| /* |
| * |
| * Copyright 2019 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| // Package attributes defines a generic key/value store used in various gRPC |
| // components. |
| // |
| // Experimental |
| // |
| // Notice: This package is EXPERIMENTAL and may be changed or removed in a |
| // later release. |
| package attributes |
| |
| import "fmt" |
| |
| // Attributes is an immutable struct for storing and retrieving generic |
| // key/value pairs. Keys must be hashable, and users should define their own |
| // types for keys. |
| type Attributes struct { |
| m map[interface{}]interface{} |
| } |
| |
| // New returns a new Attributes containing all key/value pairs in kvs. If the |
| // same key appears multiple times, the last value overwrites all previous |
| // values for that key. Panics if len(kvs) is not even. |
| func New(kvs ...interface{}) *Attributes { |
| if len(kvs)%2 != 0 { |
| panic(fmt.Sprintf("attributes.New called with unexpected input: len(kvs) = %v", len(kvs))) |
| } |
| a := &Attributes{m: make(map[interface{}]interface{}, len(kvs)/2)} |
| for i := 0; i < len(kvs)/2; i++ { |
| a.m[kvs[i*2]] = kvs[i*2+1] |
| } |
| return a |
| } |
| |
| // WithValues returns a new Attributes containing all key/value pairs in a and |
| // kvs. Panics if len(kvs) is not even. If the same key appears multiple |
| // times, the last value overwrites all previous values for that key. To |
| // remove an existing key, use a nil value. |
| func (a *Attributes) WithValues(kvs ...interface{}) *Attributes { |
| if a == nil { |
| return New(kvs...) |
| } |
| if len(kvs)%2 != 0 { |
| panic(fmt.Sprintf("attributes.New called with unexpected input: len(kvs) = %v", len(kvs))) |
| } |
| n := &Attributes{m: make(map[interface{}]interface{}, len(a.m)+len(kvs)/2)} |
| for k, v := range a.m { |
| n.m[k] = v |
| } |
| for i := 0; i < len(kvs)/2; i++ { |
| n.m[kvs[i*2]] = kvs[i*2+1] |
| } |
| return n |
| } |
| |
| // Value returns the value associated with these attributes for key, or nil if |
| // no value is associated with key. |
| func (a *Attributes) Value(key interface{}) interface{} { |
| if a == nil { |
| return nil |
| } |
| return a.m[key] |
| } |