1 files changed, 37 insertions, 0 deletions
diff --git a/example/tutorial/text_map_carrier.h b/example/tutorial/text_map_carrier.h
new file mode 100644
index 0000000..2538324
--- /dev/null
+++ b/example/tutorial/text_map_carrier.h
@@ -0,0 +1,37 @@
+#ifndef LIGHTSTEP_TEXT_MAP_CARRIER
+#define LIGHTSTEP_TEXT_MAP_CARRIER
+
+#include <opentracing/propagation.h>
+#include <string>
+#include <unordered_map>
+
+using opentracing::expected;
+using opentracing::string_view;
+using opentracing::TextMapReader;
+using opentracing::TextMapWriter;
+
+class TextMapCarrier : public TextMapReader, public TextMapWriter {
+ public:
+  TextMapCarrier(std::unordered_map<std::string, std::string>& text_map)
+      : text_map_(text_map) {}
+
+  expected<void> Set(string_view key, string_view value) const override {
+    text_map_[key] = value;
+    return {};
+  }
+
+  expected<void> ForeachKey(
+      std::function<expected<void>(string_view key, string_view value)> f)
+      const override {
+    for (const auto& key_value : text_map_) {
+      auto result = f(key_value.first, key_value.second);
+      if (!result) return result;
+    }
+    return {};
+  }
+
+ private:
+  std::unordered_map<std::string, std::string>& text_map_;
+};
+
+#endif  // LIGHTSTEP_TEXT_MAP_CARRIER