mirror of https://github.com/jackc/pgx.git
105 lines
2.0 KiB
Go
105 lines
2.0 KiB
Go
package pgtype
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import (
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"encoding/binary"
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"fmt"
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"io"
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"strconv"
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"strings"
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"github.com/jackc/pgx/pgio"
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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) DecodeText(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 fmt.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 fmt.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(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 fmt.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(w io.Writer) (bool, error) {
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switch src.Status {
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case Null:
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return true, nil
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case Undefined:
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return false, errUndefined
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}
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_, err := io.WriteString(w, fmt.Sprintf(`(%d,%d)`, src.BlockNumber, src.OffsetNumber))
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return false, err
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}
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func (src TID) EncodeBinary(w io.Writer) (bool, error) {
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switch src.Status {
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case Null:
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return true, nil
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case Undefined:
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return false, errUndefined
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}
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_, err := pgio.WriteUint32(w, src.BlockNumber)
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if err != nil {
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return false, err
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}
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_, err = pgio.WriteUint16(w, src.OffsetNumber)
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return false, err
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}
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