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// SPDX-License-Identifier: GPL-3.0-or-later
package pipeline
import (
"errors"
"fmt"
"strings"
"github.com/netdata/netdata/go/go.d.plugin/agent/discovery/sd/model"
)
type selector interface {
matches(model.Tags) bool
}
type (
exactSelector string
trueSelector struct{}
negSelector struct{ selector }
orSelector struct{ lhs, rhs selector }
andSelector struct{ lhs, rhs selector }
)
func (s exactSelector) matches(tags model.Tags) bool { _, ok := tags[string(s)]; return ok }
func (s trueSelector) matches(model.Tags) bool { return true }
func (s negSelector) matches(tags model.Tags) bool { return !s.selector.matches(tags) }
func (s orSelector) matches(tags model.Tags) bool { return s.lhs.matches(tags) || s.rhs.matches(tags) }
func (s andSelector) matches(tags model.Tags) bool { return s.lhs.matches(tags) && s.rhs.matches(tags) }
func (s exactSelector) String() string { return "{" + string(s) + "}" }
func (s negSelector) String() string { return "{!" + stringify(s.selector) + "}" }
func (s trueSelector) String() string { return "{*}" }
func (s orSelector) String() string { return "{" + stringify(s.lhs) + "|" + stringify(s.rhs) + "}" }
func (s andSelector) String() string { return "{" + stringify(s.lhs) + ", " + stringify(s.rhs) + "}" }
func stringify(sr selector) string { return strings.Trim(fmt.Sprintf("%s", sr), "{}") }
func parseSelector(line string) (sr selector, err error) {
words := strings.Fields(line)
if len(words) == 0 {
return trueSelector{}, nil
}
var srs []selector
for _, word := range words {
if idx := strings.IndexByte(word, '|'); idx > 0 {
sr, err = parseOrSelectorWord(word)
} else {
sr, err = parseSingleSelectorWord(word)
}
if err != nil {
return nil, fmt.Errorf("selector '%s' contains selector '%s' with forbidden symbol", line, word)
}
srs = append(srs, sr)
}
switch len(srs) {
case 0:
return trueSelector{}, nil
case 1:
return srs[0], nil
default:
return newAndSelector(srs[0], srs[1], srs[2:]...), nil
}
}
func parseOrSelectorWord(orWord string) (sr selector, err error) {
var srs []selector
for _, word := range strings.Split(orWord, "|") {
if sr, err = parseSingleSelectorWord(word); err != nil {
return nil, err
}
srs = append(srs, sr)
}
switch len(srs) {
case 0:
return trueSelector{}, nil
case 1:
return srs[0], nil
default:
return newOrSelector(srs[0], srs[1], srs[2:]...), nil
}
}
func parseSingleSelectorWord(word string) (selector, error) {
if len(word) == 0 {
return nil, errors.New("empty word")
}
neg := word[0] == '!'
if neg {
word = word[1:]
}
if len(word) == 0 {
return nil, errors.New("empty word")
}
if word != "*" && !isSelectorWordValid(word) {
return nil, errors.New("forbidden symbol")
}
var sr selector
switch word {
case "*":
sr = trueSelector{}
default:
sr = exactSelector(word)
}
if neg {
return negSelector{sr}, nil
}
return sr, nil
}
func newAndSelector(lhs, rhs selector, others ...selector) selector {
m := andSelector{lhs: lhs, rhs: rhs}
switch len(others) {
case 0:
return m
default:
return newAndSelector(m, others[0], others[1:]...)
}
}
func newOrSelector(lhs, rhs selector, others ...selector) selector {
m := orSelector{lhs: lhs, rhs: rhs}
switch len(others) {
case 0:
return m
default:
return newOrSelector(m, others[0], others[1:]...)
}
}
func isSelectorWordValid(word string) bool {
// valid:
// *
// ^[a-zA-Z][a-zA-Z0-9=_.]*$
if len(word) == 0 {
return false
}
if word == "*" {
return true
}
for i, b := range word {
switch {
case b >= 'a' && b <= 'z':
case b >= 'A' && b <= 'Z':
case b >= '0' && b <= '9' && i > 0:
case (b == '=' || b == '_' || b == '.') && i > 0:
default:
return false
}
}
return true
}
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