using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Collections;

namespace Interpreter
{
    /// <summary>

    /// MainApp startup class for Structural 

    /// Interpreter Design Pattern.

    /// </summary>
    /// 
    //Given a language, define a representation for its grammar along with an
    //interpreter that uses the representation to interpret sentences in the language.

    class MainApp
    {
        /// <summary>

        /// Entry point into console application.

        /// </summary>

        static void Main()
        {
            Context context = new Context();

            // Usually a tree 

            ArrayList list = new ArrayList();

            // Populate 'abstract syntax tree' 

            list.Add(new TerminalExpression());
            list.Add(new NonterminalExpression());
            list.Add(new TerminalExpression());
            list.Add(new TerminalExpression());

            // Interpret

            foreach (AbstractExpression exp in list)
            {
                exp.Interpret(context);
            }

            // Wait for user

            Console.ReadKey();
        }
    }

    /// <summary>

    /// The 'Context' class

    /// </summary>

    class Context
    {
    }

    /// <summary>

    /// The 'AbstractExpression' abstract class

    /// </summary>

    abstract class AbstractExpression
    {
        public abstract void Interpret(Context context);
    }

    /// <summary>

    /// The 'TerminalExpression' class

    /// </summary>

    class TerminalExpression : AbstractExpression
    {
        public override void Interpret(Context context)
        {
            Console.WriteLine("Called Terminal.Interpret()");
        }
    }

    /// <summary>

    /// The 'NonterminalExpression' class

    /// </summary>

    class NonterminalExpression : AbstractExpression
    {
        public override void Interpret(Context context)
        {
            Console.WriteLine("Called Nonterminal.Interpret()");
        }
    }
}