.. _program_listing_file_include_opentelemetry_baggage_propagation_baggage_propagator.h:

Program Listing for File baggage_propagator.h
=============================================

|exhale_lsh| :ref:`Return to documentation for file <file_include_opentelemetry_baggage_propagation_baggage_propagator.h>` (``include/opentelemetry/baggage/propagation/baggage_propagator.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #pragma once
   
   #include "opentelemetry/baggage/baggage.h"
   #include "opentelemetry/context/propagation/text_map_propagator.h"
   #include "opentelemetry/version.h"
   
   OPENTELEMETRY_BEGIN_NAMESPACE
   namespace baggage
   {
   namespace propagation
   {
   
   static const nostd::string_view kBaggageHeader = "baggage";
   
   inline nostd::shared_ptr<baggage::Baggage> GetBaggage(const context::Context &context)
   {
     context::ContextValue context_value = context.GetValue(kBaggageHeader);
     if (nostd::holds_alternative<nostd::shared_ptr<baggage::Baggage>>(context_value))
     {
       return nostd::get<nostd::shared_ptr<baggage::Baggage>>(context_value);
     }
     static nostd::shared_ptr<baggage::Baggage> empty_baggage{new baggage::Baggage()};
     return empty_baggage;
   }
   
   inline context::Context SetBaggage(context::Context &context,
                                      nostd::shared_ptr<baggage::Baggage> baggage)
   {
     return context.SetValue(kBaggageHeader, baggage);
   }
   
   class BaggagePropagator : public context::propagation::TextMapPropagator
   {
   public:
     void Inject(context::propagation::TextMapCarrier &carrier,
                 const context::Context &context) noexcept override
     {
       auto baggage = GetBaggage(context);
       carrier.Set(kBaggageHeader, baggage->ToHeader());
     }
   
     context::Context Extract(const context::propagation::TextMapCarrier &carrier,
                              context::Context &context) noexcept override
     {
       nostd::string_view baggage_str = carrier.Get(kBaggageHeader);
       auto baggage                   = Baggage::FromHeader(baggage_str);
       return SetBaggage(context, baggage);
     }
   };
   }  // namespace propagation
   }  // namespace baggage
   OPENTELEMETRY_END_NAMESPACE