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

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

@@ -0,0 +1,60 @@
+/*!
+@file
+Forward declares `boost::hana::find`.
+
+@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_FIND_HPP
+#define BOOST_HANA_FWD_FIND_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Finds the value associated to the given key in a structure.
+    //! @ingroup group-Searchable
+    //!
+    //! Given a `key` and a `Searchable` structure, `find` returns the `just`
+    //! the first value whose key is equal to the given `key`, or `nothing` if
+    //! there is no such key. Comparison is done with `equal`. `find` satisfies
+    //! the following:
+    //! @code
+    //!     find(xs, key) == find_if(xs, equal.to(key))
+    //! @endcode
+    //!
+    //!
+    //! @param xs
+    //! The structure to be searched.
+    //!
+    //! @param key
+    //! A key to be searched for in the structure. The key has to be
+    //! `Comparable` with the other keys of the structure. In the current
+    //! version of the library, the comparison of `key` with any other key
+    //! of the structure must return a compile-time `Logical`.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/find.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    constexpr auto find = [](auto&& xs, auto const& key) {
+        return tag-dispatched;
+    };
+#else
+    template <typename S, typename = void>
+    struct find_impl : find_impl<S, when<true>> { };
+
+    struct find_t {
+        template <typename Xs, typename Key>
+        constexpr auto operator()(Xs&& xs, Key const& key) const;
+    };
+
+    constexpr find_t find{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWD_FIND_HPP