traefik/vendor/google.golang.org/grpc/metadata/metadata.go

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/*
*
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* Copyright 2014 gRPC authors.
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*
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* 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
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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
* 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.
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*
*/
// Package metadata define the structure of the metadata supported by gRPC library.
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// Please refer to https://grpc.io/docs/guides/wire.html for more information about custom-metadata.
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package metadata // import "google.golang.org/grpc/metadata"
import (
"fmt"
"strings"
"golang.org/x/net/context"
)
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// DecodeKeyValue returns k, v, nil. It is deprecated and should not be used.
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func DecodeKeyValue(k, v string) (string, string, error) {
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return k, v, nil
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}
// MD is a mapping from metadata keys to values. Users should use the following
// two convenience functions New and Pairs to generate MD.
type MD map[string][]string
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// New creates an MD from a given key-value map.
//
// Only the following ASCII characters are allowed in keys:
// - digits: 0-9
// - uppercase letters: A-Z (normalized to lower)
// - lowercase letters: a-z
// - special characters: -_.
// Uppercase letters are automatically converted to lowercase.
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func New(m map[string]string) MD {
md := MD{}
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for k, val := range m {
key := strings.ToLower(k)
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md[key] = append(md[key], val)
}
return md
}
// Pairs returns an MD formed by the mapping of key, value ...
// Pairs panics if len(kv) is odd.
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//
// Only the following ASCII characters are allowed in keys:
// - digits: 0-9
// - uppercase letters: A-Z (normalized to lower)
// - lowercase letters: a-z
// - special characters: -_.
// Uppercase letters are automatically converted to lowercase.
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func Pairs(kv ...string) MD {
if len(kv)%2 == 1 {
panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
}
md := MD{}
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var key string
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for i, s := range kv {
if i%2 == 0 {
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key = strings.ToLower(s)
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continue
}
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md[key] = append(md[key], s)
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}
return md
}
// Len returns the number of items in md.
func (md MD) Len() int {
return len(md)
}
// Copy returns a copy of md.
func (md MD) Copy() MD {
return Join(md)
}
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// Join joins any number of mds into a single MD.
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// The order of values for each key is determined by the order in which
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// the mds containing those values are presented to Join.
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func Join(mds ...MD) MD {
out := MD{}
for _, md := range mds {
for k, v := range md {
out[k] = append(out[k], v...)
}
}
return out
}
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type mdIncomingKey struct{}
type mdOutgoingKey struct{}
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// NewContext is a wrapper for NewOutgoingContext(ctx, md). Deprecated.
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func NewContext(ctx context.Context, md MD) context.Context {
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return NewOutgoingContext(ctx, md)
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}
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// NewIncomingContext creates a new context with incoming md attached.
func NewIncomingContext(ctx context.Context, md MD) context.Context {
return context.WithValue(ctx, mdIncomingKey{}, md)
}
// NewOutgoingContext creates a new context with outgoing md attached.
func NewOutgoingContext(ctx context.Context, md MD) context.Context {
return context.WithValue(ctx, mdOutgoingKey{}, md)
}
// FromContext is a wrapper for FromIncomingContext(ctx). Deprecated.
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func FromContext(ctx context.Context) (md MD, ok bool) {
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return FromIncomingContext(ctx)
}
// FromIncomingContext returns the incoming metadata in ctx if it exists. The
// returned MD should not be modified. Writing to it may cause races.
// Modification should be made to copies of the returned MD.
func FromIncomingContext(ctx context.Context) (md MD, ok bool) {
md, ok = ctx.Value(mdIncomingKey{}).(MD)
return
}
// FromOutgoingContext returns the outgoing metadata in ctx if it exists. The
// returned MD should not be modified. Writing to it may cause races.
// Modification should be made to the copies of the returned MD.
func FromOutgoingContext(ctx context.Context) (md MD, ok bool) {
md, ok = ctx.Value(mdOutgoingKey{}).(MD)
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return
}