gtsocial-umbx

attributes.go (3335B)

---

 /*
  *
  * 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
 
 // 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.  Values should not be modified after they are added to an
 // Attributes or if they were received from one.  If values implement 'Equal(o
 // interface{}) bool', it will be called by (*Attributes).Equal to determine
 // whether two values with the same key should be considered equal.
 type Attributes struct {
 	m map[interface{}]interface{}
 }
 
 // New returns a new Attributes containing the key/value pair.
 func New(key, value interface{}) *Attributes {
 	return &Attributes{m: map[interface{}]interface{}{key: value}}
 }
 
 // WithValue returns a new Attributes containing the previous keys and values
 // and the new key/value pair.  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.  value should not be modified later.
 func (a *Attributes) WithValue(key, value interface{}) *Attributes {
 	if a == nil {
 		return New(key, value)
 	}
 	n := &Attributes{m: make(map[interface{}]interface{}, len(a.m)+1)}
 	for k, v := range a.m {
 		n.m[k] = v
 	}
 	n.m[key] = value
 	return n
 }
 
 // Value returns the value associated with these attributes for key, or nil if
 // no value is associated with key.  The returned value should not be modified.
 func (a *Attributes) Value(key interface{}) interface{} {
 	if a == nil {
 		return nil
 	}
 	return a.m[key]
 }
 
 // Equal returns whether a and o are equivalent.  If 'Equal(o interface{})
 // bool' is implemented for a value in the attributes, it is called to
 // determine if the value matches the one stored in the other attributes.  If
 // Equal is not implemented, standard equality is used to determine if the two
 // values are equal. Note that some types (e.g. maps) aren't comparable by
 // default, so they must be wrapped in a struct, or in an alias type, with Equal
 // defined.
 func (a *Attributes) Equal(o *Attributes) bool {
 	if a == nil && o == nil {
 		return true
 	}
 	if a == nil || o == nil {
 		return false
 	}
 	if len(a.m) != len(o.m) {
 		return false
 	}
 	for k, v := range a.m {
 		ov, ok := o.m[k]
 		if !ok {
 			// o missing element of a
 			return false
 		}
 		if eq, ok := v.(interface{ Equal(o interface{}) bool }); ok {
 			if !eq.Equal(ov) {
 				return false
 			}
 		} else if v != ov {
 			// Fallback to a standard equality check if Value is unimplemented.
 			return false
 		}
 	}
 	return true
 }