}", array.last())
132    }
133}
box_iter/lib.rs

box_iter/
lib.rs
