TEnumType.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <map>
#include <stdexcept>
#include <string>

namespace mrpt
{
namespace typemeta
{
namespace internal
{
template <typename KEY, typename VALUE>
struct bimap
{
    std::map<KEY, VALUE> m_k2v;
    std::map<VALUE, KEY> m_v2k;

    using const_iterator = typename std::map<KEY, VALUE>::const_iterator;
    const_iterator begin() const { return m_k2v.begin(); }
    const_iterator end() const { return m_k2v.end(); }
    bool direct(const KEY& k, VALUE& out_v) const
    {
        auto i = m_k2v.find(k);
        if (i == m_k2v.end()) return false;
        out_v = i->second;
        return true;
    }
    bool inverse(const VALUE& v, KEY& out_k) const
    {
        auto i = m_v2k.find(v);
        if (i == m_v2k.end()) return false;
        out_k = i->second;
        return true;
    }
    void insert(const KEY& k, const VALUE& v)
    {
        m_k2v[k] = v;
        m_v2k[v] = k;
    }
};  // end bimap
}  // namespace internal

/** Only specializations of this class are defined for each enum type of
 * interest
 * \sa TEnumType \ingroup mrpt_io_grp
 */
template <typename ENUMTYPE>
struct TEnumTypeFiller
{
    static void fill(internal::bimap<ENUMTYPE, std::string>& m_map);
};

#define MRPT_ENUM_TYPE_BEGIN(_ENUM_TYPE_WITH_NS)                              \
    namespace mrpt                                                            \
    {                                                                         \
    namespace typemeta                                                        \
    {                                                                         \
    template <>                                                               \
    struct TEnumTypeFiller<_ENUM_TYPE_WITH_NS>                                \
    {                                                                         \
        static void fill(                                                     \
            mrpt::typemeta::internal::bimap<_ENUM_TYPE_WITH_NS, std::string>& \
                m_map)                                                        \
        {
#define MRPT_ENUM_TYPE_BEGIN_NAMESPACE(_NAMESPACE, _ENUM_TYPE_WITH_NS) \
    MRPT_ENUM_TYPE_BEGIN(_ENUM_TYPE_WITH_NS)                           \
    using namespace _NAMESPACE;

#define MRPT_ENUM_TYPE_END() \
    }                        \
    }                        \
    ;                        \
    }                        \
    }

/** For use in specializations of TEnumTypeFiller */
#define MRPT_FILL_ENUM(_X) m_map.insert(_X, #_X)
#define MRPT_FILL_ENUM_CUSTOM_NAME(_X, _NAME) m_map.insert(_X, _NAME)
#define MRPT_FILL_ENUM_MEMBER(_CLASS, _VALUE) \
    m_map.insert(_CLASS::_VALUE, #_VALUE)

/** A helper class that can convert an enum value into its textual
 * representation, and viceversa. \ingroup mrpt_typename_grp */
template <typename ENUMTYPE>
struct TEnumType
{
#define _MRPT_AUXTOSTR(__AA) #__AA

    /** Gives the numerical name for a given enum text name \exception
     * std::exception on unknown enum name */
    static ENUMTYPE name2value(const std::string& name)
    {
        ENUMTYPE val;
        if (!getBimap().inverse(name, val))
        {
            throw std::runtime_error(
                std::string("TEnumType<" _MRPT_AUXTOSTR(
                    TEnumType) ">::name2value(): Unknown name: ") +
                name);
        }
        return val;
    }

    /** Gives the textual name for a given enum value \exception std::exception
     * on unknown enum value name */
    static std::string value2name(const ENUMTYPE val)
    {
        std::string s;
        if (!getBimap().direct(val, s))
        {
            throw std::runtime_error(
                std::string("TEnumType<" _MRPT_AUXTOSTR(
                    TEnumType) ">::value2name(): Unknown value: ") +
                std::to_string(static_cast<int>(val)));
        }
        return s;
    }

    /** Singleton access */
    static inline internal::bimap<ENUMTYPE, std::string>& getBimap()
    {
        static internal::bimap<ENUMTYPE, std::string> data;
        if (data.m_k2v.empty()) TEnumTypeFiller<ENUMTYPE>::fill(data);
        return data;
    }
#undef _MRPT_AUXTOSTR
};

}  // namespace typemeta
}  // namespace mrpt