Add mp_copy_if_q

doc/mp11/algorithm.adoc

@@ -421,6 +421,12 @@ Same as `mp_replace_at_c`, but with a type argument `I`. `I::value` must be a no
 
 Copies the elements `T` of `L` for which `mp_to_bool<P<T>>` is `mp_true` to a new list of the same type and returns it.
 
+## mp_copy_if_q<L, Q>
+
+    template<class L, class Q> using mp_copy_if_q = mp_copy_if<L, Q::template fn>;
+
+As `mp_copy_if`, but takes a quoted metafunction.
+
 ## mp_remove<L, V>
 
     template<class L, class V> using mp_remove = /*...*/;

include/boost/mp11/algorithm.hpp

@@ -412,6 +412,7 @@ template<template<class...> class L, class... T, template<class...> class P> str
 } // namespace detail
 
 template<class L, template<class...> class P> using mp_copy_if = typename detail::mp_copy_if_impl<L, P>::type;
+template<class L, class Q> using mp_copy_if_q = mp_copy_if<L, Q::template fn>;
 
 // mp_remove<L, V>
 namespace detail

test/Jamfile

@@ -57,6 +57,7 @@ run mp_replace.cpp ;
 run mp_replace_if.cpp ;
 run mp_replace_if_q.cpp ;
 run mp_copy_if.cpp ;
+run mp_copy_if_q.cpp ;
 run mp_remove.cpp ;
 run mp_remove_if.cpp ;
 run mp_partition.cpp ;

test/mp_copy_if_q.cpp

@@ -0,0 +1,72 @@
+
+// Copyright 2015-2017 Peter Dimov.
+//
+// Distributed under the Boost Software License, Version 1.0.
+//
+// See accompanying file LICENSE_1_0.txt or copy at
+// http://www.boost.org/LICENSE_1_0.txt
+
+
+#include <boost/mp11/algorithm.hpp>
+#include <boost/mp11/list.hpp>
+#include <boost/mp11/integral.hpp>
+#include <boost/mp11/utility.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
+#include <tuple>
+
+struct X1 {};
+struct X2 {};
+struct X3 {};
+
+using boost::mp11::mp_bool;
+
+struct Q_is_even
+{
+    template<class N> using fn = mp_bool<N::value % 2 == 0>;
+};
+
+int main()
+{
+    using boost::mp11::mp_list;
+    using boost::mp11::mp_copy_if_q;
+    using boost::mp11::mp_quote;
+
+    {
+        using L1 = mp_list<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L1, mp_quote<std::is_const>>, L1>));
+
+        using L2 = mp_list<X1, X1 const, X1*, X2 const, X2*, X3*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_volatile>>, L1>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_const>>, mp_list<X1 const, X2 const>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_pointer>>, mp_list<X1*, X2*, X3*>>));
+    }
+
+    {
+        using L1 = std::tuple<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L1, mp_quote<std::is_const>>, L1>));
+
+        using L2 = std::tuple<X1, X1 const, X1*, X2 const, X2*, X3*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_volatile>>, L1>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_const>>, std::tuple<X1 const, X2 const>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_copy_if_q<L2, mp_quote<std::is_pointer>>, std::tuple<X1*, X2*, X3*>>));
+    }
+
+    using boost::mp11::mp_iota_c;
+    using boost::mp11::mp_size_t;
+
+    {
+        int const N = 12;
+        using L1 = mp_iota_c<N>;
+
+        using R1 = mp_copy_if_q<L1, Q_is_even>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<R1, mp_list<mp_size_t<0>, mp_size_t<2>, mp_size_t<4>, mp_size_t<6>, mp_size_t<8>, mp_size_t<10>>>));
+    }
+
+    return boost::report_errors();
+}