---

yaml
---
r: 15192
b: refs/heads/try
c: 5e42c5c
h: refs/heads/master
v: v3

Author: brson

[refs]

@@ -2,5 +2,5 @@
 refs/heads/master: 61b1875c16de39c166b0f4d54bba19f9c6777d1a
 refs/heads/snap-stage1: e33de59e47c5076a89eadeb38f4934f58a3618a6
 refs/heads/snap-stage3: 4a81779abd786ff22d71434c6d9a5917ea4cdfff
-refs/heads/try: b3d7823381cd2d3d89ba4ca85a709df6622180ab
+refs/heads/try: 5e42c5cf19bea49adc718e8502d364897bebac66
 refs/tags/release-0.1: 1f5c5126e96c79d22cb7862f75304136e204f105

branches/try/src/libcore/str.rs

@@ -93,6 +93,7 @@ export
    is_char_boundary,
    char_at,
    reserve,
+   reserve_at_least,
 
    unsafe;
 
@@ -1505,6 +1506,30 @@ fn reserve(&s: str, n: uint) {
     rustrt::str_reserve_shared(s, n);
 }
 
+#[doc = "
+Reserves capacity for at least `n` bytes in the given string, not including
+the null terminator.
+
+Assuming single-byte characters, the resulting string will be large
+enough to hold a string of length `n`. To account for the null terminator,
+the underlying buffer will have the size `n` + 1.
+
+This function will over-allocate in order to amortize the allocation costs
+in scenarios where the caller may need to repeatedly reserve additional
+space.
+
+If the capacity for `s` is already equal to or greater than the requested
+capacity, then no action is taken.
+
+# Arguments
+
+* s - A string
+* n - The number of bytes to reserve space for
+"]
+fn reserve_at_least(&s: str, n: uint) unsafe {
+    reserve(s, uint::next_power_of_two(n + 1u) - 1u)
+}
+
 #[doc = "Unsafe operations"]
 mod unsafe {
    export