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package subex
import (
"unicode/utf8"
)
const eof rune = -1
type RuneReader struct {
input string
pos, width int
}
func (l *RuneReader) next() rune {
if l.pos >= len(l.input) {
l.width = 0
return eof
}
var r rune
r, l.width = utf8.DecodeRuneInString(l.input[l.pos:])
l.pos += l.width
return r
}
func (l *RuneReader) accept(chars string) bool {
r := l.next()
for _, char := range chars {
if char == r {
return true
}
}
l.rewind()
return false
}
func (l *RuneReader) rewind() {
l.pos -= l.width
}
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