mirror of https://github.com/jackc/pgx.git
145 lines
3.0 KiB
Go
145 lines
3.0 KiB
Go
package pgtype
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import (
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"database/sql/driver"
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"encoding/binary"
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"fmt"
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"strconv"
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"strings"
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"github.com/jackc/pgx/pgio"
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"github.com/pkg/errors"
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)
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// TID is PostgreSQL's Tuple Identifier type.
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//
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// When one does
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//
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// select ctid, * from some_table;
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//
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// it is the data type of the ctid hidden system column.
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//
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// It is currently implemented as a pair unsigned two byte integers.
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// Its conversion functions can be found in src/backend/utils/adt/tid.c
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// in the PostgreSQL sources.
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type TID struct {
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BlockNumber uint32
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OffsetNumber uint16
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Status Status
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}
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func (dst *TID) Set(src interface{}) error {
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return errors.Errorf("cannot convert %v to TID", src)
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}
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func (dst *TID) Get() interface{} {
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switch dst.Status {
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case Present:
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return dst
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case Null:
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return nil
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default:
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return dst.Status
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}
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}
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func (src *TID) AssignTo(dst interface{}) error {
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return errors.Errorf("cannot assign %v to %T", src, dst)
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}
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func (dst *TID) DecodeText(ci *ConnInfo, src []byte) error {
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if src == nil {
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*dst = TID{Status: Null}
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return nil
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}
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if len(src) < 5 {
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return errors.Errorf("invalid length for tid: %v", len(src))
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}
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parts := strings.SplitN(string(src[1:len(src)-1]), ",", 2)
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if len(parts) < 2 {
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return errors.Errorf("invalid format for tid")
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}
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blockNumber, err := strconv.ParseUint(parts[0], 10, 32)
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if err != nil {
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return err
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}
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offsetNumber, err := strconv.ParseUint(parts[1], 10, 16)
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if err != nil {
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return err
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}
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*dst = TID{BlockNumber: uint32(blockNumber), OffsetNumber: uint16(offsetNumber), Status: Present}
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return nil
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}
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func (dst *TID) DecodeBinary(ci *ConnInfo, src []byte) error {
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if src == nil {
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*dst = TID{Status: Null}
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return nil
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}
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if len(src) != 6 {
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return errors.Errorf("invalid length for tid: %v", len(src))
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}
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*dst = TID{
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BlockNumber: binary.BigEndian.Uint32(src),
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OffsetNumber: binary.BigEndian.Uint16(src[4:]),
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Status: Present,
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}
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return nil
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}
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func (src *TID) EncodeText(ci *ConnInfo, buf []byte) ([]byte, error) {
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switch src.Status {
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case Null:
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return nil, nil
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case Undefined:
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return nil, errUndefined
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}
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buf = append(buf, fmt.Sprintf(`(%d,%d)`, src.BlockNumber, src.OffsetNumber)...)
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return buf, nil
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}
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func (src *TID) EncodeBinary(ci *ConnInfo, buf []byte) ([]byte, error) {
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switch src.Status {
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case Null:
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return nil, nil
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case Undefined:
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return nil, errUndefined
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}
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buf = pgio.AppendUint32(buf, src.BlockNumber)
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buf = pgio.AppendUint16(buf, src.OffsetNumber)
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return buf, nil
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}
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// Scan implements the database/sql Scanner interface.
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func (dst *TID) Scan(src interface{}) error {
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if src == nil {
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*dst = TID{Status: Null}
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return nil
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}
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switch src := src.(type) {
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case string:
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return dst.DecodeText(nil, []byte(src))
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case []byte:
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srcCopy := make([]byte, len(src))
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copy(srcCopy, src)
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return dst.DecodeText(nil, srcCopy)
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}
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return errors.Errorf("cannot scan %T", src)
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}
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// Value implements the database/sql/driver Valuer interface.
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func (src *TID) Value() (driver.Value, error) {
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return EncodeValueText(src)
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}
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