com.exigen.ie.constrainer.GoalGenerate Maven / Gradle / Ivy

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package com.exigen.ie.constrainer;

///////////////////////////////////////////////////////////////////////////////
/*
 * Copyright Exigen Group 1998, 1999, 2000
 * 320 Amboy Ave., Metuchen, NJ, 08840, USA, www.exigengroup.com
 *
 * The copyright to the computer program(s) herein
 * is the property of Exigen Group, USA. All rights reserved.
 * The program(s) may be used and/or copied only with
 * the written permission of Exigen Group
 * or in accordance with the terms and conditions
 * stipulated in the agreement/contract under which
 * the program(s) have been supplied.
 */
///////////////////////////////////////////////////////////////////////////////

import com.exigen.ie.tools.FastVector;

/**
 * An implementation of a {@link Goal} that generates a solution
 * for the problem with the unknown integer variables.
 * 
 * This goal:
 * 

 * Selects the variable using {@link IntVarSelector}.
 * 
Tries to instantiate it using {@link GoalInstantiate}.
 *     GoalInstantiate make use of IntValueSelector taken from a constructor of GoalGenerate
 *     to work with the domain of a variable.
 * 
 * @see IntVarSelector
 * @see IntValueSelector
 * @see GoalInstantiate
 */
public class GoalGenerate extends GoalImpl
{
  private IntExpArray      _intvars;
  private IntVarSelector   _var_selector;
  private boolean          _dichotomize;
  private IntValueSelector _value_selector;
  private boolean          _recursiveInstantiate = true;

  /**
   * Returns true if the instantiation goals are recursive.
   */
  public boolean recursiveInstantiate()
  {
    return _recursiveInstantiate;
  }

  /**
   * Sets the recursive flag for the instantiation goals.
   */
  public void recursiveInstantiate(boolean recursive)
  {
    _recursiveInstantiate = recursive;
    initGoals();
  }

  /**
   * The search goals that instantiate each variable.
   */
  private FastVector _goals;

  /**
   * Constructor with a given array of variables.
   * GoalGenerate will be constructed with IntVarSelectorFirstUnbound
   * as a default variable selector and IntValueSelectorMin as a
   * default value selector and it won't use dichotomize.
   */
  public GoalGenerate(IntExpArray intvars)
  {
    this(intvars, null,  null, false);
  }

  /**
   * GoalGenerate will be constructed with IntVarSelectorFirstUnbound
   * as a default variable selector and IntValueSelectorMin as a
   * default value selector.
   */
  public GoalGenerate(IntExpArray intvars, boolean dichotomize)
  {
    this(intvars, null,  null, dichotomize);
  }

  /**
   * Constructor with a given array of variables, variable selector, and value selector.
   * GoalGenerate constructed that way won't use dichotomize procedure.
   */
  public GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, IntValueSelector value_selector)
  {
    this(intvars, var_selector, value_selector, false);
  }

  /**
   * Constructor with a given array of variables, variable selector, and "dichotomize" parameter.
   */
  public GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, boolean dichotomize)
  {
    this(intvars, var_selector, null, dichotomize);
  }

  /**
   * Constructor with full (and redundant) set of parameters.
   */
  GoalGenerate(IntExpArray intvars, IntVarSelector var_selector, IntValueSelector value_selector, boolean dichotomize)
  {
    super(intvars.constrainer(), "Generate");
    _intvars = intvars;
    _dichotomize = dichotomize;

    _var_selector = ( var_selector != null ?  var_selector :
                                              new IntVarSelectorFirstUnbound(intvars) );

    _value_selector = ( dichotomize            ? null :
                        value_selector != null ? value_selector :
                                                 new IntValueSelectorMin() );
    initGoals();
  }

  /**
   * Returns the array of the variables for this goal.
   */
  public IntExpArray vars()
  {
    return _intvars;
  }

  /**
   * Initializes an array of instantiation goals for the variables.
   */
  void initGoals()
  {
    int size = _intvars.size();
    _goals = new FastVector(size);
    for(int i=0; i < size; i++)
    {
      IntVar var = (IntVar)_intvars.elementAt(i);
      Goal goal;
      if (_dichotomize)
      {
        goal = new GoalDichotomize(var,_recursiveInstantiate);
      }
      else
      {
        goal = new GoalInstantiate(var,_value_selector,_recursiveInstantiate);
      }
      _goals.addElement(goal);
    }
  }

  /**
   * Returns a String representation of this goal.
   * @return a String representation of this goal.
   */
  public String toString()
  {
    return  "Generate("+_intvars.size()+")";
  }

  /**
   * Instantiates all variables in the order defined by the IntVarSelector.
   */
  public Goal execute() throws Failure
  {
    //Debug.on();Debug.print("Generate"+_intvars);Debug.off();
    int index = _var_selector.select();
    if (index == -1)
      return null; // all vars are instantiated

//    IntVar var = (IntVar)_intvars.elementAt(index);
//    Debug.on();Debug.print("Var Selected:"+var);Debug.off();

    Goal search_goal = (Goal)_goals.elementAt(index);

    return new GoalAnd(search_goal,this);
  }

} // ~GoalGenerate