includes/opentelemetry/trace/span_context_kv_iterable.h

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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
 
#pragma once
 
#include "opentelemetry/common/attribute_value.h"
#include "opentelemetry/common/key_value_iterable_view.h"
#include "opentelemetry/nostd/function_ref.h"
#include "opentelemetry/trace/span_context.h"
#include "opentelemetry/version.h"
 
OPENTELEMETRY_BEGIN_NAMESPACE
namespace trace
{
class SpanContextKeyValueIterable
{
public:
  virtual ~SpanContextKeyValueIterable() = default;
 
  virtual bool ForEachKeyValue(
      nostd::function_ref<bool(SpanContext, const common::KeyValueIterable &)> callback)
      const noexcept = 0;
  virtual size_t size() const noexcept = 0;
};
 
class NullSpanContext : public SpanContextKeyValueIterable
{
public:
  bool ForEachKeyValue(nostd::function_ref<bool(SpanContext, const common::KeyValueIterable &)>
                       /* callback */) const noexcept override
  {
    return true;
  }
 
  size_t size() const noexcept override { return 0; }
};
 
}  // namespace trace
OPENTELEMETRY_END_NAMESPACE