From 07b6385f1de836b6c84b6e5f35e06e5e9dbc0b1b Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Tue, 9 Jul 2013 17:22:30 -0500
Subject: [PATCH] Started refactor to messageWriter

---
 connection.go     | 41 +++++++++--------------------------------
 message_writer.go | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+), 32 deletions(-)
 create mode 100644 message_writer.go

diff --git a/connection.go b/connection.go
index 82477838..8efd2d54 100644
--- a/connection.go
+++ b/connection.go
@@ -219,27 +219,13 @@ func (c *Connection) SelectValues(sql string, arguments ...interface{}) (values
 func (c *Connection) Prepare(name, sql string) (err error) {
 	// parse
 	buf := c.getBuf()
-	_, err = buf.WriteString(name)
-	if err != nil {
-		return
+	w := newMessageWriter(buf)
+	w.writeStringNull(name)
+	w.writeStringNull(sql)
+	w.write(int16(0))
+	if w.err != nil {
+		return w.err
 	}
-	err = buf.WriteByte(0)
-	if err != nil {
-		return
-	}
-	_, err = buf.WriteString(sql)
-	if err != nil {
-		return
-	}
-	err = buf.WriteByte(0)
-	if err != nil {
-		return
-	}
-	err = binary.Write(buf, binary.BigEndian, int16(0))
-	if err != nil {
-		return
-	}
-
 	err = c.txMsg('P', buf)
 	if err != nil {
 		return
@@ -247,18 +233,9 @@ func (c *Connection) Prepare(name, sql string) (err error) {
 
 	// describe
 	buf = c.getBuf()
-	err = buf.WriteByte('S')
-	if err != nil {
-		return
-	}
-	_, err = buf.WriteString(name)
-	if err != nil {
-		return
-	}
-	err = buf.WriteByte(0)
-	if err != nil {
-		return
-	}
+	w = newMessageWriter(buf)
+	w.writeByte('S')
+	w.writeStringNull(name)
 
 	err = c.txMsg('D', buf)
 	if err != nil {
diff --git a/message_writer.go b/message_writer.go
new file mode 100644
index 00000000..9a766882
--- /dev/null
+++ b/message_writer.go
@@ -0,0 +1,41 @@
+package pgx
+
+import (
+	"bytes"
+	"encoding/binary"
+)
+
+type messageWriter struct {
+	buf *bytes.Buffer
+	err error
+}
+
+func newMessageWriter(buf *bytes.Buffer) *messageWriter {
+	return &messageWriter{buf: buf}
+}
+
+func (w *messageWriter) writeStringNull(s string) {
+	if w.err != nil {
+		return
+	}
+	if _, w.err = w.buf.WriteString(s); w.err != nil {
+		return
+	}
+	w.err = w.buf.WriteByte(0)
+}
+
+func (w *messageWriter) writeByte(b byte) {
+	if w.err != nil {
+		return
+	}
+
+	w.err = w.buf.WriteByte(b)
+}
+
+func (w *messageWriter) write(data interface{}) {
+	if w.err != nil {
+		return
+	}
+
+	w.err = binary.Write(w.buf, binary.BigEndian, data)
+}