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opts.go
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/
opts.go
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package chunk
import (
"strings"
"unicode/utf8"
)
// Bitmap used by func isRegexMetaCharacter to check whether a character needs to be escaped.
var regexMetaCharacterBytes [16]byte
// isRegexMetaCharacter reports whether byte b needs to be escaped.
func isRegexMetaCharacter(b byte) bool {
return b < utf8.RuneSelf && regexMetaCharacterBytes[b%16]&(1<<(b/16)) != 0
}
func init() {
for _, b := range []byte(`.+*?()|[]{}^$`) {
regexMetaCharacterBytes[b%16] |= 1 << (b / 16)
}
}
// FindSetMatches returns list of values that can be equality matched on.
// copied from Prometheus querier.go, removed check for Prometheus wrapper.
func FindSetMatches(pattern string) []string {
escaped := false
sets := []*strings.Builder{{}}
for i := 0; i < len(pattern); i++ {
if escaped {
switch {
case isRegexMetaCharacter(pattern[i]):
sets[len(sets)-1].WriteByte(pattern[i])
case pattern[i] == '\\':
sets[len(sets)-1].WriteByte('\\')
default:
return nil
}
escaped = false
} else {
switch {
case isRegexMetaCharacter(pattern[i]):
if pattern[i] == '|' {
sets = append(sets, &strings.Builder{})
} else {
return nil
}
case pattern[i] == '\\':
escaped = true
default:
sets[len(sets)-1].WriteByte(pattern[i])
}
}
}
matches := make([]string, 0, len(sets))
for _, s := range sets {
if s.Len() > 0 {
matches = append(matches, s.String())
}
}
return matches
}