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Fix issues with the Add/AddAssign impls for Cow<str> #37574

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merged 1 commit into from
Nov 6, 2016
Merged

Fix issues with the Add/AddAssign impls for Cow<str> #37574

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61 changes: 37 additions & 24 deletions src/libcollections/borrow.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ use core::hash::{Hash, Hasher};
use core::ops::{Add, AddAssign, Deref};

use fmt;
use string::String;

use self::Cow::*;

Expand Down Expand Up @@ -284,48 +285,60 @@ impl<'a, T: ?Sized + ToOwned> AsRef<T> for Cow<'a, T> {
}
}

#[stable(feature = "cow_add", since = "1.13.0")]
#[stable(feature = "cow_add", since = "1.14.0")]
impl<'a> Add<&'a str> for Cow<'a, str> {
type Output = Cow<'a, str>;

fn add(self, rhs: &'a str) -> Self {
if self == "" {
Cow::Borrowed(rhs)
} else if rhs == "" {
self
} else {
Cow::Owned(self.into_owned() + rhs)
}
#[inline]
fn add(mut self, rhs: &'a str) -> Self::Output {
self += rhs;
self
}
}

#[stable(feature = "cow_add", since = "1.13.0")]
#[stable(feature = "cow_add", since = "1.14.0")]
impl<'a> Add<Cow<'a, str>> for Cow<'a, str> {
type Output = Cow<'a, str>;

fn add(self, rhs: Cow<'a, str>) -> Self {
if self == "" {
rhs
} else if rhs == "" {
self
} else {
Cow::Owned(self.into_owned() + rhs.borrow())
}
#[inline]
fn add(mut self, rhs: Cow<'a, str>) -> Self::Output {
self += rhs;
self
}
}

#[stable(feature = "cow_add", since = "1.13.0")]
#[stable(feature = "cow_add", since = "1.14.0")]
impl<'a> AddAssign<&'a str> for Cow<'a, str> {
fn add_assign(&mut self, rhs: &'a str) {
if rhs == "" { return; }
self.to_mut().push_str(rhs);
if self.is_empty() {
*self = Cow::Borrowed(rhs)
} else if rhs.is_empty() {
return;
} else {
if let Cow::Borrowed(lhs) = *self {
let mut s = String::with_capacity(lhs.len() + rhs.len());
s.push_str(lhs);
*self = Cow::Owned(s);
}
self.to_mut().push_str(rhs);
}
}
}

#[stable(feature = "cow_add", since = "1.13.0")]
#[stable(feature = "cow_add", since = "1.14.0")]
impl<'a> AddAssign<Cow<'a, str>> for Cow<'a, str> {
fn add_assign(&mut self, rhs: Cow<'a, str>) {
if rhs == "" { return; }
self.to_mut().push_str(rhs.borrow());
if self.is_empty() {
*self = rhs
} else if rhs.is_empty() {
return;
} else {
if let Cow::Borrowed(lhs) = *self {
let mut s = String::with_capacity(lhs.len() + rhs.len());
s.push_str(lhs);
*self = Cow::Owned(s);
}
self.to_mut().push_str(&rhs);
}
}
}
134 changes: 105 additions & 29 deletions src/libcollectionstest/cow_str.rs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright 2012-2013-2014 The Rust Project Developers. See the COPYRIGHT
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
Expand All @@ -12,54 +12,130 @@ use std::borrow::Cow;

// check that Cow<'a, str> implements addition
#[test]
fn check_cow_add() {
borrowed1 = Cow::Borrowed("Hello, ");
borrowed2 = Cow::Borrowed("World!");
borrow_empty = Cow::Borrowed("");
fn check_cow_add_cow() {
let borrowed1 = Cow::Borrowed("Hello, ");
let borrowed2 = Cow::Borrowed("World!");
let borrow_empty = Cow::Borrowed("");

owned1 = Cow::Owned("Hi, ".into());
owned2 = Cow::Owned("Rustaceans!".into());
owned_empty = Cow::Owned("".into());
let owned1: Cow<str> = Cow::Owned(String::from("Hi, "));
let owned2: Cow<str> = Cow::Owned(String::from("Rustaceans!"));
let owned_empty: Cow<str> = Cow::Owned(String::new());

assert_eq!("Hello, World!", borrowed1 + borrowed2);
assert_eq!("Hello, Rustaceans!", borrowed1 + owned2);
assert_eq!("Hello, World!", borrowed1.clone() + borrowed2.clone());
assert_eq!("Hello, Rustaceans!", borrowed1.clone() + owned2.clone());

assert_eq!("Hello, World!", owned1 + borrowed2);
assert_eq!("Hello, Rustaceans!", owned1 + owned2);
assert_eq!("Hi, World!", owned1.clone() + borrowed2.clone());
assert_eq!("Hi, Rustaceans!", owned1.clone() + owned2.clone());

if let Cow::Owned(_) = borrowed1 + borrow_empty {
if let Cow::Owned(_) = borrowed1.clone() + borrow_empty.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrow_empty + borrowed1 {
if let Cow::Owned(_) = borrow_empty.clone() + borrowed1.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrowed1 + owned_empty {
if let Cow::Owned(_) = borrowed1.clone() + owned_empty.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = owned_empty + borrowed1 {
if let Cow::Owned(_) = owned_empty.clone() + borrowed1.clone() {
panic!("Adding empty strings to a borrow should note allocate");
}
}

fn check_cow_add_assign() {
borrowed1 = Cow::Borrowed("Hello, ");
borrowed2 = Cow::Borrowed("World!");
borrow_empty = Cow::Borrowed("");
#[test]
fn check_cow_add_str() {
let borrowed = Cow::Borrowed("Hello, ");
let borrow_empty = Cow::Borrowed("");

let owned: Cow<str> = Cow::Owned(String::from("Hi, "));
let owned_empty: Cow<str> = Cow::Owned(String::new());

owned1 = Cow::Owned("Hi, ".into());
owned2 = Cow::Owned("Rustaceans!".into());
owned_empty = Cow::Owned("".into());
assert_eq!("Hello, World!", borrowed.clone() + "World!");

let borrowed1clone = borrowed1.clone();
borrowed1clone += borrow_empty;
assert_eq!((&borrowed1clone).as_ptr(), (&borrowed1).as_ptr());
assert_eq!("Hi, World!", owned.clone() + "World!");

borrowed1clone += owned_empty;
assert_eq!((&borrowed1clone).as_ptr(), (&borrowed1).as_ptr());
if let Cow::Owned(_) = borrowed.clone() + "" {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = borrow_empty.clone() + "Hello, " {
panic!("Adding empty strings to a borrow should note allocate");
}
if let Cow::Owned(_) = owned_empty.clone() + "Hello, " {
panic!("Adding empty strings to a borrow should note allocate");
}
}

#[test]
fn check_cow_add_assign_cow() {
let mut borrowed1 = Cow::Borrowed("Hello, ");
let borrowed2 = Cow::Borrowed("World!");
let borrow_empty = Cow::Borrowed("");

let mut owned1: Cow<str> = Cow::Owned(String::from("Hi, "));
let owned2: Cow<str> = Cow::Owned(String::from("Rustaceans!"));
let owned_empty: Cow<str> = Cow::Owned(String::new());

let mut s = borrowed1.clone();
s += borrow_empty.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrow_empty.clone();
s += borrowed1.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrowed1.clone();
s += owned_empty.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = owned_empty.clone();
s += borrowed1.clone();
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}

owned1 += borrowed2;
borrowed1 += owned2;

assert_eq!("Hello, World!", owned1);
assert_eq!("Hi, World!", owned1);
assert_eq!("Hello, Rustaceans!", borrowed1);
}

#[test]
fn check_cow_add_assign_str() {
let mut borrowed = Cow::Borrowed("Hello, ");
let borrow_empty = Cow::Borrowed("");

let mut owned: Cow<str> = Cow::Owned(String::from("Hi, "));
let owned_empty: Cow<str> = Cow::Owned(String::new());

let mut s = borrowed.clone();
s += "";
assert_eq!("Hello, ", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = borrow_empty.clone();
s += "World!";
assert_eq!("World!", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}
let mut s = owned_empty.clone();
s += "World!";
assert_eq!("World!", s);
if let Cow::Owned(_) = s {
panic!("Adding empty strings to a borrow should note allocate");
}

owned += "World!";
borrowed += "World!";

assert_eq!("Hi, World!", owned);
assert_eq!("Hello, World!", borrowed);
}
1 change: 1 addition & 0 deletions src/libcollectionstest/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -42,6 +42,7 @@ mod bench;

mod binary_heap;
mod btree;
mod cow_str;
mod enum_set;
mod fmt;
mod linked_list;
Expand Down