mirror of https://github.com/rust-lang/rust
48 lines
1.3 KiB
Rust
48 lines
1.3 KiB
Rust
//@ run-pass
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trait SliceExt<T: Clone> {
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fn array_windows_example<'a, const N: usize>(&'a self) -> ArrayWindowsExample<'a, T, N>;
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}
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impl <T: Clone> SliceExt<T> for [T] {
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fn array_windows_example<'a, const N: usize>(&'a self) -> ArrayWindowsExample<'a, T, N> {
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ArrayWindowsExample{ idx: 0, slice: &self }
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}
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}
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struct ArrayWindowsExample<'a, T, const N: usize> {
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slice: &'a [T],
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idx: usize,
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}
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impl <'a, T: Clone, const N: usize> Iterator for ArrayWindowsExample<'a, T, N> {
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type Item = [T; N];
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fn next(&mut self) -> Option<Self::Item> {
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// Note: this is unsound for some `T` and not meant as an example
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// on how to implement `ArrayWindows`.
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let mut res = unsafe{ std::mem::zeroed() };
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let mut ptr = &mut res as *mut [T; N] as *mut T;
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for i in 0..N {
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match self.slice[self.idx..].get(i) {
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None => return None,
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Some(elem) => unsafe { std::ptr::write_volatile(ptr, elem.clone())},
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};
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ptr = ptr.wrapping_add(1);
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self.idx += 1;
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}
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Some(res)
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}
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}
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const FOUR: usize = 4;
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fn main() {
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let v: Vec<usize> = vec![0; 100];
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for array in v.as_slice().array_windows_example::<FOUR>() {
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assert_eq!(array, [0, 0, 0, 0])
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}
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}
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