mirror of https://github.com/rust-lang/rust
26 lines
506 B
Rust
26 lines
506 B
Rust
//@ run-pass
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trait DigitCollection: Sized {
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type Iter: Iterator<Item = u8>;
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fn digit_iter(self) -> Self::Iter;
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fn digit_sum(self) -> u32 {
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self.digit_iter()
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.map(|digit: u8| digit as u32)
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.fold(0, |sum, digit| sum + digit)
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}
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}
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impl<I> DigitCollection for I where I: Iterator<Item=u8> {
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type Iter = I;
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fn digit_iter(self) -> I {
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self
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}
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}
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fn main() {
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let xs = vec![1, 2, 3, 4, 5];
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assert_eq!(xs.into_iter().digit_sum(), 15);
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}
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