Add mp_count_if_q

doc/mp11/algorithm.adoc

@@ -187,6 +187,12 @@ using R1 = mp_fill<L1, void>; // std::pair<void, void>
 
 `mp_count_if<L, P>` returns `mp_size_t<N>`, where `N` is the number of elements `T` of `L` for which `mp_to_bool<P<T>>` is `mp_true`.
 
+## mp_count_if_q<L, Q>
+
+    template<class L, class Q> using mp_count_if_q = mp_count_if<L, Q::template fn>;
+
+As `mp_count_if`, but takes a quoted metafunction.
+
 ## mp_contains<L, V>
 
     template<class L, class V> using mp_contains = mp_to_bool<mp_count<L, V>>;

include/boost/mp11/detail/mp_count.hpp

@@ -108,6 +108,7 @@ template<template<class...> class L, class... T, template<class...> class P> str
 } // namespace detail
 
 template<class L, template<class...> class P> using mp_count_if = typename detail::mp_count_if_impl<L, P>::type;
+template<class L, class Q> using mp_count_if_q = mp_count_if<L, Q::template fn>;
 
 } // namespace mp11
 } // namespace boost

test/Jamfile

@@ -44,6 +44,7 @@ run mp_transform_if_q.cpp ;
 run mp_fill.cpp ;
 run mp_count.cpp ;
 run mp_count_if.cpp ;
+run mp_count_if_q.cpp ;
 run mp_contains.cpp ;
 run mp_repeat.cpp ;
 run mp_product.cpp ;

test/mp_count_if_q.cpp

@@ -0,0 +1,61 @@
+
+// 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>
+#include <utility>
+
+struct X1 {};
+
+int main()
+{
+    using boost::mp11::mp_list;
+    using boost::mp11::mp_count_if_q;
+    using boost::mp11::mp_size_t;
+    using boost::mp11::mp_quote;
+
+    {
+        using L1 = mp_list<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L1, mp_quote<std::is_const>>, mp_size_t<0>>));
+
+        using L2 = mp_list<X1, X1 const, X1*, X1 const, X1*, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_volatile>>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_const>>, mp_size_t<2>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_pointer>>, mp_size_t<3>>));
+    }
+
+    {
+        using L1 = std::tuple<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L1, mp_quote<std::is_const>>, mp_size_t<0>>));
+
+        using L2 = std::tuple<X1, X1 const, X1*, X1 const, X1*, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_volatile>>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_const>>, mp_size_t<2>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_pointer>>, mp_size_t<3>>));
+    }
+
+    {
+        using L2 = std::pair<X1 const, X1*>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_volatile>>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_const>>, mp_size_t<1>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_count_if_q<L2, mp_quote<std::is_pointer>>, mp_size_t<1>>));
+    }
+
+    return boost::report_errors();
+}