stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

depends/x86_64-pc-linux-gnu/include/boost/hana/fwd/intersperse.hpp

@@ -0,0 +1,57 @@
+/*!
+@file
+Forward declares `boost::hana::intersperse`.
+
+@copyright Louis Dionne 2013-2017
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_FWD_INTERSPERSE_HPP
+#define BOOST_HANA_FWD_INTERSPERSE_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Insert a value between each pair of elements in a finite sequence.
+    //! @ingroup group-Sequence
+    //!
+    //! Given a finite `Sequence` `xs` with a linearization of
+    //! `[x1, x2, ..., xn]`, `intersperse(xs, z)` is a new sequence with a
+    //! linearization of `[x1, z, x2, z, x3, ..., xn-1, z, xn]`. In other
+    //! words, it inserts the `z` element between every pair of elements of
+    //! the original sequence. If the sequence is empty or has a single
+    //! element, `intersperse` returns the sequence as-is. In all cases,
+    //! the sequence must be finite.
+    //!
+    //!
+    //! @param xs
+    //! The sequence in which a value is interspersed.
+    //!
+    //! @param z
+    //! The value to be inserted between every pair of elements of the sequence.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/intersperse.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    constexpr auto intersperse = [](auto&& xs, auto&& z) {
+        return tag-dispatched;
+    };
+#else
+    template <typename S, typename = void>
+    struct intersperse_impl : intersperse_impl<S, when<true>> { };
+
+    struct intersperse_t {
+        template <typename Xs, typename Z>
+        constexpr auto operator()(Xs&& xs, Z&& z) const;
+    };
+
+    constexpr intersperse_t intersperse{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWD_INTERSPERSE_HPP