.. _program_listing_file_include_opentelemetry_trace_trace_id.h:

Program Listing for File trace_id.h
===================================

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

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

.. code-block:: cpp

   // Copyright 2020, OpenTelemetry Authors
   //
   // Licensed under the Apache License, Version 2.0 (the "License");
   // you may not use this file except in compliance with the License.
   // You may obtain a copy of the License at
   //
   //     http://www.apache.org/licenses/LICENSE-2.0
   //
   // Unless required by applicable law or agreed to in writing, software
   // distributed under the License is distributed on an "AS IS" BASIS,
   // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   // See the License for the specific language governing permissions and
   // limitations under the License.
   
   #pragma once
   
   #include <cstdint>
   #include <cstring>
   
   #include "opentelemetry/nostd/span.h"
   #include "opentelemetry/version.h"
   
   OPENTELEMETRY_BEGIN_NAMESPACE
   namespace trace
   {
   
   // TraceId represents an opaque 128-bit trace identifier. The trace identifier
   // remains constant across the trace. A valid trace identifier is a 16-byte array with at
   // least one non-zero byte.
   class TraceId final
   {
   public:
     // The size in bytes of the TraceId.
     static constexpr int kSize = 16;
   
     // An invalid TraceId (all zeros).
     TraceId() noexcept : rep_{0} {}
   
     // Creates a TraceId with the given ID.
     explicit TraceId(nostd::span<const uint8_t, kSize> id) noexcept
     {
       memcpy(rep_, id.data(), kSize);
     }
   
     // Populates the buffer with the lowercase base16 representation of the ID.
     void ToLowerBase16(nostd::span<char, 2 * kSize> buffer) const noexcept
     {
       constexpr char kHex[] = "0123456789abcdef";
       for (int i = 0; i < kSize; ++i)
       {
         buffer[i * 2 + 0] = kHex[(rep_[i] >> 4) & 0xF];
         buffer[i * 2 + 1] = kHex[(rep_[i] >> 0) & 0xF];
       }
     }
   
     // Returns a nostd::span of the ID.
     nostd::span<const uint8_t, kSize> Id() const noexcept
     {
       return nostd::span<const uint8_t, kSize>(rep_);
     }
   
     bool operator==(const TraceId &that) const noexcept
     {
       return memcmp(rep_, that.rep_, kSize) == 0;
     }
   
     bool operator!=(const TraceId &that) const noexcept { return !(*this == that); }
   
     // Returns false if the TraceId is all zeros.
     bool IsValid() const noexcept { return *this != TraceId(); }
   
     // Copies the opaque TraceId data to dest.
     void CopyBytesTo(nostd::span<uint8_t, kSize> dest) const noexcept
     {
       memcpy(dest.data(), rep_, kSize);
     }
   
   private:
     uint8_t rep_[kSize];
   };
   
   }  // namespace trace
   OPENTELEMETRY_END_NAMESPACE