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

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

@@ -0,0 +1,60 @@
+/*!
+@file
+Forward declares `boost::hana::drop_while`.
+
+@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_DROP_WHILE_HPP
+#define BOOST_HANA_FWD_DROP_WHILE_HPP
+
+#include <boost/hana/config.hpp>
+#include <boost/hana/core/when.hpp>
+
+
+BOOST_HANA_NAMESPACE_BEGIN
+    //! Drop elements from an iterable up to, but excluding, the first
+    //! element for which the `predicate` is not satisfied.
+    //! @ingroup group-Iterable
+    //!
+    //! Specifically, `drop_while` returns an iterable containing all the
+    //! elements of the original iterable except for those in the range
+    //! delimited by [`head`, `e`), where `head` is the first element and
+    //! `e` is the first element for which the `predicate` is not satisfied.
+    //! If the iterable is not finite, the `predicate` has to return a false-
+    //! valued `Logical` at a finite index for this method to return.
+    //!
+    //!
+    //! @param iterable
+    //! The iterable from which elements are dropped.
+    //!
+    //! @param predicate
+    //! A function called as `predicate(x)`, where `x` is an element of the
+    //! structure, and returning a `Logical` representing whether `x` should
+    //! be dropped from the structure. In the current version of the library,
+    //! `predicate` should return a compile-time `Logical`.
+    //!
+    //!
+    //! Example
+    //! -------
+    //! @include example/drop_while.cpp
+#ifdef BOOST_HANA_DOXYGEN_INVOKED
+    constexpr auto drop_while = [](auto&& iterable, auto&& predicate) {
+        return tag-dispatched;
+    };
+#else
+    template <typename It, typename = void>
+    struct drop_while_impl : drop_while_impl<It, when<true>> { };
+
+    struct drop_while_t {
+        template <typename Xs, typename Pred>
+        constexpr auto operator()(Xs&& xs, Pred&& pred) const;
+    };
+
+    constexpr drop_while_t drop_while{};
+#endif
+BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_FWDDROP_WHILE_HPP