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// Copyright 2013 Canonical Ltd.
// Licensed under the LGPLv3, see LICENCE file for details.
package names
import (
"fmt"
"regexp"
"strings"
)
const RelationTagKind = "relation"
const RelationSnippet = "[a-z][a-z0-9]*(?:[_-][a-z0-9]+)*"
// Relation keys have the format "application1:relName1 application2:relName2".
// Except the peer relations, which have the format "application:relName"
// Relation tags have the format "relation-application1.rel1#application2.rel2".
// For peer relations, the format is "relation-application.rel"
var (
validRelation = regexp.MustCompile("^" + ApplicationSnippet + ":" + RelationSnippet + " " + ApplicationSnippet + ":" + RelationSnippet + "$")
validPeerRelation = regexp.MustCompile("^" + ApplicationSnippet + ":" + RelationSnippet + "$")
)
// IsValidRelation returns whether key is a valid relation key.
func IsValidRelation(key string) bool {
return validRelation.MatchString(key) || validPeerRelation.MatchString(key)
}
type RelationTag struct {
key string
}
func (t RelationTag) String() string { return t.Kind() + "-" + t.key }
func (t RelationTag) Kind() string { return RelationTagKind }
func (t RelationTag) Id() string { return relationTagSuffixToKey(t.key) }
// NewRelationTag returns the tag for the relation with the given key.
func NewRelationTag(relationKey string) RelationTag {
if !IsValidRelation(relationKey) {
panic(fmt.Sprintf("%q is not a valid relation key", relationKey))
}
// Replace both ":" with "." and the " " with "#".
relationKey = strings.Replace(relationKey, ":", ".", 2)
relationKey = strings.Replace(relationKey, " ", "#", 1)
return RelationTag{key: relationKey}
}
// ParseRelationTag parses a relation tag string.
func ParseRelationTag(relationTag string) (RelationTag, error) {
tag, err := ParseTag(relationTag)
if err != nil {
return RelationTag{}, err
}
rt, ok := tag.(RelationTag)
if !ok {
return RelationTag{}, invalidTagError(relationTag, RelationTagKind)
}
return rt, nil
}
func relationTagSuffixToKey(s string) string {
// Replace both "." with ":" and the "#" with " ".
s = strings.Replace(s, ".", ":", 2)
return strings.Replace(s, "#", " ", 1)
}
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