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