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- </head>
- <body class="article toc2 toc-left">
- <div id="header">
- <h1>Boost.Mp11: A C++11 metaprogramming library</h1>
- <div class="details">
- <span id="author" class="author">Peter Dimov</span><br>
- </div>
- <div id="toc" class="toc2">
- <div id="toctitle">Table of Contents</div>
- <ul class="sectlevel1">
- <li><a href="#overview">Overview</a></li>
- <li><a href="#definitions">Definitions</a></li>
- <li><a href="#examples">Examples</a>
- <ul class="sectlevel2">
- <li><a href="#generating_test_cases">Generating Test Cases</a></li>
- <li><a href="#writing_common_type_specializations">Writing common_type Specializations</a></li>
- <li><a href="#fixing_tuple_cat">Fixing tuple_cat</a></li>
- <li><a href="#computing_return_types">Computing Return Types</a></li>
- </ul>
- </li>
- <li><a href="#changelog">Revision History</a>
- <ul class="sectlevel2">
- <li><a href="#changes_in_1_70_0">Changes in 1.70.0</a></li>
- <li><a href="#changes_in_1_69_0">Changes in 1.69.0</a></li>
- </ul>
- </li>
- <li><a href="#reference">Reference</a>
- <ul class="sectlevel2">
- <li><a href="#integral">Integral Constants, <boost/mp11/integral.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_boolb">mp_bool<B></a></li>
- <li><a href="#mp_true">mp_true</a></li>
- <li><a href="#mp_false">mp_false</a></li>
- <li><a href="#mp_to_boolt">mp_to_bool<T></a></li>
- <li><a href="#mp_nott">mp_not<T></a></li>
- <li><a href="#mp_inti">mp_int<I></a></li>
- <li><a href="#mp_size_tn">mp_size_t<N></a></li>
- </ul>
- </li>
- <li><a href="#list">List Operations, <boost/mp11/list.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_listt">mp_list<T…​></a></li>
- <li><a href="#mp_list_ct_i">mp_list_c<T, I…​></a></li>
- <li><a href="#mp_is_listl">mp_is_list<L></a></li>
- <li><a href="#mp_sizel">mp_size<L></a></li>
- <li><a href="#mp_emptyl">mp_empty<L></a></li>
- <li><a href="#mp_assignl1_l2">mp_assign<L1, L2></a></li>
- <li><a href="#mp_clearl">mp_clear<L></a></li>
- <li><a href="#mp_frontl">mp_front<L></a></li>
- <li><a href="#mp_pop_frontl">mp_pop_front<L></a></li>
- <li><a href="#mp_firstl">mp_first<L></a></li>
- <li><a href="#mp_restl">mp_rest<L></a></li>
- <li><a href="#mp_secondl">mp_second<L></a></li>
- <li><a href="#mp_thirdl">mp_third<L></a></li>
- <li><a href="#mp_push_frontl_t">mp_push_front<L, T…​></a></li>
- <li><a href="#mp_push_backl_t">mp_push_back<L, T…​></a></li>
- <li><a href="#mp_renamel_y">mp_rename<L, Y></a></li>
- <li><a href="#mp_applyf_l">mp_apply<F, L></a></li>
- <li><a href="#mp_apply_qq_l">mp_apply_q<Q, L></a></li>
- <li><a href="#mp_appendl">mp_append<L…​></a></li>
- <li><a href="#mp_replace_frontl_t">mp_replace_front<L, T></a></li>
- <li><a href="#mp_replace_firstl_t">mp_replace_first<L, T></a></li>
- <li><a href="#mp_replace_secondl_t">mp_replace_second<L, T></a></li>
- <li><a href="#mp_replace_thirdl_t">mp_replace_third<L, T></a></li>
- <li><a href="#mp_transform_frontl_f">mp_transform_front<L, F></a></li>
- <li><a href="#mp_transform_front_ql_q">mp_transform_front_q<L, Q></a></li>
- <li><a href="#mp_transform_firstl_f">mp_transform_first<L, F></a></li>
- <li><a href="#mp_transform_first_ql_q">mp_transform_first_q<L, Q></a></li>
- <li><a href="#mp_transform_secondl_f">mp_transform_second<L, F></a></li>
- <li><a href="#mp_transform_second_ql_q">mp_transform_second_q<L, Q></a></li>
- <li><a href="#mp_transform_thirdl_f">mp_transform_third<L, F></a></li>
- <li><a href="#mp_transform_third_ql_q">mp_transform_third_q<L, Q></a></li>
- </ul>
- </li>
- <li><a href="#utility">Utility Components, <boost/mp11/utility.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_identityt">mp_identity<T></a></li>
- <li><a href="#mp_identity_tt">mp_identity_t<T></a></li>
- <li><a href="#mp_inheritt">mp_inherit<T…​></a></li>
- <li><a href="#mp_if_cc_t_e">mp_if_c<C, T, E…​></a></li>
- <li><a href="#mp_ifc_t_e">mp_if<C, T, E…​></a></li>
- <li><a href="#mp_eval_if_cc_t_f_u">mp_eval_if_c<C, T, F, U…​></a></li>
- <li><a href="#mp_eval_ifc_t_f_u">mp_eval_if<C, T, F, U…​></a></li>
- <li><a href="#mp_eval_if_qc_t_q_u">mp_eval_if_q<C, T, Q, U…​></a></li>
- <li><a href="#mp_eval_if_notc_t_f_u">mp_eval_if_not<C, T, F, U…​></a></li>
- <li><a href="#mp_eval_if_not_qc_t_q_u">mp_eval_if_not_q<C, T, Q, U…​></a></li>
- <li><a href="#mp_validf_t">mp_valid<F, T…​></a></li>
- <li><a href="#mp_valid_qq_t">mp_valid_q<Q, T…​></a></li>
- <li><a href="#mp_eval_ort_f_u">mp_eval_or<T, F, U…​></a></li>
- <li><a href="#mp_eval_or_qt_q_u">mp_eval_or_q<T, Q, U…​></a></li>
- <li><a href="#mp_condc_t_r">mp_cond<C, T, R…​></a></li>
- <li><a href="#mp_deferf_t">mp_defer<F, T…​></a></li>
- <li><a href="#mp_quotef">mp_quote<F></a></li>
- <li><a href="#mp_quote_traitf">mp_quote_trait<F></a></li>
- <li><a href="#mp_invoke_qq_t">mp_invoke_q<Q, T…​></a></li>
- <li><a href="#mp_not_fnp">mp_not_fn<P></a></li>
- <li><a href="#mp_not_fn_qq">mp_not_fn_q<Q></a></li>
- </ul>
- </li>
- <li><a href="#algorithm">Algorithms, <boost/mp11/algorithm.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_transformf_l">mp_transform<F, L…​></a></li>
- <li><a href="#mp_transform_qq_l">mp_transform_q<Q, L…​></a></li>
- <li><a href="#mp_transform_ifp_f_l">mp_transform_if<P, F, L…​></a></li>
- <li><a href="#mp_transform_if_qqp_qf_l">mp_transform_if_q<Qp, Qf, L…​></a></li>
- <li><a href="#mp_filterp_l">mp_filter<P, L…​></a></li>
- <li><a href="#mp_filter_qqp_l">mp_filter_q<Qp, L…​></a></li>
- <li><a href="#mp_filll_v">mp_fill<L, V></a></li>
- <li><a href="#mp_countl_v">mp_count<L, V></a></li>
- <li><a href="#mp_count_ifl_p">mp_count_if<L, P></a></li>
- <li><a href="#mp_count_if_ql_q">mp_count_if_q<L, Q></a></li>
- <li><a href="#mp_containsl_v">mp_contains<L, V></a></li>
- <li><a href="#mp_starts_withl1_l2">mp_starts_with<L1, L2></a></li>
- <li><a href="#mp_repeat_cl_n">mp_repeat_c<L, N></a></li>
- <li><a href="#mp_repeatl_n">mp_repeat<L, N></a></li>
- <li><a href="#mp_productf_l">mp_product<F, L…​></a></li>
- <li><a href="#mp_product_qq_l">mp_product_q<Q, L…​></a></li>
- <li><a href="#mp_drop_cl_n">mp_drop_c<L, N></a></li>
- <li><a href="#mp_dropl_n">mp_drop<L, N></a></li>
- <li><a href="#mp_from_sequences">mp_from_sequence<S></a></li>
- <li><a href="#mp_iota_cn">mp_iota_c<N></a></li>
- <li><a href="#mp_iotan">mp_iota<N></a></li>
- <li><a href="#mp_at_cl_i">mp_at_c<L, I></a></li>
- <li><a href="#mp_atl_i">mp_at<L, I></a></li>
- <li><a href="#mp_take_cl_n">mp_take_c<L, N></a></li>
- <li><a href="#mp_takel_n">mp_take<L, N></a></li>
- <li><a href="#mp_backl">mp_back<L></a></li>
- <li><a href="#mp_pop_backl">mp_pop_back<L></a></li>
- <li><a href="#mp_insert_cl_i_t">mp_insert_c<L, I, T…​></a></li>
- <li><a href="#mp_insertl_i_t">mp_insert<L, I, T…​></a></li>
- <li><a href="#mp_erase_cl_i_j">mp_erase_c<L, I, J></a></li>
- <li><a href="#mp_erasel_i_j">mp_erase<L, I, J></a></li>
- <li><a href="#mp_replacel_v_w">mp_replace<L, V, W></a></li>
- <li><a href="#mp_replace_ifl_p_w">mp_replace_if<L, P, W></a></li>
- <li><a href="#mp_replace_if_ql_q_w">mp_replace_if_q<L, Q, W></a></li>
- <li><a href="#mp_replace_at_cl_i_w">mp_replace_at_c<L, I, W></a></li>
- <li><a href="#mp_replace_atl_i_w">mp_replace_at<L, I, W></a></li>
- <li><a href="#mp_copy_ifl_p">mp_copy_if<L, P></a></li>
- <li><a href="#mp_copy_if_ql_q">mp_copy_if_q<L, Q></a></li>
- <li><a href="#mp_removel_v">mp_remove<L, V></a></li>
- <li><a href="#mp_remove_ifl_p">mp_remove_if<L, P></a></li>
- <li><a href="#mp_remove_if_ql_q">mp_remove_if_q<L, Q></a></li>
- <li><a href="#mp_partitionl_p">mp_partition<L, P></a></li>
- <li><a href="#mp_partition_ql_q">mp_partition_q<L, Q></a></li>
- <li><a href="#mp_sortl_p">mp_sort<L, P></a></li>
- <li><a href="#mp_sort_ql_q">mp_sort_q<L, Q></a></li>
- <li><a href="#mp_nth_element_cl_i_p">mp_nth_element_c<L, I, P></a></li>
- <li><a href="#mp_nth_elementl_i_p">mp_nth_element<L, I, P></a></li>
- <li><a href="#mp_nth_element_ql_i_q">mp_nth_element_q<L, I, Q></a></li>
- <li><a href="#mp_min_elementl_p">mp_min_element<L, P></a></li>
- <li><a href="#mp_min_element_ql_q">mp_min_element_q<L, Q></a></li>
- <li><a href="#mp_max_elementl_p">mp_max_element<L, P></a></li>
- <li><a href="#mp_max_element_ql_q">mp_max_element_q<L, Q></a></li>
- <li><a href="#mp_findl_v">mp_find<L, V></a></li>
- <li><a href="#mp_find_ifl_p">mp_find_if<L, P></a></li>
- <li><a href="#mp_find_if_ql_q">mp_find_if_q<L, Q></a></li>
- <li><a href="#mp_reversel">mp_reverse<L></a></li>
- <li><a href="#mp_foldl_v_f">mp_fold<L, V, F></a></li>
- <li><a href="#mp_fold_ql_v_q">mp_fold_q<L, V, Q></a></li>
- <li><a href="#mp_reverse_foldl_v_f">mp_reverse_fold<L, V, F></a></li>
- <li><a href="#mp_reverse_fold_ql_v_q">mp_reverse_fold_q<L, V, Q></a></li>
- <li><a href="#mp_uniquel">mp_unique<L></a></li>
- <li><a href="#mp_all_ofl_p">mp_all_of<L, P></a></li>
- <li><a href="#mp_all_of_ql_q">mp_all_of_q<L, Q></a></li>
- <li><a href="#mp_none_ofl_p">mp_none_of<L, P></a></li>
- <li><a href="#mp_none_of_ql_q">mp_none_of_q<L, Q></a></li>
- <li><a href="#mp_any_ofl_p">mp_any_of<L, P></a></li>
- <li><a href="#mp_any_of_ql_q">mp_any_of_q<L, Q></a></li>
- <li><a href="#mp_for_eachlf">mp_for_each<L>(f)</a></li>
- <li><a href="#mp_with_indexni_f">mp_with_index<N>(i, f)</a></li>
- </ul>
- </li>
- <li><a href="#set">Set Operations, <boost/mp11/set.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_is_sets">mp_is_set<S></a></li>
- <li><a href="#mp_set_containss_v">mp_set_contains<S, V></a></li>
- <li><a href="#mp_set_push_backs_t">mp_set_push_back<S, T…​></a></li>
- <li><a href="#mp_set_push_fronts_t">mp_set_push_front<S, T…​></a></li>
- <li><a href="#mp_set_unionl">mp_set_union<L…​></a></li>
- <li><a href="#mp_set_intersections">mp_set_intersection<S…​></a></li>
- <li><a href="#mp_set_differencel_s">mp_set_difference<L, S…​></a></li>
- </ul>
- </li>
- <li><a href="#map">Map Operations, <boost/mp11/map.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_is_mapm">mp_is_map<M></a></li>
- <li><a href="#mp_map_findm_k">mp_map_find<M, K></a></li>
- <li><a href="#mp_map_containsm_k">mp_map_contains<M, K></a></li>
- <li><a href="#mp_map_insertm_t">mp_map_insert<M, T></a></li>
- <li><a href="#mp_map_replacem_t">mp_map_replace<M, T></a></li>
- <li><a href="#mp_map_updatem_t_f">mp_map_update<M, T, F></a></li>
- <li><a href="#mp_map_update_qm_t_q">mp_map_update_q<M, T, Q></a></li>
- <li><a href="#mp_map_erasem_k">mp_map_erase<M, K></a></li>
- <li><a href="#mp_map_keysm">mp_map_keys<M></a></li>
- </ul>
- </li>
- <li><a href="#function">Helper Metafunctions, <boost/mp11/function.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_voidt">mp_void<T…​></a></li>
- <li><a href="#mp_andt">mp_and<T…​></a></li>
- <li><a href="#mp_allt">mp_all<T…​></a></li>
- <li><a href="#mp_ort">mp_or<T…​></a></li>
- <li><a href="#mp_anyt">mp_any<T…​></a></li>
- <li><a href="#mp_samet">mp_same<T…​></a></li>
- <li><a href="#mp_similart">mp_similar<T…​></a></li>
- <li><a href="#mp_plust">mp_plus<T…​></a></li>
- <li><a href="#mp_lesst1_t2">mp_less<T1, T2></a></li>
- <li><a href="#mp_mint1_t">mp_min<T1, T…​></a></li>
- <li><a href="#mp_maxt1_t">mp_max<T1, T…​></a></li>
- </ul>
- </li>
- <li><a href="#bind">Bind, <boost/mp11/bind.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#mp_argi">mp_arg<I></a></li>
- <li><a href="#1_9">_1, …​, _9</a></li>
- <li><a href="#mp_bindf_t">mp_bind<F, T…​></a></li>
- <li><a href="#mp_bind_qq_t">mp_bind_q<Q, T…​></a></li>
- <li><a href="#mp_bind_frontf_t">mp_bind_front<F, T…​></a></li>
- <li><a href="#mp_bind_front_qq_t">mp_bind_front_q<Q, T…​></a></li>
- <li><a href="#mp_bind_backf_t">mp_bind_back<F, T…​></a></li>
- <li><a href="#mp_bind_back_qq_t">mp_bind_back_q<Q, T…​></a></li>
- </ul>
- </li>
- <li><a href="#integer_sequence">Integer Sequences, <boost/mp11/integer_sequence.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#integer_sequencet_i">integer_sequence<T, I…​></a></li>
- <li><a href="#make_integer_sequencet_n">make_integer_sequence<T, N></a></li>
- <li><a href="#index_sequencei">index_sequence<I…​></a></li>
- <li><a href="#make_index_sequencen">make_index_sequence<N></a></li>
- <li><a href="#index_sequence_fort">index_sequence_for<T…​></a></li>
- </ul>
- </li>
- <li><a href="#tuple">Tuple Operations, <boost/mp11/tuple.hpp></a>
- <ul class="sectlevel3">
- <li><a href="#tuple_applyf_tp">tuple_apply(f, tp)</a></li>
- <li><a href="#construct_from_tuplettp">construct_from_tuple<T>(tp)</a></li>
- <li><a href="#tuple_for_eachtp_f">tuple_for_each(tp, f)</a></li>
- </ul>
- </li>
- <li><a href="#mp11">Convenience Header, <boost/mp11.hpp></a></li>
- <li><a href="#mpl">MPL Support, <boost/mp11/mpl.hpp></a></li>
- </ul>
- </li>
- <li><a href="#copyright_license_and_acknowledgments">Appendix A: Copyright, License, and Acknowledgments</a></li>
- </ul>
- </div>
- </div>
- <div id="content">
- <div class="sect1">
- <h2 id="overview">Overview</h2>
- <div class="sectionbody">
- <div class="paragraph">
- <p>Mp11 is a C++11 metaprogramming library for compile-time manipulation of data structures
- that contain types. It’s based on template aliases and variadic templates and implements the
- approach outlined in the article
- <a href="simple_cxx11_metaprogramming.html">"Simple C++ metaprogramming"</a>
- and <a href="simple_cxx11_metaprogramming_2.html">its sequel</a>. Reading these
- articles before proceeding with this documentation is <em>highly</em> recommended.</p>
- </div>
- <div class="paragraph">
- <p>The general principles upon which Mp11 is built are that algorithms and metafunctions are
- template aliases of the form <code>F<T…​></code> and data structures are lists of the form <code>L<T…​></code>,
- with the library placing no requirements on <code>L</code>. <code>mp_list<T…​></code> is the built-in list type,
- but <code>std::tuple<T…​></code>, <code>std::pair<T1, T2></code> and <code>std::variant<T…​></code> are also perfectly
- legitimate list types, although of course <code>std::pair<T1, T2></code>, due to having exactly two elements,
- is not resizeable and will consequently not work with algorithms that need to add or remove
- elements.</p>
- </div>
- <div class="paragraph">
- <p>Another distinguishing feature of this approach is that lists (<code>L<T…​></code>) have the same form as
- metafunctions (<code>F<T…​></code>) and can therefore be used as such. For example, applying <code>std::add_pointer_t</code>
- to the list <code>std::tuple<int, float></code> by way of <code>mp_transform<std::add_pointer_t, std::tuple<int, float>></code>
- gives us <code>std::tuple<int*, float*></code>, but we can also apply <code>mp_list</code> to the same tuple:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>using R = mp_transform<mp_list, std::tuple<int, float>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>and get <code>std::tuple<mp_list<int>, mp_list<float>></code>.</p>
- </div>
- </div>
- </div>
- <div class="sect1">
- <h2 id="definitions">Definitions</h2>
- <div class="sectionbody">
- <div class="paragraph">
- <p>A <em>list</em> is a — usually but not necessarily variadic — template class whose parameters are all types,
- for example <code>mp_list<char[], void></code>, <code>mp_list<></code>, <code>std::tuple<int, float, char></code>, <code>std::pair<int, float></code>, <code>std::shared_ptr<X></code>.</p>
- </div>
- <div class="paragraph">
- <p>A <em>metafunction</em> is a class template or a template alias whose parameters are all types, for example <code>std::add_pointer_t</code>,
- <code>std::is_const</code>, <code>mp_second</code>, <code>mp_push_front</code>, <code>mp_list</code>, <code>std::tuple</code>, <code>std::pair</code>, <code>std::shared_ptr</code>, or</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class...> using F1 = void;
- template<class T> using F2 = T*;
- template<class... T> using F3 = std::integral_constant<std::size_t, sizeof...(T)>;</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>A <em>quoted metafunction</em> is a class with a public metafunction member called <code>fn</code>, for example</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>struct Q1 { template<class...> using fn = void; };
- struct Q2 { template<class T> using fn = T*; };
- struct Q3 { template<class... T> using fn =
- std::integral_constant<std::size_t, sizeof...(T)>; };</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>An <em>integral constant type</em> is a class with a public member <code>value</code> that is an integral constant in the C++ sense. For example,
- <code>std::integral_constant<int, 7></code>, or</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>struct N { static int constexpr value = 2; };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>A <em>set</em> is a list whose elements are unique.</p>
- </div>
- <div class="paragraph">
- <p>A <em>map</em> is a list of lists, the inner lists having at least one element (the key.) The keys of the map must be unique. For example,</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>using M1 = std::tuple<std::pair<int, int*>, std::pair<float, float*>,
- std::pair<void, void*>>;
- using M2 = mp_list<mp_list<int, int*>, mp_list<float>,
- mp_list<char, char[1], char[2]>>;</code></pre>
- </div>
- </div>
- </div>
- </div>
- <div class="sect1">
- <h2 id="examples">Examples</h2>
- <div class="sectionbody">
- <div class="sect2">
- <h3 id="generating_test_cases">Generating Test Cases</h3>
- <div class="paragraph">
- <p>Let’s suppose that we have written a metafunction <code>result<T, U></code>:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class T> using promote = typename std::common_type<T, int>::type;
- template<class T, class U> using result =
- typename std::common_type<promote<T>, promote<U>>::type;</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>that ought to represent the result of an arithmetic operation on the integer types <code>T</code> and <code>U</code>,
- for example <code>t + u</code>. We want to test whether <code>result<T, U></code> gives correct results for various combinations
- of <code>T</code> and <code>U</code>, so we write the function</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class T1, class T2> void test_result()
- {
- using T3 = decltype( T1() + T2() );
- using T4 = result<T1, T2>;
- std::cout << ( std::is_same<T3, T4>::value? "[PASS]": "[FAIL]" ) << std::endl;
- }</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>and then need to call it a substantial number of times:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>int main()
- {
- test_result<char, char>();
- test_result<char, short>();
- test_result<char, int>();
- test_result<char, unsigned>();
- // ...
- }</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Writing all those type combinations by hand is unwieldy, error prone, and worst of all, boring. This is
- how we can leverage Mp11 to automate the task:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>#include <boost/mp11.hpp>
- #include <boost/core/demangle.hpp>
- #include <type_traits>
- #include <iostream>
- #include <typeinfo>
- using namespace boost::mp11;
- template<class T> std::string name()
- {
- return boost::core::demangle( typeid(T).name() );
- }
- template<class T> using promote = typename std::common_type<T, int>::type;
- template<class T, class U> using result =
- typename std::common_type<promote<T>, promote<U>>::type;
- template<class T1, class T2> void test_result( mp_list<T1, T2> const& )
- {
- using T3 = decltype( T1() + T2() );
- using T4 = result<T1, T2>;
- std::cout << ( std::is_same<T3, T4>::value? "[PASS] ": "[FAIL] " )
- << name<T1>() << " + " << name<T2>() << " -> " << name<T3>()
- << ", result: " << name<T4>() << std::endl;
- }
- int main()
- {
- using L = std::tuple<char, short, int, unsigned, long, unsigned long>;
- tuple_for_each( mp_product<mp_list, L, L>(), [](auto&& x){ test_result(x); } );
- }</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>How does it work?</p>
- </div>
- <div class="paragraph">
- <p><code>mp_product<F, L1, L2></code> calls <code>F<T1, T2></code> where <code>T1</code> varies over the elements of <code>L1</code> and <code>T2</code> varies over
- the elements of <code>L2</code>, as if by executing two nested loops. It then returns a list of these results, of the same
- type as <code>L1</code>.</p>
- </div>
- <div class="paragraph">
- <p>In our case, both lists are the same <code>std::tuple</code>, and <code>F</code> is <code>mp_list</code>, so <code>mp_product<mp_list, L, L></code> will get us
- <code>std::tuple<mp_list<char, char>, mp_list<char, short>, mp_list<char, int>, …​, mp_list<unsigned long, long>, mp_list<unsigned long, unsigned long>></code>.</p>
- </div>
- <div class="paragraph">
- <p>We then default-construct this tuple and pass it to <code>tuple_for_each</code>. <code>tuple_for_each(tp, f)</code> calls <code>f</code> for every
- tuple element; we use a (C++14) lambda that calls <code>test_result</code>.</p>
- </div>
- <div class="paragraph">
- <p>In pure C++11, we can’t use a lambda with an <code>auto&&</code> parameter, so we’ll have to make <code>test_result</code> a function object with
- a templated <code>operator()</code> and pass that to <code>tuple_for_each</code> directly:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>struct test_result
- {
- template<class T1, class T2> void operator()( mp_list<T1, T2> const& ) const
- {
- using T3 = decltype( T1() + T2() );
- using T4 = result<T1, T2>;
- std::cout << ( std::is_same<T3, T4>::value? "[PASS] ": "[FAIL] " )
- << name<T1>() << " + " << name<T2>() << " -> " << name<T3>()
- << ", result: " << name<T4>() << std::endl;
- }
- };
- int main()
- {
- using L = std::tuple<char, short, int, unsigned, long, unsigned long>;
- tuple_for_each( mp_product<mp_list, L, L>(), test_result() );
- }</code></pre>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="writing_common_type_specializations">Writing common_type Specializations</h3>
- <div class="paragraph">
- <p>The standard trait <code>std::common_type</code>, used to obtain a type to which all of its arguments can convert without
- unnecessary loss of precision, can be user-specialized when its default implementation (based on the ternary <code>?:</code>
- operator) is unsuitable.</p>
- </div>
- <div class="paragraph">
- <p>Let’s write a <code>common_type</code> specialization for two <code>std::tuple</code> arguments. For that, we need a metafunction that
- applies <code>std::common_type</code> to each pair of elements and gathers the results into a tuple:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class... T> using common_type_t =
- typename std::common_type<T...>::type; // standard in C++14
- template<class Tp1, class Tp2> using common_tuple =
- mp_transform<common_type_t, Tp1, Tp2>;</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>then specialize <code>common_type</code> to use it:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>namespace std
- {
- template<class... T1, class... T2>
- struct common_type<std::tuple<T1...>, std::tuple<T2...>>:
- mp_defer<common_tuple, std::tuple<T1...>, std::tuple<T2...>>
- {
- };
- } // std</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>(There is no need to specialize <code>std::common_type</code> for more than two arguments - it takes care of synthesizing the appropriate semantics from
- the binary case.)</p>
- </div>
- <div class="paragraph">
- <p>The subtlety here is the use of <code>mp_defer</code>. We could have defined a nested <code>type</code> to <code>common_tuple<std::tuple<T1…​>, std::tuple<T2…​>></code>,
- and it would still have worked in all valid cases. By letting <code>mp_defer</code> define <code>type</code>, though, we make our specialization <em>SFINAE-friendly</em>.</p>
- </div>
- <div class="paragraph">
- <p>That is, when our <code>common_tuple</code> causes a substitution failure instead of a hard error, <code>mp_defer</code> will not define a nested <code>type</code>,
- and <code>common_type_t</code>, which is defined as <code>typename common_type<…​>::type</code>, will also cause a substitution failure.</p>
- </div>
- <div class="paragraph">
- <p>As another example, consider the hypothetical type <code>expected<T, E…​></code> that represents either a successful return with a value of <code>T</code>,
- or an unsuccessful return with an error code of some type in the list <code>E…​</code>. The common type of <code>expected<T1, E1, E2, E3></code> and
- <code>expected<T2, E1, E4, E5></code> is <code>expected<common_type_t<T1, T2>, E1, E2, E3, E4, E5></code>. That is, the possible return values are
- combined into their common type, and we take the union of the set of error types.</p>
- </div>
- <div class="paragraph">
- <p>Therefore,</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class T1, class E1, class T2, class E2> using common_expected =
- mp_rename<mp_push_front<mp_unique<mp_append<E1, E2>>, common_type_t<T1, T2>>,
- expected>;
- namespace std
- {
- template<class T1, class... E1, class T2, class... E2>
- struct common_type<expected<T1, E1...>, expected<T2, E2...>>:
- mp_defer<common_expected, T1, mp_list<E1...>, T2, mp_list<E2...>>
- {
- };
- } // std</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Here we’ve taken a different tack; instead of passing the <code>expected</code> types to <code>common_expected</code>, we’re passing the <code>T</code> types and lists of
- the <code>E</code> types. This makes our job easier. <code>mp_unique<mp_append<E1, E2>></code> gives us the concatenation of <code>E1</code> and <code>E2</code> with the duplicates
- removed; we then add <code>common_type_t<T1, T2></code> to the front via <code>mp_push_front</code>; and finally, we <code>mp_rename</code> the resultant <code>mp_list</code>
- to <code>expected</code>.</p>
- </div>
- </div>
- <div class="sect2">
- <h3 id="fixing_tuple_cat">Fixing tuple_cat</h3>
- <div class="paragraph">
- <p>The article <a href="http://pdimov.com/cpp2/simple_cxx11_metaprogramming.html#">Simple C++11 metaprogramming</a> builds an
- implementation of the standard function <code>tuple_cat</code>, with the end result given below:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class L> using F = mp_iota<mp_size<L>>;
- template<class R, class...Is, class... Ks, class Tp>
- R tuple_cat_( mp_list<Is...>, mp_list<Ks...>, Tp tp )
- {
- return R{ std::get<Ks::value>(std::get<Is::value>(tp))... };
- }
- template<class... Tp,
- class R = mp_append<std::tuple<>, typename std::remove_reference<Tp>::type...>>
- R tuple_cat( Tp &&... tp )
- {
- std::size_t const N = sizeof...(Tp);
- // inner
- using list1 = mp_list<
- mp_rename<typename std::remove_reference<Tp>::type, mp_list>...>;
- using list2 = mp_iota_c<N>;
- using list3 = mp_transform<mp_fill, list1, list2>;
- using inner = mp_apply<mp_append, list3>;
- // outer
- using list4 = mp_transform<F, list1>;
- using outer = mp_apply<mp_append, list4>;
- //
- return tuple_cat_<R>( inner(), outer(),
- std::forward_as_tuple( std::forward<Tp>(tp)... ) );
- }</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>This function, however, is not entirely correct, in that it doesn’t handle some cases properly. For example,
- trying to concatenate tuples containing move-only elements such as <code>unique_ptr</code> fails:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>std::tuple<std::unique_ptr<int>> t1;
- std::tuple<std::unique_ptr<float>> t2;
- auto result = ::tuple_cat( std::move( t1 ), std::move( t2 ) );</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Trying to concatenate <code>const</code> tuples fails:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>std::tuple<int> const t1;
- std::tuple<float> const t2;
- auto result = ::tuple_cat( t1, t2 );</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>And finally, the standard <code>tuple_cat</code> is specified to work on arbitrary tuple-like types (that is, all types
- that support <code>tuple_size</code>, <code>tuple_element</code>, and <code>get</code>), while our implementation only works with <code>tuple</code> and
- <code>pair</code>. <code>std::array</code>, for example, fails:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>std::array<int, 2> t1{ 1, 2 };
- std::array<float, 3> t2{ 3.0f, 4.0f, 5.0f };
- auto result = ::tuple_cat( t1, t2 );</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Let’s fix these one by one. Support for move-only types is easy, if one knows where to look. The problem is
- that <code>Tp</code> that we’re passing to the helper <code>tuple_cat_</code> is (correctly) <code>tuple<unique_ptr<int>&&, unique_ptr<float>&&></code>,
- but <code>std::get<0>(tp)</code> still returns <code>unique_ptr<int>&</code>, because <code>tp</code> is an lvalue. This behavior is a bit
- surprising, but is intended to prevent inadvertent double moves.</p>
- </div>
- <div class="paragraph">
- <p>Long story short, we need <code>std::move(tp)</code> in <code>tuple_cat_</code> to make <code>tp</code> an rvalue:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class R, class...Is, class... Ks, class Tp>
- R tuple_cat_( mp_list<Is...>, mp_list<Ks...>, Tp tp )
- {
- return R{ std::get<Ks::value>(std::get<Is::value>(std::move(tp)))... };
- }</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Next, <code>const</code>-qualified tuples. The issue here is that we’re stripping references from the input tuples, but not
- <code>const</code>. As a result, we’re trying to manipulate types such as <code>tuple<int> const</code> with Mp11 algorithms, and these
- types do not fit the list concept. We just need to strip qualifiers as well, by defining the useful <code>remove_cv_ref</code>
- primitive that is inexplicably missing from the standard library:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> using remove_cv_ref = typename std::remove_cv<
- typename std::remove_reference<T>::type>::type;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>and then by using <code>remove_cv_ref<Tp></code> in place of <code>typename std::remove_reference<Tp>::type</code>:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class... Tp,
- class R = mp_append<std::tuple<>, remove_cv_ref<Tp>...>>
- R tuple_cat( Tp &&... tp )
- {
- std::size_t const N = sizeof...(Tp);
- // inner
- using list1 = mp_list<mp_rename<remove_cv_ref<Tp>, mp_list>...>;
- // ...</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Finally, tuple-like types. We’ve so far exploited the fact that <code>std::pair</code> and <code>std::tuple</code> are valid Mp11 lists,
- but in general, arbitrary tuple-like types aren’t, so we need to convert them into such. For that, we’ll need to
- define a metafunction <code>from_tuple_like</code> that will take an arbitrary tuple-like type and will return, in our case,
- the corresponding <code>mp_list</code>.</p>
- </div>
- <div class="paragraph">
- <p>Technically, a more principled approach would’ve been to return <code>std::tuple</code>, but here <code>mp_list</code> will prove more
- convenient.</p>
- </div>
- <div class="paragraph">
- <p>What we need is, given a tuple-like type <code>Tp</code>, to obtain <code>mp_list<std::tuple_element<0, Tp>::type, std::tuple_element<1, Tp>::type,
- …​, std::tuple_element<N-1, Tp>::type></code>, where <code>N</code> is <code>tuple_size<Tp>::value</code>. Here’s one way to do it:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class T, class I> using tuple_element =
- typename std::tuple_element<I::value, T>::type;
- template<class T> using from_tuple_like =
- mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>;</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>(<code>mp_iota<N></code> is an algorithm that returns an <code>mp_list</code> with elements <code>mp_size_t<0></code>, <code>mp_size_t<1></code>, …​, <code>mp_size_t<N-1></code>.)</p>
- </div>
- <div class="paragraph">
- <p>Remember that <code>mp_product<F, L1, L2></code> performs the equivalent of two nested loops over the elements of <code>L1</code> and <code>L2</code>,
- applying <code>F</code> to the two variables and gathering the result. In our case <code>L1</code> consists of the single element <code>T</code>, so
- only the second loop (over <code>mp_iota<N></code>, where <code>N</code> is <code>tuple_size<T></code>), remains, and we get a list of the same type
- as <code>L1</code> (an <code>mp_list</code>) with contents <code>tuple_element<T, mp_size_t<0>></code>, <code>tuple_element<T, mp_size_t<1>></code>, …​,
- <code>tuple_element<T, mp_size_t<N-1>></code>.</p>
- </div>
- <div class="paragraph">
- <p>For completeness’s sake, here’s another, more traditional way to achieve the same result:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> using from_tuple_like =
- mp_transform_q<mp_bind_front<tuple_element, T>, mp_iota<std::tuple_size<T>>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>With all these fixes applied, our fully operational <code>tuple_cat</code> now looks like this:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class L> using F = mp_iota<mp_size<L>>;
- template<class R, class...Is, class... Ks, class Tp>
- R tuple_cat_( mp_list<Is...>, mp_list<Ks...>, Tp tp )
- {
- return R{ std::get<Ks::value>(std::get<Is::value>(std::move(tp)))... };
- }
- template<class T> using remove_cv_ref = typename std::remove_cv<
- typename std::remove_reference<T>::type>::type;
- template<class T, class I> using tuple_element =
- typename std::tuple_element<I::value, T>::type;
- template<class T> using from_tuple_like =
- mp_product<tuple_element, mp_list<T>, mp_iota<std::tuple_size<T>>>;
- template<class... Tp,
- class R = mp_append<std::tuple<>, from_tuple_like<remove_cv_ref<Tp>>...>>
- R tuple_cat( Tp &&... tp )
- {
- std::size_t const N = sizeof...(Tp);
- // inner
- using list1 = mp_list<from_tuple_like<remove_cv_ref<Tp>>...>;
- using list2 = mp_iota_c<N>;
- using list3 = mp_transform<mp_fill, list1, list2>;
- using inner = mp_apply<mp_append, list3>;
- // outer
- using list4 = mp_transform<F, list1>;
- using outer = mp_apply<mp_append, list4>;
- //
- return tuple_cat_<R>( inner(), outer(),
- std::forward_as_tuple( std::forward<Tp>(tp)... ) );
- }</code></pre>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="computing_return_types">Computing Return Types</h3>
- <div class="paragraph">
- <p>C++17 has a standard variant type, called <code>std::variant</code>. It also defines a function template
- <code>std::visit</code> that can be used to apply a function to the contained value of one or more variants.
- So for instance, if the variant <code>v1</code> contains <code>1</code>, and the variant <code>v2</code> contains <code>2.0f</code>,
- <code>std::visit(f, v1, v2)</code> will call <code>f(1, 2.0f)</code>.</p>
- </div>
- <div class="paragraph">
- <p>However, <code>std::visit</code> has one limitation: it cannot return a result unless all
- possible applications of the function have the same return type. If, for instance, <code>v1</code> and <code>v2</code>
- are both of type <code>std::variant<short, int, float></code>,</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>std::visit( []( auto const& x, auto const& y ){ return x + y; }, v1, v2 );</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>will fail to compile because the result of <code>x + y</code> can be either <code>int</code> or <code>float</code> depending on
- what <code>v1</code> and <code>v2</code> hold.</p>
- </div>
- <div class="paragraph">
- <p>A type that can hold either <code>int</code> or <code>float</code> already exists, called, surprisingly enough, <code>std::variant<int, float></code>.
- Let’s write our own function template <code>rvisit</code> that is the same as <code>visit</code> but returns a <code>variant</code>:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>template<class F, class... V> auto rvisit( F&& f, V&&... v )
- {
- using R = /*...*/;
- return std::visit( [&]( auto&&... x )
- { return R( std::forward<F>(f)( std::forward<decltype(x)>(x)... ) ); },
- std::forward<V>( v )... );
- }</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>What this does is basically calls <code>std::visit</code> to do the work, but instead of passing it <code>f</code>, we pass a lambda that does the same as <code>f</code> except
- it converts the result to a common type <code>R</code>. <code>R</code> is supposed to be <code>std::variant<…​></code> where the ellipsis denotes the return types of
- calling <code>f</code> with all possible combinations of variant values.</p>
- </div>
- <div class="paragraph">
- <p>We’ll first define a helper quoted metafunction <code>Qret<F></code> that returns the result of the application of <code>F</code> to arguments of type <code>T…​</code>:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class F> struct Qret
- {
- template<class... T> using fn =
- decltype( std::declval<F>()( std::declval<T>()... ) );
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>(Unfortunately, we can’t just define this metafunction inside <code>rvisit</code>; the language prohibits defining template aliases inside functions.)</p>
- </div>
- <div class="paragraph">
- <p>With <code>Qret</code> in hand, a <code>variant</code> of the possible return types is just a matter of applying it over the possible combinations of the variant values:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>using R = mp_product_q<Qret<F>, std::remove_reference_t<V>...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Why does this work? <code>mp_product<F, L1<T1…​>, L2<T2…​>, …​, Ln<Tn…​>></code> returns <code>L1<F<U1, U2, …​, Un>, …​></code>, where <code>Ui</code> traverse all
- possible combinations of list values. Since in our case all <code>Li</code> are <code>std::variant</code>, the result will also be <code>std::variant</code>. (<code>mp_product_q</code> is
- the same as <code>mp_product</code>, but for quoted metafunctions such as our <code>Qret<F></code>.)</p>
- </div>
- <div class="paragraph">
- <p>One more step remains. Suppose that, as above, we’re passing two variants of type <code>std::variant<short, int, float></code> and <code>F</code> is
- <code>[]( auto const& x, auto const& y ){ return x + y; }</code>. This will generate <code>R</code> of length 9, one per each combination, but many of those
- elements will be the same, either <code>int</code> or <code>float</code>, and we need to filter out the duplicates. So, we pass the result to <code>mp_unique</code>:</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>using R = mp_unique<mp_product_q<Qret<F>, std::remove_reference_t<V>...>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>and we’re done:</p>
- </div>
- <div class="listingblock">
- <div class="content">
- <pre class="highlight"><code>#include <boost/mp11.hpp>
- #include <boost/core/demangle.hpp>
- #include <variant>
- #include <type_traits>
- #include <typeinfo>
- #include <iostream>
- using namespace boost::mp11;
- template<class F> struct Qret
- {
- template<class... T> using fn =
- decltype( std::declval<F>()( std::declval<T>()... ) );
- };
- template<class F, class... V> auto rvisit( F&& f, V&&... v )
- {
- using R = mp_unique<mp_product_q<Qret<F>, std::remove_reference_t<V>...>>;
- return std::visit( [&]( auto&&... x )
- { return R( std::forward<F>(f)( std::forward<decltype(x)>(x)... ) ); },
- std::forward<V>( v )... );
- }
- template<class T> std::string name()
- {
- return boost::core::demangle( typeid(T).name() );
- }
- template<class V> void print_variant( char const * n, V const& v )
- {
- std::cout << "(" << name<decltype(v)>() << ")" << n << ": ";
- std::visit( []( auto const& x )
- { std::cout << "(" << name<decltype(x)>() << ")" << x << std::endl; }, v );
- }
- int main()
- {
- std::variant<char, int, float> v1( 1 );
- print_variant( "v1", v1 );
- std::variant<short, int, double> v2( 3.14 );
- print_variant( "v2", v2 );
- auto v3 = rvisit( []( auto const& x, auto const& y ){ return x + y; }, v1, v2 );
- print_variant( "v3", v3 );
- }</code></pre>
- </div>
- </div>
- </div>
- </div>
- </div>
- <div class="sect1">
- <h2 id="changelog">Revision History</h2>
- <div class="sectionbody">
- <div class="sect2">
- <h3 id="changes_in_1_70_0">Changes in 1.70.0</h3>
- <div class="ulist">
- <ul>
- <li>
- <p>Renamed <code>mp_invoke</code> to <code>mp_invoke_q</code></p>
- </li>
- <li>
- <p>Added <code>mp_similar</code></p>
- </li>
- <li>
- <p>Added <code>mp_set_union</code>, <code>mp_set_intersection</code>, <code>mp_set_difference</code></p>
- </li>
- <li>
- <p>Added <code>mp_not_fn</code></p>
- </li>
- <li>
- <p>Added <code>mp_transform_first</code>, <code>mp_transform_second</code>, <code>mp_transform_third</code></p>
- </li>
- <li>
- <p>Added <code>mp_filter</code></p>
- </li>
- <li>
- <p>Added <code>mp_eval_if_not</code>, <code>mp_eval_or</code>, <code>mp_valid_q</code></p>
- </li>
- <li>
- <p>Added <code>mp_back</code>, <code>mp_pop_back</code></p>
- </li>
- <li>
- <p>Added <code>BOOST_MP11_VERSION</code></p>
- </li>
- </ul>
- </div>
- </div>
- <div class="sect2">
- <h3 id="changes_in_1_69_0">Changes in 1.69.0</h3>
- <div class="ulist">
- <ul>
- <li>
- <p>Removed dependency on Boost.Config; Mp11 is now standalone</p>
- </li>
- <li>
- <p>Improved code generation for <code>mp_with_index</code></p>
- </li>
- <li>
- <p>Added <code>mp_starts_with</code> (contributed by Glen Fernandes)</p>
- </li>
- <li>
- <p>Added CMake support</p>
- </li>
- </ul>
- </div>
- </div>
- </div>
- </div>
- <div class="sect1">
- <h2 id="reference">Reference</h2>
- <div class="sectionbody">
- <div class="paragraph">
- <p>The contents of the library are in namespace <code>boost::mp11</code>.</p>
- </div>
- <div class="sect2">
- <h3 id="integral">Integral Constants, <boost/mp11/integral.hpp></h3>
- <div class="paragraph">
- <p>For an Mp11 integral constant type <code>T</code>, <code>T::value</code> is an integral constant in the C++ sense.</p>
- </div>
- <div class="sect3">
- <h4 id="mp_boolb">mp_bool<B></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<bool B> using mp_bool = std::integral_constant<bool, B>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>std::bool_constant</code> in C++17.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_true">mp_true</h4>
- <div class="literalblock">
- <div class="content">
- <pre>using mp_true = mp_bool<true>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>std::true_type</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_false">mp_false</h4>
- <div class="literalblock">
- <div class="content">
- <pre>using mp_false = mp_bool<false>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>std::false_type</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_to_boolt">mp_to_bool<T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> using mp_to_bool = mp_bool<static_cast<bool>(T::value)>;</pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_nott">mp_not<T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> using mp_not = mp_bool< !T::value >;</pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_inti">mp_int<I></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<int I> using mp_int = std::integral_constant<int, I>;</pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_size_tn">mp_size_t<N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t N> using mp_size_t = std::integral_constant<std::size_t, N>;</pre>
- </div>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="list">List Operations, <boost/mp11/list.hpp></h3>
- <div class="sect3">
- <h4 id="mp_listt">mp_list<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> struct mp_list {};</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_list</code> is the standard list type of Mp11, although the library is not restricted to it and can operate on arbitrary class templates
- such as <code>std::tuple</code> or <code>std::variant</code>. Even <code>std::pair</code> can be used if the transformation does not alter the number of the elements in
- the list.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_list_ct_i">mp_list_c<T, I…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, T... I> using mp_list_c =
- mp_list<std::integral_constant<T, I>...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_list_c</code> produces an <code>mp_list</code> of the <code>std::integral_constant</code> types corresponding to its integer template arguments.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 1. Using mp_list_c</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = mp_list_c<int, 2, 3>; // mp_list<mp_int<2>, mp_int<3>></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_is_listl">mp_is_list<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_is_list = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_is_list<L></code> is <code>mp_true</code> if <code>L</code> is a list (an instantiation of a class template whose template parameters are types), <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_sizel">mp_size<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_size = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_size<L></code> returns the number of elements in the list <code>L</code>, as a <code>mp_size_t</code>. In other words, <code>mp_size<L<T…​>></code> is an alias for
- <code>mp_size_t<sizeof…​(T)></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 2. Using mp_size with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = mp_list<>;
- using R1 = mp_size<L1>; // mp_size_t<0></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 3. Using mp_size with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::pair<int, int>;
- using R2 = mp_size<L2>; // mp_size_t<2></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 4. Using mp_size with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L3 = std::tuple<float>;
- using R3 = mp_size<L3>; // mp_size_t<1></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_emptyl">mp_empty<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_empty = mp_bool<mp_size<L>::value == 0>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_empty<L></code> is an alias for <code>mp_true</code> if the list <code>L</code> is empty, for <code>mp_false</code> otherwise.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 5. Using mp_empty with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<float>;
- using R1 = mp_empty<L1>; // mp_false
- using L2 = std::tuple<>;
- using R2 = mp_empty<L2>; // mp_true</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_assignl1_l2">mp_assign<L1, L2></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L1, class L2> using mp_assign = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_assign<L1<T1…​>, L2<T2…​>></code> is an alias for <code>L1<T2…​></code>. That is, it replaces the elements of <code>L1</code> with those of <code>L2</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 6. Using mp_assign with mp_list and std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<long>;
- using L2 = mp_list<int, float>;
- using R1 = mp_assign<L1, L2>; // std::tuple<int, float></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 7. Using mp_assign with mp_list and std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<long, char>;
- using L2 = mp_list<int, float>;
- using R1 = mp_assign<L1, L2>; // std::pair<int, float></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_clearl">mp_clear<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_clear = mp_assign<L, mp_list<>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_clear<L<T…​>></code> is an alias for <code>L<></code>, that is, it removes the elements of <code>L</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 8. Using mp_clear with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<int, float>;
- using R1 = mp_clear<L1>; // std::tuple<></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_frontl">mp_front<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_front = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_front<L></code> is the first element of the list <code>L</code>. That is, <code>mp_front<L<T1, T…​>></code> is an alias for <code>T1</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 9. Using mp_front with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<int, float>;
- using R1 = mp_front<L1>; // int</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 10. Using mp_front with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::tuple<float, double, long double>;
- using R2 = mp_front<L2>; // float</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 11. Using mp_front with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L3 = mp_list<char[1], char[2], char[3], char[4]>;
- using R3 = mp_front<L3>; // char[1]</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_pop_frontl">mp_pop_front<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_pop_front = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_pop_front<L></code> removes the first element of the list <code>L</code>. That is, <code>mp_pop_front<L<T1, T…​>></code> is an alias for <code>L<T…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 12. Using mp_pop_front with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<float, double, long double>;
- using R1 = mp_pop_front<L1>; // std::tuple<double, long double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 13. Using mp_pop_front with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = mp_list<void>;
- using R2 = mp_pop_front<L2>; // mp_list<></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_firstl">mp_first<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_first = mp_front<L>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_first</code> is another name for <code>mp_front</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_restl">mp_rest<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_rest = mp_pop_front<L>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_rest</code> is another name for <code>mp_pop_front</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_secondl">mp_second<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_second = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_second<L></code> is the second element of the list <code>L</code>. That is, <code>mp_second<L<T1, T2, T…​>></code> is an alias for <code>T2</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 14. Using mp_second with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<int, float>;
- using R1 = mp_second<L1>; // float</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 15. Using mp_second with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::tuple<float, double, long double>;
- using R2 = mp_second<L2>; // double</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 16. Using mp_second with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L3 = mp_list<char[1], char[2], char[3], char[4]>;
- using R3 = mp_second<L3>; // char[2]</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_thirdl">mp_third<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_third = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_third<L></code> is the third element of the list <code>L</code>. That is, <code>mp_third<L<T1, T2, T3, T…​>></code> is an alias for <code>T3</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 17. Using mp_third with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<float, double, long double>;
- using R1 = mp_third<L1>; // long double</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 18. Using mp_third with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = mp_list<char[1], char[2], char[3], char[4]>;
- using R2 = mp_third<L2>; // char[3]</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_push_frontl_t">mp_push_front<L, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class... T> using mp_push_front = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_push_front<L, T…​></code> inserts the elements <code>T…​</code> at the front of the list <code>L</code>. That is, <code>mp_push_front<L<U…​>, T…​></code>
- is an alias for <code>L<T…​, U…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 19. Using mp_push_front with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<double, long double>;
- using R1 = mp_push_front<L1, float>; // std::tuple<float, double, long double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 20. Using mp_push_front with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = mp_list<void>;
- using R2 = mp_push_front<L2, char[1], char[2]>; // mp_list<char[1], char[2], void></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_push_backl_t">mp_push_back<L, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class... T> using mp_push_back = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_push_back<L, T…​></code> inserts the elements <code>T…​</code> at the back of the list <code>L</code>. That is, <code>mp_push_back<L<U…​>, T…​></code>
- is an alias for <code>L<U…​, T…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 21. Using mp_push_back with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<double, long double>;
- using R1 = mp_push_back<L1, float>; // std::tuple<double, long double, float></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 22. Using mp_push_back with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = mp_list<void>;
- using R2 = mp_push_back<L2, char[1], char[2]>; // mp_list<void, char[1], char[2]></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_renamel_y">mp_rename<L, Y></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class Y> using mp_rename = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_rename<L, Y></code> changes the type of the list <code>L</code> to <code>Y</code>. That is, <code>mp_rename<L<T…​>, Y></code> is an alias for <code>Y<T…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 23. Using mp_rename to rename std::pair to std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<double, long double>;
- using R1 = mp_rename<L1, std::tuple>; // std::tuple<double, long double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 24. Using mp_rename to rename std::tuple to mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::tuple<void>;
- using R2 = mp_rename<L2, mp_list>; // mp_list<void></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_applyf_l">mp_apply<F, L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class L> using mp_apply = mp_rename<L, F>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_apply<F, L></code> applies the metafunction <code>F</code> to the contents of the list <code>L</code>, that is, <code>mp_apply<F, L<T…​>></code> is an alias for <code>F<T…​></code>.
- (<code>mp_apply</code> is the same as <code>mp_rename</code> with the arguments reversed.)</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 25. Using mp_apply with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<double, long double>;
- using R1 = mp_apply<std::is_same, L1>; // std::is_same<double, long double></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_apply_qq_l">mp_apply_q<Q, L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class L> using mp_apply_q = mp_apply<Q::template fn, L>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_apply</code>, but takes a quoted metafunction.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 26. Using mp_apply_q with mp_bind_front</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<double, long double>;
- using L2 = mp_list<int, long>;
- using R1 = mp_apply_q<mp_bind_front<mp_push_back, L1>, L2>;
- // R1 is std::tuple<double, long double, int, long></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_appendl">mp_append<L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... L> using mp_append = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_append<L…​></code> concatenates the lists in <code>L…​</code> into a single list that has the same type as the first list. <code>mp_append<></code>
- is an alias for <code>mp_list<></code>. <code>mp_append<L1<T1…​>, L2<T2…​>, …​, Ln<Tn…​>></code> is an alias for <code>L1<T1…​, T2…​, …​, Tn…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 27. Using mp_append with lists of various types</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<double, long double>;
- using L2 = mp_list<int>;
- using L3 = std::pair<short, long>;
- using L4 = mp_list<>;
- using R1 = mp_append<L1, L2, L3, L4>;
- // std::tuple<double, long double, int, short, long></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_frontl_t">mp_replace_front<L, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class T> using mp_replace_front = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_replace_front<L, T></code> replaces the first element of the list <code>L</code> with <code>T</code>. That is, <code>mp_replace_front<L<U1, U…​>, T></code> is
- an alias for <code>L<T, U…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 28. Using mp_replace_front with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<int, float>;
- using R1 = mp_replace_front<L1, void>; // std::pair<void, float></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 29. Using mp_replace_front with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::tuple<float, double, long double>;
- using R2 = mp_replace_front<L2, void>; // std::tuple<void, double, long double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 30. Using mp_replace_front with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L3 = mp_list<char[1], char[2], char[3], char[4]>;
- using R3 = mp_replace_front<L3, void>; // mp_list<void, char[2], char[3], char[4]>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_firstl_t">mp_replace_first<L, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class T> using mp_replace_first = mp_replace_front<L, T>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_replace_first</code> is another name for <code>mp_replace_front</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_secondl_t">mp_replace_second<L, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class T> using mp_replace_second = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_replace_second<L, T></code> replaces the second element of the list <code>L</code> with <code>T</code>. That is, <code>mp_replace_second<L<U1, U2, U…​>, T></code>
- is an alias for <code>L<U1, T, U…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 31. Using mp_replace_second with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<int, float>;
- using R1 = mp_replace_second<L1, void>; // std::pair<int, void></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 32. Using mp_replace_second with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = std::tuple<float, double, long double>;
- using R2 = mp_replace_second<L2, void>; // std::tuple<float, void, long double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 33. Using mp_replace_front with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L3 = mp_list<char[1], char[2], char[3], char[4]>;
- using R3 = mp_replace_second<L3, void>; // mp_list<char[1], void, char[3], char[4]>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_thirdl_t">mp_replace_third<L, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class T> using mp_replace_third = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_replace_third<L, T></code> replaces the third element of the list <code>L</code> with <code>T</code>. That is, <code>mp_replace_third<L<U1, U2, U3, U…​>, T></code>
- is an alias for <code>L<U1, U2, T, U…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 34. Using mp_replace_third with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<float, double, long double>;
- using R1 = mp_replace_third<L1, void>; // std::tuple<float, double, void></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 35. Using mp_replace_third with mp_list</div>
- <div class="content">
- <pre class="highlight"><code>using L2 = mp_list<char[1], char[2], char[3], char[4]>;
- using R2 = mp_replace_third<L2, void>; // mp_list<char[1], char[2], void, char[4]>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_frontl_f">mp_transform_front<L, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class F> using mp_transform_front =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform_front<L, F></code> replaces the first element <code>T1</code> of the list <code>L</code> with <code>F<T1></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_front_ql_q">mp_transform_front_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_transform_front_q =
- mp_transform_front<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform_front</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_firstl_f">mp_transform_first<L, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class F> using mp_transform_first =
- mp_transform_front<L, F>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform_first</code> is another name for <code>mp_transform_front</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_first_ql_q">mp_transform_first_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_transform_first_q =
- mp_transform_first<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform_first</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_secondl_f">mp_transform_second<L, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class F> using mp_transform_second =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform_second<L, F></code> replaces the second element <code>T2</code> of the list <code>L</code> with <code>F<T2></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_second_ql_q">mp_transform_second_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_transform_second_q =
- mp_transform_second<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform_second</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_thirdl_f">mp_transform_third<L, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class F> using mp_transform_third =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform_third<L, F></code> replaces the third element <code>T3</code> of the list <code>L</code> with <code>F<T3></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_third_ql_q">mp_transform_third_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_transform_third_q =
- mp_transform_third<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform_third</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="utility">Utility Components, <boost/mp11/utility.hpp></h3>
- <div class="sect3">
- <h4 id="mp_identityt">mp_identity<T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> struct mp_identity
- {
- using type = T;
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_identity</code> is a simple <em>transformation type trait</em> (as per the C++ standard)
- that just returns the same type. It’s useful both as such, and as a type wrapper
- for passing types as values to functions.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 36. Using mp_identity as a type trait</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using addp_if_not_ref =
- typename mp_if<std::is_reference<T>, mp_identity<T>, std::add_pointer<T>>::type;</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 37. Using mp_identity to protect qualifiers and references</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> void print1()
- {
- std::cout << typeid(T).name() << std::endl;
- }
- template<class T> void print2()
- {
- std::cout << typeid(mp_identity<T>).name() << std::endl;
- }
- int main()
- {
- print1<int const&>(); // 'int'
- print2<int const&>(); // 'mp_identity<int const &>'
- }</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_identity_tt">mp_identity_t<T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T> using mp_identity_t = typename mp_identity<T>::type;</pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_inheritt">mp_inherit<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> struct mp_inherit: T... {};</pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_if_cc_t_e">mp_if_c<C, T, E…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<bool C, class T, class... E> using mp_if_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_if_c<true, T, E…​></code> is an alias for <code>T</code>. <code>mp_if_c<false, T, E></code> is an alias for <code>E</code>. Otherwise, the result is a substitution failure.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 38. Using mp_if_c to select between two alternatives</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_if_c<true, int, void>; // int
- using R2 = mp_if_c<false, int, void>; // void</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 39. Using mp_if_c to fail substitution when a condition is not met</div>
- <div class="content">
- <pre class="highlight"><code>template<class I> using void_if_5 = mp_if_c<I::value == 5, void>;</code></pre>
- </div>
- </div>
- <div class="paragraph">
- <p>This example returns <code>void</code> when <code>I::value</code> is 5, and generates a substitution failure
- otherwise. It’s the same as <code>std::enable_if_t<I::value == 5></code> in C++14, or
- <code>typename std::enable_if<I::value == 5>::type</code> in C++11.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_ifc_t_e">mp_if<C, T, E…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, class... E> using mp_if =
- mp_if_c<static_cast<bool>(C::value), T, E...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_if_c</code>, but the first argument is a type.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 40. Using mp_if to select between two alternatives</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_if<mp_true, int, void>; // int
- using R2 = mp_if<mp_false, int, void>; // void</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 41. Using mp_if to fail substitution when a condition is not met</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using void_if_const = mp_if<std::is_const<T>, void>;
- template<class... T> using void_if_all_const =
- mp_if<mp_all<std::is_const<T>...>, void>;
- template<class T> using if_non_const = mp_if<mp_not<std::is_const<T>>, T>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_if_cc_t_f_u">mp_eval_if_c<C, T, F, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<bool C, class T, template<class...> class F, class... U> using mp_eval_if_c =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_eval_if_c<C, T, F, U…​></code> is an alias for <code>T</code> when <code>C</code> is <code>true</code>, for <code>F<U…​></code> otherwise. Its purpose
- is to avoid evaluating <code>F<U…​></code> when the condition is <code>true</code> as it may not be valid in this case.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 42. Using mp_eval_if_c to select the first pack element, or void</div>
- <div class="content">
- <pre class="highlight"><code>template<class... T> using first_or_void =
- mp_eval_if_c<sizeof...(T) == 0, void, mp_apply, mp_first, mp_list<T...>>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_ifc_t_f_u">mp_eval_if<C, T, F, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, template<class...> class F, class... U> using mp_eval_if =
- mp_eval_if_c<static_cast<bool>(C::value), T, F, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_eval_if_c</code>, but the first argument is a type.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 43. Using mp_eval_if to select the first list element, or void</div>
- <div class="content">
- <pre class="highlight"><code>template<class L> using first_or_void = mp_eval_if<mp_empty<L>, void, mp_first, L>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_if_qc_t_q_u">mp_eval_if_q<C, T, Q, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, class Q, class... U> using mp_eval_if_q =
- mp_eval_if<C, T, Q::template fn, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_eval_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_if_notc_t_f_u">mp_eval_if_not<C, T, F, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, template<class...> class F, class... U>
- using mp_eval_if_not = mp_eval_if<mp_not<C>, T, F, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_eval_if</code>, but the condition is reversed.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_if_not_qc_t_q_u">mp_eval_if_not_q<C, T, Q, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, class Q, class... U> using mp_eval_if_not_q =
- mp_eval_if_not<C, T, Q::template fn, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_eval_if_not</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_validf_t">mp_valid<F, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... T> using mp_valid = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_valid<F, T…​></code> is an alias for <code>mp_true</code> when <code>F<T…​></code> is a valid expression, for <code>mp_false</code> otherwise.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 44. Using mp_valid to write a metafunction that checks for the existence of a nested type</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using get_nested_type = typename T::type;
- template<class T> struct has_nested_type: mp_valid<get_nested_type, T> {};</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_valid_qq_t">mp_valid_q<Q, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... T> using mp_valid_q = mp_valid<Q::template fn, T...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_valid</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_ort_f_u">mp_eval_or<T, F, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, template<class...> class F, class... U> using mp_eval_or =
- mp_eval_if_not<mp_valid<F, U...>, T, F, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_eval_or<T, F, U…​></code> is an alias for <code>F<U…​></code> when this expression is valid, for <code>T</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_eval_or_qt_q_u">mp_eval_or_q<T, Q, U…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, class Q, class... U> using mp_eval_or_q =
- mp_eval_or<T, Q::template fn, U...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_eval_or</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_condc_t_r">mp_cond<C, T, R…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class C, class T, class... R> using mp_cond = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_cond<C, T, R…​></code> is an alias for <code>T</code> when <code>static_cast<bool>(C::value)</code> is <code>true</code>.
- When <code>static_cast<bool>(C::value)</code> is <code>false</code>, it’s an alias for <code>mp_cond<R…​></code>.</p>
- </div>
- <div class="paragraph">
- <p>(If <code>static_cast<bool>(C::value)</code> is a substitution failure, the result is too a substitution
- failure.)</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 45. Using mp_cond</div>
- <div class="content">
- <pre class="highlight"><code>template<int N> using unsigned_ = mp_cond<
- mp_bool<N == 8>, uint8_t,
- mp_bool<N == 16>, uint16_t,
- mp_bool<N == 32>, uint32_t,
- mp_bool<N == 64>, uint64_t,
- mp_true, unsigned // default case
- >;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_deferf_t">mp_defer<F, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... T> using mp_defer = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>When <code>mp_valid<F, T…​></code> is <code>mp_true</code>, <code>mp_defer<F, T…​></code> is a struct with a nested type <code>type</code> which is an alias for <code>F<T…​></code>. Otherwise,
- <code>mp_defer<F, T…​></code> is an empty struct.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_quotef">mp_quote<F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F> struct mp_quote
- {
- template<class... T> using fn = F<T...>;
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_quote<F></code> transforms the template <code>F</code> into a <em>quoted metafunction</em>, a type with a nested template <code>fn</code> such that <code>fn<T…​></code> returns <code>F<T…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 46. Using mp_quote to make a list of metafunctions</div>
- <div class="content">
- <pre class="highlight"><code>using LQ = mp_list<mp_quote<std::is_const>, mp_quote<std::is_volatile>>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_quote_traitf">mp_quote_trait<F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F> struct mp_quote_trait
- {
- template<class... T> using fn = typename F<T...>::type;
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_quote_trait<F></code> transforms the C++03-style trait <code>F</code> into a quoted metafunction.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 47. Using mp_quote_trait with std::add_pointer</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = mp_list<int, void, float>;
- using R1 = mp_transform_q<mp_quote_trait<std::add_pointer>, L1>;
- // mp_list<int*, void*, float*></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_invoke_qq_t">mp_invoke_q<Q, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... T> using mp_invoke_q = typename Q::template fn<T...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_invoke_q<Q, T…​></code> evaluates the nested template <code>fn</code> of a quoted metafunction. <code>mp_invoke_q<mp_quote<F>, T…​></code> returns <code>F<T…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 48. Using mp_invoke_q to invoke a list of metafunctions, technique 1</div>
- <div class="content">
- <pre class="highlight"><code>using LQ = mp_list<mp_quote<std::is_const>, mp_quote<std::is_volatile>>;
- template<class T> using is_const_and_volatile =
- mp_all<mp_product<mp_invoke_q, LQ, mp_list<T>>>;</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 49. Using mp_invoke_q to invoke a list of metafunctions, technique 2</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using is_const_and_volatile =
- mp_all<mp_transform_q<mp_bind_back<mp_invoke_q, T>, LQ>>;</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 50. Using mp_invoke_q to invoke a list of metafunctions, technique 3</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using is_const_and_volatile =
- mp_all<mp_transform<mp_invoke_q, LQ, mp_fill<LQ, T>>>;</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_not_fnp">mp_not_fn<P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class P> struct mp_not_fn
- {
- template<class... T> using fn = mp_not<P<T...>>;
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_not_fn<P></code> returns a quoted metafunction <code>Q</code> such that <code>Q::fn<T…​></code> returns <code>mp_not<P<T…​>></code>.</p>
- </div>
- <div class="paragraph">
- <p>That is, it negates the result of <code>P</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_not_fn_qq">mp_not_fn_q<Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q> using mp_not_fn_q = mp_not_fn<Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_not_fn</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="algorithm">Algorithms, <boost/mp11/algorithm.hpp></h3>
- <div class="sect3">
- <h4 id="mp_transformf_l">mp_transform<F, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... L> using mp_transform = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform<F, L1<T1…​>, L2<T2…​>, …​, Ln<Tn…​>></code> applies <code>F</code> to each successive tuple of elements and returns <code>L1<F<T1, T2, …​, Tn>…​></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 51. Using mp_transform to produce a list of pointers from a list of pointees</div>
- <div class="content">
- <pre class="highlight"><code>template<class T> using add_pointer_t =
- typename std::add_pointer<T>::type; // std::add_pointer_t in C++14
- using L1 = std::tuple<void, int, float>;
- using R1 = mp_transform<add_pointer_t, L1>; // std::tuple<void*, int*, float*></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 52. Using mp_transform to compare the contents of two lists of types</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float>;
- using L2 = mp_list<void, int, float>;
- using R1 = mp_all<mp_transform<std::is_same, L1, L2>>; // mp_true</code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 53. Using mp_transform to compare the contents of two lists of integral constants</div>
- <div class="content">
- <pre class="highlight"><code>template<class T1, class T2> using eq = mp_bool<T1::value == T2::value>;
- using L1 = std::tuple<mp_int<1>, mp_int<2>, mp_int<3>>;
- using L2 = mp_list<mp_size_t<1>, mp_size_t<2>, mp_size_t<3>>;
- using R1 = mp_all<mp_transform<eq, L1, L2>>; // mp_true</code></pre>
- </div>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 1. mp_transform on one list</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_transform<F, L1></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>n</sub>></code></p></td>
- </tr>
- </tbody>
- </table>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 2. mp_transform on two lists</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L2</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_transform<F, L1, L2></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>1</sub>,B<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>n</sub>,B<sub>n</sub>></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_qq_l">mp_transform_q<Q, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... L> using mp_transform_q =
- mp_transform<Q::template fn, L...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform</code>, but takes a quoted metafunction.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 54. Using mp_transform_q to count the occurrences of <code>void</code> in a list</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float, void, int>;
- using R1 = mp_apply<mp_plus,
- mp_transform_q<mp_bind_front<std::is_same, void>, L1>>; // mp_int<2></code></pre>
- </div>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 3. mp_transform_q on two lists</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L2</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_transform_q<Q, L1, L2></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>Q::fn<A<sub>1</sub>,B<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>Q::fn<A<sub>2</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>Q::fn<A<sub>n</sub>,B<sub>n</sub>></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_ifp_f_l">mp_transform_if<P, F, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class P, template<class...> class F, class... L>
- using mp_transform_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_transform_if<P, F, L1, L2, …​, Ln></code> replaces the elements of the list <code>L1</code> for which <code>mp_to_bool<P<T1, T2, …​, Tn>></code> is <code>mp_true</code> with
- <code>F<T1, T2, …​, Tn></code>, and returns the result, where <code>Ti</code> are the corresponding elements of <code>Li</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 55. Using mp_transform_if to replace the occurrences of 'void' in a list with the corresponding elements of a second list</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float, void, int>;
- using L2 = std::tuple<char[1], char[2], char[3], char[4], char[5]>;
- template<class T1, class T2> using first_is_void = std::is_same<T1, void>;
- template<class T1, class T2> using second = T2;
- using R1 = mp_transform_if<first_is_void, second, L1, L2>;
- // std::tuple<char[1], int, float, char[4], int></code></pre>
- </div>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 4. mp_transform_if</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L2</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>P<A<sub>i</sub>, B<sub>i</sub>></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_true</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_transform_if<P, F, L1, L2></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_transform_if_qqp_qf_l">mp_transform_if_q<Qp, Qf, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Qp, class Qf, class... L> using mp_transform_if_q =
- mp_transform_if<Qp::template fn, Qf::template fn, L...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_transform_if</code>, but takes quoted metafunctions.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 56. Using mp_transform_if_q to replace the occurrences of 'void' in a list with the corresponding elements of a second list</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float, void, int>;
- using L2 = std::tuple<char[1], char[2], char[3], char[4], char[5]>;
- using R1 = mp_transform_if_q<mp_bind<std::is_same, _1, void>, _2, L1, L2>;
- // std::tuple<char[1], int, float, char[4], int></code></pre>
- </div>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 5. mp_transform_if_q</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L2</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>Qp::fn<A<sub>i</sub>, B<sub>i</sub>></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_true</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_transform_if_q<Qp, _2, L1, L2></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_filterp_l">mp_filter<P, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class P, class... L> using mp_filter = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_filter<P, L1, L2, …​, Ln></code> removes the elements of the list <code>L1</code> for which <code>mp_to_bool<P<T1, T2, …​, Tn>></code>
- is <code>mp_false</code> and returns the result, where <code>Ti</code> are the corresponding elements of <code>Li</code>.</p>
- </div>
- <div class="paragraph">
- <p>See also <code>mp_copy_if</code> and <code>mp_remove_if</code>, less general variants of <code>mp_filter</code> that only take a single list.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_filter_qqp_l">mp_filter_q<Qp, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Qp, class... L> using mp_filter_q =
- mp_filter<Qp::template fn, L...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_filter</code>, but takes a quoted metafunction.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 57. Using mp_filter_q to pick elements of a list based on a mask in another list</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float>;
- using L2 = mp_list<mp_true, mp_false, mp_true>;
- using R1 = mp_filter_q<_2, L1, L2>; // std::tuple<void, float></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_filll_v">mp_fill<L, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V> using mp_fill = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_fill<L<T…​>, V></code> returns <code>L<V, V, …​, V></code>, with the result having the same size as the input.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 58. Using mp_fill with std::tuple</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::tuple<void, int, float>;
- using R1 = mp_fill<L1, double>; // std::tuple<double, double, double></code></pre>
- </div>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 59. Using mp_fill with std::pair</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = std::pair<int, float>;
- using R1 = mp_fill<L1, void>; // std::pair<void, void></code></pre>
- </div>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 6. mp_fill</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_fill<L1, V></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>V</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>V</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>V</code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_countl_v">mp_count<L, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V> using mp_count = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_count<L, V></code> returns <code>mp_size_t<N></code>, where <code>N</code> is the number of elements of <code>L</code> same as <code>V</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_count_ifl_p">mp_count_if<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_count_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_count_if<L, P></code> returns <code>mp_size_t<N></code>, where <code>N</code> is the number of elements <code>T</code> of <code>L</code> for which <code>mp_to_bool<P<T>></code> is <code>mp_true</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_count_if_ql_q">mp_count_if_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_count_if_q = mp_count_if<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_count_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_containsl_v">mp_contains<L, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V> using mp_contains = mp_to_bool<mp_count<L, V>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_contains<L, V></code> is <code>mp_true</code> when <code>L</code> contains an element <code>V</code>, <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_starts_withl1_l2">mp_starts_with<L1, L2></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L1, class L2> using mp_starts_with = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_starts_with<L1, L2></code> is <code>mp_true</code> when <code>L1</code> starts with <code>L2</code>, <code>mp_false</code>
- otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_repeat_cl_n">mp_repeat_c<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t N> using mp_repeat_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_repeat_c<L, N></code> returns a list of the same form as <code>L</code> that consists of <code>N</code> concatenated copies of <code>L</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 60. Using mp_repeat_c</div>
- <div class="content">
- <pre class="highlight"><code>using L1 = tuple<int>;
- using R1 = mp_repeat_c<L1, 3>; // tuple<int, int, int>
- using L2 = pair<int, float>;
- using R2 = mp_repeat_c<L2, 1>; // pair<int, float>
- using L3 = mp_list<int, float>;
- using R3 = mp_repeat_c<L3, 2>; // mp_list<int, float, int, float>
- using L4 = mp_list<int, float, double>;
- using R4 = mp_repeat_c<L4, 0>; // mp_list<></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_repeatl_n">mp_repeat<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class N> using mp_repeat = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_repeat_c</code> but with a type argument <code>N</code>. The number of copies is <code>N::value</code> and must be nonnegative.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_productf_l">mp_product<F, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... L> using mp_product = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_product<F, L1<T1…​>, L2<T2…​>, …​, Ln<Tn…​>></code> evaluates <code>F<U1, U2, …​, Un></code> for values <code>Ui</code> taken from
- the Cartesian product of the lists, as if the elements <code>Ui</code> are formed by <code>n</code> nested loops, each traversing <code>Li</code>.
- It returns a list of the form <code>L1<V…​></code> containing the results of the application of <code>F</code>.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 7. mp_product on two lists</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L2</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>m</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_product<F, L1, L2></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>1</sub>,B<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>1</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>1</sub>,B<sub>m</sub>></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>,B<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>2</sub>,B<sub>m</sub>></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"></td>
- <td class="tableblock halign-center valign-middle" colspan="4"><p class="tableblock"><code>…​</code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>n</sub>,B<sub>1</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>n</sub>,B<sub>2</sub>></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>F<A<sub>n</sub>,B<sub>m</sub>></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_product_qq_l">mp_product_q<Q, L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... L> using mp_product_q = mp_product<Q::template fn, L...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_product</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_drop_cl_n">mp_drop_c<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t N> using mp_drop_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_drop_c<L, N></code> removes the first <code>N</code> elements of <code>L</code> and returns the result.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 8. mp_drop_c</caption>
- <colgroup>
- <col style="width: 40%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m+1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="7"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_drop_c<L1, M></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m+1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- <td class="tableblock halign-center valign-middle" colspan="3"></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_dropl_n">mp_drop<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class N> using mp_drop = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_drop_c</code>, but with a type argument <code>N</code>. <code>N::value</code> must be a nonnegative number.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_from_sequences">mp_from_sequence<S></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class S> using mp_from_sequence = /*...*/</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_from_sequence</code> transforms an integer sequence produced by <code>make_integer_sequence</code> into an <code>mp_list</code>
- of the corresponding <code>std::integral_constant</code> types. Given</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, T... I> struct S;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_from_sequence<S<T, I…​>></code> is an alias for <code>mp_list<std::integral_constant<T, I>…​></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_iota_cn">mp_iota_c<N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t N> using mp_iota_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_iota_c<N></code> is an alias for <code>mp_list<mp_size_t<0>, mp_size_t<1>, …​, mp_size_t<N-1>></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_iotan">mp_iota<N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class N> using mp_iota = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_iota_c</code>, but with a type argument <code>N</code>. <code>N::value</code> must be a nonnegative number. Returns
- <code>mp_list<std::integral_constant<T, 0>, std::integral_constant<T, 1>, …​, std::integral_constant<T, N::value-1>></code>
- where <code>T</code> is the type of <code>N::value</code>.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 9. mp_iota</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_iota<mp_int<4>></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_int<0></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_int<1></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_int<2></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_int<3></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_at_cl_i">mp_at_c<L, I></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t I> using mp_at_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_at_c<L, I></code> returns the <code>I</code>-th element of <code>L</code>, zero-based.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_atl_i">mp_at<L, I></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I> using mp_at = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_at_c</code>, but with a type argument <code>I</code>. <code>I::value</code> must be a nonnegative number.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_take_cl_n">mp_take_c<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t N> using mp_take_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_take_c<L, N></code> returns a list of the same form as <code>L</code> containing the first <code>N</code> elements of <code>L</code>.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 10. mp_take_c</caption>
- <colgroup>
- <col style="width: 40%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- <col style="width: 10%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m+1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="7"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_take_c<L1, M></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m</sub></code></p></td>
- <td class="tableblock halign-center valign-middle" colspan="3"></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_takel_n">mp_take<L, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class N> using mp_take = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_take_c</code>, but with a type argument <code>N</code>. <code>N::value</code> must be a nonnegative number.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_backl">mp_back<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_back = mp_at_c<L, mp_size<L>::value - 1>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_back<L></code> returns the last element of the list <code>L</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_pop_backl">mp_pop_back<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_pop_back = mp_take_c<L, mp_size<L>::value - 1>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_pop_back<L></code> removes the last element of the list <code>L</code> and returns the result.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_insert_cl_i_t">mp_insert_c<L, I, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t I, class... T> using mp_insert_c =
- mp_append<mp_take_c<L, I>, mp_push_front<mp_drop_c<L, I>, T...>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Inserts the elements <code>T…​</code> into the list <code>L</code> at position <code>I</code> (a zero-based index).</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 11. mp_insert_c with two elements</caption>
- <colgroup>
- <col style="width: 33.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3333%;">
- <col style="width: 8.3336%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m+1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- <td class="tableblock halign-center valign-middle" colspan="2"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="9"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_insert_c<L1, M, B<sub>1</sub>, B<sub>2</sub>></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>B<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>m+1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_insertl_i_t">mp_insert<L, I, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I, class... T> using mp_insert =
- mp_append<mp_take<L, I>, mp_push_front<mp_drop<L, I>, T...>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_insert_c</code>, but with a type argument <code>I</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_erase_cl_i_j">mp_erase_c<L, I, J></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t I, std::size_t J> using mp_erase_c =
- mp_append<mp_take_c<L, I>, mp_drop_c<L, J>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Removes from the list <code>L</code> the elements with indices from <code>I</code> (inclusive) to <code>J</code> (exclusive).</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 12. mp_erase_c</caption>
- <colgroup>
- <col style="width: 30.7692%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6923%;">
- <col style="width: 7.6924%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>0</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>i-1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>i</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>j-1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>j</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n-1</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="10"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_erase_c<L1, I, J></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>0</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>i-1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>j</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n-1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle" colspan="3"></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_erasel_i_j">mp_erase<L, I, J></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I, class J> using mp_erase =
- mp_append<mp_take<L, I>, mp_drop<L, J>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_erase_c</code>, but with a type arguments <code>I</code> and <code>J</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replacel_v_w">mp_replace<L, V, W></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V, class W> using mp_replace = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Replaces all <code>V</code> elements of <code>L</code> with <code>W</code> and returns the result.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 13. mp_replace</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>V</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_replace<L1, V, W></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>W</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_ifl_p_w">mp_replace_if<L, P, W></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P, class W> using mp_replace_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Replaces all <code>T</code> elements of <code>L</code> for which <code>mp_to_bool<P<T>></code> is <code>mp_true</code> with <code>W</code> and returns the result.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 14. mp_replace_if</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>P<A<sub>i</sub>></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_true</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>mp_false</code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_replace_if<L1, P, W></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>W</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_if_ql_q_w">mp_replace_if_q<L, Q, W></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q, class W> using mp_replace_if_q =
- mp_replace_if<L, Q::template fn, W>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_replace_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_at_cl_i_w">mp_replace_at_c<L, I, W></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t I, class W> using mp_replace_at_c = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Replaces the element of <code>L</code> at zero-based index <code>I</code> with <code>W</code> and returns the result.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_replace_atl_i_w">mp_replace_at<L, I, W></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I, class W> using mp_replace_at = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>mp_replace_at_c</code>, but with a type argument <code>I</code>. <code>I::value</code> must be a nonnegative number.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_copy_ifl_p">mp_copy_if<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_copy_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Copies the elements <code>T</code> of <code>L</code> for which <code>mp_to_bool<P<T>></code> is <code>mp_true</code> to a new list of the same form and returns it.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_copy_if_ql_q">mp_copy_if_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_copy_if_q = mp_copy_if<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_copy_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_removel_v">mp_remove<L, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V> using mp_remove = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Removes all <code>V</code> elements of <code>L</code> and returns the result.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_remove_ifl_p">mp_remove_if<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_remove_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Removes all elements <code>T</code> of <code>L</code> for which <code>mp_to_bool<P<T>></code> is <code>mp_true</code> and returns the result.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_remove_if_ql_q">mp_remove_if_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_remove_if_q = mp_remove_if<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_remove_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_partitionl_p">mp_partition<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_partition = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_partition<L<T…​>, P></code> partitions <code>L</code> into two lists <code>L<U1…​></code> and <code>L<U2…​></code> such that <code>mp_to_bool<P<T>></code> is <code>mp_true</code>
- for the elements of <code>L<U1…​></code> and <code>mp_false</code> for the elements of <code>L<U2…​></code>. Returns <code>L<L<U1…​>, L<U2…​>></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_partition_ql_q">mp_partition_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_partition_q = mp_partition<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_partition</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_sortl_p">mp_sort<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_sort = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_sort<L, P></code> sorts the list <code>L</code> according to the strict weak ordering <code>mp_to_bool<P<T, U>></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 61. Using mp_sort to sort a list of std::ratio values</div>
- <div class="content">
- <pre>#include <ratio>
- using L1 = mp_list<std::ratio<1,2>, std::ratio<1,4>>;
- using R1 = mp_sort<L1, std::ratio_less>; // mp_list<ratio<1,4>, ratio<1,2>></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_sort_ql_q">mp_sort_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_sort_q = mp_sort<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_sort</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_nth_element_cl_i_p">mp_nth_element_c<L, I, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, std::size_t I, template<class...> class P> using mp_nth_element_c =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Returns the element at position <code>I</code> in <code>mp_sort<L, P></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_nth_elementl_i_p">mp_nth_element<L, I, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I, template<class...> class P> using mp_nth_element = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_nth_element_c</code>, but with a type argument <code>I</code>. <code>I::value</code> must be a nonnegative number.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_nth_element_ql_i_q">mp_nth_element_q<L, I, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class I, class Q> using mp_nth_element_q =
- mp_nth_element<L, I, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Like <code>mp_nth_element</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_min_elementl_p">mp_min_element<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_min_element = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_min_element<L, P></code> returns the minimal element of the list <code>L</code> according to the ordering <code>mp_to_bool<P<T, U>></code>.</p>
- </div>
- <div class="paragraph">
- <p>It’s equivalent to <code>mp_fold<mp_rest<L>, mp_first<L>, F></code>, where <code>F<T, U></code> returns <code>mp_if<P<T, U>, T, U></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_min_element_ql_q">mp_min_element_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_min_element_q = mp_min_element<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_min_element</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_max_elementl_p">mp_max_element<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_max_element = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_max_element<L, P></code> returns the maximal element of the list <code>L</code> according to the ordering <code>mp_to_bool<P<T, U>></code>.</p>
- </div>
- <div class="paragraph">
- <p>It’s equivalent to <code>mp_fold<mp_rest<L>, mp_first<L>, F></code>, where <code>F<T, U></code> returns <code>mp_if<P<U, T>, T, U></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_max_element_ql_q">mp_max_element_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_max_element_q = mp_max_element<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_max_element</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_findl_v">mp_find<L, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V> using mp_find = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_find<L, V></code> returns the index at which the type <code>V</code> is located in the list <code>L</code>. It’s an alias for <code>mp_size_t<I></code>,
- where <code>I</code> is the zero-based index of the first occurrence of <code>V</code> in <code>L</code>. If <code>L</code> does not contain <code>V</code>, <code>mp_find<L, V></code>
- is <code>mp_size<L></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_find_ifl_p">mp_find_if<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_find_if = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_find_f<L, P></code> is an alias for <code>mp_size_t<I></code>, where <code>I</code> is the zero-based index of the first element <code>T</code> in <code>L</code> for which
- <code>mp_to_bool<P<T>></code> is <code>mp_true</code>. If there is no such element, <code>mp_find_if<L, P></code> is <code>mp_size<L></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_find_if_ql_q">mp_find_if_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_find_if_q = mp_find_if<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_find_if</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_reversel">mp_reverse<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_reverse = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_reverse<L<T1, T2, …​, Tn>></code> is <code>L<Tn, …​, T2, T1></code>.</p>
- </div>
- <table class="tableblock frame-all grid-all" style="width: 85%;">
- <caption class="title">Illustration 15. mp_reverse</caption>
- <colgroup>
- <col style="width: 50%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- <col style="width: 12.5%;">
- </colgroup>
- <tbody>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>L1</strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>2</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle" colspan="5"></td>
- </tr>
- <tr>
- <td class="tableblock halign-left valign-middle"><p class="tableblock"><code><strong>mp_reverse<L1></strong></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>n-1</sub></code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>…​</code></p></td>
- <td class="tableblock halign-center valign-middle"><p class="tableblock"><code>A<sub>1</sub></code></p></td>
- </tr>
- </tbody>
- </table>
- </div>
- <div class="sect3">
- <h4 id="mp_foldl_v_f">mp_fold<L, V, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V, template<class...> class F> using mp_fold = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_fold<L<T1, T2, …​, Tn>, V, F></code> is <code>F< F< F< F<V, T1>, T2>, …​>, Tn></code>, or <code>V</code>, if <code>L</code> is empty.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 62. Using mp_fold to add the contents of a list of std::ratio values</div>
- <div class="content">
- <pre>#include <ratio>
- using L1 = mp_list<std::ratio<1,8>, std::ratio<1,4>, std::ratio<1,2>>;
- using R1 = mp_fold<L1, std::ratio<0,1>, std::ratio_add>; // std::ratio<7,8></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_fold_ql_v_q">mp_fold_q<L, V, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V, class Q> using mp_fold_q =
- mp_fold<L, V, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_fold</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_reverse_foldl_v_f">mp_reverse_fold<L, V, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V, template<class...> class F> using mp_reverse_fold =
- /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_reverse_fold<L<T1, T2, …​, Tn>, V, F></code> is <code>F<T1, F<T2, F<…​, F<Tn, V>>>></code>, or <code>V</code>, if <code>L</code> is empty.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_reverse_fold_ql_v_q">mp_reverse_fold_q<L, V, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class V, class Q> using mp_reverse_fold_q =
- mp_reverse_fold<L, V, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_reverse_fold</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_uniquel">mp_unique<L></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L> using mp_unique = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_unique<L></code> returns a list of the same form as <code>L</code> with the duplicate elements removed.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_all_ofl_p">mp_all_of<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_all_of =
- mp_bool< mp_count_if<L, P>::value == mp_size<L>::value >;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_all_of<L, P></code> is <code>mp_true</code> when <code>P</code> holds for all elements of <code>L</code>, <code>mp_false</code> otherwise. When <code>L</code> is empty, the result is <code>mp_true</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_all_of_ql_q">mp_all_of_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_all_of_q = mp_all_of<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_all_of</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_none_ofl_p">mp_none_of<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_none_of =
- mp_bool< mp_count_if<L, P>::value == 0 >;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_none_of<L, P></code> is <code>mp_true</code> when <code>P</code> holds for no element of <code>L</code>, <code>mp_false</code> otherwise. When <code>L</code> is empty, the result is <code>mp_true</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_none_of_ql_q">mp_none_of_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_none_of_q = mp_none_of<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_none_of</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_any_ofl_p">mp_any_of<L, P></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, template<class...> class P> using mp_any_of =
- mp_bool< mp_count_if<L, P>::value != 0 >;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_any_of<L, P></code> is <code>mp_true</code> when <code>P</code> holds for at least one element of <code>L</code>, <code>mp_false</code> otherwise. When <code>L</code> is empty, the result is <code>mp_false</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_any_of_ql_q">mp_any_of_q<L, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class Q> using mp_any_of_q = mp_any_of<L, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_any_of</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_for_eachlf">mp_for_each<L>(f)</h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class F> constexpr F mp_for_each(F&& f);</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_for_each<L>(f)</code> calls <code>f</code> with <code>T()</code> for each element <code>T</code> of the list <code>L</code>, in order.</p>
- </div>
- <div class="paragraph">
- <p>Returns <code>std::forward<F>(f)</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 63. Using mp_for_each and a C++14 lambda to print a tuple</div>
- <div class="content">
- <pre class="highlight"><code>template<class... T> void print( std::tuple<T...> const & tp )
- {
- std::size_t const N = sizeof...(T);
- mp_for_each<mp_iota_c<N>>( [&]( auto I ){
- // I is mp_size_t<0>, mp_size_t<1>, ..., mp_size_t<N-1>
- std::cout << std::get<I>(tp) << std::endl;
- });
- }</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_with_indexni_f">mp_with_index<N>(i, f)</h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t N, class F>
- constexpr auto mp_with_index( std::size_t i, F && f )
- -> decltype(std::declval<F>()(std::declval<mp_size_t<0>>()));</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_with_index<N>(i, f)</code> calls <code>f</code> with <code>mp_size_t<i>()</code> and returns the result. <code>i</code> must be less than <code>N</code>.
- Only <code>constexpr</code> on C++14 and higher.</p>
- </div>
- <div class="literalblock">
- <div class="content">
- <pre>template<class N, class F>
- constexpr auto mp_with_index( std::size_t i, F && f )
- -> decltype(std::declval<F>()(std::declval<mp_size_t<0>>()));</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Returns <code>mp_with_index<N::value>(i, f)</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 64. Using mp_with_index and a C++14 lambda to print the active element of a variant</div>
- <div class="content">
- <pre class="highlight"><code>template<class... T> void print( std::variant<T...> const& v )
- {
- mp_with_index<sizeof...(T)>( v.index(), [&]( auto I ) {
- // I is mp_size_t<v.index()>{} here
- std::cout << std::get<I>( v ) << std::endl;
- });
- }</code></pre>
- </div>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="set">Set Operations, <boost/mp11/set.hpp></h3>
- <div class="paragraph">
- <p>A set is a list whose elements are unique.</p>
- </div>
- <div class="sect3">
- <h4 id="mp_is_sets">mp_is_set<S></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class S> using mp_is_set = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_is_set<S></code> is <code>mp_true</code> if <code>S</code> is a set, <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_containss_v">mp_set_contains<S, V></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class S, class V> using mp_set_contains = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_set_contains<S, V></code> is <code>mp_true</code> if the type <code>V</code> is an element of the set <code>S</code>, <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_push_backs_t">mp_set_push_back<S, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class S, class... T> using mp_set_push_back = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>For each <code>T1</code> in <code>T…​</code>, <code>mp_set_push_back<S, T…​></code> appends <code>T1</code> to the end of the set <code>S</code> if it’s not already an element of <code>S</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_push_fronts_t">mp_set_push_front<S, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class S, class... T> using mp_set_push_front = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_set_push_front<S, T…​></code> inserts at the front of the set <code>S</code> those elements of <code>T…​</code> for which <code>S</code> does not already contain the same type.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_unionl">mp_set_union<L…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... L> using mp_set_union = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_set_union<S, L…​></code> is <code>mp_set_push_back<S, T…​></code>, where <code>T…​</code> are the combined elements of the lists <code>L…​</code>.
- <code>mp_set_union<></code> is <code>mp_list<></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_intersections">mp_set_intersection<S…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... S> using mp_set_intersection = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_set_intersection<S…​></code> returns a set that contains the elements that occur in all of the sets <code>S…​</code>.
- <code>mp_set_intersection<></code> is <code>mp_list<></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_set_differencel_s">mp_set_difference<L, S…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class L, class... S> using mp_set_difference = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_set_difference<L, S…​></code> removes the elements of the list <code>L</code> that appear in any of the sets <code>S…​</code> and
- returns the result.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="map">Map Operations, <boost/mp11/map.hpp></h3>
- <div class="paragraph">
- <p>A map is a list of lists, the inner lists having at least one element (the key.) The keys of the map must be unique.</p>
- </div>
- <div class="sect3">
- <h4 id="mp_is_mapm">mp_is_map<M></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M> using mp_is_map = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_is_map<M></code> is <code>mp_true</code> if <code>M</code> is a map, <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_findm_k">mp_map_find<M, K></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class K> using mp_map_find = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_map_find<M, K></code> is an alias for the element of the map <code>M</code> with a key <code>K</code>, or for <code>void</code>, if there is no such element.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_containsm_k">mp_map_contains<M, K></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class K> using mp_map_contains =
- mp_not<std::is_same<mp_map_find<M, K>, void>>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_map_contains<M, K></code> is <code>mp_true</code> if the map <code>M</code> contains an element with a key <code>K</code>, <code>mp_false</code> otherwise.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_insertm_t">mp_map_insert<M, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class T> using mp_map_insert =
- mp_if< mp_map_contains<M, mp_first<T>>, M, mp_push_back<M, T> >;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Inserts the element <code>T</code> into the map <code>M</code>, if an element with a key <code>mp_first<T></code> is not already in <code>M</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_replacem_t">mp_map_replace<M, T></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class T> using mp_map_replace = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>If the map <code>M</code> does not contain an element with a key <code>mp_first<T></code>, inserts it (using <code>mp_push_back<M, T></code>); otherwise,
- replaces the existing element with <code>T</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_updatem_t_f">mp_map_update<M, T, F></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class T, template<class...> class F> using mp_map_update = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>If the map <code>M</code> does not contain an element with a key <code>mp_first<T></code>, inserts it (using <code>mp_push_back<M, T></code>); otherwise,
- replaces the existing element <code>L<X, Y…​></code> with <code>L<X, F<X, Y…​>></code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 65. Using mp_map_update to count the number of occurrences of types in a list</div>
- <div class="content">
- <pre class="highlight"><code>template<class T, class U> using inc2nd = mp_int<U::value + 1>;
- template<class M, class T> using count_types =
- mp_map_update<M, std::pair<T, mp_int<1>>, inc2nd>;
- using L1 = mp_list<float, char, float, float, float, float, char, float>;
- using R1 = mp_fold<L1, std::tuple<>, count_types>;
- // std::tuple<std::pair<float, mp_int<6>>, std::pair<char, mp_int<2>>></code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_update_qm_t_q">mp_map_update_q<M, T, Q></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class T, class Q> using mp_map_update_q =
- mp_map_update<M, T, Q::template fn>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_map_update</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_erasem_k">mp_map_erase<M, K></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M, class K> using mp_map_erase = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>If the map <code>M</code> contains an element with a key <code>K</code>, removes it.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_map_keysm">mp_map_keys<M></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class M> using mp_map_keys = mp_transform<mp_first, M>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_map_keys<M></code> returns a list of the keys of <code>M</code>. When <code>M</code> is a valid map, the keys are unique, so the result is a set.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="function">Helper Metafunctions, <boost/mp11/function.hpp></h3>
- <div class="sect3">
- <h4 id="mp_voidt">mp_void<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_void = void;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>Same as <code>std::void_t</code> from C++17.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_andt">mp_and<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_and = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_and<T…​></code> applies <code>mp_to_bool</code> to the types in <code>T…​</code>, in order. If the result of an application is <code>mp_false</code>, <code>mp_and</code>
- returns <code>mp_false</code>. If the application causes a substitution failure, returns <code>mp_false</code>. If all results are <code>mp_true</code>,
- returns <code>mp_true</code>. <code>mp_and<></code> is <code>mp_true</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 66. mp_and behavior</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_and<mp_true, mp_true>; // mp_true
- using R2 = mp_and<mp_false, void>; // mp_false, void is not reached
- using R3 = mp_and<mp_false, mp_false>; // mp_false
- using R4 = mp_and<void, mp_true>; // mp_false (!)</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_allt">mp_all<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_all = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_all<T…​></code> is <code>mp_true</code> if <code>mp_to_bool<U></code> is <code>mp_true</code> for all types <code>U</code> in <code>T…​</code>, <code>mp_false</code> otherwise. Same as
- <code>mp_and</code>, but does not perform short-circuit evaluation. <code>mp_and<mp_false, void></code> is <code>mp_false</code>, but <code>mp_all<mp_false, void></code>
- is an error because <code>void</code> does not have a nested <code>value</code>. The upside is that <code>mp_all</code> is potentially faster and does not
- mask substitution failures as <code>mp_and</code> does.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 67. mp_all behavior</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_all<mp_true, mp_true>; // mp_true
- using R2 = mp_all<mp_false, void>; // compile-time error
- using R3 = mp_all<mp_false, mp_false>; // mp_false
- using R4 = mp_all<void, mp_true>; // compile-time error</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_ort">mp_or<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_or = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_or<T…​></code> applies <code>mp_to_bool</code> to the types in <code>T…​</code>, in order. If the result of an application is <code>mp_true</code>, <code>mp_or</code>
- returns <code>mp_true</code>. If all results are <code>mp_false</code>, returns <code>mp_false</code>. <code>mp_or<></code> is <code>mp_false</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 68. mp_or behavior</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_or<mp_true, mp_false>; // mp_true
- using R2 = mp_or<mp_true, void>; // mp_true, void is not reached
- using R3 = mp_or<mp_false, mp_false>; // mp_false
- using R4 = mp_or<void, mp_true>; // compile-time error</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_anyt">mp_any<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_any = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_any<T…​></code> is <code>mp_true</code> if <code>mp_to_bool<U></code> is <code>mp_true</code> for any type <code>U</code> in <code>T…​</code>, <code>mp_false</code> otherwise. Same as
- <code>mp_or</code>, but does not perform short-circuit evaluation.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 69. mp_any behavior</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_any<mp_true, mp_false>; // mp_true
- using R2 = mp_any<mp_true, void>; // compile-time error
- using R3 = mp_any<mp_false, mp_false>; // mp_false
- using R4 = mp_any<void, mp_true>; // compile-time error</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_samet">mp_same<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_same = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_same<T…​></code> is <code>mp_true</code> if all the types in <code>T…​</code> are the same type, <code>mp_false</code> otherwise. <code>mp_same<></code> is <code>mp_true</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_similart">mp_similar<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_similar = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_similar<T…​></code> is <code>mp_true</code> if all the types in <code>T…​</code> are the same type, or instantiations of the same class template
- whose parameters are all types, <code>mp_false</code> otherwise. <code>mp_similar<></code> is <code>mp_true</code>.</p>
- </div>
- <div class="listingblock">
- <div class="title">Code Example 70. mp_similar</div>
- <div class="content">
- <pre class="highlight"><code>using R1 = mp_similar<void>; // mp_true
- using R2 = mp_similar<void, void>; // mp_true
- using R3 = mp_similar<void, void, void>; // mp_true
- using R4 = mp_similar<void, void, float>; // mp_false
- template<class T> struct X;
- template<class... T> struct Y;
- using R5 = mp_similar<X<int>, X<void>, X<float>>; // mp_true
- using R6 = mp_similar<Y<>, Y<void>, Y<void, void>>; // mp_true
- using R7 = mp_similar<X<void>, Y<void>>; // mp_false</code></pre>
- </div>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_plust">mp_plus<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using mp_plus = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_plus<T…​></code> is an integral constant type with a value that is the sum of <code>U::value</code> for all types <code>U</code> in <code>T…​</code>.
- <code>mp_plus<></code> is <code>mp_int<0></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_lesst1_t2">mp_less<T1, T2></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T1, class T2> using mp_less = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_less<T1, T2></code> is <code>mp_true</code> when the numeric value of <code>T1::value</code> is less than the numeric value of <code>T2::value</code>,
- <code>mp_false</code> otherwise.</p>
- </div>
- <div class="paragraph">
- <p>(Note that this is not necessarily the same as <code>T1::value < T2::value</code> when comparing between signed and unsigned types;
- <code>-1 < 1u</code> is <code>false</code>, but <code>mp_less<mp_int<-1>, mp_size_t<1>></code> is <code>mp_true</code>.)</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_mint1_t">mp_min<T1, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T1, class... T> using mp_min = mp_min_element<mp_list<T1, T...>, mp_less>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_min<T…​></code> returns the type <code>U</code> in <code>T…​</code> with the lowest <code>U::value</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_maxt1_t">mp_max<T1, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T1, class... T> using mp_max = mp_max_element<mp_list<T1, T...>, mp_less>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_max<T…​></code> returns the type <code>U</code> in <code>T…​</code> with the highest <code>U::value</code>.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="bind">Bind, <boost/mp11/bind.hpp></h3>
- <div class="sect3">
- <h4 id="mp_argi">mp_arg<I></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t I> struct mp_arg;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_arg<I></code> is a quoted metafunction whose nested template <code>fn<T…​></code> returns the <code>I</code>-th zero-based element of <code>T…​</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="1_9">_1, …​, _9</h4>
- <div class="literalblock">
- <div class="content">
- <pre>using _1 = mp_arg<0>;
- using _2 = mp_arg<1>;
- using _3 = mp_arg<2>;
- using _4 = mp_arg<3>;
- using _5 = mp_arg<4>;
- using _6 = mp_arg<5>;
- using _7 = mp_arg<6>;
- using _8 = mp_arg<7>;
- using _9 = mp_arg<8>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>_1</code> to <code>_9</code> are placeholder types, the equivalent to the placeholders of <code>boost::bind</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bindf_t">mp_bind<F, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... T> struct mp_bind;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_bind<F, T…​></code> is a quoted metafunction that implements the type-based
- equivalent of <code>boost::bind</code>. Its nested template <code>fn<U…​></code> returns <code>F<V…​></code>,
- where <code>V…​</code> is <code>T…​</code> with the placeholders replaced by the corresponding
- element of <code>U…​</code> and the <code>mp_bind</code>, <code>mp_bind_front</code>, and <code>mp_bind_back</code>
- expressions replaced with their corresponding evaluations against <code>U…​</code>.</p>
- </div>
- <div class="paragraph">
- <p>For example, <code>mp_bind<F, int, _2, mp_bind<G, _1>>::fn<float, void></code> is <code>F<int, void, G<float>></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bind_qq_t">mp_bind_q<Q, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... T> using mp_bind_q = mp_bind<Q::template fn, T...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_bind</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bind_frontf_t">mp_bind_front<F, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... T> struct mp_bind_front;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_bind_front<F, T…​></code> binds the leftmost arguments of <code>F</code> to <code>T…​</code>. Its nested template <code>fn<U…​></code> returns <code>F<T…​, U…​></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bind_front_qq_t">mp_bind_front_q<Q, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... T> using mp_bind_front_q =
- mp_bind_front<Q::template fn, T...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_bind_front</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bind_backf_t">mp_bind_back<F, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<template<class...> class F, class... T> struct mp_bind_back;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>mp_bind_back<F, T…​></code> binds the rightmost arguments of <code>F</code> to <code>T…​</code>. Its nested template <code>fn<U…​></code> returns <code>F<U…​, T…​></code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="mp_bind_back_qq_t">mp_bind_back_q<Q, T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Q, class... T> using mp_bind_back_q =
- mp_bind_back<Q::template fn, T...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p>As <code>mp_bind_back</code>, but takes a quoted metafunction.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="integer_sequence">Integer Sequences, <boost/mp11/integer_sequence.hpp></h3>
- <div class="sect3">
- <h4 id="integer_sequencet_i">integer_sequence<T, I…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, T... I> struct integer_sequence
- {
- };</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>integer_sequence<T, I…​></code> holds a sequence of integers of type <code>T</code>. Same as C++14’s <code>std::integer_sequence</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="make_integer_sequencet_n">make_integer_sequence<T, N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, T N> using make_integer_sequence = /*...*/;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>make_integer_sequence<T, N></code> is <code>integer_sequence<T, 0, 1, …​, N-1></code>. Same as C++14’s <code>std::make_integer_sequence</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="index_sequencei">index_sequence<I…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t... I> using index_sequence = integer_sequence<std::size_t, I...>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>index_sequence<I…​></code> is an alias for <code>integer_sequence<size_t, I…​></code>. Same as C++14’s <code>std::index_sequence</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="make_index_sequencen">make_index_sequence<N></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<std::size_t N> using make_index_sequence =
- make_integer_sequence<std::size_t, N>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>make_index_sequence<N></code> is <code>index_sequence<0, 1, …​, N-1></code>. Same as C++14’s <code>std::make_index_sequence</code>.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="index_sequence_fort">index_sequence_for<T…​></h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class... T> using index_sequence_for =
- make_integer_sequence<std::size_t, sizeof...(T)>;</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>index_sequence_for<N></code> is <code>make_index_sequence<sizeof…​(T)></code>. Same as C++14’s <code>std::index_sequence_for</code>.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="tuple">Tuple Operations, <boost/mp11/tuple.hpp></h3>
- <div class="sect3">
- <h4 id="tuple_applyf_tp">tuple_apply(f, tp)</h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class F, class Tp> constexpr /*...*/ tuple_apply(F&& f, Tp&& tp);</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>tuple_apply(f, tp)</code> returns <code>std::forward<F>(f)(std::get<J>(std::forward<Tp>(tp))…​)</code> for <code>J</code> in 0..<code>N-1</code>,
- where <code>N</code> is <code>std::tuple_size<typename std::remove_reference<Tp>::type>::value</code>. Same as <code>std::apply</code> in C++17.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="construct_from_tuplettp">construct_from_tuple<T>(tp)</h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class T, class Tp> T construct_from_tuple(Tp&& tp);</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>construct_from_tuple<T>(tp)</code> returns <code>T(std::get<J>(std::forward<Tp>(tp))…​)</code> for <code>J</code> in 0..<code>N-1</code>,
- where <code>N</code> is <code>std::tuple_size<typename std::remove_reference<Tp>::type>::value</code>. Same as <code>std::make_from_tuple</code> in C++17.
- The name of the function doesn’t match the C++17 one to avoid ambiguities when both are visible or in unqualified calls.</p>
- </div>
- </div>
- <div class="sect3">
- <h4 id="tuple_for_eachtp_f">tuple_for_each(tp, f)</h4>
- <div class="literalblock">
- <div class="content">
- <pre>template<class Tp, class F> constexpr F tuple_for_each(Tp&& tp, F&& f);</pre>
- </div>
- </div>
- <div class="paragraph">
- <p><code>tuple_for_each(tp, f)</code> applies the function object <code>f</code> to each element of <code>tp</code> by evaluating the
- expression <code>f(std::get<J>(std::forward<Tp>(tp)))</code> for <code>J</code> in 0..<code>N-1</code>, where <code>N</code> is <code>std::tuple_size<typename std::remove_reference<Tp>::type>::value</code>.</p>
- </div>
- <div class="paragraph">
- <p>Returns <code>std::forward<F>(f)</code>.</p>
- </div>
- </div>
- </div>
- <div class="sect2">
- <h3 id="mp11">Convenience Header, <boost/mp11.hpp></h3>
- <div class="paragraph">
- <p>The convenience header <code><boost/mp11.hpp></code> includes all of the
- headers listed previously in this reference.</p>
- </div>
- </div>
- <div class="sect2">
- <h3 id="mpl">MPL Support, <boost/mp11/mpl.hpp></h3>
- <div class="paragraph">
- <p>The header <code><boost/mp11/mpl.hpp></code>, when included, defines the
- necessary support infrastructure for <code>mp_list</code> and <code>std::tuple</code>
- to be valid <a href="../../../../libs/mpl">MPL</a> sequences.</p>
- </div>
- <div class="admonitionblock note">
- <table>
- <tr>
- <td class="icon">
- <div class="title">Note</div>
- </td>
- <td class="content">
- <code>mpl.hpp</code> is not included by <code><boost/mp11.hpp></code>.
- </td>
- </tr>
- </table>
- </div>
- <div class="paragraph">
- <p>It’s also possible to only enable support for <code>mp_list</code> by
- including <code><boost/mp11/mpl_list.hpp></code>, and for <code>std::tuple</code>
- by including <code><boost/mp11/mpl_tuple.hpp></code>. This may be required
- because some libraries, such as Boost.Fusion, contain their own MPL
- support for <code>std::tuple</code>, which conflicts with Mp11’s one.</p>
- </div>
- </div>
- </div>
- </div>
- <div class="sect1">
- <h2 id="copyright_license_and_acknowledgments">Appendix A: Copyright, License, and Acknowledgments</h2>
- <div class="sectionbody">
- <div class="paragraph">
- <p>This documentation is</p>
- </div>
- <div class="ulist">
- <ul>
- <li>
- <p>Copyright 2017-2019 Peter Dimov</p>
- </li>
- <li>
- <p>Copyright 2017 Bjørn Reese</p>
- </li>
- </ul>
- </div>
- <div class="paragraph">
- <p>and is distributed under the <a href="http://www.boost.org/LICENSE_1_0.txt">Boost Software License, Version 1.0</a>.</p>
- </div>
- <div class="paragraph">
- <p>The "Simple C++11 metaprogramming" articles have been graciously converted to Asciidoc format for incorporation
- into this documentation by Glen Fernandes.</p>
- </div>
- </div>
- </div>
- </div>
- <div id="footer">
- <div id="footer-text">
- Last updated 2019-12-10 00:19:27 UTC
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