| [/============================================================================== |
| Copyright (C) 2001-2010 Joel de Guzman |
| Copyright (C) 2001-2005 Dan Marsden |
| Copyright (C) 2001-2010 Thomas Heller |
| |
| 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) |
| ===============================================================================/] |
| |
| |
| [section Placeholder Unification] |
| |
| Phoenix uses `boost::is_placeholder` for recognizing placeholders: |
| |
| template <typename T> |
| struct is_placeholder |
| { |
| static const int value = 0; |
| }; |
| |
| To adapt your own placeholder, the nested value needs to be greater than 0 |
| for your types. This is done by specializing this trait. |
| |
| [endsect] |
