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