39 lines
1.1 KiB
Rust
39 lines
1.1 KiB
Rust
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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fn iterate<T, F>(initial: T, f: F) -> Iterate<T, F> {
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Iterate {
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state: initial,
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f: f,
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}
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}
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pub struct Iterate<T, F> {
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state: T,
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f: F
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}
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impl<T: Clone, F> Iterator for Iterate<T, F> where F: Fn(&T) -> T {
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type Item = T;
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#[inline]
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fn next(&mut self) -> Option<Self::Item> {
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self.state = (self.f)(&self.state);
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Some(self.state.clone())
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}
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#[inline]
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fn size_hint(&self) -> (usize, Option<usize>) { (std::usize::MAX, None) }
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}
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fn main() {
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let a = iterate(0, |x| x+1);
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println!("{:?}", a.iter().take(10).collect::<Vec<usize>>());
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//~^ ERROR no method named `iter` found for type `Iterate<{integer}
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}
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