From 856ae3dc6cf2be7c381d7a0aa3b883851259d350 Mon Sep 17 00:00:00 2001
From: Peter Dimov <pdimov@pdimov.com>
Date: Wed, 15 Jul 2015 17:14:00 +0300
Subject: [PATCH] Add mp_find_index.

---
 include/boost/mp11/algorithm.hpp | 64 +++++++++++++++++++++++++++++++-
 test/Jamfile.v2                  |  1 +
 test/mp_find_index.cpp           | 63 +++++++++++++++++++++++++++++++
 3 files changed, 126 insertions(+), 2 deletions(-)
 create mode 100644 test/mp_find_index.cpp

diff --git a/include/boost/mp11/algorithm.hpp b/include/boost/mp11/algorithm.hpp
index e4640f9..7b06d13 100644
--- a/include/boost/mp11/algorithm.hpp
+++ b/include/boost/mp11/algorithm.hpp
@@ -497,10 +497,70 @@ template<template<class...> class L, class T1, class... T, template<class...> cl
 
 template<class L, template<class...> class P> using mp_sort = typename detail::mp_sort_impl<L, P>::type;
 
+// mp_find_index<L, V>
+namespace detail
+{
+
+template<class L, class V> struct mp_find_index_impl;
+
+#if !defined( BOOST_NO_CXX11_CONSTEXPR )
+
+template<template<class...> class L, class V> struct mp_find_index_impl<L<>, V>
+{
+    using type = mp_size_t<0>;
+};
+
+constexpr std::size_t cx_find_index( bool const * first, bool const * last )
+{
+    return first == last || *first? 0: 1 + cx_find_index( first + 1, last );
+}
+
+template<template<class...> class L, class... T, class V> struct mp_find_index_impl<L<T...>, V>
+{
+    static constexpr bool _v[] = { std::is_same<T, V>::value... };
+    using type = mp_size_t< cx_find_index( _v, _v + sizeof...(T) ) >;
+};
+
+#else
+
+#if defined( BOOST_MSVC ) && BOOST_WORKAROUND( BOOST_MSVC, <= 1800 )
+
+template<template<class...> class L, class... T, class V> struct mp_find_index_impl<L<T...>, V>
+{
+    static_assert( sizeof...(T) == 0, "T... must be empty" );
+    using type = mp_size_t<0>;
+};
+
+#else
+
+template<template<class...> class L, class V> struct mp_find_index_impl<L<>, V>
+{
+    using type = mp_size_t<0>;
+};
+
+#endif
+
+template<template<class...> class L, class... T, class V> struct mp_find_index_impl<L<V, T...>, V>
+{
+    using type = mp_size_t<0>;
+};
+
+template<template<class...> class L, class T1, class... T, class V> struct mp_find_index_impl<L<T1, T...>, V>
+{
+    using _r = typename mp_find_index_impl<mp_list<T...>, V>::type;
+    using type = mp_size_t<1 + _r::value>;
+};
+
+#endif
+
+} // namespace detail
+
+template<class L, class V> using mp_find_index = typename detail::mp_find_index_impl<L, V>::type;
+
+// mp_find_index_if<L, P>
 // mp_find<L, V>
 // mp_find_if<L, P>
-// mp_find_index<L, V>
-// mp_find_index_if<L, P>
+
 // mp_reverse<L>
 // mp_fold<L, V, F>
 // mp_reverse_fold<L, V, F>
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
index d344063..5deab2a 100644
--- a/test/Jamfile.v2
+++ b/test/Jamfile.v2
@@ -44,6 +44,7 @@ run mp_copy_if.cpp : : : $(REQ) ;
 run mp_remove_if.cpp : : : $(REQ) ;
 run mp_partition.cpp : : : $(REQ) ;
 run mp_sort.cpp : : : $(REQ) ;
+run mp_find_index.cpp : : : $(REQ) ;
 
 # integral
 run integral.cpp : : : $(REQ) ;
diff --git a/test/mp_find_index.cpp b/test/mp_find_index.cpp
new file mode 100644
index 0000000..570f641
--- /dev/null
+++ b/test/mp_find_index.cpp
@@ -0,0 +1,63 @@
+
+//  Copyright 2015 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/core/lightweight_test_trait.hpp>
+#include <type_traits>
+#include <tuple>
+#include <utility>
+
+struct X1 {};
+struct X2 {};
+struct X3 {};
+
+int main()
+{
+    using boost::mp_list;
+    using boost::mp_find_index;
+    using boost::mp_size_t;
+
+    {
+        using L1 = mp_list<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L1, void>, mp_size_t<0>>));
+
+        using L2 = mp_list<X1, X2, X2, X3, X3, X3>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L2, void>, mp_size_t<6>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L2, X1>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L2, X2>, mp_size_t<1>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L2, X3>, mp_size_t<3>>));
+    }
+
+    {
+        using L3 = std::tuple<>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L3, void>, mp_size_t<0>>));
+
+        using L4 = std::tuple<X1, X2, X2, X3, X3, X3>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L4, void>, mp_size_t<6>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L4, X1>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L4, X2>, mp_size_t<1>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L4, X3>, mp_size_t<3>>));
+    }
+
+    {
+        using L5 = std::pair<X1, X2>;
+
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L5, void>, mp_size_t<2>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L5, X1>, mp_size_t<0>>));
+        BOOST_TEST_TRAIT_TRUE((std::is_same<mp_find_index<L5, X2>, mp_size_t<1>>));
+    }
+
+    return boost::report_errors();
+}