Move all tuple_*.h files into sigc++/tuple-utils/

1 files changed, 80 insertions, 0 deletions

diff --git a/sigc++/tuple-utils/tuple_start.h b/sigc++/tuple-utils/tuple_start.h
new file mode 100644
index 0000000..95fda2e
--- /dev/null
+++ b/sigc++/tuple-utils/tuple_start.h
@@ -0,0 +1,80 @@
+/* Copyright (C) 2016 Murray Cumming
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/
+ */
+
+#ifndef SIGC_TUPLE_UTILS_TUPLE_START_H
+#define SIGC_TUPLE_UTILS_TUPLE_START_H
+
+#include <tuple>
+#include <utility>
+
+namespace sigc {
+
+namespace detail {
+
+template <typename T, typename Seq>
+struct tuple_type_start_impl;
+
+template <typename T, std::size_t... I>
+struct tuple_type_start_impl<T, std::index_sequence<I...>> {
+  using type = std::tuple<typename std::tuple_element<I, T>::type...>;
+};
+
+} // detail namespace
+
+/**
+ * Get the type of a tuple with just the first @len items.
+ */
+template <typename T, std::size_t len>
+struct tuple_type_start
+  : detail::tuple_type_start_impl<T, std::make_index_sequence<len>> {};
+
+namespace detail {
+
+template <typename T, typename Seq>
+struct tuple_start_impl;
+
+template <typename T, std::size_t... I>
+struct tuple_start_impl<T, std::index_sequence<I...>> {
+  static decltype(auto)
+  tuple_start(T&& t) {
+    constexpr auto size = std::tuple_size<std::decay_t<T>>::value;
+    constexpr auto len = sizeof...(I);
+    static_assert(len <= size, "The tuple size must be less than or equal to the length.");
+
+    using start = typename tuple_type_start<std::decay_t<T>, len>::type;
+    return start(std::get<I>(std::forward<T>(t))...);
+  }
+};
+
+} // detail namespace
+
+/**
+ * Get the tuple with the last @a len items of the original.
+ */
+template <std::size_t len, typename T>
+decltype(auto) // typename tuple_type_end<T, len>::type
+  tuple_start(T&& t) {
+  //We use std::decay_t<> because tuple_size is not defined for references.
+  constexpr auto size = std::tuple_size<std::decay_t<T>>::value;
+  static_assert(len <= size, "The tuple size must be less than or equal to the length.");
+
+  return detail::tuple_start_impl<T, std::make_index_sequence<len>>::tuple_start(
+    std::forward<T>(t));
+}
+
+} // namespace sigc;
+
+#endif //SIGC_TUPLE_UTILS_TUPLE_START_H