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diff --git a/vendor/google.golang.org/grpc/attributes/attributes.go b/vendor/google.golang.org/grpc/attributes/attributes.go
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+/*
+ *
+ * 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
+}