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gitea/vendor/github.com/kevinburke/ssh_config/lexer.go

240 lines
4.0 KiB

package ssh_config
import (
"bytes"
)
// Define state functions
type sshLexStateFn func() sshLexStateFn
type sshLexer struct {
inputIdx int
input []rune // Textual source
buffer []rune // Runes composing the current token
tokens chan token
line int
col int
endbufferLine int
endbufferCol int
}
func (s *sshLexer) lexComment(previousState sshLexStateFn) sshLexStateFn {
return func() sshLexStateFn {
growingString := ""
for next := s.peek(); next != '\n' && next != eof; next = s.peek() {
if next == '\r' && s.follow("\r\n") {
break
}
growingString += string(next)
s.next()
}
s.emitWithValue(tokenComment, growingString)
s.skip()
return previousState
}
}
// lex the space after an equals sign in a function
func (s *sshLexer) lexRspace() sshLexStateFn {
for {
next := s.peek()
if !isSpace(next) {
break
}
s.skip()
}
return s.lexRvalue
}
func (s *sshLexer) lexEquals() sshLexStateFn {
for {
next := s.peek()
if next == '=' {
s.emit(tokenEquals)
s.skip()
return s.lexRspace
}
// TODO error handling here; newline eof etc.
if !isSpace(next) {
break
}
s.skip()
}
return s.lexRvalue
}
func (s *sshLexer) lexKey() sshLexStateFn {
growingString := ""
for r := s.peek(); isKeyChar(r); r = s.peek() {
// simplified a lot here
if isSpace(r) || r == '=' {
s.emitWithValue(tokenKey, growingString)
s.skip()
return s.lexEquals
}
growingString += string(r)
s.next()
}
s.emitWithValue(tokenKey, growingString)
return s.lexEquals
}
func (s *sshLexer) lexRvalue() sshLexStateFn {
growingString := ""
for {
next := s.peek()
switch next {
case '\r':
if s.follow("\r\n") {
s.emitWithValue(tokenString, growingString)
s.skip()
return s.lexVoid
}
case '\n':
s.emitWithValue(tokenString, growingString)
s.skip()
return s.lexVoid
case '#':
s.emitWithValue(tokenString, growingString)
s.skip()
return s.lexComment(s.lexVoid)
case eof:
s.next()
}
if next == eof {
break
}
growingString += string(next)
s.next()
}
s.emit(tokenEOF)
return nil
}
func (s *sshLexer) read() rune {
r := s.peek()
if r == '\n' {
s.endbufferLine++
s.endbufferCol = 1
} else {
s.endbufferCol++
}
s.inputIdx++
return r
}
func (s *sshLexer) next() rune {
r := s.read()
if r != eof {
s.buffer = append(s.buffer, r)
}
return r
}
func (s *sshLexer) lexVoid() sshLexStateFn {
for {
next := s.peek()
switch next {
case '#':
s.skip()
return s.lexComment(s.lexVoid)
case '\r':
fallthrough
case '\n':
s.emit(tokenEmptyLine)
s.skip()
continue
}
if isSpace(next) {
s.skip()
}
if isKeyStartChar(next) {
return s.lexKey
}
// removed IsKeyStartChar and lexKey. probably will need to readd
if next == eof {
s.next()
break
}
}
s.emit(tokenEOF)
return nil
}
func (s *sshLexer) ignore() {
s.buffer = make([]rune, 0)
s.line = s.endbufferLine
s.col = s.endbufferCol
}
func (s *sshLexer) skip() {
s.next()
s.ignore()
}
func (s *sshLexer) emit(t tokenType) {
s.emitWithValue(t, string(s.buffer))
}
func (s *sshLexer) emitWithValue(t tokenType, value string) {
tok := token{
Position: Position{s.line, s.col},
typ: t,
val: value,
}
s.tokens <- tok
s.ignore()
}
func (s *sshLexer) peek() rune {
if s.inputIdx >= len(s.input) {
return eof
}
r := s.input[s.inputIdx]
return r
}
func (s *sshLexer) follow(next string) bool {
inputIdx := s.inputIdx
for _, expectedRune := range next {
if inputIdx >= len(s.input) {
return false
}
r := s.input[inputIdx]
inputIdx++
if expectedRune != r {
return false
}
}
return true
}
func (s *sshLexer) run() {
for state := s.lexVoid; state != nil; {
state = state()
}
close(s.tokens)
}
func lexSSH(input []byte) chan token {
runes := bytes.Runes(input)
l := &sshLexer{
input: runes,
tokens: make(chan token),
line: 1,
col: 1,
endbufferLine: 1,
endbufferCol: 1,
}
go l.run()
return l.tokens
}