/
filter.go
106 lines (95 loc) · 1.87 KB
/
filter.go
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package alertmanager
import (
"bufio"
"github.com/synyx/tuwat/pkg/config"
"strings"
)
type fieldMatcher struct {
field string
m config.RuleMatcher
}
func parseFilter(val string) []fieldMatcher {
var matchers []fieldMatcher
s := newFilterScanner(val)
for {
matcher := s.scan()
if matcher.field == "" {
return matchers
}
matchers = append(matchers, matcher)
}
}
type scanner struct {
r *bufio.Reader
}
var invalid = rune(0)
func newFilterScanner(s string) *scanner {
return &scanner{r: bufio.NewReader(strings.NewReader(s))}
}
// read reads the next rune from the buffered reader.
// Returns the rune(0) if an error occurs (or io.EOF is returned).
func (s *scanner) read() rune {
ch, _, err := s.r.ReadRune()
if err != nil {
return invalid
}
return ch
}
// unread places the previously read rune back on the reader.
func (s *scanner) unread() { _ = s.r.UnreadRune() }
func (s *scanner) scan() fieldMatcher {
top:
ch := s.read()
switch ch {
case '{', ',', ' ':
// we're just starting, go on
goto top
case '}':
// last element
return fieldMatcher{}
default:
s.unread()
field := s.parseField()
prefix := s.parsePrefix()
str := s.parseString()
return fieldMatcher{
field: field,
m: config.ParseRuleMatcher(prefix + " " + str),
}
}
}
func (s *scanner) parseField() string {
var field []rune
for {
ch := s.read()
if ch == '~' || ch == '!' || ch == '=' {
s.unread()
return string(field)
}
field = append(field, ch)
}
}
func (s *scanner) parsePrefix() string {
var prefix []rune
for {
ch := s.read()
if ch == '~' || ch == '!' || ch == '=' {
prefix = append(prefix, ch)
} else {
s.unread()
return string(prefix)
}
}
}
func (s *scanner) parseString() string {
var prefix []rune
_ = s.read() // "
for {
ch := s.read()
if ch == '"' {
return string(prefix)
} else {
prefix = append(prefix, ch)
}
}
}