160 lines
2.4 KiB
Go
160 lines
2.4 KiB
Go
package argh
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import (
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"bufio"
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"bytes"
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"errors"
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"io"
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"log"
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"unicode"
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)
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type Scanner struct {
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r *bufio.Reader
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i int
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cfg *ScannerConfig
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}
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func NewScanner(r io.Reader, cfg *ScannerConfig) *Scanner {
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if cfg == nil {
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cfg = POSIXyScannerConfig
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}
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return &Scanner{
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r: bufio.NewReader(r),
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cfg: cfg,
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}
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}
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func (s *Scanner) Scan() (Token, string, Pos) {
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ch, pos := s.read()
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if s.cfg.IsBlankspace(ch) {
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_ = s.unread()
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return s.scanBlankspace()
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}
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if s.cfg.IsAssignmentOperator(ch) {
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return ASSIGN, string(ch), pos
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}
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if s.cfg.IsMultiValueDelim(ch) {
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return MULTI_VALUE_DELIMITER, string(ch), pos
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}
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if ch == eol {
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return EOL, "", pos
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}
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if ch == nul {
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return ARG_DELIMITER, string(ch), pos
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}
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if unicode.IsGraphic(ch) {
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_ = s.unread()
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return s.scanArg()
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}
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return ILLEGAL, string(ch), pos
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}
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func (s *Scanner) read() (rune, Pos) {
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ch, _, err := s.r.ReadRune()
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s.i++
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if errors.Is(err, io.EOF) {
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return eol, Pos(s.i)
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} else if err != nil {
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log.Printf("unknown scanner error=%+v", err)
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return eol, Pos(s.i)
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}
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return ch, Pos(s.i)
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}
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func (s *Scanner) unread() Pos {
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_ = s.r.UnreadRune()
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s.i--
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return Pos(s.i)
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}
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func (s *Scanner) scanBlankspace() (Token, string, Pos) {
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buf := &bytes.Buffer{}
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ch, pos := s.read()
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buf.WriteRune(ch)
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for {
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ch, pos = s.read()
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if ch == eol {
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break
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} else if !s.cfg.IsBlankspace(ch) {
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pos = s.unread()
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break
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} else {
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_, _ = buf.WriteRune(ch)
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}
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}
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return BS, buf.String(), pos
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}
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func (s *Scanner) scanArg() (Token, string, Pos) {
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buf := &bytes.Buffer{}
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ch, pos := s.read()
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buf.WriteRune(ch)
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for {
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ch, pos = s.read()
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if ch == eol || ch == nul || s.cfg.IsAssignmentOperator(ch) || s.cfg.IsMultiValueDelim(ch) {
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pos = s.unread()
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break
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}
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_, _ = buf.WriteRune(ch)
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}
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str := buf.String()
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if len(str) == 0 {
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return EMPTY, str, pos
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}
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ch0 := rune(str[0])
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if len(str) == 1 {
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if s.cfg.IsFlagPrefix(ch0) {
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return STDIN_FLAG, str, pos
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}
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if s.cfg.IsAssignmentOperator(ch0) {
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return ASSIGN, str, pos
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}
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return IDENT, str, pos
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}
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ch1 := rune(str[1])
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if len(str) == 2 {
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if s.cfg.IsFlagPrefix(ch0) && s.cfg.IsFlagPrefix(ch1) {
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return STOP_FLAG, str, pos
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}
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if s.cfg.IsFlagPrefix(ch0) {
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return SHORT_FLAG, str, pos
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}
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}
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if s.cfg.IsFlagPrefix(ch0) {
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if s.cfg.IsFlagPrefix(ch1) {
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return LONG_FLAG, str, pos
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}
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return COMPOUND_SHORT_FLAG, str, pos
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}
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return IDENT, str, pos
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}
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