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remove the wrapping arithmetics

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This commit is contained in:
Michał Krasnoborski 2017-02-02 03:38:12 +01:00
parent 7403ee9d07
commit ecda7f314f
1 changed files with 5 additions and 10 deletions
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15
src/libcore/fmt/mod.rs
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@ -274,16 +274,12 @@ impl<'a> Arguments<'a> {
#[unstable(feature = "fmt_internals", reason = "internal to format_args!",
issue = "0")]
pub fn estimated_capacity(&self) -> usize {
// Using wrapping arithmetics in this function, because
// wrong result is highly unlikely and doesn't cause unsafety.
use ::num::Wrapping as W;
let pieces_length: W<usize> = self.pieces.iter()
.map(|x| W(x.len())).sum();
let pieces_length: usize = self.pieces.iter()
.map(|x| x.len()).sum();
if self.args.is_empty() {
pieces_length.0
} else if self.pieces[0] == "" && pieces_length < W(16) {
pieces_length
} else if self.pieces[0] == "" && pieces_length < 16 {
// If the format string starts with an argument,
// don't preallocate anything, unless length
// of pieces is significant.
@ -292,9 +288,8 @@ impl<'a> Arguments<'a> {
// There are some arguments, so any additional push
// will reallocate the string. To avoid that,
// we're "pre-doubling" the capacity here.
(pieces_length * W(2)).0
pieces_length.checked_mul(2).unwrap_or(0)
}
}
}