code: //==============================================================================
  //	
  //	Copyright (c) 2016-
  //	Authors:
  //	* Steffen Maercker <maercker@tcs.inf.tu-dresden.de> (TU Dresden)
  //	* Joachim Klein <klein@tcs.inf.tu-dresden.de> (TU Dresden)
  //	
  //------------------------------------------------------------------------------
  //	
  //	This file is part of PRISM.
  //	
  //	PRISM is free software; you can redistribute it and/or modify
  //	it under the terms of the GNU General Public License as published by
  //	the Free Software Foundation; either version 2 of the License, or
  //	(at your option) any later version.
  //	
  //	PRISM is distributed in the hope that it will be useful,
  //	but WITHOUT ANY WARRANTY; without even the implied warranty of
  //	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  //	GNU General Public License for more details.
  //	
  //	You should have received a copy of the GNU General Public License
  //	along with PRISM; if not, write to the Free Software Foundation,
  //	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  //	
  //==============================================================================
  
  package explicit;
  
  import java.util.BitSet;
  import java.util.function.IntFunction;
  
  import common.IterableBitSet;
  import parser.type.TypeBool;
  import parser.type.TypeDouble;
  import parser.type.TypeInt;
  import prism.PrismException;
  
  /**
   * Base class for model transformations, providing support for mapping between states.
   */
  public class BasicModelTransformation<OM extends Model, TM extends Model> implements ModelTransformation<OM, TM>
  {
  	public static final IntFunction<Integer> IDENTITY = Integer::valueOf;
  
  	public static final boolean DEFAULT_BOOLEAN = false;
  	public static final double DEFAULT_DOUBLE   = Double.NaN;
  	public static final int DEFAULT_INTEGER     = -1;
  
  	protected final OM originalModel;
  	protected final TM transformedModel;
  	protected final IntFunction<Integer> mapToTransformedModel;
  
  	protected final int numberOfStates;
  
  	/** Constructor for a model transformation that maps states one-on-one. */
  	public BasicModelTransformation(final OM originalModel, final TM transformedModel)
  	{
  		this(originalModel, transformedModel, IDENTITY);
  	}
  
  	/**
  	 * Constructor for a model transformation where the state mapping is given
  	 * by a function
  	 */
  	public BasicModelTransformation(final OM originalModel, final TM transformedModel, final IntFunction<Integer> mapToTransformedModel)
  	{
  		this.originalModel               = originalModel;
  		this.transformedModel            = transformedModel;
  		this.numberOfStates              = originalModel.getNumStates();
  		this.mapToTransformedModel       = mapToTransformedModel;
  	}
  
  	@Override
  	public OM getOriginalModel()
  	{
  		return originalModel;
  	}
  
  	@Override
  	public TM getTransformedModel()
  	{
  		return transformedModel;
  	}
  
  	@Override
  	public StateValues projectToOriginalModel(final StateValues sv) throws PrismException
  	{
  		if (sv.getType() instanceof TypeBool) {
  			assert(sv.getBitSet() != null) : "State values are undefined.";
  
  			final BitSet mapped = projectToOriginalModel(sv.getBitSet());
  			return StateValues.createFromBitSet(mapped, originalModel);
  		}
  		if (sv.getType() instanceof TypeDouble) {
  			assert(sv.getDoubleArray() != null) : "State values are undefined.";
  
  			final double[] mapped = projectToOriginalModel(sv.getDoubleArray());
  			return StateValues.createFromDoubleArray(mapped, originalModel);
  		}
  		if (sv.getType() instanceof TypeInt) {
  			assert(sv.getIntArray() != null) : "State values are undefined.";
  
  			final int[] mapped = projectToOriginalModel(sv.getIntArray());
  			return StateValues.createFromIntegerArray(mapped, originalModel);
  		}
  		throw new PrismException("Unsupported type of state values");
  	}
  
  	public BitSet projectToOriginalModel(final BitSet values)
  	{
  		final BitSet result = new BitSet(numberOfStates);
  
  		for (int state = 0; state < numberOfStates; state++) {
  			final Integer mappedState = mapToTransformedModel(state);
  			final boolean mappedValue = (mappedState == null) ? DEFAULT_BOOLEAN : values.get(mappedState);
  			result.set(state, mappedValue);
  		}
  		return result;
  	}
  
  	public double[] projectToOriginalModel(final double[] values)
  	{
  		final double[] result = new double[numberOfStates];
  
  		for (int state = 0; state < numberOfStates; state++) {
  			final Integer mappedState = mapToTransformedModel(state);
  			final double mappedValue = (mappedState == null) ? DEFAULT_DOUBLE : values[mappedState];
  			result[state] = mappedValue;
  		}
  		return result;
  	}
  
  	public int[] projectToOriginalModel(final int[] values)
  	{
  		final int[] result = new int[numberOfStates];
  
  		for (int state = 0; state < numberOfStates; state++) {
  			final Integer mappedState = mapToTransformedModel(state);
  			final int mappedValue = (mappedState == null) ? DEFAULT_INTEGER : values[mappedState];
  			result[state] = mappedValue;
  		}
  		return result;
  	}
  
  	public Integer mapToTransformedModel(final int state)
  	{
  		if (state >= numberOfStates) {
  			throw new IndexOutOfBoundsException("State index does not belong to original model.");
  		}
  		return mapToTransformedModel.apply(state);
  	}
  
  	public BitSet mapToTransformedModel(final BitSet states)
  	{
  		final BitSet result = new BitSet();
  
  		for (int state : new IterableBitSet(states)) {
  			final Integer mappedState = mapToTransformedModel(state);
  			if (mappedState != null) {
  				result.set(mappedState);
  			}
  		}
  		return result;
  	}
  
  }
  