Skip to content

Optimized string FromIterator + Extend impls #56548

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Dec 6, 2018
Merged

Optimized string FromIterator + Extend impls #56548

Changes from 2 commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
180dcc3
Optimized string FromIterator impls
Lucretiel Dec 5, 2018
823dd8c
Fixed mutability
Lucretiel Dec 5, 2018
811a2bf
Added explainatory comments
Lucretiel Dec 6, 2018
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
41 changes: 23 additions & 18 deletions src/liballoc/string.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1732,18 +1732,31 @@ impl<'a> FromIterator<&'a str> for String {
#[stable(feature = "extend_string", since = "1.4.0")]
impl FromIterator<String> for String {
fn from_iter<I: IntoIterator<Item = String>>(iter: I) -> String {
let mut buf = String::new();
buf.extend(iter);
buf
let mut iterator = iter.into_iter();

match iterator.next() {
None => String::new(),
Some(mut buf) => {
buf.extend(iterator);
buf
}
}
}
}

#[stable(feature = "herd_cows", since = "1.19.0")]
impl<'a> FromIterator<Cow<'a, str>> for String {
fn from_iter<I: IntoIterator<Item = Cow<'a, str>>>(iter: I) -> String {
let mut buf = String::new();
buf.extend(iter);
buf
let mut iterator = iter.into_iter();

match iterator.next() {
None => String::new(),
Some(cow) => {
let mut buf = cow.into_owned();
buf.extend(iterator);
buf
}
}
}
}

Expand All @@ -1753,9 +1766,7 @@ impl Extend<char> for String {
let iterator = iter.into_iter();
let (lower_bound, _) = iterator.size_hint();
self.reserve(lower_bound);
for ch in iterator {
self.push(ch)
}
iterator.for_each(move |c| self.push(c));
}
}

Expand All @@ -1769,27 +1780,21 @@ impl<'a> Extend<&'a char> for String {
#[stable(feature = "rust1", since = "1.0.0")]
impl<'a> Extend<&'a str> for String {
fn extend<I: IntoIterator<Item = &'a str>>(&mut self, iter: I) {
for s in iter {
self.push_str(s)
}
iter.into_iter().for_each(move |s| self.push_str(s));
}
}

#[stable(feature = "extend_string", since = "1.4.0")]
impl Extend<String> for String {
fn extend<I: IntoIterator<Item = String>>(&mut self, iter: I) {
for s in iter {
self.push_str(&s)
}
iter.into_iter().for_each(move |s| self.push_str(&s));
}
}

#[stable(feature = "herd_cows", since = "1.19.0")]
impl<'a> Extend<Cow<'a, str>> for String {
fn extend<I: IntoIterator<Item = Cow<'a, str>>>(&mut self, iter: I) {
for s in iter {
self.push_str(&s)
}
iter.into_iter().for_each(move |s| self.push_str(&s));
}
}

Expand Down