ParameterSpec.java

package bsearch.space;

import org.nlogo.api.LogoList;
import org.nlogo.util.MersenneTwisterFast;

/**
 *  Note: the Objects need to be types that NetLogo understands
 *   (e.g. Double, String, LogoList, Boolean...) 
 */
public strictfp abstract class ParameterSpec {
	String name;
	
	public ParameterSpec(String name)
	{
		this.name = name;
	}
	public String getParameterName()
	{
		return name;
	}
	public abstract Object generateRandomValue(MersenneTwisterFast rng);
	public abstract Object mutate(Object obj, double mutStrength, MersenneTwisterFast rng);

	public abstract Object getValueFromChoice(long choice, long maxNumChoices);
	public abstract long getChoiceIndexFromValue(Object val, long maxNumChoices);
	/**
	 * The special value -1 indicates a continuous parameter.
	 */
	public abstract int choiceCount();
	//	public abstract Object enforceValid(Object obj1); 
	
	
	//TODO: Hmm, for BITSTRING type, we could do crossover at the gene level too. 
	//public abstract T crossover(T obj1, T obj2, MersenneTwisterFast rng);
	
	
	/**
	 * Takes a textual parameter specification, and gives back an appropriate ParameterSpec object 
	 * @param paramString
	 */
	public static ParameterSpec fromString(String paramString)
	{
		try {
			Object obj = bsearch.nlogolink.Utils.evaluateNetLogoReporterInEmptyWorkspace(paramString);
			if (obj instanceof LogoList)
			{
				LogoList lst = (LogoList) obj;
				String name = (String) lst.get( 0 );
				obj = lst.get(1);
				if (obj instanceof LogoList) // ranged specification
				{
					LogoList innerLst = (LogoList) obj; 
					if (innerLst.size() != 3)
					{
						throw new IllegalArgumentException("Invalid parameter range spec: " + paramString); 
					}
					Double dMin = (Double) innerLst.get( 0 );
					Object incr = innerLst.get( 1 );
					if (incr instanceof Double)  // discrete step size
					{
						Double dStep = (Double) incr;
						Double dMax = (Double) innerLst.get( 2 );
						return new DoubleDiscreteSpec(name, dMin, dStep, dMax) ;
					}
					else if (incr.toString().equals( "C" )) // continuous step size
					{
						Double dMax = (Double) innerLst.get( 2 );
						return new DoubleContinuousSpec(name, dMin, dMax) ;
					}
					else
					{
						throw new IllegalArgumentException("Invalid ranged parameter spec, increment must be either \"C\" or a number. " + paramString); 
					}					
				}
				else // discrete list of items
				{
					if (lst.size() > 2)
					{
						return new CategoricalSpec(name, lst.butFirst());
					}
					else
					{
						return new ConstantSpec(name, lst.get(1));
					}
				}
			}
			else
			{
				throw new IllegalArgumentException("Invalid parameter spec: " + paramString + " | Object=" + obj ); 
			}
		} catch (Exception ex)
		{
			if (ex instanceof IllegalArgumentException)
			{
				throw (IllegalArgumentException) ex;
			}
			//TODO: Better error messages?
			throw new IllegalArgumentException("Invalid parameter range spec: " + paramString + ".  Error was " + ex.getMessage(), ex); 			
		}
	}	
	
}