telegraf/filter/filter.go

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package filter
import (
"strings"
"github.com/gobwas/glob"
)
type Filter interface {
Match(string) bool
}
// Compile takes a list of string filters and returns a Filter interface
// for matching a given string against the filter list. The filter list
// supports glob matching too, ie:
//
// f, _ := Compile([]string{"cpu", "mem", "net*"})
// f.Match("cpu") // true
// f.Match("network") // true
// f.Match("memory") // false
//
func Compile(filters []string) (Filter, error) {
// return if there is nothing to compile
if len(filters) == 0 {
return nil, nil
}
// check if we can compile a non-glob filter
noGlob := true
for _, filter := range filters {
if hasMeta(filter) {
noGlob = false
break
}
}
switch {
case noGlob:
// return non-globbing filter if not needed.
return compileFilterNoGlob(filters), nil
case len(filters) == 1:
return glob.Compile(filters[0])
default:
return glob.Compile("{" + strings.Join(filters, ",") + "}")
}
}
// hasMeta reports whether path contains any magic glob characters.
func hasMeta(s string) bool {
return strings.IndexAny(s, "*?[") >= 0
}
type filter struct {
m map[string]struct{}
}
func (f *filter) Match(s string) bool {
_, ok := f.m[s]
return ok
}
type filtersingle struct {
s string
}
func (f *filtersingle) Match(s string) bool {
return f.s == s
}
func compileFilterNoGlob(filters []string) Filter {
if len(filters) == 1 {
return &filtersingle{s: filters[0]}
}
out := filter{m: make(map[string]struct{})}
for _, filter := range filters {
out.m[filter] = struct{}{}
}
return &out
}