osmium/builder/attr.hpp

#ifndef OSMIUM_BUILDER_ATTR_HPP
#define OSMIUM_BUILDER_ATTR_HPP

/*

This file is part of Osmium (https://osmcode.org/libosmium).

Copyright 2013-2021 Jochen Topf <jochen@topf.org> and others (see README).

Boost Software License - Version 1.0 - August 17th, 2003

Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:

The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

*/

#include <osmium/builder/builder.hpp>
#include <osmium/builder/osm_object_builder.hpp>
#include <osmium/memory/buffer.hpp>
#include <osmium/osm/changeset.hpp>
#include <osmium/osm/item_type.hpp>
#include <osmium/osm/location.hpp>
#include <osmium/osm/node.hpp>
#include <osmium/osm/node_ref.hpp>
#include <osmium/osm/object.hpp>
#include <osmium/osm/relation.hpp>
#include <osmium/osm/timestamp.hpp>
#include <osmium/osm/types.hpp>
#include <osmium/util/string.hpp>

#include <cstddef>
#include <cstdint>
#include <ctime>
#include <initializer_list>
#include <iterator>
#include <string>
#include <tuple>
#include <type_traits>
#include <utility>

namespace osmium {

    namespace builder {

        namespace detail {

#ifdef _MSC_VER
            // workaround for bug in MSVC

            template <typename THandler, typename... TTypes>
            struct is_handled_by;

            template <typename THandler>
            struct is_handled_by<THandler> {
                static constexpr bool value = false;
            };

            template <typename THandler, typename T, typename... TRest>
            struct is_handled_by<THandler, T, TRest...> {
                static constexpr bool value = std::is_base_of<typename T::handler, THandler>::value ||
                                              is_handled_by<THandler, TRest...>::value;
            };

            template <typename THandler, typename... TTypes>
            struct are_all_handled_by;

            template <typename THandler, typename T>
            struct are_all_handled_by<THandler, T> {
                static constexpr bool value = std::is_base_of<typename T::handler, THandler>::value;
            };

            template <typename THandler, typename T, typename... TRest>
            struct are_all_handled_by<THandler, T, TRest...> {
                static constexpr bool value = std::is_base_of<typename T::handler, THandler>::value &&
                                              are_all_handled_by<THandler, TRest...>::value;
            };
#else
            // True if Predicate matches for none of the types Ts
            template <template <typename> class Predicate, typename... Ts>
            struct static_none_of : std::is_same<std::tuple<std::false_type, typename Predicate<Ts>::type...>,
                                                 std::tuple<typename Predicate<Ts>::type..., std::false_type>>
            {};

            // True if Predicate matches for all of the types Ts
            template <template <typename> class Predicate, typename... Ts>
            struct static_all_of : std::is_same<std::tuple<std::true_type, typename Predicate<Ts>::type...>,
                                                std::tuple<typename Predicate<Ts>::type..., std::true_type>>
            {};

            // True if THandler is derived from the handler for at least one of the types in TTypes
            template <typename THandler, typename... TTypes>
            struct is_handled_by {
                template <typename T>
                using HasHandler = std::is_base_of<typename T::handler, THandler>;

                static constexpr bool value = !static_none_of<HasHandler, TTypes...>::value;
            };

            // True if THandler is derived from the handlers of all the types in TTypes
            template <typename THandler, typename... TTypes>
            struct are_all_handled_by {
                template <typename T>
                using HasHandler = std::is_base_of<typename T::handler, THandler>;

                static constexpr bool value = static_all_of<HasHandler, TTypes...>::value;
            };
#endif


            // Wraps any type, so that we can derive from it
            template <typename TType>
            struct type_wrapper {

                using type = TType;

                TType value;

                constexpr explicit type_wrapper(const TType& v) :
                    value(v) {
                }

            }; // struct type_wrapper

            // Small wrapper for begin/end iterator
            template <typename TType>
            struct iterator_wrapper {

                using type = TType;

                TType first;
                TType last;

                constexpr iterator_wrapper(TType begin, TType end) :
                    first(begin),
                    last(end) {}

                constexpr TType begin() const {
                    return first;
                }

                constexpr TType end() const {
                    return last;
                }

            }; // struct iterator_wrapper


            struct entity_handler {};
            struct object_handler;
            struct node_handler;
            struct tags_handler;
            struct nodes_handler;
            struct members_handler;
            struct changeset_handler;
            struct discussion_handler;
            struct ring_handler;

        } // namespace detail

#define OSMIUM_ATTRIBUTE(_handler, _name, _type) \
    struct _name : public osmium::builder::detail::type_wrapper<_type> { \
        using handler = osmium::builder::detail::_handler;

#define OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(_handler, _name, _type) \
    OSMIUM_ATTRIBUTE(_handler, _name, _type) \
        constexpr explicit _name(std::add_const<_type>::type& value) : \
            type_wrapper(value) {} \
    }

#define OSMIUM_ATTRIBUTE_ITER(_handler, _name) \
    template <typename TIterator> \
    struct _name : public osmium::builder::detail::iterator_wrapper<TIterator> { \
        using handler = osmium::builder::detail::_handler; \
        constexpr _name(TIterator first, TIterator last) : \
            osmium::builder::detail::iterator_wrapper<TIterator>(first, last) {} \
    }

        namespace attr {

            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(object_handler, _id, osmium::object_id_type);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(object_handler, _version, osmium::object_version_type);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(entity_handler, _uid, osmium::user_id_type);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(entity_handler, _cid, osmium::changeset_id_type);

            OSMIUM_ATTRIBUTE(object_handler, _deleted, bool)
                constexpr explicit _deleted(bool value = true) noexcept :
                    type_wrapper(value) {}
            };

            OSMIUM_ATTRIBUTE(object_handler, _visible, bool)
                constexpr explicit _visible(bool value = true) noexcept :
                    type_wrapper(value) {}
            };

            OSMIUM_ATTRIBUTE(object_handler, _timestamp, osmium::Timestamp)
                constexpr explicit _timestamp(const osmium::Timestamp& value) noexcept :
                    type_wrapper(value) {}
                constexpr explicit _timestamp(time_t value) noexcept :
                    type_wrapper(osmium::Timestamp{value}) {}
                constexpr explicit _timestamp(uint32_t value) noexcept :
                    type_wrapper(osmium::Timestamp{value}) {}
                explicit _timestamp(const char* value) :
                    type_wrapper(osmium::Timestamp{value}) {}
                explicit _timestamp(const std::string& value) :
                    type_wrapper(osmium::Timestamp{value}) {}
            };

            OSMIUM_ATTRIBUTE(node_handler, _location, osmium::Location)
                constexpr explicit _location(const osmium::Location& value) noexcept :
                    type_wrapper(value) {}
                explicit _location(double lon, double lat) :
                    type_wrapper(osmium::Location{lon, lat}) {}
            };

            OSMIUM_ATTRIBUTE(entity_handler, _user, const char*)
                constexpr explicit _user(const char* val) noexcept :
                    type_wrapper(val) {}
                explicit _user(const std::string& val) noexcept :
                    type_wrapper(val.c_str()) {}
            };

            using pair_of_cstrings = std::pair<const char* const, const char* const>;
            using pair_of_strings = std::pair<const std::string&, const std::string&>;

            class member_type {

                osmium::item_type      m_type;
                osmium::object_id_type m_ref;
                const char*            m_role;

            public:

                constexpr member_type(osmium::item_type type, osmium::object_id_type ref, const char* role = "") noexcept :
                    m_type(type),
                    m_ref(ref),
                    m_role(role) {
                }

                member_type(char type, osmium::object_id_type ref, const char* role = "") noexcept :
                    member_type(osmium::char_to_item_type(type), ref, role) {
                }

                constexpr osmium::item_type type() const noexcept {
                    return m_type;
                }

                constexpr osmium::object_id_type ref() const noexcept {
                    return m_ref;
                }

                constexpr const char* role() const noexcept {
                    return m_role;
                }

            }; // class member_type

            class member_type_string {

                osmium::item_type      m_type;
                osmium::object_id_type m_ref;
                std::string            m_role;

            public:

                member_type_string(osmium::item_type type, osmium::object_id_type ref, std::string&& role) :
                    m_type(type),
                    m_ref(ref),
                    m_role(std::move(role)) {
                }

                member_type_string(char type, osmium::object_id_type ref, std::string&& role) noexcept :
                    member_type_string(osmium::char_to_item_type(type), ref, std::move(role)) {
                }

                osmium::item_type type() const noexcept {
                    return m_type;
                }

                osmium::object_id_type ref() const noexcept {
                    return m_ref;
                }

                const char* role() const noexcept {
                    return m_role.c_str();
                }

            }; // class member_type_string

            class comment_type {

                osmium::Timestamp    m_date;
                osmium::user_id_type m_uid;
                const char*          m_user;
                const char*          m_text;

            public:

                constexpr comment_type(osmium::Timestamp date, osmium::user_id_type uid, const char* user, const char* text) noexcept :
                    m_date(date),
                    m_uid(uid),
                    m_user(user),
                    m_text(text) {
                }

                constexpr osmium::Timestamp date() const noexcept {
                    return m_date;
                }

                constexpr osmium::user_id_type uid() const noexcept {
                    return m_uid;
                }

                constexpr const char* user() const noexcept {
                    return m_user;
                }

                constexpr const char* text() const noexcept {
                    return m_text;
                }

            }; // class comment_type

            namespace detail {

                OSMIUM_ATTRIBUTE_ITER(tags_handler, tags_from_iterator_pair);

                OSMIUM_ATTRIBUTE_ITER(nodes_handler, nodes_from_iterator_pair);

                OSMIUM_ATTRIBUTE_ITER(members_handler, members_from_iterator_pair);

                OSMIUM_ATTRIBUTE_ITER(discussion_handler, comments_from_iterator_pair);

                OSMIUM_ATTRIBUTE_ITER(ring_handler, outer_ring_from_iterator_pair);
                OSMIUM_ATTRIBUTE_ITER(ring_handler, inner_ring_from_iterator_pair);

            } // namespace detail

            OSMIUM_ATTRIBUTE(tags_handler, _tag, pair_of_cstrings)
                explicit _tag(const pair_of_cstrings& value) noexcept :
                    type_wrapper(value) {}
                explicit _tag(const std::pair<const char* const, const char*>& value) :
                    type_wrapper(pair_of_cstrings{value.first, value.second}) {}
                explicit _tag(const std::pair<const char*, const char* const>& value) :
                    type_wrapper(pair_of_cstrings{value.first, value.second}) {}
                explicit _tag(const std::pair<const char*, const char*>& value) :
                    type_wrapper(pair_of_cstrings{value.first, value.second}) {}
                explicit _tag(const pair_of_strings& value) :
                    type_wrapper(std::make_pair(value.first.c_str(), value.second.c_str())) {}
                explicit _tag(const char* key, const char* val) :
                    type_wrapper(std::make_pair(key, val)) {}
                explicit _tag(const std::string& key, const std::string& val) :
                    type_wrapper(std::make_pair(key.c_str(), val.c_str())) {}
                explicit _tag(const char* const key_value) :
                    type_wrapper(pair_of_cstrings{key_value, nullptr}) {}
                explicit _tag(const std::string& key_value) :
                    type_wrapper(pair_of_cstrings{key_value.c_str(), nullptr}) {}
            };

            OSMIUM_ATTRIBUTE(tags_handler, _t, const char*)
                explicit _t(const char *tags) :
                    type_wrapper(tags) {}
            };

            template <typename TTagIterator>
            inline constexpr detail::tags_from_iterator_pair<TTagIterator> _tags(TTagIterator first, TTagIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::tags_from_iterator_pair<typename TContainer::const_iterator> _tags(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using tag_ilist = std::initializer_list<std::pair<const char*, const char*>>;
            inline detail::tags_from_iterator_pair<tag_ilist::const_iterator> _tags(const tag_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }


            OSMIUM_ATTRIBUTE(nodes_handler, _node, osmium::NodeRef)
                constexpr explicit _node(osmium::object_id_type value) noexcept :
                    type_wrapper(NodeRef{value}) {}
                constexpr explicit _node(const NodeRef& value) noexcept :
                    type_wrapper(value) {}
            };

            template <typename TIdIterator>
            inline constexpr detail::nodes_from_iterator_pair<TIdIterator> _nodes(TIdIterator first, TIdIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::nodes_from_iterator_pair<typename TContainer::const_iterator> _nodes(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using object_id_ilist = std::initializer_list<osmium::object_id_type>;
            inline detail::nodes_from_iterator_pair<object_id_ilist::const_iterator> _nodes(const object_id_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using node_ref_ilist = std::initializer_list<osmium::NodeRef>;
            inline detail::nodes_from_iterator_pair<node_ref_ilist::const_iterator> _nodes(const node_ref_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }


            OSMIUM_ATTRIBUTE(members_handler, _member, member_type)
                constexpr explicit _member(const member_type& value) noexcept :
                    type_wrapper(value) {}
                constexpr explicit _member(osmium::item_type type, osmium::object_id_type id) noexcept :
                    type_wrapper({type, id}) {}
                constexpr explicit _member(osmium::item_type type, osmium::object_id_type id, const char* role) noexcept :
                    type_wrapper({type, id, role}) {}
                explicit _member(osmium::item_type type, osmium::object_id_type id, const std::string& role) noexcept :
                    type_wrapper({type, id, role.c_str()}) {}
                explicit _member(const osmium::RelationMember& member) noexcept :
                    type_wrapper({member.type(), member.ref(), member.role()}) {}
            };

            template <typename TMemberIterator>
            inline constexpr detail::members_from_iterator_pair<TMemberIterator> _members(TMemberIterator first, TMemberIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::members_from_iterator_pair<typename TContainer::const_iterator> _members(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using member_ilist = std::initializer_list<member_type>;
            inline detail::members_from_iterator_pair<member_ilist::const_iterator> _members(const member_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }


            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(changeset_handler, _num_changes, osmium::num_changes_type);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(changeset_handler, _num_comments, osmium::num_comments_type);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(changeset_handler, _created_at, osmium::Timestamp);
            OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR(changeset_handler, _closed_at, osmium::Timestamp);

            OSMIUM_ATTRIBUTE(discussion_handler, _comment, comment_type)
                constexpr explicit _comment(const comment_type& value) noexcept :
                    type_wrapper(value) {}
                explicit _comment(const osmium::ChangesetComment& comment) noexcept :
                    type_wrapper({comment.date(), comment.uid(), comment.user(), comment.text()}) {}
            };

            template <typename TCommentIterator>
            inline constexpr detail::comments_from_iterator_pair<TCommentIterator> _comments(TCommentIterator first, TCommentIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::comments_from_iterator_pair<typename TContainer::const_iterator> _comments(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using comment_ilist = std::initializer_list<comment_type>;
            inline detail::comments_from_iterator_pair<comment_ilist::const_iterator> _comments(const comment_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }


            template <typename TIdIterator>
            inline constexpr detail::outer_ring_from_iterator_pair<TIdIterator> _outer_ring(TIdIterator first, TIdIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::outer_ring_from_iterator_pair<typename TContainer::const_iterator> _outer_ring(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using object_id_ilist = std::initializer_list<osmium::object_id_type>;
            inline detail::outer_ring_from_iterator_pair<object_id_ilist::const_iterator> _outer_ring(const object_id_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using node_ref_ilist = std::initializer_list<osmium::NodeRef>;
            inline detail::outer_ring_from_iterator_pair<node_ref_ilist::const_iterator> _outer_ring(const node_ref_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            template <typename TIdIterator>
            inline constexpr detail::inner_ring_from_iterator_pair<TIdIterator> _inner_ring(TIdIterator first, TIdIterator last) {
                return {first, last};
            }

            template <typename TContainer>
            inline detail::inner_ring_from_iterator_pair<typename TContainer::const_iterator> _inner_ring(const TContainer& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using object_id_ilist = std::initializer_list<osmium::object_id_type>;
            inline detail::inner_ring_from_iterator_pair<object_id_ilist::const_iterator> _inner_ring(const object_id_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }

            using node_ref_ilist = std::initializer_list<osmium::NodeRef>;
            inline detail::inner_ring_from_iterator_pair<node_ref_ilist::const_iterator> _inner_ring(const node_ref_ilist& container) {
                using std::begin;
                using std::end;
                return {begin(container), end(container)};
            }


        } // namespace attr

#undef OSMIUM_ATTRIBUTE_ITER
#undef OSMIUM_ATTRIBUTE_WITH_CONSTRUCTOR
#undef OSMIUM_ATTRIBUTE

        namespace detail {

            struct changeset_handler : public entity_handler {

                template <typename TDummy>
                static void set_value(osmium::Changeset& /*changeset*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(osmium::Changeset& changeset, attr::_cid id) noexcept {
                    changeset.set_id(id.value);
                }

                static void set_value(osmium::Changeset& changeset, attr::_num_changes num_changes) noexcept {
                    changeset.set_num_changes(num_changes.value);
                }

                static void set_value(osmium::Changeset& changeset, attr::_num_comments num_comments) noexcept {
                    changeset.set_num_comments(num_comments.value);
                }

                static void set_value(osmium::Changeset& changeset, attr::_created_at created_at) noexcept {
                    changeset.set_created_at(created_at.value);
                }

                static void set_value(osmium::Changeset& changeset, attr::_closed_at closed_at) noexcept {
                    changeset.set_closed_at(closed_at.value);
                }

                static void set_value(osmium::Changeset& changeset, attr::_uid uid) noexcept {
                    changeset.set_uid(uid.value);
                }

            };

            struct object_handler : public entity_handler {

                template <typename TDummy>
                static void set_value(osmium::OSMObject& /*object*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(osmium::OSMObject& object, attr::_id id) noexcept {
                    object.set_id(id.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_version version) noexcept {
                    object.set_version(version.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_visible visible) noexcept {
                    object.set_visible(visible.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_deleted deleted) noexcept {
                    object.set_deleted(deleted.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_timestamp timestamp) noexcept {
                    object.set_timestamp(timestamp.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_cid changeset) noexcept {
                    object.set_changeset(changeset.value);
                }

                static void set_value(osmium::OSMObject& object, attr::_uid uid) noexcept {
                    object.set_uid(uid.value);
                }

            }; // object_handler

            struct node_handler : public object_handler {

                using object_handler::set_value;

                static void set_value(osmium::Node& node, attr::_location location) noexcept {
                    node.set_location(location.value);
                }

            }; // node_handler

            template <typename THandler, typename TBuilder, typename... TArgs>
            inline void add_basic(TBuilder& builder, const TArgs&... args) noexcept {
                (void)std::initializer_list<int>{
                    (THandler::set_value(builder.object(), args), 0)...
                };
            }

            // ==============================================================

            template <typename... TArgs>
            inline constexpr const char* get_user(const attr::_user& user, const TArgs&... /*args*/) noexcept {
                return user.value;
            }

            inline constexpr const char* get_user() noexcept {
                return "";
            }

            template <typename TFirst, typename... TRest>
            inline constexpr typename std::enable_if<!std::is_same<attr::_user, TFirst>::value, const char*>::type
            get_user(const TFirst& /*first*/, const TRest&... args) noexcept {
                return get_user(args...);
            }

            template <typename TBuilder, typename... TArgs>
            inline void add_user(TBuilder& builder, const TArgs&... args) {
                builder.set_user(get_user(args...));
            }

            // ==============================================================

            struct tags_handler {

                template <typename TDummy>
                static void set_value(TagListBuilder& /*tlb*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(TagListBuilder& builder, const attr::_tag& tag) {
                    if (tag.value.second != nullptr) {
                        builder.add_tag(tag.value);
                        return;
                    }
                    const char* key = tag.value.first;
                    const char* const equal_sign = std::strchr(key, '=');
                    if (!equal_sign) {
                        builder.add_tag(key, "");
                        return;
                    }
                    const char* value = equal_sign + 1;
                    builder.add_tag(key, equal_sign - key,
                                    value, std::strlen(value));
                }

                template <typename TIterator>
                static void set_value(TagListBuilder& builder, const attr::detail::tags_from_iterator_pair<TIterator>& tags) {
                    for (const auto& tag : tags) {
                        builder.add_tag(tag);
                    }
                }

                static void set_value(TagListBuilder& builder, const attr::_t& tags) {
                    const auto taglist = osmium::split_string(tags.value, ',', true);
                    for (const auto& tag : taglist) {
                        const std::size_t pos = tag.find_first_of('=');
                        if (pos == std::string::npos) {
                            builder.add_tag(tag, "");
                        } else {
                            const char* value = tag.c_str() + pos + 1;
                            builder.add_tag(tag.c_str(), pos,
                                            value, tag.size() - pos - 1);
                        }

                    }
                }

            }; // struct tags_handler

            struct nodes_handler {

                template <typename TDummy>
                static void set_value(WayNodeListBuilder& /*wnlb*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(WayNodeListBuilder& builder, const attr::_node& node_ref) {
                    builder.add_node_ref(node_ref.value);
                }

                template <typename TIterator>
                static void set_value(WayNodeListBuilder& builder, const attr::detail::nodes_from_iterator_pair<TIterator>& nodes) {
                    for (const auto& ref : nodes) {
                        builder.add_node_ref(ref);
                    }
                }

            }; // struct nodes_handler

            struct members_handler {

                template <typename TDummy>
                static void set_value(RelationMemberListBuilder& /*rmlb*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(RelationMemberListBuilder& builder, const attr::_member& member) {
                    builder.add_member(member.value.type(), member.value.ref(), member.value.role());
                }

                template <typename TIterator>
                static void set_value(RelationMemberListBuilder& builder, const attr::detail::members_from_iterator_pair<TIterator>& members) {
                    for (const auto& member : members) {
                        builder.add_member(member.type(), member.ref(), member.role());
                    }
                }

            }; // struct members_handler

            struct discussion_handler {

                template <typename TDummy>
                static void set_value(ChangesetDiscussionBuilder& /*cdb*/, const TDummy& /*dummy*/) noexcept {
                }

                static void set_value(ChangesetDiscussionBuilder& builder, const attr::_comment& comment) {
                    builder.add_comment(comment.value.date(), comment.value.uid(), comment.value.user());
                    builder.add_comment_text(comment.value.text());
                }

                template <typename TIterator>
                static void set_value(ChangesetDiscussionBuilder& builder, const attr::detail::comments_from_iterator_pair<TIterator>& comments) {
                    for (const auto& comment : comments) {
                        builder.add_comment(comment.date(), comment.uid(), comment.user());
                        builder.add_comment_text(comment.text());
                    }
                }

            }; // struct discussion_handler

            struct ring_handler {

                template <typename TDummy>
                static void set_value(AreaBuilder& /*ab*/, const TDummy& /*dummy*/) noexcept {
                }

                template <typename TIterator>
                static void set_value(AreaBuilder& parent, const attr::detail::outer_ring_from_iterator_pair<TIterator>& nodes) {
                    OuterRingBuilder builder(parent.buffer(), &parent);
                    for (const auto& ref : nodes) {
                        builder.add_node_ref(ref);
                    }
                }

                template <typename TIterator>
                static void set_value(AreaBuilder& parent, const attr::detail::inner_ring_from_iterator_pair<TIterator>& nodes) {
                    InnerRingBuilder builder(parent.buffer(), &parent);
                    for (const auto& ref : nodes) {
                        builder.add_node_ref(ref);
                    }
                }

            }; // struct ring_handler

            // ==============================================================

            template <typename TBuilder, typename THandler, typename... TArgs>
            inline typename std::enable_if<!is_handled_by<THandler, TArgs...>::value>::type
            add_list(osmium::builder::Builder& /*parent*/, const TArgs&... /*args*/) noexcept {
            }

            template <typename TBuilder, typename THandler, typename... TArgs>
            inline typename std::enable_if<is_handled_by<THandler, TArgs...>::value>::type
            add_list(osmium::builder::Builder& parent, const TArgs&... args) {
                TBuilder builder{parent.buffer(), &parent};
                (void)std::initializer_list<int>{
                    (THandler::set_value(builder, args), 0)...
                };
            }

            struct any_node_handlers : public node_handler, public tags_handler {};
            struct any_way_handlers : public object_handler, public tags_handler, public nodes_handler {};
            struct any_relation_handlers : public object_handler, public tags_handler, public members_handler {};
            struct any_area_handlers : public object_handler, public tags_handler, public ring_handler {};
            struct any_changeset_handlers : public changeset_handler, public tags_handler, public discussion_handler {};

        } // namespace detail


        /**
         * Create a node using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the node will be added.
         * @param args The attributes of the node.
         * @returns The position in the buffer where this node was added.
         */
        template <typename... TArgs>
        inline size_t add_node(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_node() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::any_node_handlers, TArgs...>::value, "Attribute not allowed in add_node()");

            {
                NodeBuilder builder{buffer};

                detail::add_basic<detail::node_handler>(builder, args...);
                detail::add_user(builder, args...);
                detail::add_list<TagListBuilder, detail::tags_handler>(builder, args...);
            }

            return buffer.commit();
        }

        /**
         * Create a way using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the way will be added.
         * @param args The attributes of the way.
         * @returns The position in the buffer where this way was added.
         */
        template <typename... TArgs>
        inline size_t add_way(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_way() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::any_way_handlers, TArgs...>::value, "Attribute not allowed in add_way()");

            {
                WayBuilder builder{buffer};

                detail::add_basic<detail::object_handler>(builder, args...);
                detail::add_user(builder, args...);
                detail::add_list<TagListBuilder, detail::tags_handler>(builder, args...);
                detail::add_list<WayNodeListBuilder, detail::nodes_handler>(builder, args...);
            }

            return buffer.commit();
        }

        /**
         * Create a relation using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the relation will be added.
         * @param args The attributes of the relation.
         * @returns The position in the buffer where this relation was added.
         */
        template <typename... TArgs>
        inline size_t add_relation(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_relation() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::any_relation_handlers, TArgs...>::value, "Attribute not allowed in add_relation()");

            {
                RelationBuilder builder{buffer};

                detail::add_basic<detail::object_handler>(builder, args...);
                detail::add_user(builder, args...);
                detail::add_list<TagListBuilder, detail::tags_handler>(builder, args...);
                detail::add_list<RelationMemberListBuilder, detail::members_handler>(builder, args...);
            }

            return buffer.commit();
        }

        /**
         * Create a changeset using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the changeset will be added.
         * @param args The attributes of the changeset.
         * @returns The position in the buffer where this changeset was added.
         */
        template <typename... TArgs>
        inline size_t add_changeset(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_changeset() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::any_changeset_handlers, TArgs...>::value, "Attribute not allowed in add_changeset()");

            {
                ChangesetBuilder builder{buffer};

                detail::add_basic<detail::changeset_handler>(builder, args...);
                detail::add_user(builder, args...);
                detail::add_list<TagListBuilder, detail::tags_handler>(builder, args...);
                detail::add_list<ChangesetDiscussionBuilder, detail::discussion_handler>(builder, args...);
            }

            return buffer.commit();
        }

        /**
         * Create a area using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the area will be added.
         * @param args The attributes of the area.
         * @returns The position in the buffer where this area was added.
         */
        template <typename... TArgs>
        inline size_t add_area(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_area() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::any_area_handlers, TArgs...>::value, "Attribute not allowed in add_area()");

            {
                AreaBuilder builder{buffer};

                detail::add_basic<detail::object_handler>(builder, args...);
                detail::add_user(builder, args...);
                detail::add_list<TagListBuilder, detail::tags_handler>(builder, args...);

                (void)std::initializer_list<int>{
                    (detail::ring_handler::set_value(builder, args), 0)...
                };
            }

            return buffer.commit();
        }

        /**
         * Create a WayNodeList using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the list will be added.
         * @param args The contents of the list.
         * @returns The position in the buffer where this list was added.
         */
        template <typename... TArgs>
        inline size_t add_way_node_list(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_way_node_list() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::nodes_handler, TArgs...>::value, "Attribute not allowed in add_way_node_list()");

            {
                WayNodeListBuilder builder{buffer};
                (void)std::initializer_list<int>{
                    (detail::nodes_handler::set_value(builder, args), 0)...
                };
            }

            return buffer.commit();
        }

        /**
         * Create a TagList using the given arguments and add it to the given buffer.
         *
         * @param buffer The buffer to which the list will be added.
         * @param args The contents of the list.
         * @returns The position in the buffer where this list was added.
         */
        template <typename... TArgs>
        inline size_t add_tag_list(osmium::memory::Buffer& buffer, const TArgs&... args) {
            static_assert(sizeof...(args) > 0, "add_tag_list() must have buffer and at least one additional argument");
            static_assert(detail::are_all_handled_by<detail::tags_handler, TArgs...>::value, "Attribute not allowed in add_tag_list()");

            {
                TagListBuilder builder{buffer};
                (void)std::initializer_list<int>{
                    (detail::tags_handler::set_value(builder, args), 0)...
                };
            }

            return buffer.commit();
        }

    } // namespace builder

} // namespace osmium

#endif // OSMIUM_BUILDER_ATTR_HPP