in_list.hpp

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#ifndef EAGINE_VALID_IF_IN_LIST_HPP
#define EAGINE_VALID_IF_IN_LIST_HPP
 
#include "decl.hpp"
 
namespace eagine {
 
template <typename T, typename Range>
struct valid_if_in_list_policy {
    Range _choices = {};
 
    valid_if_in_list_policy(const Range& choices)
      : _choices(choices) {}
 
    auto operator()(const T& value) const noexcept -> bool {
        for(const T& choice : _choices) {
            if(are_equal(value, choice)) {
                return true;
            }
        }
        return false;
    }
 
    struct do_log {
        Range _choices;
 
        inline do_log(const valid_if_in_list_policy<T, Range>& p) noexcept
          : _choices(p._choices) {}
 
        template <typename Log>
        void operator()(Log& log, const T& v) const {
            log << "Value '" << v << "', "
                << "other than one of the values [";
 
            bool first = true;
            for(const T& choice : _choices) {
                log << (first ? "" : ", ") << "'" << choice << "'";
                first = false;
            }
            log << "] is invalid";
        }
    };
};
 
template <typename T, typename Range>
using valid_if_in_list = valid_if<T, valid_if_in_list_policy<T, Range>>;
 
} // namespace eagine
 
#endif // EAGINE_VALID_IF_IN_LIST_HPP