Move cid to pgtype

conn.go

@@ -270,6 +270,7 @@ func (c *Conn) connect(config ConnConfig, network, address string, tlsConfig *tl
 	c.oidPgtypeValues = map[OID]pgtype.Value{
 		BoolArrayOID:        &pgtype.BoolArray{},
 		BoolOID:             &pgtype.Bool{},
+		CIDOID:              &pgtype.CID{},
 		CidrArrayOID:        &pgtype.CidrArray{},
 		CidrOID:             &pgtype.Inet{},
 		DateArrayOID:        &pgtype.DateArray{},

pgtype/cid.go

@@ -0,0 +1,141 @@
+package pgtype
+
+import (
+	"fmt"
+	"io"
+	"strconv"
+
+	"github.com/jackc/pgx/pgio"
+)
+
+// CID is PostgreSQL's Command Identifier type.
+//
+// When one does
+//
+// 	select cmin, cmax, * from some_table;
+//
+// it is the data type of the cmin and cmax hidden system columns.
+//
+// It is currently implemented as an unsigned four byte integer.
+// Its definition can be found in src/include/c.h as CommandId
+// in the PostgreSQL sources.
+type CID struct {
+	Uint   uint32
+	Status Status
+}
+
+// ConvertFrom converts from src to dst. Note that as CID is not a general
+// number type ConvertFrom does not do automatic type conversion as other number
+// types do.
+func (dst *CID) ConvertFrom(src interface{}) error {
+	switch value := src.(type) {
+	case CID:
+		*dst = value
+	case uint32:
+		*dst = CID{Uint: value, Status: Present}
+	default:
+		return fmt.Errorf("cannot convert %v to CID", value)
+	}
+
+	return nil
+}
+
+// AssignTo assigns from src to dst. Note that as CID is not a general number
+// type AssignTo does not do automatic type conversion as other number types do.
+func (src *CID) AssignTo(dst interface{}) error {
+	switch v := dst.(type) {
+	case *uint32:
+		if src.Status == Present {
+			*v = src.Uint
+		} else {
+			return fmt.Errorf("cannot assign %v into %T", src, dst)
+		}
+	case **uint32:
+		if src.Status == Present {
+			n := src.Uint
+			*v = &n
+		} else {
+			*v = nil
+		}
+	}
+
+	return nil
+}
+
+func (dst *CID) DecodeText(r io.Reader) error {
+	size, err := pgio.ReadInt32(r)
+	if err != nil {
+		return err
+	}
+
+	if size == -1 {
+		*dst = CID{Status: Null}
+		return nil
+	}
+
+	buf := make([]byte, int(size))
+	_, err = r.Read(buf)
+	if err != nil {
+		return err
+	}
+
+	n, err := strconv.ParseUint(string(buf), 10, 32)
+	if err != nil {
+		return err
+	}
+
+	*dst = CID{Uint: uint32(n), Status: Present}
+	return nil
+}
+
+func (dst *CID) DecodeBinary(r io.Reader) error {
+	size, err := pgio.ReadInt32(r)
+	if err != nil {
+		return err
+	}
+
+	if size == -1 {
+		*dst = CID{Status: Null}
+		return nil
+	}
+
+	if size != 4 {
+		return fmt.Errorf("invalid length for cid: %v", size)
+	}
+
+	n, err := pgio.ReadUint32(r)
+	if err != nil {
+		return err
+	}
+
+	*dst = CID{Uint: n, Status: Present}
+	return nil
+}
+
+func (src CID) EncodeText(w io.Writer) error {
+	if done, err := encodeNotPresent(w, src.Status); done {
+		return err
+	}
+
+	s := strconv.FormatUint(uint64(src.Uint), 10)
+	_, err := pgio.WriteInt32(w, int32(len(s)))
+	if err != nil {
+		return nil
+	}
+	_, err = w.Write([]byte(s))
+	return err
+}
+
+func (src CID) EncodeBinary(w io.Writer) error {
+	if done, err := encodeNotPresent(w, src.Status); done {
+		return err
+	}
+
+	_, err := pgio.WriteInt32(w, 4)
+	if err != nil {
+		return err
+	}
+
+	_, err = pgio.WriteUint32(w, src.Uint)
+	return err
+}

pgtype/cid_test.go

@@ -0,0 +1,94 @@
+package pgtype_test
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/jackc/pgx/pgtype"
+)
+
+func TestCIDTranscode(t *testing.T) {
+	testSuccessfulTranscode(t, "cid", []interface{}{
+		pgtype.CID{Uint: 42, Status: pgtype.Present},
+		pgtype.CID{Status: pgtype.Null},
+	})
+}
+
+func TestCIDConvertFrom(t *testing.T) {
+	successfulTests := []struct {
+		source interface{}
+		result pgtype.CID
+	}{
+		{source: uint32(1), result: pgtype.CID{Uint: 1, Status: pgtype.Present}},
+	}
+
+	for i, tt := range successfulTests {
+		var r pgtype.CID
+		err := r.ConvertFrom(tt.source)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if r != tt.result {
+			t.Errorf("%d: expected %v to convert to %v, but it was %v", i, tt.source, tt.result, r)
+		}
+	}
+}
+
+func TestCIDAssignTo(t *testing.T) {
+	var ui32 uint32
+	var pui32 *uint32
+
+	simpleTests := []struct {
+		src      pgtype.CID
+		dst      interface{}
+		expected interface{}
+	}{
+		{src: pgtype.CID{Uint: 42, Status: pgtype.Present}, dst: &ui32, expected: uint32(42)},
+		{src: pgtype.CID{Status: pgtype.Null}, dst: &pui32, expected: ((*uint32)(nil))},
+	}
+
+	for i, tt := range simpleTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if dst := reflect.ValueOf(tt.dst).Elem().Interface(); dst != tt.expected {
+			t.Errorf("%d: expected %v to assign %v, but result was %v", i, tt.src, tt.expected, dst)
+		}
+	}
+
+	pointerAllocTests := []struct {
+		src      pgtype.CID
+		dst      interface{}
+		expected interface{}
+	}{
+		{src: pgtype.CID{Uint: 42, Status: pgtype.Present}, dst: &pui32, expected: uint32(42)},
+	}
+
+	for i, tt := range pointerAllocTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err != nil {
+			t.Errorf("%d: %v", i, err)
+		}
+
+		if dst := reflect.ValueOf(tt.dst).Elem().Elem().Interface(); dst != tt.expected {
+			t.Errorf("%d: expected %v to assign %v, but result was %v", i, tt.src, tt.expected, dst)
+		}
+	}
+
+	errorTests := []struct {
+		src pgtype.CID
+		dst interface{}
+	}{
+		{src: pgtype.CID{Status: pgtype.Null}, dst: &ui32},
+	}
+
+	for i, tt := range errorTests {
+		err := tt.src.AssignTo(tt.dst)
+		if err == nil {
+			t.Errorf("%d: expected error but none was returned (%v -> %v)", i, tt.src, tt.dst)
+		}
+	}
+}

pgtype/pgtype.go

@@ -20,7 +20,7 @@ const (
 	OIDOID              = 26
 	TidOID              = 27
 	XidOID              = 28
-	CidOID              = 29
+	CIDOID              = 29
 	JSONOID             = 114
 	CidrOID             = 650
 	CidrArrayOID        = 651

values.go

@@ -29,7 +29,7 @@ const (
 	OIDOID              = 26
 	TidOID              = 27
 	XidOID              = 28
-	CidOID              = 29
+	CIDOID              = 29
 	JSONOID             = 114
 	CidrOID             = 650
 	CidrArrayOID        = 651
@@ -645,58 +645,6 @@ func (n NullXid) Encode(w *WriteBuf, oid OID) error {
 	return encodeXid(w, oid, n.Xid)
 }
 
-// Cid is PostgreSQL's Command Identifier type.
-//
-// When one does
-//
-// 	select cmin, cmax, * from some_table;
-//
-// it is the data type of the cmin and cmax hidden system columns.
-//
-// It is currently implemented as an unsigned four byte integer.
-// Its definition can be found in src/include/c.h as CommandId
-// in the PostgreSQL sources.
-type Cid uint32
-
-// NullCid represents a Command Identifier (Cid) that may be null. NullCid implements the
-// Scanner and Encoder interfaces so it may be used both as an argument to
-// Query[Row] and a destination for Scan.
-//
-// If Valid is false then the value is NULL.
-type NullCid struct {
-	Cid   Cid
-	Valid bool // Valid is true if Cid is not NULL
-}
-
-func (n *NullCid) Scan(vr *ValueReader) error {
-	if vr.Type().DataType != CidOID {
-		return SerializationError(fmt.Sprintf("NullCid.Scan cannot decode OID %d", vr.Type().DataType))
-	}
-
-	if vr.Len() == -1 {
-		n.Cid, n.Valid = 0, false
-		return nil
-	}
-	n.Valid = true
-	n.Cid = decodeCid(vr)
-	return vr.Err()
-}
-
-func (n NullCid) FormatCode() int16 { return BinaryFormatCode }
-
-func (n NullCid) Encode(w *WriteBuf, oid OID) error {
-	if oid != CidOID {
-		return SerializationError(fmt.Sprintf("NullCid.Encode cannot encode into OID %d", oid))
-	}
-
-	if !n.Valid {
-		w.WriteInt32(-1)
-		return nil
-	}
-
-	return encodeCid(w, oid, n.Cid)
-}
-
 // Tid is PostgreSQL's Tuple Identifier type.
 //
 // When one does
@@ -1087,8 +1035,6 @@ func Encode(wbuf *WriteBuf, oid OID, arg interface{}) error {
 		return encodeOID(wbuf, oid, arg)
 	case Xid:
 		return encodeXid(wbuf, oid, arg)
-	case Cid:
-		return encodeCid(wbuf, oid, arg)
 	default:
 		if strippedArg, ok := stripNamedType(&refVal); ok {
 			return Encode(wbuf, oid, strippedArg)
@@ -1170,8 +1116,6 @@ func Decode(vr *ValueReader, d interface{}) error {
 		*v = decodeXid(vr)
 	case *Tid:
 		*v = decodeTid(vr)
-	case *Cid:
-		*v = decodeCid(vr)
 	case *string:
 		*v = decodeText(vr)
 	case *[]AclItem:
@@ -1493,49 +1437,6 @@ func encodeXid(w *WriteBuf, oid OID, value Xid) error {
 	return nil
 }
 
-func decodeCid(vr *ValueReader) Cid {
-	if vr.Len() == -1 {
-		vr.Fatal(ProtocolError("Cannot decode null into Cid"))
-		return Cid(0)
-	}
-
-	if vr.Type().DataType != CidOID {
-		vr.Fatal(ProtocolError(fmt.Sprintf("Cannot decode oid %v into pgx.Cid", vr.Type().DataType)))
-		return Cid(0)
-	}
-
-	// Unlikely Cid will ever go over the wire as text format, but who knows?
-	switch vr.Type().FormatCode {
-	case TextFormatCode:
-		s := vr.ReadString(vr.Len())
-		n, err := strconv.ParseUint(s, 10, 32)
-		if err != nil {
-			vr.Fatal(ProtocolError(fmt.Sprintf("Received invalid OID: %v", s)))
-		}
-		return Cid(n)
-	case BinaryFormatCode:
-		if vr.Len() != 4 {
-			vr.Fatal(ProtocolError(fmt.Sprintf("Received an invalid size for an OID: %d", vr.Len())))
-			return Cid(0)
-		}
-		return Cid(vr.ReadUint32())
-	default:
-		vr.Fatal(ProtocolError(fmt.Sprintf("Unknown field description format code: %v", vr.Type().FormatCode)))
-		return Cid(0)
-	}
-}
-
-func encodeCid(w *WriteBuf, oid OID, value Cid) error {
-	if oid != CidOID {
-		return fmt.Errorf("cannot encode Go %s into oid %d", "pgx.Cid", oid)
-	}
-
-	w.WriteInt32(4)
-	w.WriteUint32(uint32(value))
-
-	return nil
-}
-
 // Note that we do not match negative numbers, because neither the
 // BlockNumber nor OffsetNumber of a Tid can be negative.
 var tidRegexp *regexp.Regexp = regexp.MustCompile(`^\((\d*),(\d*)\)$`)

values_test.go

@@ -573,7 +573,6 @@ func TestNullX(t *testing.T) {
 		n   pgx.NullName
 		oid pgx.NullOID
 		xid pgx.NullXid
-		cid pgx.NullCid
 		tid pgx.NullTid
 		i64 pgx.NullInt64
 		f32 pgx.NullFloat32
@@ -611,9 +610,6 @@ func TestNullX(t *testing.T) {
 		{"select $1::aclitem", []interface{}{pgx.NullAclItem{AclItem: "postgres=arwdDxt/postgres", Valid: false}}, []interface{}{&actual.a}, allTypes{a: pgx.NullAclItem{AclItem: "", Valid: false}}},
 		// A tricky (and valid) aclitem can still be used, especially with Go's useful backticks
 		{"select $1::aclitem", []interface{}{pgx.NullAclItem{AclItem: `postgres=arwdDxt/" tricky, ' } "" \ test user "`, Valid: true}}, []interface{}{&actual.a}, allTypes{a: pgx.NullAclItem{AclItem: `postgres=arwdDxt/" tricky, ' } "" \ test user "`, Valid: true}}},
-		{"select $1::cid", []interface{}{pgx.NullCid{Cid: 1, Valid: true}}, []interface{}{&actual.cid}, allTypes{cid: pgx.NullCid{Cid: 1, Valid: true}}},
-		{"select $1::cid", []interface{}{pgx.NullCid{Cid: 1, Valid: false}}, []interface{}{&actual.cid}, allTypes{cid: pgx.NullCid{Cid: 0, Valid: false}}},
-		{"select $1::cid", []interface{}{pgx.NullCid{Cid: 4294967295, Valid: true}}, []interface{}{&actual.cid}, allTypes{cid: pgx.NullCid{Cid: 4294967295, Valid: true}}},
 		{"select $1::tid", []interface{}{pgx.NullTid{Tid: pgx.Tid{BlockNumber: 1, OffsetNumber: 1}, Valid: true}}, []interface{}{&actual.tid}, allTypes{tid: pgx.NullTid{Tid: pgx.Tid{BlockNumber: 1, OffsetNumber: 1}, Valid: true}}},
 		{"select $1::tid", []interface{}{pgx.NullTid{Tid: pgx.Tid{BlockNumber: 1, OffsetNumber: 1}, Valid: false}}, []interface{}{&actual.tid}, allTypes{tid: pgx.NullTid{Tid: pgx.Tid{BlockNumber: 0, OffsetNumber: 0}, Valid: false}}},
 		{"select $1::tid", []interface{}{pgx.NullTid{Tid: pgx.Tid{BlockNumber: 4294967295, OffsetNumber: 65535}, Valid: true}}, []interface{}{&actual.tid}, allTypes{tid: pgx.NullTid{Tid: pgx.Tid{BlockNumber: 4294967295, OffsetNumber: 65535}, Valid: true}}},