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hstore.go
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hstore.go
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package pgtype
import (
"database/sql/driver"
"encoding/binary"
"errors"
"fmt"
"strings"
"github.com/jackc/pgx/v5/internal/pgio"
)
type HstoreScanner interface {
ScanHstore(v Hstore) error
}
type HstoreValuer interface {
HstoreValue() (Hstore, error)
}
// Hstore represents an hstore column that can be null or have null values
// associated with its keys.
type Hstore map[string]*string
func (h *Hstore) ScanHstore(v Hstore) error {
*h = v
return nil
}
func (h Hstore) HstoreValue() (Hstore, error) {
return h, nil
}
// Scan implements the database/sql Scanner interface.
func (h *Hstore) Scan(src any) error {
if src == nil {
*h = nil
return nil
}
switch src := src.(type) {
case string:
return scanPlanTextAnyToHstoreScanner{}.scanString(src, h)
}
return fmt.Errorf("cannot scan %T", src)
}
// Value implements the database/sql/driver Valuer interface.
func (h Hstore) Value() (driver.Value, error) {
if h == nil {
return nil, nil
}
buf, err := HstoreCodec{}.PlanEncode(nil, 0, TextFormatCode, h).Encode(h, nil)
if err != nil {
return nil, err
}
return string(buf), err
}
type HstoreCodec struct{}
func (HstoreCodec) FormatSupported(format int16) bool {
return format == TextFormatCode || format == BinaryFormatCode
}
func (HstoreCodec) PreferredFormat() int16 {
return BinaryFormatCode
}
func (HstoreCodec) PlanEncode(m *Map, oid uint32, format int16, value any) EncodePlan {
if _, ok := value.(HstoreValuer); !ok {
return nil
}
switch format {
case BinaryFormatCode:
return encodePlanHstoreCodecBinary{}
case TextFormatCode:
return encodePlanHstoreCodecText{}
}
return nil
}
type encodePlanHstoreCodecBinary struct{}
func (encodePlanHstoreCodecBinary) Encode(value any, buf []byte) (newBuf []byte, err error) {
hstore, err := value.(HstoreValuer).HstoreValue()
if err != nil {
return nil, err
}
if hstore == nil {
return nil, nil
}
buf = pgio.AppendInt32(buf, int32(len(hstore)))
for k, v := range hstore {
buf = pgio.AppendInt32(buf, int32(len(k)))
buf = append(buf, k...)
if v == nil {
buf = pgio.AppendInt32(buf, -1)
} else {
buf = pgio.AppendInt32(buf, int32(len(*v)))
buf = append(buf, (*v)...)
}
}
return buf, nil
}
type encodePlanHstoreCodecText struct{}
func (encodePlanHstoreCodecText) Encode(value any, buf []byte) (newBuf []byte, err error) {
hstore, err := value.(HstoreValuer).HstoreValue()
if err != nil {
return nil, err
}
if len(hstore) == 0 {
// distinguish between empty and nil: Not strictly required by Postgres, since its protocol
// explicitly marks NULL column values separately. However, the Binary codec does this, and
// this means we can "round trip" Encode and Scan without data loss.
// nil: []byte(nil); empty: []byte{}
if hstore == nil {
return nil, nil
}
return []byte{}, nil
}
firstPair := true
for k, v := range hstore {
if firstPair {
firstPair = false
} else {
buf = append(buf, ',', ' ')
}
// unconditionally quote hstore keys/values like Postgres does
// this avoids a Mac OS X Postgres hstore parsing bug:
// https://www.postgresql.org/message-id/CA%2BHWA9awUW0%2BRV_gO9r1ABZwGoZxPztcJxPy8vMFSTbTfi4jig%40mail.gmail.com
buf = append(buf, '"')
buf = append(buf, quoteArrayReplacer.Replace(k)...)
buf = append(buf, '"')
buf = append(buf, "=>"...)
if v == nil {
buf = append(buf, "NULL"...)
} else {
buf = append(buf, '"')
buf = append(buf, quoteArrayReplacer.Replace(*v)...)
buf = append(buf, '"')
}
}
return buf, nil
}
func (HstoreCodec) PlanScan(m *Map, oid uint32, format int16, target any) ScanPlan {
switch format {
case BinaryFormatCode:
switch target.(type) {
case HstoreScanner:
return scanPlanBinaryHstoreToHstoreScanner{}
}
case TextFormatCode:
switch target.(type) {
case HstoreScanner:
return scanPlanTextAnyToHstoreScanner{}
}
}
return nil
}
type scanPlanBinaryHstoreToHstoreScanner struct{}
func (scanPlanBinaryHstoreToHstoreScanner) Scan(src []byte, dst any) error {
scanner := (dst).(HstoreScanner)
if src == nil {
return scanner.ScanHstore(Hstore(nil))
}
rp := 0
const uint32Len = 4
if len(src[rp:]) < uint32Len {
return fmt.Errorf("hstore incomplete %v", src)
}
pairCount := int(int32(binary.BigEndian.Uint32(src[rp:])))
rp += uint32Len
hstore := make(Hstore, pairCount)
// one allocation for all *string, rather than one per string, just like text parsing
valueStrings := make([]string, pairCount)
for i := 0; i < pairCount; i++ {
if len(src[rp:]) < uint32Len {
return fmt.Errorf("hstore incomplete %v", src)
}
keyLen := int(int32(binary.BigEndian.Uint32(src[rp:])))
rp += uint32Len
if len(src[rp:]) < keyLen {
return fmt.Errorf("hstore incomplete %v", src)
}
key := string(src[rp : rp+keyLen])
rp += keyLen
if len(src[rp:]) < uint32Len {
return fmt.Errorf("hstore incomplete %v", src)
}
valueLen := int(int32(binary.BigEndian.Uint32(src[rp:])))
rp += 4
if valueLen >= 0 {
valueStrings[i] = string(src[rp : rp+valueLen])
rp += valueLen
hstore[key] = &valueStrings[i]
} else {
hstore[key] = nil
}
}
return scanner.ScanHstore(hstore)
}
type scanPlanTextAnyToHstoreScanner struct{}
func (s scanPlanTextAnyToHstoreScanner) Scan(src []byte, dst any) error {
scanner := (dst).(HstoreScanner)
if src == nil {
return scanner.ScanHstore(Hstore(nil))
}
return s.scanString(string(src), scanner)
}
// scanString does not return nil hstore values because string cannot be nil.
func (scanPlanTextAnyToHstoreScanner) scanString(src string, scanner HstoreScanner) error {
hstore, err := parseHstore(src)
if err != nil {
return err
}
return scanner.ScanHstore(hstore)
}
func (c HstoreCodec) DecodeDatabaseSQLValue(m *Map, oid uint32, format int16, src []byte) (driver.Value, error) {
return codecDecodeToTextFormat(c, m, oid, format, src)
}
func (c HstoreCodec) DecodeValue(m *Map, oid uint32, format int16, src []byte) (any, error) {
if src == nil {
return nil, nil
}
var hstore Hstore
err := codecScan(c, m, oid, format, src, &hstore)
if err != nil {
return nil, err
}
return hstore, nil
}
type hstoreParser struct {
str string
pos int
nextBackslash int
}
func newHSP(in string) *hstoreParser {
return &hstoreParser{
pos: 0,
str: in,
nextBackslash: strings.IndexByte(in, '\\'),
}
}
func (p *hstoreParser) atEnd() bool {
return p.pos >= len(p.str)
}
// consume returns the next byte of the string, or end if the string is done.
func (p *hstoreParser) consume() (b byte, end bool) {
if p.pos >= len(p.str) {
return 0, true
}
b = p.str[p.pos]
p.pos++
return b, false
}
func unexpectedByteErr(actualB byte, expectedB byte) error {
return fmt.Errorf("expected '%c' ('%#v'); found '%c' ('%#v')", expectedB, expectedB, actualB, actualB)
}
// consumeExpectedByte consumes expectedB from the string, or returns an error.
func (p *hstoreParser) consumeExpectedByte(expectedB byte) error {
nextB, end := p.consume()
if end {
return fmt.Errorf("expected '%c' ('%#v'); found end", expectedB, expectedB)
}
if nextB != expectedB {
return unexpectedByteErr(nextB, expectedB)
}
return nil
}
// consumeExpected2 consumes two expected bytes or returns an error.
// This was a bit faster than using a string argument (better inlining? Not sure).
func (p *hstoreParser) consumeExpected2(one byte, two byte) error {
if p.pos+2 > len(p.str) {
return errors.New("unexpected end of string")
}
if p.str[p.pos] != one {
return unexpectedByteErr(p.str[p.pos], one)
}
if p.str[p.pos+1] != two {
return unexpectedByteErr(p.str[p.pos+1], two)
}
p.pos += 2
return nil
}
var errEOSInQuoted = errors.New(`found end before closing double-quote ('"')`)
// consumeDoubleQuoted consumes a double-quoted string from p. The double quote must have been
// parsed already. This copies the string from the backing string so it can be garbage collected.
func (p *hstoreParser) consumeDoubleQuoted() (string, error) {
// fast path: assume most keys/values do not contain escapes
nextDoubleQuote := strings.IndexByte(p.str[p.pos:], '"')
if nextDoubleQuote == -1 {
return "", errEOSInQuoted
}
nextDoubleQuote += p.pos
if p.nextBackslash == -1 || p.nextBackslash > nextDoubleQuote {
// clone the string from the source string to ensure it can be garbage collected separately
// TODO: use strings.Clone on Go 1.20; this could get optimized away
s := strings.Clone(p.str[p.pos:nextDoubleQuote])
p.pos = nextDoubleQuote + 1
return s, nil
}
// slow path: string contains escapes
s, err := p.consumeDoubleQuotedWithEscapes(p.nextBackslash)
p.nextBackslash = strings.IndexByte(p.str[p.pos:], '\\')
if p.nextBackslash != -1 {
p.nextBackslash += p.pos
}
return s, err
}
// consumeDoubleQuotedWithEscapes consumes a double-quoted string containing escapes, starting
// at p.pos, and with the first backslash at firstBackslash. This copies the string so it can be
// garbage collected separately.
func (p *hstoreParser) consumeDoubleQuotedWithEscapes(firstBackslash int) (string, error) {
// copy the prefix that does not contain backslashes
var builder strings.Builder
builder.WriteString(p.str[p.pos:firstBackslash])
// skip to the backslash
p.pos = firstBackslash
// copy bytes until the end, unescaping backslashes
for {
nextB, end := p.consume()
if end {
return "", errEOSInQuoted
} else if nextB == '"' {
break
} else if nextB == '\\' {
// escape: skip the backslash and copy the char
nextB, end = p.consume()
if end {
return "", errEOSInQuoted
}
if !(nextB == '\\' || nextB == '"') {
return "", fmt.Errorf("unexpected escape in quoted string: found '%#v'", nextB)
}
builder.WriteByte(nextB)
} else {
// normal byte: copy it
builder.WriteByte(nextB)
}
}
return builder.String(), nil
}
// consumePairSeparator consumes the Hstore pair separator ", " or returns an error.
func (p *hstoreParser) consumePairSeparator() error {
return p.consumeExpected2(',', ' ')
}
// consumeKVSeparator consumes the Hstore key/value separator "=>" or returns an error.
func (p *hstoreParser) consumeKVSeparator() error {
return p.consumeExpected2('=', '>')
}
// consumeDoubleQuotedOrNull consumes the Hstore key/value separator "=>" or returns an error.
func (p *hstoreParser) consumeDoubleQuotedOrNull() (Text, error) {
// peek at the next byte
if p.atEnd() {
return Text{}, errors.New("found end instead of value")
}
next := p.str[p.pos]
if next == 'N' {
// must be the exact string NULL: use consumeExpected2 twice
err := p.consumeExpected2('N', 'U')
if err != nil {
return Text{}, err
}
err = p.consumeExpected2('L', 'L')
if err != nil {
return Text{}, err
}
return Text{String: "", Valid: false}, nil
} else if next != '"' {
return Text{}, unexpectedByteErr(next, '"')
}
// skip the double quote
p.pos += 1
s, err := p.consumeDoubleQuoted()
if err != nil {
return Text{}, err
}
return Text{String: s, Valid: true}, nil
}
func parseHstore(s string) (Hstore, error) {
p := newHSP(s)
// This is an over-estimate of the number of key/value pairs. Use '>' because I am guessing it
// is less likely to occur in keys/values than '=' or ','.
numPairsEstimate := strings.Count(s, ">")
// makes one allocation of strings for the entire Hstore, rather than one allocation per value.
valueStrings := make([]string, 0, numPairsEstimate)
result := make(Hstore, numPairsEstimate)
first := true
for !p.atEnd() {
if !first {
err := p.consumePairSeparator()
if err != nil {
return nil, err
}
} else {
first = false
}
err := p.consumeExpectedByte('"')
if err != nil {
return nil, err
}
key, err := p.consumeDoubleQuoted()
if err != nil {
return nil, err
}
err = p.consumeKVSeparator()
if err != nil {
return nil, err
}
value, err := p.consumeDoubleQuotedOrNull()
if err != nil {
return nil, err
}
if value.Valid {
valueStrings = append(valueStrings, value.String)
result[key] = &valueStrings[len(valueStrings)-1]
} else {
result[key] = nil
}
}
return result, nil
}