00001 /* 00002 QoreNullNode.h 00003 00004 Qore Programming Language 00005 00006 Copyright 2003 - 2009 David Nichols 00007 00008 This library is free software; you can redistribute it and/or 00009 modify it under the terms of the GNU Lesser General Public 00010 License as published by the Free Software Foundation; either 00011 version 2.1 of the License, or (at your option) any later version. 00012 00013 This library is distributed in the hope that it will be useful, 00014 but WITHOUT ANY WARRANTY; without even the implied warranty of 00015 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00016 Lesser General Public License for more details. 00017 00018 You should have received a copy of the GNU Lesser General Public 00019 License along with this library; if not, write to the Free Software 00020 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA 00021 */ 00022 00023 #ifndef _QORE_QORENULLNODE_H 00024 00025 #define _QORE_QORENULLNODE_H 00026 00027 #include <qore/AbstractQoreNode.h> 00028 00033 00034 00041 class QoreNullNode : public UniqueValueQoreNode 00042 { 00043 protected: 00045 00047 DLLLOCAL AbstractQoreNode *evalImpl(class ExceptionSink *xsink) const; 00048 00049 public: 00050 DLLEXPORT QoreNullNode(); 00051 00052 DLLEXPORT virtual ~QoreNullNode(); 00053 00055 00061 DLLEXPORT virtual int getAsString(QoreString &str, int foff, class ExceptionSink *xsink) const; 00062 00064 00071 DLLEXPORT virtual QoreString *getAsString(bool &del, int foff, class ExceptionSink *xsink) const; 00072 00074 00078 DLLEXPORT virtual bool is_equal_soft(const AbstractQoreNode *v, ExceptionSink *xsink) const; 00079 00081 00085 DLLEXPORT virtual bool is_equal_hard(const AbstractQoreNode *v, ExceptionSink *xsink) const; 00086 00088 DLLEXPORT virtual const char *getTypeName() const; 00089 00090 DLLLOCAL static const char *getStaticTypeName() 00091 { 00092 return "NULL"; 00093 } 00094 }; 00095 00097 static inline bool is_null(const AbstractQoreNode *n) 00098 { 00099 // this is faster than a dynamic_cast<const QoreNullNode *> operation 00100 return n && n->getType() == NT_NULL; 00101 } 00102 00104 DLLEXPORT extern QoreNullNode Null; 00105 00107 static inline QoreNullNode *null() 00108 { 00109 return &Null; 00110 } 00111 00112 #endif