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comment.go
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comment.go
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package json
import (
"bufio"
"io"
)
// kanged from v2ray
type commentFilterState = byte
const (
commentFilterStateContent commentFilterState = iota
commentFilterStateEscape
commentFilterStateDoubleQuote
commentFilterStateDoubleQuoteEscape
commentFilterStateSingleQuote
commentFilterStateSingleQuoteEscape
commentFilterStateComment
commentFilterStateSlash
commentFilterStateMultilineComment
commentFilterStateMultilineCommentStar
)
type CommentFilter struct {
br *bufio.Reader
state commentFilterState
}
func NewCommentFilter(reader io.Reader) io.Reader {
return &CommentFilter{br: bufio.NewReader(reader)}
}
func (v *CommentFilter) Read(b []byte) (int, error) {
p := b[:0]
for len(p) < len(b)-2 {
x, err := v.br.ReadByte()
if err != nil {
if len(p) == 0 {
return 0, err
}
return len(p), nil
}
switch v.state {
case commentFilterStateContent:
switch x {
case '"':
v.state = commentFilterStateDoubleQuote
p = append(p, x)
case '\'':
v.state = commentFilterStateSingleQuote
p = append(p, x)
case '\\':
v.state = commentFilterStateEscape
case '#':
v.state = commentFilterStateComment
case '/':
v.state = commentFilterStateSlash
default:
p = append(p, x)
}
case commentFilterStateEscape:
p = append(p, '\\', x)
v.state = commentFilterStateContent
case commentFilterStateDoubleQuote:
switch x {
case '"':
v.state = commentFilterStateContent
p = append(p, x)
case '\\':
v.state = commentFilterStateDoubleQuoteEscape
default:
p = append(p, x)
}
case commentFilterStateDoubleQuoteEscape:
p = append(p, '\\', x)
v.state = commentFilterStateDoubleQuote
case commentFilterStateSingleQuote:
switch x {
case '\'':
v.state = commentFilterStateContent
p = append(p, x)
case '\\':
v.state = commentFilterStateSingleQuoteEscape
default:
p = append(p, x)
}
case commentFilterStateSingleQuoteEscape:
p = append(p, '\\', x)
v.state = commentFilterStateSingleQuote
case commentFilterStateComment:
if x == '\n' {
v.state = commentFilterStateContent
p = append(p, '\n')
}
case commentFilterStateSlash:
switch x {
case '/':
v.state = commentFilterStateComment
case '*':
v.state = commentFilterStateMultilineComment
default:
p = append(p, '/', x)
}
case commentFilterStateMultilineComment:
switch x {
case '*':
v.state = commentFilterStateMultilineCommentStar
case '\n':
p = append(p, '\n')
}
case commentFilterStateMultilineCommentStar:
switch x {
case '/':
v.state = commentFilterStateContent
case '*':
// Stay
case '\n':
p = append(p, '\n')
default:
v.state = commentFilterStateMultilineComment
}
default:
panic("Unknown state.")
}
}
return len(p), nil
}