How to build an in-memory state engine at runtime

//	Copyright � 2007, solosTec
//  All rights reserved.
//---------------------------------------------------------------------
//	License for redistribution is the GNU General Public License v2.
//	See the included readme.txt for details.
//---------------------------------------------------------------------
//	developed by solosTec
//	http://www.solostec.de
//---------------------------------------------------------------------
//
//	$Author: $
//	$Revision: $
/*	$Log: $
*/
//---------------------------------------------------------------------

//#define _WIN32_WINNT 0x0501
#include <iostream>
#include <string>
#include <container/tag_tree.h>

/**
*	Simulate a data source (file or socket). Note that there is 
*	no <code>back()</code> or <code>previous()</code> method required.
*/
class Source
{
public:
	Source();
	char next();
	size_t position() const;

private:
	char const* content_;
	char *  pos_;
};

/**
*	Scanner for a specific syntax.
*/
class Scanner
{
public:
	typedef enum 
	{
		KEY_UNKNOWN,
		KEY_EOS,
		KEY_KEYWORD, 
		KEY_STRING,
		KEY_AND,
	} KEY;

	typedef turban::container::tag_tree < std::string, KEY >	TagTree_;
	typedef TagTree_::MyPtr_	TagTreePtr_;

public:
	Scanner();
	void run( Source& );

private:
	KEY consume( Source& );

private:
	TagTree_	tagTree_;
};