From a99e698628cbd396c8100ef776d10ac61d911847 Mon Sep 17 00:00:00 2001
From: Aaron Turon <aturon@mozilla.com>
Date: Wed, 11 Feb 2015 23:16:32 -0800
Subject: Stabilize std::borrow

This commit stabilizes `std::borrow`, making the following modifications
to catch up the API with language changes:

* It renames `BorrowFrom` to `Borrow`, as was originally intended (but
  blocked for technical reasons), and reorders the parameters
  accordingly.

* It moves the type parameter of `ToOwned` to an associated type. This
  is somewhat less flexible, in that each borrowed type must have a
  unique owned type, but leads to a significant simplification for
  `Cow`. Flexibility can be regained by using newtyped slices, which is
  advisable for other reasons anyway.

* It removes the owned type parameter from `Cow`, making the type much
  less verbose.

* Deprecates the `is_owned` and `is_borrowed` predicates in favor of
  direct matching.

The above API changes are relatively minor; the basic functionality
remains the same, and essentially the whole module is now marked
`#[stable]`.

[breaking-change]
---
 src/libcollections/string.rs | 35 +++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

(limited to 'src/libcollections/string.rs')

diff --git a/src/libcollections/string.rs b/src/libcollections/string.rs
index 69fd28d1723..f03ee671ffa 100644
--- a/src/libcollections/string.rs
+++ b/src/libcollections/string.rs
@@ -16,7 +16,6 @@
 
 use core::prelude::*;
 
-use core::borrow::{Cow, IntoCow};
 use core::default::Default;
 use core::error::Error;
 use core::fmt;
@@ -29,6 +28,7 @@ use core::raw::Slice as RawSlice;
 use unicode::str as unicode_str;
 use unicode::str::Utf16Item;
 
+use borrow::{Cow, IntoCow};
 use str::{self, CharRange, FromStr, Utf8Error};
 use vec::{DerefVec, Vec, as_vec};
 
@@ -142,7 +142,7 @@ impl String {
     /// assert_eq!(output.as_slice(), "Hello \u{FFFD}World");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> CowString<'a> {
+    pub fn from_utf8_lossy<'a>(v: &'a [u8]) -> Cow<'a, str> {
         let mut i = 0;
         match str::from_utf8(v) {
             Ok(s) => return Cow::Borrowed(s),
@@ -780,10 +780,10 @@ macro_rules! impl_eq {
 }
 
 impl_eq! { String, &'a str }
-impl_eq! { CowString<'a>, String }
+impl_eq! { Cow<'a, str>, String }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, 'b> PartialEq<&'b str> for CowString<'a> {
+impl<'a, 'b> PartialEq<&'b str> for Cow<'a, str> {
     #[inline]
     fn eq(&self, other: &&'b str) -> bool { PartialEq::eq(&**self, &**other) }
     #[inline]
@@ -791,11 +791,11 @@ impl<'a, 'b> PartialEq<&'b str> for CowString<'a> {
 }
 
 #[stable(feature = "rust1", since = "1.0.0")]
-impl<'a, 'b> PartialEq<CowString<'a>> for &'b str {
+impl<'a, 'b> PartialEq<Cow<'a, str>> for &'b str {
     #[inline]
-    fn eq(&self, other: &CowString<'a>) -> bool { PartialEq::eq(&**self, &**other) }
+    fn eq(&self, other: &Cow<'a, str>) -> bool { PartialEq::eq(&**self, &**other) }
     #[inline]
-    fn ne(&self, other: &CowString<'a>) -> bool { PartialEq::ne(&**self, &**other) }
+    fn ne(&self, other: &Cow<'a, str>) -> bool { PartialEq::ne(&**self, &**other) }
 }
 
 #[unstable(feature = "collections", reason = "waiting on Str stabilization")]
@@ -958,31 +958,34 @@ impl<T: fmt::Display + ?Sized> ToString for T {
     }
 }
 
-impl IntoCow<'static, String, str> for String {
+#[stable(feature = "rust1", since = "1.0.0")]
+impl IntoCow<'static, str> for String {
     #[inline]
-    fn into_cow(self) -> CowString<'static> {
+    fn into_cow(self) -> Cow<'static, str> {
         Cow::Owned(self)
     }
 }
 
-impl<'a> IntoCow<'a, String, str> for &'a str {
+#[stable(feature = "rust1", since = "1.0.0")]
+impl<'a> IntoCow<'a, str> for &'a str {
     #[inline]
-    fn into_cow(self) -> CowString<'a> {
+    fn into_cow(self) -> Cow<'a, str> {
         Cow::Borrowed(self)
     }
 }
 
-/// A clone-on-write string
-#[stable(feature = "rust1", since = "1.0.0")]
-pub type CowString<'a> = Cow<'a, String, str>;
-
-impl<'a> Str for CowString<'a> {
+impl<'a> Str for Cow<'a, str> {
     #[inline]
     fn as_slice<'b>(&'b self) -> &'b str {
         &**self
     }
 }
 
+/// A clone-on-write string
+#[deprecated(since = "1.0.0", reason = "use Cow<'a, str> instead")]
+#[stable(feature = "rust1", since = "1.0.0")]
+pub type CowString<'a> = Cow<'a, str>;
+
 #[stable(feature = "rust1", since = "1.0.0")]
 impl fmt::Write for String {
     #[inline]
-- 
cgit 1.4.1-3-g733a5