factor out placeholder for a (planned) Symbol datatype

src/common/query.hpp

@@ -30,15 +30,16 @@
 
 #include <boost/format.hpp>
 
+#include "include/symbol.hpp"
+
+
+namespace lumiera {
 
-namespace lumiera
-  {
   using std::string;
   using boost::format;
 
-  /* ==== comon definitions for rule based queries ==== */
+  /* ==== common definitions for rule based queries ==== */
   
-  typedef const char * const Symbol;  
       
 
   /** 

src/include/symbol.hpp

@@ -0,0 +1,54 @@
+/*
+  SYMBOL.hpp  -  symbolic constant datatype 
+ 
+  Copyright (C)         Lumiera.org
+    2008,               Hermann Vosseler <Ichthyostega@web.de>
+ 
+  This program is free software; you can redistribute it and/or
+  modify it under the terms of the GNU General Public License as
+  published by the Free Software Foundation; either version 2 of the
+  License, or (at your option) any later version.
+ 
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+ 
+  You should have received a copy of the GNU General Public License
+  along with this program; if not, write to the Free Software
+  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ 
+*/
+
+/** @file symbol.hpp
+ ** WIP placeholder definition for a planned Symbol datatype.
+ ** 
+ ** @todo the (currently just planned as of 11/08) rules based configuration
+ ** in the Proc-Layer a explicit Symbol datatype will probably very helpful.
+ ** For now we just a typedef is sufficient. A real Symbol datatype should 
+ ** - be definable by string constant
+ ** - integrate smoothly with std::string
+ ** - provide a unique numeric index for each distinct Symbol
+ ** - automatically maintain a symbol table at runtime to support this
+ ** - provide some magic (macros) allowing to build distinct types based on symbols.
+ ** 
+ ** @see configrules.hpp
+ ** @see query.hpp
+ */
+
+
+#ifndef LUMIERA_SYMBOL_H
+#define LUMIERA_SYMBOL_H
+
+
+
+
+namespace lumiera {
+  
+  typedef const char * const Symbol;  //TODO define a real Symbol class, i.e. same literal string==same pointer,
+
+  
+  
+} // namespace lumiera
+
+#endif