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package mssql
import (
"bytes"
"io"
"strconv"
)
type parser struct {
r *bytes.Reader
w bytes.Buffer
paramCount int
paramMax int
// using map as a set
namedParams map [string]bool
}
func (p *parser) next() (rune, bool) {
ch, _, err := p.r.ReadRune()
if err != nil {
if err != io.EOF {
panic(err)
}
return 0, false
}
return ch, true
}
func (p *parser) unread() {
err := p.r.UnreadRune()
if err != nil {
panic(err)
}
}
func (p *parser) write(ch rune) {
p.w.WriteRune(ch)
}
type stateFunc func(*parser) stateFunc
func parseParams(query string) (string, int) {
p := &parser{
r: bytes.NewReader([]byte(query)),
namedParams: map [string]bool{},
}
state := parseNormal
for state != nil {
state = state(p)
}
return p.w.String(), p.paramMax + len(p.namedParams)
}
func parseNormal(p *parser) stateFunc {
for {
ch, ok := p.next()
if !ok {
return nil
}
if ch == '?' {
return parseOrdinalParameter
} else if ch == '$' || ch == ':' {
ch2, ok := p.next()
if !ok {
p.write(ch)
return nil
}
p.unread()
if ch2 >= '0' && ch2 <= '9' {
return parseOrdinalParameter
} else if 'a' <= ch2 && ch2 <= 'z' || 'A' <= ch2 && ch2 <= 'Z' {
return parseNamedParameter
}
}
p.write(ch)
switch ch {
case '\'':
return parseQuote
case '"':
return parseDoubleQuote
case '[':
return parseBracket
case '-':
return parseLineComment
case '/':
return parseComment
}
}
}
func parseOrdinalParameter(p *parser) stateFunc {
var paramN int
var ok bool
for {
var ch rune
ch, ok = p.next()
if ok && ch >= '0' && ch <= '9' {
paramN = paramN*10 + int(ch-'0')
} else {
break
}
}
if ok {
p.unread()
}
if paramN == 0 {
p.paramCount++
paramN = p.paramCount
}
if paramN > p.paramMax {
p.paramMax = paramN
}
p.w.WriteString("@p")
p.w.WriteString(strconv.Itoa(paramN))
if !ok {
return nil
}
return parseNormal
}
func parseNamedParameter(p *parser) stateFunc {
var paramName string
var ok bool
for {
var ch rune
ch, ok = p.next()
if ok && (ch >= '0' && ch <= '9' || 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z') {
paramName = paramName + string(ch)
} else {
break
}
}
if ok {
p.unread()
}
p.namedParams[paramName] = true
p.w.WriteString("@")
p.w.WriteString(paramName)
if !ok {
return nil
}
return parseNormal
}
func parseQuote(p *parser) stateFunc {
for {
ch, ok := p.next()
if !ok {
return nil
}
p.write(ch)
if ch == '\'' {
return parseNormal
}
}
}
func parseDoubleQuote(p *parser) stateFunc {
for {
ch, ok := p.next()
if !ok {
return nil
}
p.write(ch)
if ch == '"' {
return parseNormal
}
}
}
func parseBracket(p *parser) stateFunc {
for {
ch, ok := p.next()
if !ok {
return nil
}
p.write(ch)
if ch == ']' {
ch, ok = p.next()
if !ok {
return nil
}
if ch != ']' {
p.unread()
return parseNormal
}
p.write(ch)
}
}
}
func parseLineComment(p *parser) stateFunc {
ch, ok := p.next()
if !ok {
return nil
}
if ch != '-' {
p.unread()
return parseNormal
}
p.write(ch)
for {
ch, ok = p.next()
if !ok {
return nil
}
p.write(ch)
if ch == '\n' {
return parseNormal
}
}
}
func parseComment(p *parser) stateFunc {
var nested int
ch, ok := p.next()
if !ok {
return nil
}
if ch != '*' {
p.unread()
return parseNormal
}
p.write(ch)
for {
ch, ok = p.next()
if !ok {
return nil
}
p.write(ch)
for ch == '*' {
ch, ok = p.next()
if !ok {
return nil
}
p.write(ch)
if ch == '/' {
if nested == 0 {
return parseNormal
} else {
nested--
}
}
}
for ch == '/' {
ch, ok = p.next()
if !ok {
return nil
}
p.write(ch)
if ch == '*' {
nested++
}
}
}
}
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