/**
 * interpreter.h
 * Implemented by Blueprint Technologies, Inc.
 */

#ifndef _interpreter_h
#define _interpreter_h

/**
 * Contains information that's global to the interpreter.
 */

class Context
{
};

/**
 * Declares an abstract Interpret operation that is common
 * to all nodes in the abstract syntax tree.
 */

class AbstractExpression
{

public:
	virtual void interpret( Context* context ) = 0;

};

/**
 * Implements an Interpret operation associated with terminal
 * symbols in the grammar.
 */

class TerminalExpression: public AbstractExpression
{

public:
	virtual void interpret( Context* context )
	{
	};

};

/**
 * One such class is required for every rule in the
 * grammar. Maintains instance variables of type AbstractExpression
 * for each of the symbols.
 */

class NonterminalExpression: public AbstractExpression
{

private:
	AbstractExpression* next;

public:
	NonterminalExpression(): 
	  AbstractExpression(), next(0) {};

	virtual void interpret( Context* context )
	{
		//
		// Interpret your portion here.
		//

		// Call the next interpreter if we have one.

		if( next ) next -> interpret( context );
	};

	void setNext( AbstractExpression* next )
	{
		this -> next = next;
	};

	AbstractExpression* getNext()
	{
		return next;
	};

};

#endif