telegraf/internal/templating/matcher.go

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package templating
import (
"strings"
)
// matcher determines which template should be applied to a given metric
// based on a filter tree.
type matcher struct {
root *node
defaultTemplate *Template
}
// newMatcher creates a new matcher.
func newMatcher(defaultTemplate *Template) *matcher {
return &matcher{
root: &node{},
defaultTemplate: defaultTemplate,
}
}
func (m *matcher) addSpec(tmplt templateSpec) error {
// Parse out the default tags specific to this template
tags := map[string]string{}
if tmplt.tagstring != "" {
for _, kv := range strings.Split(tmplt.tagstring, ",") {
parts := strings.Split(kv, "=")
tags[parts[0]] = parts[1]
}
}
tmpl, err := NewTemplate(tmplt.separator, tmplt.template, tags)
if err != nil {
return err
}
m.add(tmplt.filter, tmpl)
return nil
}
// add inserts the template in the filter tree based the given filter
func (m *matcher) add(filter string, template *Template) {
if filter == "" {
m.defaultTemplate = template
m.root.separator = template.separator
return
}
m.root.insert(filter, template)
}
// match returns the template that matches the given measurement line.
// If no template matches, the default template is returned.
func (m *matcher) match(line string) *Template {
tmpl := m.root.search(line)
if tmpl != nil {
return tmpl
}
return m.defaultTemplate
}