Add pgtype interfaces

conn.go

@@ -7,7 +7,6 @@ import (
 	"encoding/hex"
 	"errors"
 	"fmt"
-	"golang.org/x/net/context"
 	"io"
 	"net"
 	"net/url"
@@ -20,7 +19,10 @@ import (
 	"sync/atomic"
 	"time"
 
+	"golang.org/x/net/context"
+
 	"github.com/jackc/pgx/chunkreader"
+	"github.com/jackc/pgx/pgtype"
 )
 
 const (
@@ -102,6 +104,8 @@ type Conn struct {
 	ctxInProgress bool
 	doneChan      chan struct{}
 	closedChan    chan error
+
+	oidPgtypeValues map[OID]pgtype.Value
 }
 
 // PreparedStatement is a description of a prepared statement
@@ -275,6 +279,16 @@ func (c *Conn) connect(config ConnConfig, network, address string, tlsConfig *tl
 	c.doneChan = make(chan struct{})
 	c.closedChan = make(chan error)
 
+	i2 := pgtype.Int2(0)
+	i4 := pgtype.Int4(0)
+	i8 := pgtype.Int8(0)
+
+	c.oidPgtypeValues = map[OID]pgtype.Value{
+		Int2OID: &i2,
+		Int4OID: &i4,
+		Int8OID: &i8,
+	}
+
 	if tlsConfig != nil {
 		if c.shouldLog(LogLevelDebug) {
 			c.log(LogLevelDebug, "Starting TLS handshake")

pgtype/int2.go

@@ -11,7 +11,7 @@ import (
 
 type Int2 int16
 
-func (i *Int2) Convert(src interface{}) error {
+func (i *Int2) ConvertFrom(src interface{}) error {
 	switch value := src.(type) {
 	case Int2:
 		*i = value
@@ -73,7 +73,7 @@ func (i *Int2) Convert(src interface{}) error {
 		*i = Int2(num)
 	default:
 		if originalSrc, ok := underlyingIntType(src); ok {
-			return i.Convert(originalSrc)
+			return i.ConvertFrom(originalSrc)
 		}
 		return fmt.Errorf("cannot convert %v to Int2", value)
 	}
@@ -81,6 +81,10 @@ func (i *Int2) Convert(src interface{}) error {
 	return nil
 }
 
+func (i *Int2) AssignTo(dst interface{}) error {
+	return nil
+}
+
 func (i *Int2) DecodeText(r io.Reader) error {
 	size, err := pgio.ReadInt32(r)
 	if err != nil {

pgtype/int2_test.go

@@ -86,7 +86,7 @@ func TestInt2Transcode(t *testing.T) {
 	}
 }
 
-func TestInt2Convert(t *testing.T) {
+func TestInt2ConvertFrom(t *testing.T) {
 	type _int8 int8
 
 	successfulTests := []struct {
@@ -111,7 +111,7 @@ func TestInt2Convert(t *testing.T) {
 
 	for i, tt := range successfulTests {
 		var r pgtype.Int2
-		err := r.Convert(tt.source)
+		err := r.ConvertFrom(tt.source)
 		if err != nil {
 			t.Errorf("%d: %v", i, err)
 		}

pgtype/int4.go

@@ -11,7 +11,7 @@ import (
 
 type Int4 int32
 
-func (i *Int4) Convert(src interface{}) error {
+func (i *Int4) ConvertFrom(src interface{}) error {
 	switch value := src.(type) {
 	case Int4:
 		*i = value
@@ -64,7 +64,7 @@ func (i *Int4) Convert(src interface{}) error {
 		*i = Int4(num)
 	default:
 		if originalSrc, ok := underlyingIntType(src); ok {
-			return i.Convert(originalSrc)
+			return i.ConvertFrom(originalSrc)
 		}
 		return fmt.Errorf("cannot convert %v to Int8", value)
 	}
@@ -72,6 +72,10 @@ func (i *Int4) Convert(src interface{}) error {
 	return nil
 }
 
+func (i *Int4) AssignTo(dst interface{}) error {
+	return nil
+}
+
 func (i *Int4) DecodeText(r io.Reader) error {
 	size, err := pgio.ReadInt32(r)
 	if err != nil {

pgtype/int4_test.go

@@ -86,7 +86,7 @@ func TestInt4Transcode(t *testing.T) {
 	}
 }
 
-func TestInt4Convert(t *testing.T) {
+func TestInt4ConvertFrom(t *testing.T) {
 	type _int8 int8
 
 	successfulTests := []struct {
@@ -111,7 +111,7 @@ func TestInt4Convert(t *testing.T) {
 
 	for i, tt := range successfulTests {
 		var r pgtype.Int4
-		err := r.Convert(tt.source)
+		err := r.ConvertFrom(tt.source)
 		if err != nil {
 			t.Errorf("%d: %v", i, err)
 		}

pgtype/int8.go

@@ -11,7 +11,7 @@ import (
 
 type Int8 int64
 
-func (i *Int8) Convert(src interface{}) error {
+func (i *Int8) ConvertFrom(src interface{}) error {
 	switch value := src.(type) {
 	case Int8:
 		*i = value
@@ -55,7 +55,7 @@ func (i *Int8) Convert(src interface{}) error {
 		*i = Int8(num)
 	default:
 		if originalSrc, ok := underlyingIntType(src); ok {
-			return i.Convert(originalSrc)
+			return i.ConvertFrom(originalSrc)
 		}
 		return fmt.Errorf("cannot convert %v to Int8", value)
 	}
@@ -63,6 +63,10 @@ func (i *Int8) Convert(src interface{}) error {
 	return nil
 }
 
+func (i *Int8) AssignTo(dst interface{}) error {
+	return nil
+}
+
 func (i *Int8) DecodeText(r io.Reader) error {
 	size, err := pgio.ReadInt32(r)
 	if err != nil {

pgtype/int8_test.go

@@ -86,7 +86,7 @@ func TestInt8Transcode(t *testing.T) {
 	}
 }
 
-func TestInt8Convert(t *testing.T) {
+func TestInt8ConvertFrom(t *testing.T) {
 	type _int8 int8
 
 	successfulTests := []struct {
@@ -111,7 +111,7 @@ func TestInt8Convert(t *testing.T) {
 
 	for i, tt := range successfulTests {
 		var r pgtype.Int8
-		err := r.Convert(tt.source)
+		err := r.ConvertFrom(tt.source)
 		if err != nil {
 			t.Errorf("%d: %v", i, err)
 		}

pgtype/pgtype.go

@@ -0,0 +1,26 @@
+package pgtype
+
+import (
+	"io"
+)
+
+type Value interface {
+	ConvertFrom(src interface{}) error
+	AssignTo(dst interface{}) error
+}
+
+type BinaryDecoder interface {
+	DecodeBinary(r io.Reader) error
+}
+
+type TextDecoder interface {
+	DecodeText(r io.Reader) error
+}
+
+type BinaryEncoder interface {
+	EncodeBinary(w io.Writer) error
+}
+
+type TextEncoder interface {
+	EncodeText(w io.Writer) error
+}

values.go

@@ -1060,28 +1060,12 @@ func Encode(wbuf *WriteBuf, oid OID, arg interface{}) error {
 		return encodeJSONB(wbuf, oid, arg)
 	}
 
-	switch oid {
-	case Int2OID:
-		var i2 pgtype.Int2
-		err := i2.Convert(arg)
+	if value, ok := wbuf.conn.oidPgtypeValues[oid]; ok {
+		err := value.ConvertFrom(arg)
 		if err != nil {
 			return err
 		}
-		return i2.EncodeBinary(wbuf)
-	case Int4OID:
-		var i4 pgtype.Int4
-		err := i4.Convert(arg)
-		if err != nil {
-			return err
-		}
-		return i4.EncodeBinary(wbuf)
-	case Int8OID:
-		var i8 pgtype.Int8
-		err := i8.Convert(arg)
-		if err != nil {
-			return err
-		}
-		return i8.EncodeBinary(wbuf)
+		return value.(pgtype.BinaryEncoder).EncodeBinary(wbuf)
 	}
 
 	switch arg := arg.(type) {