telegraf/plugins/parsers/wavefront/scanner.go

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2018-08-13 23:37:06 +00:00
package wavefront
import (
"bufio"
"io"
)
// Lexical Point Scanner
type PointScanner struct {
r *bufio.Reader
}
func NewScanner(r io.Reader) *PointScanner {
return &PointScanner{r: bufio.NewReader(r)}
}
// read reads the next rune from the buffered reader.
// Returns rune(0) if an error occurs (or io.EOF is returned).
func (s *PointScanner) read() rune {
ch, _, err := s.r.ReadRune()
if err != nil {
return eof
}
return ch
}
// unread places the previously read rune back on the reader.
func (s *PointScanner) unread() {
_ = s.r.UnreadRune()
}
// Scan returns the next token and literal value.
func (s *PointScanner) Scan() (Token, string) {
// Read the next rune
ch := s.read()
if isWhitespace(ch) {
return WS, string(ch)
} else if isLetter(ch) {
return LETTER, string(ch)
} else if isNumber(ch) {
return NUMBER, string(ch)
} else if isDelta(ch) {
return DELTA, string(ch)
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}
// Otherwise read the individual character.
switch ch {
case eof:
return EOF, ""
case '\n':
return NEWLINE, string(ch)
case '.':
return DOT, string(ch)
case '-':
return MINUS_SIGN, string(ch)
case '_':
return UNDERSCORE, string(ch)
case '/':
return SLASH, string(ch)
case '\\':
return BACKSLASH, string(ch)
case ',':
return COMMA, string(ch)
case '"':
return QUOTES, string(ch)
case '=':
return EQUALS, string(ch)
}
return ILLEGAL, string(ch)
}