Move Tid to pgtype

pgtype/pgtype.go

@@ -16,7 +16,7 @@ const (
 	Int4OID             = 23
 	TextOID             = 25
 	OIDOID              = 26
-	TidOID              = 27
+	TIDOID              = 27
 	XIDOID              = 28
 	CIDOID              = 29
 	JSONOID             = 114
@@ -66,8 +66,13 @@ const (
 	NegativeInfinity InfinityModifier = -Infinity
 )
 
-type Value interface {
+type Value interface{}
+
+type ConverterFrom interface {
 	ConvertFrom(src interface{}) error
+}
+
+type AssignerTo interface {
 	AssignTo(dst interface{}) error
 }
 

pgtype/tid.go

@@ -0,0 +1,104 @@
+package pgtype
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+
+	"github.com/jackc/pgx/pgio"
+)
+
+// TID is PostgreSQL's Tuple Identifier type.
+//
+// When one does
+//
+// 	select ctid, * from some_table;
+//
+// it is the data type of the ctid hidden system column.
+//
+// It is currently implemented as a pair unsigned two byte integers.
+// Its conversion functions can be found in src/backend/utils/adt/tid.c
+// in the PostgreSQL sources.
+type TID struct {
+	BlockNumber  uint32
+	OffsetNumber uint16
+	Status       Status
+}
+
+func (dst *TID) DecodeText(src []byte) error {
+	if src == nil {
+		*dst = TID{Status: Null}
+		return nil
+	}
+
+	if len(src) < 5 {
+		return fmt.Errorf("invalid length for tid: %v", len(src))
+	}
+
+	parts := strings.SplitN(string(src[1:len(src)-1]), ",", 2)
+	if len(parts) < 2 {
+		return fmt.Errorf("invalid format for tid")
+	}
+
+	blockNumber, err := strconv.ParseUint(parts[0], 10, 32)
+	if err != nil {
+		return err
+	}
+
+	offsetNumber, err := strconv.ParseUint(parts[1], 10, 16)
+	if err != nil {
+		return err
+	}
+
+	*dst = TID{BlockNumber: uint32(blockNumber), OffsetNumber: uint16(offsetNumber), Status: Present}
+	return nil
+}
+
+func (dst *TID) DecodeBinary(src []byte) error {
+	if src == nil {
+		*dst = TID{Status: Null}
+		return nil
+	}
+
+	if len(src) != 6 {
+		return fmt.Errorf("invalid length for tid: %v", len(src))
+	}
+
+	*dst = TID{
+		BlockNumber:  binary.BigEndian.Uint32(src),
+		OffsetNumber: binary.BigEndian.Uint16(src[4:]),
+		Status:       Present,
+	}
+	return nil
+}
+
+func (src TID) EncodeText(w io.Writer) (bool, error) {
+	switch src.Status {
+	case Null:
+		return true, nil
+	case Undefined:
+		return false, errUndefined
+	}
+
+	_, err := io.WriteString(w, fmt.Sprintf(`(%d,%d)`, src.BlockNumber, src.OffsetNumber))
+	return false, err
+}
+
+func (src TID) EncodeBinary(w io.Writer) (bool, error) {
+	switch src.Status {
+	case Null:
+		return true, nil
+	case Undefined:
+		return false, errUndefined
+	}
+
+	_, err := pgio.WriteUint32(w, src.BlockNumber)
+	if err != nil {
+		return false, err
+	}
+
+	_, err = pgio.WriteUint16(w, src.OffsetNumber)
+	return false, err
+}

pgtype/tid_test.go

@@ -0,0 +1,15 @@
+package pgtype_test
+
+import (
+	"testing"
+
+	"github.com/jackc/pgx/pgtype"
+)
+
+func TestTIDTranscode(t *testing.T) {
+	testSuccessfulTranscode(t, "tid", []interface{}{
+		pgtype.TID{BlockNumber: 42, OffsetNumber: 43, Status: pgtype.Present},
+		pgtype.TID{BlockNumber: 4294967295, OffsetNumber: 65535, Status: pgtype.Present},
+		pgtype.TID{Status: pgtype.Null},
+	})
+}