.. _program_listing_file_include_opentelemetry_trace_propagation_text_map_propagator.h:

Program Listing for File text_map_propagator.h
==============================================

|exhale_lsh| :ref:`Return to documentation for file <file_include_opentelemetry_trace_propagation_text_map_propagator.h>` (``include/opentelemetry/trace/propagation/text_map_propagator.h``)

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

.. code-block:: cpp

   #pragma once
   
   #include <cstdint>
   #include "opentelemetry/context/context.h"
   #include "opentelemetry/nostd/string_view.h"
   #include "opentelemetry/version.h"
   
   OPENTELEMETRY_BEGIN_NAMESPACE
   namespace trace
   {
   namespace propagation
   {
   
   // The TextMapPropagator class provides an interface that enables extracting and injecting
   // context into carriers that travel in-band across process boundaries. HTTP frameworks and clients
   // can integrate with TextMapPropagator by providing the object containing the
   // headers, and a getter and setter function for the extraction and
   // injection of values, respectively.
   template <typename T>
   class TextMapPropagator
   {
   public:
     // Rules that manages how context will be extracted from carrier.
     using Getter = nostd::string_view (*)(const T &carrier, nostd::string_view trace_type);
   
     // Rules that manages how context will be injected to carrier.
     using Setter = void (*)(T &carrier,
                             nostd::string_view trace_type,
                             nostd::string_view trace_description);
   
     // Returns the context that is stored in the carrier with the getter as extractor.
     virtual context::Context Extract(Getter get_from_carrier,
                                      const T &carrier,
                                      context::Context &context) noexcept = 0;
   
     // Sets the context for carrier with self defined rules.
     virtual void Inject(Setter set_from_carrier,
                         T &carrier,
                         const context::Context &context) noexcept = 0;
   };
   }  // namespace propagation
   }  // namespace trace
   OPENTELEMETRY_END_NAMESPACE