1 // Copyright 2017, OpenCensus Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 16 package tag 17 18 // Key represents a tag key. 19 type Key struct { 20 name string 21 } 22 23 // NewKey creates or retrieves a string key identified by name. 24 // Calling NewKey more than once with the same name returns the same key. 25 func NewKey(name string) (Key, error) { 26 if !checkKeyName(name) { 27 return Key{}, errInvalidKeyName 28 } 29 return Key{name: name}, nil 30 } 31 32 // MustNewKey returns a key with the given name, and panics if name is an invalid key name. 33 func MustNewKey(name string) Key { 34 k, err := NewKey(name) 35 if err != nil { 36 panic(err) 37 } 38 return k 39 } 40 41 // Name returns the name of the key. 42 func (k Key) Name() string { 43 return k.name 44 } 45