Use protozero for tile decoding

protozero/pbf_message.hpp

@@ -0,0 +1,94 @@
+#ifndef PROTOZERO_PBF_MESSAGE_HPP
+#define PROTOZERO_PBF_MESSAGE_HPP
+
+/*****************************************************************************
+
+protozero - Minimalistic protocol buffer decoder and encoder in C++.
+
+This file is from https://github.com/mapbox/protozero where you can find more
+documentation.
+
+*****************************************************************************/
+
+/**
+ * @file pbf_message.hpp
+ *
+ * @brief Contains the pbf_message class.
+ */
+
+#include <type_traits>
+
+#include <protozero/pbf_reader.hpp>
+#include <protozero/types.hpp>
+
+namespace protozero {
+
+/**
+ * This class represents a protobuf message. Either a top-level message or
+ * a nested sub-message. Top-level messages can be created from any buffer
+ * with a pointer and length:
+ *
+ * @code
+ *    enum class Message : protozero::pbf_tag_type {
+ *       ...
+ *    };
+ *
+ *    std::string buffer;
+ *    // fill buffer...
+ *    pbf_message<Message> message(buffer.data(), buffer.size());
+ * @endcode
+ *
+ * Sub-messages are created using get_message():
+ *
+ * @code
+ *    enum class SubMessage : protozero::pbf_tag_type {
+ *       ...
+ *    };
+ *
+ *    pbf_message<Message> message(...);
+ *    message.next();
+ *    pbf_message<SubMessage> submessage = message.get_message();
+ * @endcode
+ *
+ * All methods of the pbf_message class except get_bytes() and get_string()
+ * provide the strong exception guarantee, ie they either succeed or do not
+ * change the pbf_message object they are called on. Use the get_data() method
+ * instead of get_bytes() or get_string(), if you need this guarantee.
+ *
+ * This template class is based on the pbf_reader class and has all the same
+ * methods. The difference is that whereever the pbf_reader class takes an
+ * integer tag, this template class takes a tag of the template type T.
+ *
+ * Read the tutorial to understand how this class is used.
+ */
+template <typename T>
+class pbf_message : public pbf_reader {
+
+    static_assert(std::is_same<pbf_tag_type, typename std::underlying_type<T>::type>::value, "T must be enum with underlying type protozero::pbf_tag_type");
+
+public:
+
+    using enum_type = T;
+
+    template <typename... Args>
+    pbf_message(Args&&... args) noexcept :
+        pbf_reader(std::forward<Args>(args)...) {
+    }
+
+    inline bool next() {
+        return pbf_reader::next();
+    }
+
+    inline bool next(T tag) {
+        return pbf_reader::next(pbf_tag_type(tag));
+    }
+
+    inline T tag() const noexcept {
+        return T(pbf_reader::tag());
+    }
+
+};
+
+} // end namespace protozero
+
+#endif // PROTOZERO_PBF_MESSAGE_HPP