Added boost header

test/external/boost/proto/transform/lazy.hpp

@@ -0,0 +1,52 @@
+///////////////////////////////////////////////////////////////////////////////
+/// \file lazy.hpp
+/// Contains definition of the lazy<> transform.
+//
+//  Copyright 2008 Eric Niebler. 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)
+
+#ifndef BOOST_PROTO_TRANSFORM_LAZY_HPP_EAN_12_02_2007
+#define BOOST_PROTO_TRANSFORM_LAZY_HPP_EAN_12_02_2007
+
+#include <boost/preprocessor/iteration/iterate.hpp>
+#include <boost/preprocessor/repetition/enum_params.hpp>
+#include <boost/preprocessor/repetition/enum_trailing_params.hpp>
+#include <boost/proto/proto_fwd.hpp>
+#include <boost/proto/transform/make.hpp>
+#include <boost/proto/transform/call.hpp>
+#include <boost/proto/transform/impl.hpp>
+
+namespace boost { namespace proto
+{
+    /// \brief A PrimitiveTransform that uses <tt>make\<\></tt> to build
+    /// a CallableTransform, and then uses <tt>call\<\></tt> to apply it.
+    ///
+    /// <tt>lazy\<\></tt> is useful as a higher-order transform, when the
+    /// transform to be applied depends on the current state of the
+    /// transformation. The invocation of the <tt>make\<\></tt> transform
+    /// evaluates any nested transforms, and the resulting type is treated
+    /// as a CallableTransform, which is evaluated with <tt>call\<\></tt>.
+    template<typename Object>
+    struct lazy : transform<lazy<Object> >
+    {
+        template<typename Expr, typename State, typename Data>
+        struct impl
+          : call<
+                typename make<Object>::template impl<Expr, State, Data>::result_type
+            >::template impl<Expr, State, Data>
+        {};
+    };
+
+    #include <boost/proto/transform/detail/lazy.hpp>
+
+    /// INTERNAL ONLY
+    ///
+    template<typename Object>
+    struct is_callable<lazy<Object> >
+      : mpl::true_
+    {};
+
+}}
+
+#endif