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#ifndef RFL_XML_READER_HPP_
#define RFL_XML_READER_HPP_
#include <exception>
#include <optional>
#include <pugixml.hpp>
#include <string>
#include <string_view>
#include <type_traits>
#include <variant>
#include "../Result.hpp"
#include "../always_false.hpp"
#include "../parsing/is_view_reader.hpp"
namespace rfl {
namespace xml {
struct Reader {
struct XMLInputArray {
XMLInputArray(pugi::xml_node _node) : node_(_node) {}
pugi::xml_node node_;
};
struct XMLInputObject {
XMLInputObject(pugi::xml_node _node) : node_(_node) {}
pugi::xml_node node_;
};
struct XMLInputVar {
XMLInputVar() : node_or_attribute_(pugi::xml_node()) {}
XMLInputVar(pugi::xml_attribute _attr) : node_or_attribute_(_attr) {}
XMLInputVar(pugi::xml_node _node) : node_or_attribute_(_node) {}
std::variant<pugi::xml_node, pugi::xml_attribute> node_or_attribute_;
};
using InputArrayType = XMLInputArray;
using InputObjectType = XMLInputObject;
using InputVarType = XMLInputVar;
// TODO
template <class T>
static constexpr bool has_custom_constructor = false;
rfl::Result<InputVarType> get_field_from_array(
const size_t _idx, const InputArrayType& _arr) const noexcept {
const auto name = _arr.node_.name();
size_t i = 0;
for (auto node = _arr.node_; node; node = node.next_sibling(name)) {
if (i == _idx) {
return InputVarType(node);
}
}
return error("Index " + std::to_string(_idx) + " of of bounds.");
}
rfl::Result<InputVarType> get_field_from_object(
const std::string& _name, const InputObjectType _obj) const noexcept {
const auto node = _obj.node_.child(_name.c_str());
if (!node) {
return error("Object contains no field named '" + _name + "'.");
}
return InputVarType(node);
}
bool is_empty(const InputVarType _var) const noexcept {
const auto wrap = [](const auto& _node) { return !_node; };
return std::visit(cast_as_node, _var.node_or_attribute_)
.transform(wrap)
.value_or(false);
}
template <class T>
rfl::Result<T> to_basic_type(const InputVarType _var) const noexcept {
const auto get_value = [](const auto& _n) -> std::string {
using Type = std::remove_cvref_t<decltype(_n)>;
if constexpr (std::is_same<Type, pugi::xml_node>()) {
return std::string(_n.child_value());
} else {
return std::string(_n.value());
}
};
if constexpr (std::is_same<std::remove_cvref_t<T>, std::string>()) {
return std::visit(get_value, _var.node_or_attribute_);
} else if constexpr (std::is_same<std::remove_cvref_t<T>, bool>()) {
return std::visit(get_value, _var.node_or_attribute_) == "true";
} else if constexpr (std::is_floating_point<std::remove_cvref_t<T>>()) {
const auto str = std::visit(get_value, _var.node_or_attribute_);
try {
return static_cast<T>(std::stod(str));
} catch (std::exception& e) {
return error("Could not cast '" + std::string(str) +
"' to floating point value.");
}
} else if constexpr (std::is_integral<std::remove_cvref_t<T>>()) {
const auto str = std::visit(get_value, _var.node_or_attribute_);
try {
return static_cast<T>(std::stoi(str));
} catch (std::exception& e) {
return error("Could not cast '" + std::string(str) + "' to integer.");
}
} else {
static_assert(rfl::always_false_v<T>, "Unsupported type.");
}
}
rfl::Result<InputArrayType> to_array(const InputVarType _var) const noexcept {
const auto wrap = [](const auto& _node) { return InputArrayType(_node); };
return std::visit(cast_as_node, _var.node_or_attribute_).transform(wrap);
}
template <class ArrayReader>
std::optional<Error> read_array(const ArrayReader& _array_reader,
const InputArrayType& _arr) const noexcept {
const auto name = _arr.node_.name();
for (auto node = _arr.node_; node; node = node.next_sibling(name)) {
const auto err = _array_reader.read(InputVarType(node));
if (err) {
return err;
}
}
return std::nullopt;
}
template <class ObjectReader>
std::optional<Error> read_object(const ObjectReader& _object_reader,
const InputObjectType& _obj) const noexcept {
for (auto child = _obj.node_.first_child(); child;
child = child.next_sibling()) {
_object_reader.read(std::string_view(child.name()), InputVarType(child));
}
for (auto attr = _obj.node_.first_attribute(); attr;
attr = attr.next_attribute()) {
_object_reader.read(std::string_view(attr.name()), InputVarType(attr));
}
if constexpr (parsing::is_view_reader_v<ObjectReader>) {
_object_reader.read(std::string_view("xml_content"),
InputVarType(_obj.node_));
}
return std::nullopt;
}
rfl::Result<InputObjectType> to_object(
const InputVarType _var) const noexcept {
const auto wrap = [](const auto& _node) { return InputObjectType(_node); };
return std::visit(cast_as_node, _var.node_or_attribute_).transform(wrap);
}
template <class T>
rfl::Result<T> use_custom_constructor(
const InputVarType _var) const noexcept {
return error("TODO");
}
private:
/// XML-only helper function. This is needed because XML distinguishes between
/// nodes and attributes.
static rfl::Result<pugi::xml_node> cast_as_node(
const std::variant<pugi::xml_node, pugi::xml_attribute>&
_node_or_attribute) {
const auto cast = [](const auto& _n) -> Result<pugi::xml_node> {
using Type = std::remove_cvref_t<decltype(_n)>;
if constexpr (std::is_same<Type, pugi::xml_node>()) {
return _n;
} else {
return error("Field '" + std::string(_n.name()) + "' is an attribute.");
}
};
return std::visit(cast, _node_or_attribute);
}
};
} // namespace xml
} // namespace rfl
#endif
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