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#ifndef RFL_ONEOF_HPP_
#define RFL_ONEOF_HPP_
#include <sstream>
#include <string>
#include <utility>
#include <vector>
#include "Result.hpp"
#include "parsing/schema/ValidationType.hpp"
namespace rfl {
/// Requires that all of the contraints C and Cs be true.
template <class C, class... Cs>
struct OneOf {
template <class T>
static rfl::Result<T> validate(const T& _value) noexcept {
return validate_impl<T, C, Cs...>(_value, {});
}
template <class T>
static parsing::schema::ValidationType to_schema() {
using ValidationType = parsing::schema::ValidationType;
const auto types = std::vector<ValidationType>(
{C::template to_schema<T>(), Cs::template to_schema<T>()...});
return ValidationType{ValidationType::OneOf{.types_ = types}};
}
private:
static std::string make_error_message(const std::vector<Error>& _errors) {
std::stringstream stream;
stream << "Expected exactly 1 out of " << sizeof...(Cs) + 1
<< " validations to pass, but " << sizeof...(Cs) + 1 - _errors.size()
<< " of them did. The following errors were generated: ";
for (size_t i = 0; i < _errors.size(); ++i) {
stream << "\n" << i + 1 << ") " << _errors.at(i).what();
}
return stream.str();
}
template <class T, class Head, class... Tail>
static rfl::Result<T> validate_impl(const T& _value,
std::vector<Error> _errors) {
return Head::validate(_value)
.and_then([&](auto&& _res) -> rfl::Result<T> {
if constexpr (sizeof...(Tail) == 0) {
if (_errors.size() == sizeof...(Cs)) {
return _value;
}
return error(make_error_message(_errors));
} else {
return validate_impl<T, Tail...>(_value, std::move(_errors));
}
})
.or_else([&](auto&& _err) -> rfl::Result<T> {
_errors.emplace_back(std::move(_err));
if constexpr (sizeof...(Tail) == 0) {
return error(make_error_message(_errors));
} else {
return validate_impl<T, Tail...>(_value, std::move(_errors));
}
});
}
};
} // namespace rfl
#endif
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