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diff --git a/include/tracer.h b/include/tracer.h
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+++ b/include/tracer.h
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+/***
+ * Copyright 2020 HAProxy Technologies
+ *
+ * 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.
+ */
+#ifndef _OPENTRACING_C_WRAPPER_TRACER_H_
+#define _OPENTRACING_C_WRAPPER_TRACER_H_
+
+using TextMap = std::unordered_map<std::string, std::string>;
+
+
+class TextMapCarrier : public opentracing::TextMapReader, public opentracing::TextMapWriter {
+	public:
+	TextMapCarrier(TextMap &text_map) : tm_data(text_map) {}
+
+	/***
+	 * TextMapWriter: Set a key:value pair to the carrier.  Multiple calls
+	 * to Set() for the same key leads to undefined behavior.
+	 */
+	opentracing::expected<void> Set(opentracing::string_view key, opentracing::string_view value) const override
+	{
+		tm_data[key] = value;
+
+		return {};
+	}
+
+	/***
+	 * TextMapReader: LookupKey() returns the value for the specified
+	 * key if available.  If no such key is present, it returns
+	 * key_not_found_error.
+	 */
+	opentracing::expected<opentracing::string_view> LookupKey(opentracing::string_view key) const override
+	{
+		auto iter = tm_data.find(key);
+		if (iter != tm_data.end())
+			return opentracing::string_view{iter->second};
+
+		return opentracing::make_unexpected(opentracing::key_not_found_error);
+	}
+
+	/***
+	 * TextMapReader: ForeachKey() returns TextMap contents via repeated
+	 * calls to the f() function.  If any call to f() returns an error,
+	 * ForeachKey() terminates and returns that error.
+	 */
+	opentracing::expected<void> ForeachKey(std::function<opentracing::expected<void>(opentracing::string_view key, opentracing::string_view value)> f) const override
+	{
+		for (const auto &text_map : tm_data) {
+			auto result = f(text_map.first, text_map.second);
+			if (!result)
+				return result;
+		}
+
+		return {};
+	}
+
+	private:
+	TextMap &tm_data;
+};
+
+
+class HTTPHeadersCarrier : public opentracing::HTTPHeadersReader, public opentracing::HTTPHeadersWriter {
+	public:
+	HTTPHeadersCarrier(TextMap &text_map) : tm_data(text_map) {}
+
+	/***
+	 * HTTPHeadersWriter: Set a key:value pair to the carrier.  Multiple calls
+	 * to Set() for the same key leads to undefined behavior.
+	 */
+	opentracing::expected<void> Set(opentracing::string_view key, opentracing::string_view value) const override
+	{
+		tm_data[key] = value;
+
+		return {};
+	}
+
+	/***
+	 * HTTPHeadersReader: LookupKey() returns the value for the specified
+	 * key if available.  If no such key is present, it returns
+	 * key_not_found_error.
+	 */
+	opentracing::expected<opentracing::string_view> LookupKey(opentracing::string_view key) const override
+	{
+		auto iter = tm_data.find(key);
+		if (iter != tm_data.end())
+			return opentracing::string_view{iter->second};
+
+		return opentracing::make_unexpected(opentracing::key_not_found_error);
+	}
+
+	/***
+	 * HTTPHeadersReader: ForeachKey() returns TextMap contents via repeated
+	 * calls to the f() function.  If any call to f() returns an error,
+	 * ForeachKey() terminates and returns that error.
+	 */
+	opentracing::expected<void> ForeachKey(std::function<opentracing::expected<void>(opentracing::string_view key, opentracing::string_view value)> f) const override
+	{
+		for (const auto &text_map : tm_data) {
+			auto result = f(text_map.first, text_map.second);
+			if (!result)
+				return result;
+		}
+
+		return {};
+	}
+
+	private:
+	TextMap &tm_data;
+};
+
+
+struct otc_tracer *ot_tracer_new(void);
+
+#endif /* _OPENTRACING_C_WRAPPER_TRACER_H_ */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ *
+ * vi: noexpandtab shiftwidth=8 tabstop=8
+ */