/* -*- C++ -*- */

#ifndef _EXPRESSION_TREE_COMMAND_H_

#define _EXPRESSION_TREE_COMMAND_H_

#include "Refcounter.h"

#include "Expression_Tree_Command_Impl.h"

/**

* @class Expression_Tree_Command

* @brief Interface for the Command pattern to define a command that

* performs an operation on the expression tree when executed.

*

* Plays the role of the "abstraction" class in the Bridge

* pattern and delegates to the appropriate "implementor"

* class that performs the command.

*/

class Expression_Tree_Command

{

public:

/// Constructor that assumes ownership of an @a Expression_Tree_Command_Impl *.

Expression_Tree_Command (Expression_Tree_Command_Impl * = 0);

/// Copy ctor.

Expression_Tree_Command (const Expression_Tree_Command &);

/// Assignment operator.

Expression_Tree_Command &operator= (const Expression_Tree_Command &);

/// Dtor.

~Expression_Tree_Command (void);

/// Runs the command.

bool execute (void);

/// Print the valid commands available to users.

void print_valid_commands (void);

private:

/// Pointer to actual implementation, i.e., the "bridge", which is

/// reference counted to automate memory management.

Refcounter <Expression_Tree_Command_Impl> command_impl_;

};

#endif /* _EXPRESSION_TREE_COMMAND_H_ */