From 5325d0140732d8287c5bb102ea8fbfc4fb0ef83f Mon Sep 17 00:00:00 2001
From: Chen Yufei <cyfdecyf@gmail.com>
Date: Wed, 3 Jun 2015 00:47:10 +0800
Subject: [PATCH] Remove unused function copyNWithBuf.

---
 util.go      | 61 ----------------------------------------------------
 util_test.go | 54 ----------------------------------------------
 2 files changed, 115 deletions(-)

diff --git a/util.go b/util.go
index b3e3134..03ae87a 100644
--- a/util.go
+++ b/util.go
@@ -281,67 +281,6 @@ func copyN(dst io.Writer, src *bufio.Reader, n, rdSize int) (err error) {
 	return err
 }
 
-// copyNWithBuf copys N bytes from src to dst, using the specified buf as buffer. pre and
-// end are written to w before and after the n bytes. copyN will try to
-// minimize number of writes.
-// No longer used now.
-func copyNWithBuf(dst io.Writer, src io.Reader, n int, buf, pre, end []byte) (err error) {
-	// XXX well, this is complicated in order to save writes
-	var nn int
-	bufLen := len(buf)
-	var b []byte
-	for n != 0 {
-		if pre != nil {
-			if len(pre) >= bufLen {
-				// pre is larger than bufLen, can't save write operation here
-				if _, err = dst.Write(pre); err != nil {
-					return
-				}
-				pre = nil
-				continue
-			}
-			// append pre to buf to save one write
-			copy(buf, pre)
-			if len(pre)+n < bufLen {
-				// only need to read n bytes
-				b = buf[len(pre) : len(pre)+n]
-			} else {
-				b = buf[len(pre):]
-			}
-		} else {
-			if n < bufLen {
-				b = buf[:n]
-			} else {
-				b = buf
-			}
-		}
-		if nn, err = src.Read(b); err != nil {
-			return
-		}
-		n -= nn
-		if pre != nil {
-			// nn is how much we need to write next
-			nn += len(pre)
-			pre = nil
-		}
-		// see if we can append end in buffer to save one write
-		if n == 0 && end != nil && nn+len(end) <= bufLen {
-			copy(buf[nn:], end)
-			nn += len(end)
-			end = nil
-		}
-		if _, err = dst.Write(buf[:nn]); err != nil {
-			return
-		}
-	}
-	if end != nil {
-		if _, err = dst.Write(end); err != nil {
-			return
-		}
-	}
-	return
-}
-
 func md5sum(ss ...string) string {
 	h := md5.New()
 	for _, s := range ss {
diff --git a/util_test.go b/util_test.go
index 031374d..42a623d 100644
--- a/util_test.go
+++ b/util_test.go
@@ -202,60 +202,6 @@ func TestCopyN(t *testing.T) {
 	}
 }
 
-func TestCopyNWithBuf(t *testing.T) {
-	testStr := "hello world"
-	src := bytes.NewBufferString(testStr)
-	dst := new(bytes.Buffer)
-	buf := make([]byte, 5)
-
-	copyNWithBuf(dst, src, len(testStr), buf, nil, nil)
-	if dst.String() != "hello world" {
-		t.Error("copy without pre and end failed, got:", dst.String())
-	}
-
-	src.Reset()
-	dst.Reset()
-	src.WriteString(testStr)
-	copyNWithBuf(dst, src, len(testStr), buf, []byte("by cyf "), nil)
-	if dst.String() != "by cyf hello world" {
-		t.Error("copy with pre no end failed, got:", dst.String())
-	}
-
-	src.Reset()
-	dst.Reset()
-	src.WriteString(testStr)
-	copyNWithBuf(dst, src, len(testStr), buf, []byte("by cyf "), []byte(" welcome"))
-	if dst.String() != "by cyf hello world welcome" {
-		t.Error("copy with both pre and end failed, got:", dst.String())
-	}
-
-	src.Reset()
-	dst.Reset()
-	src.WriteString(testStr)
-	copyNWithBuf(dst, src, len(testStr), buf, []byte("pre longer then buffer "), []byte(" welcome"))
-	if dst.String() != "pre longer then buffer hello world welcome" {
-		t.Error("copy with long pre failed, got:", dst.String())
-	}
-
-	src.Reset()
-	dst.Reset()
-	testStr = "34"
-	src.WriteString(testStr)
-	copyNWithBuf(dst, src, len(testStr), buf, []byte("12"), []byte(" welcome"))
-	if dst.String() != "1234 welcome" {
-		t.Error("copy len(pre)+size<bufLen failed, got:", dst.String())
-	}
-
-	src.Reset()
-	dst.Reset()
-	testStr = "2"
-	src.WriteString(testStr)
-	copyNWithBuf(dst, src, len(testStr), buf, []byte("1"), []byte("34"))
-	if dst.String() != "1234" {
-		t.Error("copy len(pre)+size+len(end)<bufLen failed, got:", dst.String())
-	}
-}
-
 func TestIsFileExists(t *testing.T) {
 	err := isFileExists("testdata")
 	if err == nil {