From 1042f095ee3ecebc5406a7a789de328c9692c7b5 Mon Sep 17 00:00:00 2001
From: Jack Christensen <jack@jackchristensen.com>
Date: Sun, 30 Jun 2013 09:25:19 -0500
Subject: [PATCH] More pluggable value transcoding

---
 data_row_reader.go  | 63 +++++-------------------------
 value_transcoder.go | 94 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 103 insertions(+), 54 deletions(-)
 create mode 100644 value_transcoder.go

diff --git a/data_row_reader.go b/data_row_reader.go
index d37d0813..55072fe0 100644
--- a/data_row_reader.go
+++ b/data_row_reader.go
@@ -1,13 +1,9 @@
 package pgx
 
-import (
-	"fmt"
-	"strconv"
-)
-
 type DataRowReader struct {
-	mr     *MessageReader
-	fields []FieldDescription
+	mr              *MessageReader
+	fields          []FieldDescription
+	currentFieldIdx int
 }
 
 func newDataRowReader(mr *MessageReader, fields []FieldDescription) (r *DataRowReader) {
@@ -24,55 +20,14 @@ func newDataRowReader(mr *MessageReader, fields []FieldDescription) (r *DataRowR
 }
 
 func (r *DataRowReader) ReadValue() interface{} {
+	dataType := r.fields[r.currentFieldIdx].DataType
+	r.currentFieldIdx++
+
 	size := r.mr.ReadInt32()
 	if size > -1 {
-		switch r.fields[0].DataType {
-		case oid(16): // bool
-			s := r.mr.ReadByteString(size)
-			switch s {
-			case "t":
-				return true
-			case "f":
-				return false
-			default:
-				panic(fmt.Sprintf("Received invalid bool: %v", s))
-			}
-		case oid(20): // int8
-			s := r.mr.ReadByteString(size)
-			n, err := strconv.ParseInt(s, 10, 64)
-			if err != nil {
-				panic(fmt.Sprintf("Received invalid int8: %v", s))
-			}
-			return n
-		case oid(21): // int2
-			s := r.mr.ReadByteString(size)
-			n, err := strconv.ParseInt(s, 10, 16)
-			if err != nil {
-				panic(fmt.Sprintf("Received invalid int2: %v", s))
-			}
-			return int16(n)
-		case oid(23): // int4
-			s := r.mr.ReadByteString(size)
-			n, err := strconv.ParseInt(s, 10, 32)
-			if err != nil {
-				panic(fmt.Sprintf("Received invalid int4: %v", s))
-			}
-			return int32(n)
-		case oid(700): // float4
-			s := r.mr.ReadByteString(size)
-			n, err := strconv.ParseFloat(s, 32)
-			if err != nil {
-				panic(fmt.Sprintf("Received invalid float4: %v", s))
-			}
-			return float32(n)
-		case oid(701): //float8
-			s := r.mr.ReadByteString(size)
-			v, err := strconv.ParseFloat(s, 64)
-			if err != nil {
-				panic(fmt.Sprintf("Received invalid float8: %v", s))
-			}
-			return v
-		default:
+		if vt, present := valueTranscoders[dataType]; present {
+			return vt.FromText(r.mr, size)
+		} else {
 			return r.mr.ReadByteString(size)
 		}
 	} else {
diff --git a/value_transcoder.go b/value_transcoder.go
new file mode 100644
index 00000000..a072b976
--- /dev/null
+++ b/value_transcoder.go
@@ -0,0 +1,94 @@
+package pgx
+
+import (
+	"fmt"
+	"strconv"
+)
+
+type valueTranscoder struct {
+	FromText func(*MessageReader, int32) interface{}
+	// FromBinary func(*MessageReader, int32) interface{}
+	// ToText func(interface{}) string
+	// ToBinary func(interface{}) []byte
+}
+
+var valueTranscoders map[oid]*valueTranscoder
+
+func init() {
+	valueTranscoders = make(map[oid]*valueTranscoder)
+
+	// bool
+	valueTranscoders[oid(16)] = &valueTranscoder{FromText: decodeBoolFromText}
+
+	// int8
+	valueTranscoders[oid(20)] = &valueTranscoder{FromText: decodeInt8FromText}
+
+	// int2
+	valueTranscoders[oid(21)] = &valueTranscoder{FromText: decodeInt2FromText}
+
+	// int4
+	valueTranscoders[oid(23)] = &valueTranscoder{FromText: decodeInt4FromText}
+
+	// float4
+	valueTranscoders[oid(700)] = &valueTranscoder{FromText: decodeFloat4FromText}
+
+	// float8
+	valueTranscoders[oid(701)] = &valueTranscoder{FromText: decodeFloat8FromText}
+}
+
+func decodeBoolFromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	switch s {
+	case "t":
+		return true
+	case "f":
+		return false
+	default:
+		panic(fmt.Sprintf("Received invalid bool: %v", s))
+	}
+}
+
+func decodeInt8FromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	n, err := strconv.ParseInt(s, 10, 64)
+	if err != nil {
+		panic(fmt.Sprintf("Received invalid int8: %v", s))
+	}
+	return n
+}
+
+func decodeInt2FromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	n, err := strconv.ParseInt(s, 10, 16)
+	if err != nil {
+		panic(fmt.Sprintf("Received invalid int2: %v", s))
+	}
+	return int16(n)
+}
+
+func decodeInt4FromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	n, err := strconv.ParseInt(s, 10, 32)
+	if err != nil {
+		panic(fmt.Sprintf("Received invalid int4: %v", s))
+	}
+	return int32(n)
+}
+
+func decodeFloat4FromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	n, err := strconv.ParseFloat(s, 32)
+	if err != nil {
+		panic(fmt.Sprintf("Received invalid float4: %v", s))
+	}
+	return float32(n)
+}
+
+func decodeFloat8FromText(mr *MessageReader, size int32) interface{} {
+	s := mr.ReadByteString(size)
+	v, err := strconv.ParseFloat(s, 64)
+	if err != nil {
+		panic(fmt.Sprintf("Received invalid float8: %v", s))
+	}
+	return v
+}