---

yaml
---
r: 220535
b: refs/heads/tmp
c: 7469914
h: refs/heads/master
i:
  220533: d9479b6
  220531: f7db19a
  220527: fecf5f9
v: v3

Author: SimonSapin

[refs]

@@ -25,7 +25,7 @@ refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
 refs/heads/beta: c8bab9d06a179028a0d5129aa62f09d694d9cc49
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
-refs/heads/tmp: f9005512a9d84f469b30f0d469ccc401607ce64c
+refs/heads/tmp: 7469914e96a511487e8248d2f8a583befb02149f
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: 1b28ffa5216c845d1cef6b0cb3e5ac7db12025d0
 refs/tags/1.0.0-beta: 8cbb92b53468ee2b0c2d3eeb8567005953d40828

branches/tmp/src/libcollections/str.rs

@@ -793,6 +793,12 @@ impl str {
         core_str::StrExt::split_at(self, mid)
     }
 
+    /// Divide one mutable string slice into two at an index.
+    #[inline]
+    pub fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str) {
+        core_str::StrExt::split_at_mut(self, mid)
+    }
+
     /// An iterator over the codepoints of `self`.
     ///
     /// # Examples

branches/tmp/src/libcollectionstest/lib.rs

@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(ascii)]
 #![feature(append)]
 #![feature(bitset)]
 #![feature(bitvec)]

branches/tmp/src/libcollectionstest/str.rs

@@ -701,6 +701,18 @@ fn test_split_at() {
     assert_eq!(b, "");
 }
 
+#[test]
+fn test_split_at_mut() {
+    use std::ascii::AsciiExt;
+    let mut s = "Hello World".to_string();
+    {
+        let (a, b) = s.split_at_mut(5);
+        a.make_ascii_uppercase();
+        b.make_ascii_lowercase();
+    }
+    assert_eq!(s, "HELLO world");
+}
+
 #[test]
 #[should_panic]
 fn test_split_at_boundscheck() {

branches/tmp/src/libcore/str/mod.rs

@@ -1279,6 +1279,7 @@ pub trait StrExt {
         where P::Searcher: ReverseSearcher<'a>;
     fn find_str<'a, P: Pattern<'a>>(&'a self, pat: P) -> Option<usize>;
     fn split_at(&self, mid: usize) -> (&str, &str);
+    fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str);
     fn slice_shift_char<'a>(&'a self) -> Option<(char, &'a str)>;
     fn subslice_offset(&self, inner: &str) -> usize;
     fn as_ptr(&self) -> *const u8;
@@ -1591,6 +1592,20 @@ impl StrExt for str {
         }
     }
 
+    fn split_at_mut(&mut self, mid: usize) -> (&mut str, &mut str) {
+        // is_char_boundary checks that the index is in [0, .len()]
+        if self.is_char_boundary(mid) {
+            let len = self.len();
+            unsafe {
+                let self2: &mut str = mem::transmute_copy(&self);
+                (self.slice_mut_unchecked(0, mid),
+                 self2.slice_mut_unchecked(mid, len))
+            }
+        } else {
+            slice_error_fail(self, 0, mid)
+        }
+    }
+
     #[inline]
     fn slice_shift_char(&self) -> Option<(char, &str)> {
         if self.is_empty() {