From 5478ebb553c5b0df91efde8d9da4b0eaac6c91fa Mon Sep 17 00:00:00 2001
From: Brandon Sanderson <singingboyo@hotmail.com>
Date: Sat, 24 Aug 2013 00:22:40 -0700
Subject: [PATCH] Add with_mem_writer to std::rt::io::mem.

This is in many ways a replacement for the current
std::io::with_str_writer.
---
 src/libstd/rt/io/mem.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/libstd/rt/io/mem.rs b/src/libstd/rt/io/mem.rs
index b278f10aed083..808e9f3a383e1 100644
--- a/src/libstd/rt/io/mem.rs
+++ b/src/libstd/rt/io/mem.rs
@@ -196,6 +196,14 @@ impl<'self> Seek for BufReader<'self> {
     fn seek(&mut self, _pos: i64, _style: SeekStyle) { fail!() }
 }
 
+///Calls a function with a MemWriter and returns
+///the writer's stored vector.
+pub fn with_mem_writer(writeFn:&fn(&mut MemWriter)) -> ~[u8] {
+  let mut writer = MemWriter::new();
+  writeFn(&mut writer);
+  writer.inner()
+}
+
 #[cfg(test)]
 mod test {
     use prelude::*;
@@ -255,4 +263,10 @@ mod test {
         assert_eq!(reader.read(buf), None);
         assert!(reader.eof());
     }
+
+    #[test]
+    fn test_with_mem_writer() {
+        let buf = with_mem_writer(|wr| wr.write([1,2,3,4,5,6,7]));
+        assert_eq!(buf, ~[1,2,3,4,5,6,7]);
+    }
 }