package edu.vt.marian.search;

import java.util.*;
import java.io.*;

import edu.vt.marian.common.*;


/**
	Scaled Weighted Object Set.  A transformation of some other WtdObjSet
		where every element has been scaled by the same factor.

	@author Robert France
	@see WtdObjSet
*/
public class ScaledWtdObjSet implements WtdObjSet
{
	protected Debug debug;
	protected WtdObjSet set;
	protected Weight scFactor;

	/**
		Enumeration for a Scaled Weighted Object Set.
		<P>
		<B>NOTE:</B>  We presume that the base Enumeration is creating new WtdObjs for
			distribution to the outside world.  Thus we only need to scale them, not
			copy them.  Nor do we need to copy the baseEnumeration in the constructor,
			as it is ours and ours alone.
		<P>
			   In this implementation, each Enumeration does its
			own scaling.  This is potentially wasteful if the set
			spawns many Enumerations.  We don't really expect this
			to happen, but if it does some cache should be added.
		<P>
		<B>Synchronization Note:</B>  baseEnumeration should alrady be synchronizing 
			calls to all at-risk methods, so this does not.

		@author Robert France
		@see WtdObjSetEnumeration
	*/

	public class Enum implements WtdObjSetEnumeration
	{
		protected WtdObjSetEnumeration baseEnum;

		public Enum(WtdObjSetEnumeration baseEnumeration)
		{
			baseEnum = baseEnumeration;
		}


		public Object nextElement() throws NoSuchElementException
		{
			WtdObj nextObj = (WtdObj) baseEnum.nextElement();
			nextObj.scale(scFactor);
			return( nextObj );
		}

		public boolean hasMoreElements()
		{
			return( baseEnum.hasMoreElements() );
		}

		public void skip(int k)
		{
			baseEnum.skip(k);
		}

  		public int sample(int num, WtdObjBag sampleBag)
		{
			int base = sampleBag.size();
			int Err = baseEnum.sample(num, sampleBag);
			int i;						// We cannot simply use 
			for (i=base; i<sampleBag.size(); i++)		//  WtdObjBag.scale()
				((WtdObj) sampleBag.elementAt(i)).scale(scFactor);	//  because that would 
			return(Err);					//  also scale anything
		}							//  already in sampleBag.

  		public int sampleToWt(Weight minWt, WtdObjBag sampleBag)
		{
			int base = sampleBag.size();
			int Err = baseEnum.sampleToWt(minWt, sampleBag);
			int i;						// We cannot simply use 
			for (i=base; i<sampleBag.size(); i++)		//  WtdObjBag.scale()
				((WtdObj) sampleBag.elementAt(i)).scale(scFactor);	//  because that would 
			return(Err);					//  also scale anything
		}							//  already in sampleBag.


		public int exactNumRemaining()
		{
			return( baseEnum.exactNumRemaining() );
		}

		public int approxNumRemaining()
		{
			return( baseEnum.approxNumRemaining() );
		}

		public int maxNumRemaining()
		{
			return( baseEnum.maxNumRemaining() );
		}

	}	// end ScaledWtdObjSet.Enum


	public ScaledWtdObjSet(WtdObjSet baseSet, Weight scalingFactor, Debug d)
	{
		debug = d;
		set = baseSet;
		scFactor = scalingFactor;
	}

	// Each of the WtdObjSet methods get passed to set, and the results
	//  scaled by scFactor.
	public WtdObjSetEnumeration elements()
	{
		return( new Enum(set.elements()) );
	}


	public boolean isEmpty()
	{
		return( set.isEmpty() );
	}

	public Weight isElt(FullID ID)
	{
		return( set.isElt(ID) );
	}


	public int exactSize()
	{
		return( set.exactSize() );
	}

	public int approxSize()
	{
		return( set.approxSize() );
	}

	public int maxSize()
	{
		return( set.maxSize() );
	}


	public String toString()
	{
		String baseStr = set.toString();
		return( new String("{" + scFactor + "*" + baseStr + "}") );
	}

	public String profile()
	{
		String baseStr = set.profile();
		return( new String("{" + scFactor + "*" + baseStr + "}") );
	}

}