---

yaml
---
r: 223423
b: refs/heads/beta
c: a6dd203
h: refs/heads/master
i:
  223421: 63170ff
  223419: ccd8faa
  223415: 3b99f4e
  223407: e2e2764
  223391: 4f764ea
  223359: 2c5a508
v: v3

Author: Ulrik Sverdrup

[refs]

@@ -23,7 +23,7 @@ refs/tags/0.9: 36870b185fc5f5486636d4515f0e22677493f225
 refs/tags/0.10: ac33f2b15782272ae348dbd7b14b8257b2148b5a
 refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
-refs/heads/beta: b890b7bbc732cd26f13c309573b5a3e45d0748de
+refs/heads/beta: a6dd2031a363d0b46caea06ef77209f678327719
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
 refs/heads/tmp: 938f5d7af401e2d8238522fed4a612943b6e77fd
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f

branches/beta/src/libcore/str/pattern.rs

@@ -343,23 +343,6 @@ unsafe impl<'a, C: CharEq> ReverseSearcher<'a> for CharEqSearcher<'a, C> {
 
 impl<'a, C: CharEq> DoubleEndedSearcher<'a> for CharEqSearcher<'a, C> {}
 
-/////////////////////////////////////////////////////////////////////////////
-// Impl for &str
-/////////////////////////////////////////////////////////////////////////////
-
-/// Non-allocating substring search.
-///
-/// Will handle the pattern `""` as returning empty matches at each character
-/// boundary.
-impl<'a, 'b> Pattern<'a> for &'b str {
-    type Searcher = StrSearcher<'a, 'b>;
-
-    #[inline]
-    fn into_searcher(self, haystack: &'a str) -> StrSearcher<'a, 'b> {
-        StrSearcher::new(haystack, self)
-    }
-}
-
 /////////////////////////////////////////////////////////////////////////////
 
 macro_rules! pattern_methods {
@@ -511,6 +494,39 @@ impl<'a, 'b> Pattern<'a> for &'b &'b str {
     pattern_methods!(StrSearcher<'a, 'b>, |&s| s, |s| s);
 }
 
+/////////////////////////////////////////////////////////////////////////////
+// Impl for &str
+/////////////////////////////////////////////////////////////////////////////
+
+/// Non-allocating substring search.
+///
+/// Will handle the pattern `""` as returning empty matches at each character
+/// boundary.
+impl<'a, 'b> Pattern<'a> for &'b str {
+    type Searcher = StrSearcher<'a, 'b>;
+
+    #[inline]
+    fn into_searcher(self, haystack: &'a str) -> StrSearcher<'a, 'b> {
+        StrSearcher::new(haystack, self)
+    }
+
+    /// Checks whether the pattern matches at the front of the haystack
+    #[inline]
+    fn is_prefix_of(self, haystack: &'a str) -> bool {
+        // Use `as_bytes` so that we can slice through a character in the haystack.
+        // Since self is always valid UTF-8, this can't result in a false positive.
+        self.len() <= haystack.len() &&
+            self.as_bytes() == &haystack.as_bytes()[..self.len()]
+    }
+
+    /// Checks whether the pattern matches at the back of the haystack
+    #[inline]
+    fn is_suffix_of(self, haystack: &'a str) -> bool {
+        self.len() <= haystack.len() &&
+            self.as_bytes() == &haystack.as_bytes()[haystack.len() - self.len()..]
+    }
+}
+
 
 /////////////////////////////////////////////////////////////////////////////
 // Two Way substring searcher