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