includes/opentelemetry/context/propagation/composite_propagator.h

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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
 
#pragma once
 
#include <memory>
#include <vector>
 
#include "opentelemetry/context/propagation/text_map_propagator.h"
#include "opentelemetry/version.h"
 
OPENTELEMETRY_BEGIN_NAMESPACE
namespace context
{
namespace propagation
{
 
class CompositePropagator : public TextMapPropagator
{
public:
  CompositePropagator(std::vector<std::unique_ptr<TextMapPropagator>> propagators)
      : propagators_(std::move(propagators))
  {}
 
  void Inject(TextMapCarrier &carrier, const context::Context &context) noexcept override
  {
    for (auto &p : propagators_)
    {
      p->Inject(carrier, context);
    }
  }
 
  context::Context Extract(const TextMapCarrier &carrier,
                           context::Context &context) noexcept override
  {
    auto first = true;
    context::Context tmp_context;
    for (auto &p : propagators_)
    {
      if (first)
      {
        tmp_context = p->Extract(carrier, context);
        first       = false;
      }
      else
      {
        tmp_context = p->Extract(carrier, tmp_context);
      }
    }
    return propagators_.size() ? tmp_context : context;
  }
 
  bool Fields(nostd::function_ref<bool(nostd::string_view)> callback) const noexcept override
  {
    bool status = true;
    for (auto &p : propagators_)
    {
      status = status && p->Fields(callback);
    }
    return status;
  }
 
private:
  std::vector<std::unique_ptr<TextMapPropagator>> propagators_;
};
}  // namespace propagation
}  // namespace context
OPENTELEMETRY_END_NAMESPACE