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