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Implement SizeHint trait for BufReader, Emtpy, and Chain

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This commit is contained in:
Xavientois 2021-01-16 15:03:58 -05:00
parent c8e0f8aaa3
commit 96255f82c9
3 changed files with 29 additions and 8 deletions
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20
library/std/src/io/mod.rs
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@ -2239,6 +2239,20 @@ impl<T: BufRead, U: BufRead> BufRead for Chain<T, U> {
}
}
impl<T, U> SizeHint for Chain<T, U> {
fn lower_bound(&self) -> usize {
SizeHint::lower_bound(&self.first) + SizeHint::lower_bound(&self.second)
}
fn upper_bound(&self) -> Option<usize > {
match (SizeHint::upper_bound(&self.first), SizeHint::upper_bound(&self.second)) {
(Some(first), Some(second)) => Some(first + second),
_ => None,
}
}
}
/// Reader adaptor which limits the bytes read from an underlying reader.
///
/// This struct is generally created by calling [`take`] on a reader.
@ -2491,12 +2505,6 @@ impl<T> SizeHint for T {
}
}
impl<T> SizeHint for BufReader<T> {
fn lower_bound(&self) -> usize {
self.buffer().len()
}
}
/// An iterator over the contents of an instance of `BufRead` split on a
/// particular byte.
///