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lexer.go
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lexer.go
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// Copyright 2016 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package parser
import (
"bytes"
"fmt"
"strings"
"unicode"
"unicode/utf8"
"github.com/pingcap/parser/mysql"
)
var _ = yyLexer(&Scanner{})
// Pos represents the position of a token.
type Pos struct {
Line int
Col int
Offset int
}
// Scanner implements the yyLexer interface.
type Scanner struct {
r reader
buf bytes.Buffer
errs []error
stmtStartPos int
// For scanning such kind of comment: /*! MySQL-specific code */ or /*+ optimizer hint */
specialComment specialCommentScanner
sqlMode mysql.SQLMode
// If the lexer should recognize keywords for window function.
// It may break the compatibility when support those keywords,
// because some application may already use them as identifiers.
supportWindowFunc bool
}
type specialCommentScanner interface {
scan() (tok int, pos Pos, lit string)
}
type mysqlSpecificCodeScanner struct {
*Scanner
Pos
}
func (s *mysqlSpecificCodeScanner) scan() (tok int, pos Pos, lit string) {
tok, pos, lit = s.Scanner.scan()
pos.Line += s.Pos.Line
pos.Col += s.Pos.Col
pos.Offset += s.Pos.Offset
return
}
type optimizerHintScanner struct {
*Scanner
Pos
end bool
}
func (s *optimizerHintScanner) scan() (tok int, pos Pos, lit string) {
tok, pos, lit = s.Scanner.scan()
pos.Line += s.Pos.Line
pos.Col += s.Pos.Col
pos.Offset += s.Pos.Offset
if tok == 0 {
if !s.end {
tok = hintEnd
s.end = true
}
}
return
}
// Errors returns the errors during a scan.
func (s *Scanner) Errors() []error {
return s.errs
}
// reset resets the sql string to be scanned.
func (s *Scanner) reset(sql string) {
s.r = reader{s: sql, p: Pos{Line: 1}}
s.buf.Reset()
s.errs = s.errs[:0]
s.stmtStartPos = 0
s.specialComment = nil
}
func (s *Scanner) stmtText() string {
endPos := s.r.pos().Offset
if s.r.s[endPos-1] == '\n' {
endPos = endPos - 1 // trim new line
}
if s.r.s[s.stmtStartPos] == '\n' {
s.stmtStartPos++
}
text := s.r.s[s.stmtStartPos:endPos]
s.stmtStartPos = endPos
return text
}
// Errorf tells scanner something is wrong.
// Scanner satisfies yyLexer interface which need this function.
func (s *Scanner) Errorf(format string, a ...interface{}) {
str := fmt.Sprintf(format, a...)
val := s.r.s[s.r.pos().Offset:]
if len(val) > 2048 {
val = val[:2048]
}
err := fmt.Errorf("line %d column %d near \"%s\"%s (total length %d)", s.r.p.Line, s.r.p.Col, val, str, len(s.r.s))
s.errs = append(s.errs, err)
}
// Lex returns a token and store the token value in v.
// Scanner satisfies yyLexer interface.
// 0 and invalid are special token id this function would return:
// return 0 tells parser that scanner meets EOF,
// return invalid tells parser that scanner meets illegal character.
func (s *Scanner) Lex(v *yySymType) int {
tok, pos, lit := s.scan()
v.offset = pos.Offset
v.ident = lit
if tok == identifier {
tok = handleIdent(v)
}
if tok == identifier {
if tok1 := s.isTokenIdentifier(lit, pos.Offset); tok1 != 0 {
tok = tok1
}
}
if s.sqlMode.HasANSIQuotesMode() &&
tok == stringLit &&
s.r.s[v.offset] == '"' {
tok = identifier
}
if tok == pipes && !(s.sqlMode.HasPipesAsConcatMode()) {
return pipesAsOr
}
if tok == not && s.sqlMode.HasHighNotPrecedenceMode() {
return not2
}
switch tok {
case intLit:
return toInt(s, v, lit)
case floatLit:
return toFloat(s, v, lit)
case decLit:
return toDecimal(s, v, lit)
case hexLit:
return toHex(s, v, lit)
case bitLit:
return toBit(s, v, lit)
case singleAtIdentifier, doubleAtIdentifier, cast, extract:
v.item = lit
return tok
case null:
v.item = nil
case quotedIdentifier:
tok = identifier
}
if tok == unicode.ReplacementChar && s.r.eof() {
return 0
}
return tok
}
// SetSQLMode sets the SQL mode for scanner.
func (s *Scanner) SetSQLMode(mode mysql.SQLMode) {
s.sqlMode = mode
}
// GetSQLMode return the SQL mode of scanner.
func (s *Scanner) GetSQLMode() mysql.SQLMode {
return s.sqlMode
}
// EnableWindowFunc controls whether the scanner recognize the keywords of window function.
func (s *Scanner) EnableWindowFunc(val bool) {
s.supportWindowFunc = val
}
// NewScanner returns a new scanner object.
func NewScanner(s string) *Scanner {
return &Scanner{r: reader{s: s}}
}
func (s *Scanner) skipWhitespace() rune {
return s.r.incAsLongAs(unicode.IsSpace)
}
func (s *Scanner) scan() (tok int, pos Pos, lit string) {
if s.specialComment != nil {
// Enter specialComment scan mode.
// for scanning such kind of comment: /*! MySQL-specific code */
specialComment := s.specialComment
tok, pos, lit = specialComment.scan()
if tok != 0 {
// return the specialComment scan result as the result
return
}
// leave specialComment scan mode after all stream consumed.
s.specialComment = nil
}
ch0 := s.r.peek()
if unicode.IsSpace(ch0) {
ch0 = s.skipWhitespace()
}
pos = s.r.pos()
if s.r.eof() {
// when scanner meets EOF, the returned token should be 0,
// because 0 is a special token id to remind the parser that stream is end.
return 0, pos, ""
}
if !s.r.eof() && isIdentExtend(ch0) {
return scanIdentifier(s)
}
// search a trie to get a token.
node := &ruleTable
for ch0 >= 0 && ch0 <= 255 {
if node.childs[ch0] == nil || s.r.eof() {
break
}
node = node.childs[ch0]
if node.fn != nil {
return node.fn(s)
}
s.r.inc()
ch0 = s.r.peek()
}
tok, lit = node.token, s.r.data(&pos)
return
}
func startWithXx(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
if s.r.peek() == '\'' {
s.r.inc()
s.scanHex()
if s.r.peek() == '\'' {
s.r.inc()
tok, lit = hexLit, s.r.data(&pos)
} else {
tok = unicode.ReplacementChar
}
return
}
s.r.incAsLongAs(isIdentChar)
tok, lit = identifier, s.r.data(&pos)
return
}
func startWithNn(s *Scanner) (tok int, pos Pos, lit string) {
tok, pos, lit = scanIdentifier(s)
// The National Character Set, N'some text' or n'some test'.
// See https://dev.mysql.com/doc/refman/5.7/en/string-literals.html
// and https://dev.mysql.com/doc/refman/5.7/en/charset-national.html
if lit == "N" || lit == "n" {
if s.r.peek() == '\'' {
tok = underscoreCS
lit = "utf8"
}
}
return
}
func startWithBb(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
if s.r.peek() == '\'' {
s.r.inc()
s.scanBit()
if s.r.peek() == '\'' {
s.r.inc()
tok, lit = bitLit, s.r.data(&pos)
} else {
tok = unicode.ReplacementChar
}
return
}
s.r.incAsLongAs(isIdentChar)
tok, lit = identifier, s.r.data(&pos)
return
}
func startWithSharp(s *Scanner) (tok int, pos Pos, lit string) {
s.r.incAsLongAs(func(ch rune) bool {
return ch != '\n'
})
return s.scan()
}
func startWithDash(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
if strings.HasPrefix(s.r.s[pos.Offset:], "--") {
remainLen := len(s.r.s[pos.Offset:])
if remainLen == 2 || (remainLen > 2 && unicode.IsSpace(rune(s.r.s[pos.Offset+2]))) {
s.r.incAsLongAs(func(ch rune) bool {
return ch != '\n'
})
return s.scan()
}
}
if strings.HasPrefix(s.r.s[pos.Offset:], "->>") {
tok = juss
s.r.incN(3)
return
}
if strings.HasPrefix(s.r.s[pos.Offset:], "->") {
tok = jss
s.r.incN(2)
return
}
tok = int('-')
s.r.inc()
return
}
func startWithSlash(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
ch0 := s.r.peek()
if ch0 == '*' {
s.r.inc()
startWithAsterisk := false
for {
ch0 = s.r.readByte()
if startWithAsterisk && ch0 == '/' {
// Meets */, means comment end.
break
} else if ch0 == '*' {
startWithAsterisk = true
} else {
startWithAsterisk = false
}
if ch0 == unicode.ReplacementChar && s.r.eof() {
// unclosed comment
s.errs = append(s.errs, ParseErrorWith(s.r.data(&pos), s.r.p.Line))
return
}
}
comment := s.r.data(&pos)
// See https://dev.mysql.com/doc/refman/5.7/en/optimizer-hints.html
if strings.HasPrefix(comment, "/*+") {
begin := sqlOffsetInComment(comment)
end := len(comment) - 2
sql := comment[begin:end]
s.specialComment = &optimizerHintScanner{
Scanner: NewScanner(sql),
Pos: Pos{
pos.Line,
pos.Col,
pos.Offset + begin,
},
}
tok = hintBegin
return
}
// See http://dev.mysql.com/doc/refman/5.7/en/comments.html
// Convert "/*!VersionNumber MySQL-specific-code */" to "MySQL-specific-code".
if strings.HasPrefix(comment, "/*!") {
sql := specCodePattern.ReplaceAllStringFunc(comment, TrimComment)
s.specialComment = &mysqlSpecificCodeScanner{
Scanner: NewScanner(sql),
Pos: Pos{
pos.Line,
pos.Col,
pos.Offset + sqlOffsetInComment(comment),
},
}
}
return s.scan()
}
tok = int('/')
return
}
func sqlOffsetInComment(comment string) int {
// find the first SQL token offset in pattern like "/*!40101 mysql specific code */"
offset := 0
for i := 0; i < len(comment); i++ {
if unicode.IsSpace(rune(comment[i])) {
offset = i
break
}
}
for offset < len(comment) {
offset++
if !unicode.IsSpace(rune(comment[offset])) {
break
}
}
return offset
}
func startWithAt(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
ch1 := s.r.peek()
if ch1 == '\'' || ch1 == '"' {
nTok, nPos, nLit := startString(s)
if nTok == stringLit {
tok = singleAtIdentifier
pos = nPos
lit = nLit
} else {
tok = int('@')
}
} else if ch1 == '`' {
nTok, nPos, nLit := scanQuotedIdent(s)
if nTok == quotedIdentifier {
tok = singleAtIdentifier
pos = nPos
lit = nLit
} else {
tok = int('@')
}
} else if isUserVarChar(ch1) {
s.r.incAsLongAs(isUserVarChar)
tok, lit = singleAtIdentifier, s.r.data(&pos)
} else if ch1 == '@' {
s.r.inc()
stream := s.r.s[pos.Offset+2:]
for _, v := range []string{"global.", "session.", "local."} {
if len(v) > len(stream) {
continue
}
if strings.EqualFold(stream[:len(v)], v) {
s.r.incN(len(v))
break
}
}
s.r.incAsLongAs(isIdentChar)
tok, lit = doubleAtIdentifier, s.r.data(&pos)
} else {
tok, lit = singleAtIdentifier, s.r.data(&pos)
}
return
}
func scanIdentifier(s *Scanner) (int, Pos, string) {
pos := s.r.pos()
s.r.inc()
s.r.incAsLongAs(isIdentChar)
return identifier, pos, s.r.data(&pos)
}
var (
quotedIdentifier = -identifier
)
func scanQuotedIdent(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
s.buf.Reset()
for {
ch := s.r.readByte()
if ch == unicode.ReplacementChar && s.r.eof() {
tok = unicode.ReplacementChar
return
}
if ch == '`' {
if s.r.peek() != '`' {
// don't return identifier in case that it's interpreted as keyword token later.
tok, lit = quotedIdentifier, s.buf.String()
return
}
s.r.inc()
}
s.buf.WriteRune(ch)
}
}
func startString(s *Scanner) (tok int, pos Pos, lit string) {
return s.scanString()
}
// lazyBuf is used to avoid allocation if possible.
// it has a useBuf field indicates whether bytes.Buffer is necessary. if
// useBuf is false, we can avoid calling bytes.Buffer.String(), which
// make a copy of data and cause allocation.
type lazyBuf struct {
useBuf bool
r *reader
b *bytes.Buffer
p *Pos
}
func (mb *lazyBuf) setUseBuf(str string) {
if !mb.useBuf {
mb.useBuf = true
mb.b.Reset()
mb.b.WriteString(str)
}
}
func (mb *lazyBuf) writeRune(r rune, w int) {
if mb.useBuf {
if w > 1 {
mb.b.WriteRune(r)
} else {
mb.b.WriteByte(byte(r))
}
}
}
func (mb *lazyBuf) data() string {
var lit string
if mb.useBuf {
lit = mb.b.String()
} else {
lit = mb.r.data(mb.p)
lit = lit[1 : len(lit)-1]
}
return lit
}
func (s *Scanner) scanString() (tok int, pos Pos, lit string) {
tok, pos = stringLit, s.r.pos()
mb := lazyBuf{false, &s.r, &s.buf, &pos}
ending := s.r.readByte()
ch0 := s.r.peek()
for !s.r.eof() {
if ch0 == ending {
s.r.inc()
if s.r.peek() != ending {
lit = mb.data()
return
}
str := mb.r.data(&pos)
mb.setUseBuf(str[1 : len(str)-1])
} else if ch0 == '\\' && !s.sqlMode.HasNoBackslashEscapesMode() {
mb.setUseBuf(mb.r.data(&pos)[1:])
ch0 = handleEscape(s)
}
mb.writeRune(ch0, s.r.w)
if !s.r.eof() {
s.r.inc()
ch0 = s.r.peek()
}
}
tok = unicode.ReplacementChar
return
}
// handleEscape handles the case in scanString when previous char is '\'.
func handleEscape(s *Scanner) rune {
s.r.inc()
ch0 := s.r.peek()
/*
\" \' \\ \n \0 \b \Z \r \t ==> escape to one char
\% \_ ==> preserve both char
other ==> remove \
*/
switch ch0 {
case 'n':
ch0 = '\n'
case '0':
ch0 = 0
case 'b':
ch0 = 8
case 'Z':
ch0 = 26
case 'r':
ch0 = '\r'
case 't':
ch0 = '\t'
case '%', '_':
s.buf.WriteByte('\\')
}
return ch0
}
func startWithNumber(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
tok = intLit
ch0 := s.r.readByte()
if ch0 == '0' {
tok = intLit
ch1 := s.r.peek()
switch {
case ch1 >= '0' && ch1 <= '7':
s.r.inc()
s.scanOct()
case ch1 == 'x' || ch1 == 'X':
s.r.inc()
s.scanHex()
tok = hexLit
case ch1 == 'b':
s.r.inc()
s.scanBit()
tok = bitLit
case ch1 == '.':
return s.scanFloat(&pos)
case ch1 == 'B':
tok = unicode.ReplacementChar
return
}
}
s.scanDigits()
ch0 = s.r.peek()
if ch0 == '.' || ch0 == 'e' || ch0 == 'E' {
return s.scanFloat(&pos)
}
// Identifiers may begin with a digit but unless quoted may not consist solely of digits.
if !s.r.eof() && isIdentChar(ch0) {
s.r.incAsLongAs(isIdentChar)
return identifier, pos, s.r.data(&pos)
}
lit = s.r.data(&pos)
return
}
func startWithDot(s *Scanner) (tok int, pos Pos, lit string) {
pos = s.r.pos()
s.r.inc()
save := s.r.pos()
if isDigit(s.r.peek()) {
tok, _, lit = s.scanFloat(&pos)
if s.r.eof() || !isIdentChar(s.r.peek()) {
return
}
// Fail to parse a float, reset to dot.
s.r.p = save
}
tok, lit = int('.'), "."
return
}
func (s *Scanner) scanOct() {
s.r.incAsLongAs(func(ch rune) bool {
return ch >= '0' && ch <= '7'
})
}
func (s *Scanner) scanHex() {
s.r.incAsLongAs(func(ch rune) bool {
return ch >= '0' && ch <= '9' ||
ch >= 'a' && ch <= 'f' ||
ch >= 'A' && ch <= 'F'
})
}
func (s *Scanner) scanBit() {
s.r.incAsLongAs(func(ch rune) bool {
return ch == '0' || ch == '1'
})
}
func (s *Scanner) scanFloat(beg *Pos) (tok int, pos Pos, lit string) {
s.r.p = *beg
// float = D1 . D2 e D3
s.scanDigits()
ch0 := s.r.peek()
if ch0 == '.' {
s.r.inc()
s.scanDigits()
ch0 = s.r.peek()
}
if ch0 == 'e' || ch0 == 'E' {
s.r.inc()
ch0 = s.r.peek()
if ch0 == '-' || ch0 == '+' {
s.r.inc()
}
s.scanDigits()
tok = floatLit
} else {
tok = decLit
}
pos, lit = *beg, s.r.data(beg)
return
}
func (s *Scanner) scanDigits() string {
pos := s.r.pos()
s.r.incAsLongAs(isDigit)
return s.r.data(&pos)
}
type reader struct {
s string
p Pos
w int
}
var eof = Pos{-1, -1, -1}
func (r *reader) eof() bool {
return r.p.Offset >= len(r.s)
}
// peek() peeks a rune from underlying reader.
// if reader meets EOF, it will return unicode.ReplacementChar. to distinguish from
// the real unicode.ReplacementChar, the caller should call r.eof() again to check.
func (r *reader) peek() rune {
if r.eof() {
return unicode.ReplacementChar
}
v, w := rune(r.s[r.p.Offset]), 1
switch {
case v == 0:
r.w = w
return v // illegal UTF-8 encoding
case v >= 0x80:
v, w = utf8.DecodeRuneInString(r.s[r.p.Offset:])
if v == utf8.RuneError && w == 1 {
v = rune(r.s[r.p.Offset]) // illegal UTF-8 encoding
}
}
r.w = w
return v
}
// inc increase the position offset of the reader.
// peek must be called before calling inc!
func (r *reader) inc() {
if r.s[r.p.Offset] == '\n' {
r.p.Line++
r.p.Col = 0
}
r.p.Offset += r.w
r.p.Col++
}
func (r *reader) incN(n int) {
for i := 0; i < n; i++ {
r.inc()
}
}
func (r *reader) readByte() (ch rune) {
ch = r.peek()
if ch == unicode.ReplacementChar && r.eof() {
return
}
r.inc()
return
}
func (r *reader) pos() Pos {
return r.p
}
func (r *reader) data(from *Pos) string {
return r.s[from.Offset:r.p.Offset]
}
func (r *reader) incAsLongAs(fn func(rune) bool) rune {
for {
ch := r.peek()
if !fn(ch) {
return ch
}
if ch == unicode.ReplacementChar && r.eof() {
return 0
}
r.inc()
}
}