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|
package pgx
import (
"context"
"strconv"
"strings"
"unicode/utf8"
)
// NamedArgs can be used as the first argument to a query method. It will replace every '@' named placeholder with a '$'
// ordinal placeholder and construct the appropriate arguments.
//
// For example, the following two queries are equivalent:
//
// conn.Query(ctx, "select * from widgets where foo = @foo and bar = @bar", pgx.NamedArgs{"foo": 1, "bar": 2})
// conn.Query(ctx, "select * from widgets where foo = $1 and bar = $2", 1, 2)
type NamedArgs map[string]any
// RewriteQuery implements the QueryRewriter interface.
func (na NamedArgs) RewriteQuery(ctx context.Context, conn *Conn, sql string, args []any) (newSQL string, newArgs []any, err error) {
l := &sqlLexer{
src: sql,
stateFn: rawState,
nameToOrdinal: make(map[namedArg]int, len(na)),
}
for l.stateFn != nil {
l.stateFn = l.stateFn(l)
}
sb := strings.Builder{}
for _, p := range l.parts {
switch p := p.(type) {
case string:
sb.WriteString(p)
case namedArg:
sb.WriteRune('$')
sb.WriteString(strconv.Itoa(l.nameToOrdinal[p]))
}
}
newArgs = make([]any, len(l.nameToOrdinal))
for name, ordinal := range l.nameToOrdinal {
newArgs[ordinal-1] = na[string(name)]
}
return sb.String(), newArgs, nil
}
type namedArg string
type sqlLexer struct {
src string
start int
pos int
nested int // multiline comment nesting level.
stateFn stateFn
parts []any
nameToOrdinal map[namedArg]int
}
type stateFn func(*sqlLexer) stateFn
func rawState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case 'e', 'E':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune == '\'' {
l.pos += width
return escapeStringState
}
case '\'':
return singleQuoteState
case '"':
return doubleQuoteState
case '@':
nextRune, _ := utf8.DecodeRuneInString(l.src[l.pos:])
if isLetter(nextRune) {
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos-width])
}
l.start = l.pos
return namedArgState
}
case '-':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune == '-' {
l.pos += width
return oneLineCommentState
}
case '/':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune == '*' {
l.pos += width
return multilineCommentState
}
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
func isLetter(r rune) bool {
return (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z')
}
func namedArgState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
if r == utf8.RuneError {
if l.pos-l.start > 0 {
na := namedArg(l.src[l.start:l.pos])
if _, found := l.nameToOrdinal[na]; !found {
l.nameToOrdinal[na] = len(l.nameToOrdinal) + 1
}
l.parts = append(l.parts, na)
l.start = l.pos
}
return nil
} else if !(isLetter(r) || (r >= '0' && r <= '9') || r == '_') {
l.pos -= width
na := namedArg(l.src[l.start:l.pos])
if _, found := l.nameToOrdinal[na]; !found {
l.nameToOrdinal[na] = len(l.nameToOrdinal) + 1
}
l.parts = append(l.parts, namedArg(na))
l.start = l.pos
return rawState
}
}
}
func singleQuoteState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case '\'':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune != '\'' {
return rawState
}
l.pos += width
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
func doubleQuoteState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case '"':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune != '"' {
return rawState
}
l.pos += width
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
func escapeStringState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case '\\':
_, width = utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
case '\'':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune != '\'' {
return rawState
}
l.pos += width
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
func oneLineCommentState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case '\\':
_, width = utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
case '\n', '\r':
return rawState
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
func multilineCommentState(l *sqlLexer) stateFn {
for {
r, width := utf8.DecodeRuneInString(l.src[l.pos:])
l.pos += width
switch r {
case '/':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune == '*' {
l.pos += width
l.nested++
}
case '*':
nextRune, width := utf8.DecodeRuneInString(l.src[l.pos:])
if nextRune != '/' {
continue
}
l.pos += width
if l.nested == 0 {
return rawState
}
l.nested--
case utf8.RuneError:
if l.pos-l.start > 0 {
l.parts = append(l.parts, l.src[l.start:l.pos])
l.start = l.pos
}
return nil
}
}
}
|
