/* Tomas George Bogdan
 * Problema 1 - TDA Lista
 */
package Liste;
import java.io.*;
import java.util.*;

public class ListaInlantuita implements Lista
{

	protected Element start = null;


	public Object primul()
		{
   		return start == null ? null : start.info();
		}

   public boolean esteVida()
    	{
     		return start == null;
  	 	}

	public boolean estePlina()
    	{
     	 	return false;
   	}

   public void adaugaInceput(Object x)
      {
     		if(x == null)
     			return;
        	if( !estePlina())
        		start = new Element(x, start);
   	}

   /*metoda recursiva care parcurge lista si returneaza adresa
    *ultimului element. Necesara pentru metoda adaugaSfarsit
    */
   public Element ultimul(Element p)
   	{
   		if(p == null || p.urmator() == null)
   			return p;
   		else
			return ultimul(p.urmator());
   	}

	public void adaugaSfarsit(Object x)
		{
			if(x == null)
				return;
			if( esteVida())
				{
					this.adaugaInceput(x);
					return;
				}
			if( !estePlina())
				(ultimul(start)).urm = new Element(x, null);
		}

   public void stergePrimul()
    	{
     		if( !esteVida())
        	 	start = start.urmator();
    	}

   public String toString()
    	{
    		String sir;

       	if( esteVida())
         	sir = " ListaInlantuita vida";
       	else
       		{
    	  			sir = "{";

           		for(Element p = start; p != null; p = p.urmator())
           			{
              			sir += "" + p;
              			if(p.urmator() != null)
              				sir += ", ";
        				}
           		sir += "}";
      		}
      	return sir;
		}

	public void afisare(String text)
		{
			System.out.println(text + this);
		}

	public void citireFisier(String numeFis) throws IOException
		{
			String text;

			try
		   	{
			 		BufferedReader bf = new BufferedReader(
			 					  new FileReader(numeFis));

					while( (text = bf.readLine()) != null)
				  		{
			  		  		StringTokenizer st = new StringTokenizer(text," \n\r\t");

					  		while(st.hasMoreTokens())
						  		this.adaugaInceput(new Integer(st.nextToken()));
				  		}
			   }catch(FileNotFoundException s) {
			   				System.out.println("Eroare la deschiderea fisierului " + numeFis); }
		}

	public ListaInlantuita elemNegative()
		{
			ListaInlantuita rezultat = new ListaInlantuita();

			for(Element p = start; p != null; p = p.urmator())
	            if( ( (Integer)p.info() ).intValue() < 0 )
					rezultat.adaugaSfarsit( (Integer)p.info() );
			return rezultat;
		}

	public ListaInlantuita elemPozitive()
		{
			ListaInlantuita rezultat = new ListaInlantuita();

			for(Element p = start; p != null; p = p.urmator())
	      	  	if( ( (Integer)p.info() ).intValue() > 0 )
					rezultat.adaugaSfarsit( (Integer)p.info() );
			return rezultat;
		}

	public ListaInlantuita concatenare(ListaInlantuita l)
		{
			ListaInlantuita rezultat = new ListaInlantuita();

			if( !this.esteVida())
		   		for(Element p = start; p != null; p = p.urmator())
           			rezultat.adaugaSfarsit((Integer)p.info());

		    if( !l.esteVida())
         		for(Element p = l.start; p != null; p = p.urmator())
	           		rezultat.adaugaSfarsit((Integer)p.info());
			return rezultat;
		}
}