/**
 * Copyright 2018, OpenCensus 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.
 */ import { SpanContext } from '../model/types' ; /**
 * An transport and environment neutral API for getting request headers.
 */ export interface HeaderGetter { getHeader ( name ) : string | string [ ] | undefined ; } /**
 * A transport and environment neutral API for setting headers.
 */ export interface HeaderSetter { setHeader ( name , value ) : void ; } /**
 *  Propagation interface
 */ export interface Propagation { extract ( getter ) : SpanContext | null ; inject ( setter , spanContext ) : void ; generate ( ) : SpanContext ; }