.. _program_listing_file_include_opentelemetry_trace_span_context_kv_iterable.h:

Program Listing for File span_context_kv_iterable.h
===================================================

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

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

.. code-block:: cpp

   // 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/version.h"
   
   OPENTELEMETRY_BEGIN_NAMESPACE
   namespace trace
   {
   class SpanContextKeyValueIterable
   {
   public:
     virtual ~SpanContextKeyValueIterable() = default;
   
     virtual bool ForEachKeyValue(
         nostd::function_ref<bool(SpanContext, const opentelemetry::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 opentelemetry::common::KeyValueIterable &)>
         /* callback */) const noexcept override
     {
       return true;
     }
   
     size_t size() const noexcept override { return 0; };
   };
   
   }  // namespace trace
   OPENTELEMETRY_END_NAMESPACE