Null.h

00001 /*
00002  * Tiny Vector Matrix Library
00003  * Dense Vector Matrix Libary of Tiny size using Expression Templates
00004  *
00005  * Copyright (C) 2001 - 2007 Olaf Petzold <opetzold@users.sourceforge.net>
00006  *
00007  * This library is free software; you can redistribute it and/or
00008  * modify it under the terms of the GNU Lesser General Public
00009  * License as published by the Free Software Foundation; either
00010  * version 2.1 of the License, or (at your option) any later version.
00011  *
00012  * This library is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00015  * Lesser General Public License for more details.
00016  *
00017  * You should have received a copy of the GNU Lesser General Public
00018  * License along with this library; if not, write to the Free Software
00019  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00020  *
00021  * $Id: Null.h,v 1.11 2007-06-23 15:59:00 opetzold Exp $
00022  */
00023 
00024 #ifndef TVMET_XPR_NULL_H
00025 #define TVMET_XPR_NULL_H
00026 
00027 namespace tvmet {
00028 
00029 
00030 /**
00031  * \class XprNull Null.h "tvmet/xpr/Null.h"
00032  * \brief Null object design pattern
00033  */
00034 class XprNull
00035   : public TvmetBase< XprNull >
00036 {
00037   XprNull& operator=(const XprNull&);
00038 
00039 public:
00040   explicit XprNull() { }
00041 
00042 public: // debugging Xpr parse tree
00043   void print_xpr(std::ostream& os, std::size_t l=0) const {
00044     os << IndentLevel(l) << "XprNull[O=0]" << std::endl;
00045   }
00046 };
00047 
00048 
00049 #define TVMET_BINARY_OPERATOR(OP)                               \
00050 template< class T >                                     \
00051 inline                                          \
00052 T operator OP (const T& lhs, XprNull) { return lhs; }
00053 
00054 TVMET_BINARY_OPERATOR(+)
00055 TVMET_BINARY_OPERATOR(-)
00056 TVMET_BINARY_OPERATOR(*)
00057 TVMET_BINARY_OPERATOR(/)
00058 
00059 #undef TVMET_BINARY_OPERATOR
00060 
00061 
00062 } // namespace tvmet
00063 
00064 #endif // TVMET_XPR_NULL_H
00065 
00066 // Local Variables:
00067 // mode:C++
00068 // tab-width:8
00069 // End: