From a5cc17adaadf9bc4da3b6b375879fda55ed823c9 Mon Sep 17 00:00:00 2001
From: Ulrik Sverdrup <bluss@users.noreply.github.com>
Date: Wed, 8 Jul 2015 03:20:00 +0200
Subject: io: Simplify BufReader::with_capacity

Use the vec![] macro directly to create a sized, zeroed vector.

This should result in a big speedup when creating BufReader, because
vec![0; cap] compiles to a memset call, while the previous extend code
currently did not.
---
 src/libstd/io/buffered.rs | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

(limited to 'src/libstd')

diff --git a/src/libstd/io/buffered.rs b/src/libstd/io/buffered.rs
index 1d0152e2751..28033b4c1a9 100644
--- a/src/libstd/io/buffered.rs
+++ b/src/libstd/io/buffered.rs
@@ -19,7 +19,6 @@ use error;
 use fmt;
 use io::{self, DEFAULT_BUF_SIZE, Error, ErrorKind, SeekFrom};
 use ptr;
-use iter;
 
 /// Wraps a `Read` and buffers input from it
 ///
@@ -63,11 +62,9 @@ impl<R: Read> BufReader<R> {
     /// Creates a new `BufReader` with the specified buffer capacity
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn with_capacity(cap: usize, inner: R) -> BufReader<R> {
-        let mut buf = Vec::with_capacity(cap);
-        buf.extend(iter::repeat(0).take(cap));
         BufReader {
             inner: inner,
-            buf: buf,
+            buf: vec![0; cap],
             pos: 0,
             cap: 0,
         }
-- 
cgit 1.4.1-3-g733a5