137 lines
4.3 KiB
C++
137 lines
4.3 KiB
C++
#ifndef FLEXBUF_READER_HPP_
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#define FLEXBUF_READER_HPP_
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#include <exception>
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#include <flatbuffers/flexbuffers.h>
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#include <map>
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#include <sstream>
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#include <stdexcept>
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#include <string>
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#include <string_view>
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#include <type_traits>
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#include <vector>
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#include "../Result.hpp"
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#include "../always_false.hpp"
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namespace rfl {
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namespace flexbuf {
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struct Reader {
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using InputArrayType = flexbuffers::Vector;
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using InputObjectType = flexbuffers::Map;
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using InputVarType = flexbuffers::Reference;
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template <class T, class = void>
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struct has_from_flexbuf : std::false_type {};
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template <class T>
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struct has_from_flexbuf<
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T,
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std::enable_if_t<std::is_invocable_r<T, decltype(T::from_flexbuf), InputVarType>::value>>
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: std::true_type {};
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template <class T>
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struct has_from_flexbuf<
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T,
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std::enable_if_t<
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std::is_invocable_r<rfl::Result<T>, decltype(T::from_flexbuf), InputVarType>::value>>
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: std::true_type {};
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template <class T>
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static constexpr bool has_custom_constructor = has_from_flexbuf<T>::value;
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rfl::Result<InputVarType> get_field(const std::string& _name, const InputObjectType& _obj)
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const noexcept {
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const auto keys = _obj.Keys();
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for (size_t i = 0; i < keys.size(); ++i) {
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if (_name == keys[i].AsString().c_str()) {
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return _obj.Values()[i];
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}
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}
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return rfl::Error("Map does not contain any element called '" + _name + "'.");
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}
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bool is_empty(const InputVarType& _var) const noexcept { return _var.IsNull(); }
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template <class T>
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rfl::Result<T> to_basic_type(const InputVarType& _var) const noexcept {
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if constexpr (std::is_same<std::remove_cvref_t<T>, std::string>()) {
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if (!_var.IsString()) {
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return rfl::Error("Could not cast to string.");
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}
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return std::string(_var.AsString().c_str());
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} else if constexpr (std::is_same<std::remove_cvref_t<T>, bool>()) {
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if (!_var.IsBool()) {
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return rfl::Error("Could not cast to boolean.");
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}
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return _var.AsBool();
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} else if constexpr (std::is_floating_point<std::remove_cvref_t<T>>()) {
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if (!_var.IsNumeric()) {
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return rfl::Error("Could not cast to double.");
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}
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return static_cast<T>(_var.AsDouble());
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} else if constexpr (std::is_integral<std::remove_cvref_t<T>>()) {
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if (!_var.IsNumeric()) {
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return rfl::Error("Could not cast to int.");
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}
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return static_cast<T>(_var.AsInt64());
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} else {
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static_assert(rfl::always_false_v<T>, "Unsupported type.");
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}
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}
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template <class ArrayReader>
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std::optional<Error> read_array(const ArrayReader& _array_reader, const InputArrayType& _arr)
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const noexcept {
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const auto size = _arr.size();
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for (size_t i = 0; i < size; ++i) {
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const auto err = _array_reader.read(InputVarType(_arr[i]));
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if (err) {
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return err;
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}
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}
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return std::nullopt;
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}
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template <class ObjectReader>
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std::optional<Error>
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read_object(const ObjectReader& _object_reader, const InputObjectType& _obj) const noexcept {
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const auto keys = _obj.Keys();
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const auto values = _obj.Values();
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const auto num_values = std::min(keys.size(), values.size());
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for (size_t i = 0; i < num_values; ++i) {
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_object_reader.read(std::string_view(keys[i].AsString().c_str()), values[i]);
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}
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return std::nullopt;
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}
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rfl::Result<InputArrayType> to_array(const InputVarType& _var) const noexcept {
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if (!_var.IsVector()) {
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return rfl::Error("Could not cast to Vector.");
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}
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return _var.AsVector();
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}
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rfl::Result<InputObjectType> to_object(const InputVarType& _var) const noexcept {
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if (!_var.IsMap()) {
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return rfl::Error("Could not cast to Map!");
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}
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return _var.AsMap();
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}
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template <class T>
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rfl::Result<T> use_custom_constructor(const InputVarType& _var) const noexcept {
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try {
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return T::from_flexbuf(_var);
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} catch (std::exception& e) { return rfl::Error(e.what()); }
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}
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};
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} // namespace flexbuf
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} // namespace rfl
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#endif
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