code: //==============================================================================
  //	
  //	Copyright (c) 2013-
  //	Authors:
  //	* Ernst Moritz Hahn <emhahn@cs.ox.ac.uk> (University of Oxford)
  //	
  //------------------------------------------------------------------------------
  //	
  //	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 param;
  
  /**
   * TODO implement completely
   * @author Ernst Moritz Hahn <emhahn@cs.ox.ac.uk> (University of Oxford)
   */
  public class DagFunction extends Function {
  	private DagFunctionFactory dagFactory;
  	private DagOperator num;
  	private DagOperator den;
  	int type;
  	final static int NORMAL = 0;
  	final static int INF = 1;
  	final static int MINF = 2;
  	final static int NAN = 3;
  	
  	public DagFunction(FunctionFactory factory, DagOperator num, DagOperator den) {
  		super(factory);
  		dagFactory = (DagFunctionFactory) factory;
  		this.num = num;
  		this.den = den;
  		this.type = NORMAL;
  	}
  	
  	public DagFunction(FunctionFactory factory, int type) {
  		super(factory);
  		this.type = type;
  		num = null;
  		den = null;
  	}	
  
  	public DagOperator getNum() {
  		return num;
  	}
  	
  	public DagOperator getDen() {
  		return den;
  	}
  	
  	@Override
  	public boolean equals(Object obj) {
  		if (!(obj instanceof DagFunction)) {
  			return false;
  		}
  		DagFunction other = (DagFunction) obj;
  		if (this.type != NORMAL) {
  			return this.type == other.type;
  		}
  		if (other.type != NORMAL) {
  			return false;
  		}
  		
  		BigRational thisRat = new BigRational(this.num.getCValue(), this.den.getCValue());
  		BigRational otherRat = new BigRational(other.num.getCValue(), other.den.getCValue());
  		return thisRat.equals(otherRat);
  	}
  	
  	@Override
  	public int hashCode() {
  		if (type != NORMAL) {
  			return type;
  		}
  		BigRational thisRat = new BigRational(num.getCValue(), den.getCValue());
  		return thisRat.hashCode();
  	}
  
  	
  	@Override
  	public Function add(Function other) {
  		return dagFactory.add(this, (DagFunction) other);
  	}
  
  	@Override
  	public Function negate() {
  		return dagFactory.negate(this);
  	}
  	
  	@Override
  	public Function subtract(Function other) {
  		return dagFactory.subtract(this, (DagFunction) other);
  	}
  
  	@Override
  	public Function multiply(Function other) {
  		return dagFactory.multiply(this, (DagFunction) other);
  	}
  
  	@Override
  	public Function divide(Function other) {
  		return dagFactory.divide(this, (DagFunction) other);
  	}
  
  	@Override
  	public Function star() {
  		return dagFactory.star(this);
  	}
  
  	@Override
  	public Function toConstraint() {
  		return dagFactory.toConstraint(this);
  	}
  
  	@Override
  	public BigRational evaluate(Point point, boolean cancel) {
  		BigRational result = dagFactory.evaluate(this, point, cancel);
  		return result;
  	}
  
  	@Override
  	public BigRational asBigRational() {
  		switch (type) {
  		case NORMAL:
  			return dagFactory.asBigRational(this);
  		case NAN:
  			return BigRational.NAN;
  		case INF:
  			return BigRational.INF;
  		case MINF:
  			return BigRational.MINF;
  		}
  		throw new RuntimeException("Illegal type");
  	}
  
  	@Override
  	public boolean isNaN() {
  		return type == NAN;
  	}
  
  	@Override
  	public boolean isInf() {
  		return type == INF;
  	}
  
  	@Override
  	public boolean isMInf() {
  		return type == MINF;
  	}
  
  	@Override
  	public boolean isOne() {
  		return dagFactory.isOne(this);
  	}
  
  	@Override
  	public boolean isZero() {
  		return dagFactory.isZero(this);
  	}
  	
  	@Override
  	public String toString() {
  		return dagFactory.toString(this);
  	}
  
  	public int getType() {
  		return type;
  	}
  
  	@Override
  	public boolean isConstant()
  	{
  		if (type != NORMAL)
  			return true;
  
  		return dagFactory.isConstant(num) && dagFactory.isConstant(den);
  	}
  }
  