package Sequenic.T2.Coverage;

import java.util.Arrays;
import java.util.HashMap;
import java.util.Map;

/**
 * DEPRECATED, it was a bad idea: we aren't using it anymore.
 * 
 * A tree structure that can be used to cache int[] objects by maintaining a single
 * canonical version of each.
 * 
 * Also maintains a cache of BasicPaths.
 * 
 * Useful for TrieSensor and BasicPath.
 * 
 * to do: Perhaps use SoftReference (or WeakReference) strategically to 
 * allow garbage collection of unused instances. 
 * Currently there is always a chain of strong references from EMPTY_ARRAY
 * to any CanonicalIntArray instance and its associated BasicPaths.
 * 
 * For caches it is a Java best practice to use SoftReferences.
 * These are only cleared when memory is low.
 */
final class CanonicalIntArray {
	
	final int[] intArray;
	private final Map<Integer,CanonicalIntArray> children;
	private final Map<String, BasicPath> basicpaths;
	
	private CanonicalIntArray(final int[] intArray) 
	{
		this.intArray = intArray;
		children = new HashMap<Integer, CanonicalIntArray>();
		basicpaths = new HashMap<String, BasicPath>();
	}
	
	synchronized CanonicalIntArray extend(Integer i) 
	{
		CanonicalIntArray child = children.get(i);
		if(child==null)
		{
			int[] newPath = Arrays.copyOf(intArray, intArray.length+1);
			newPath[intArray.length] = i;
			children.put(i, child = new CanonicalIntArray(newPath));
		}
		return child;
	}
	
	BasicPath basicPath(String methodName)
	{
		synchronized (basicpaths)
		{
			BasicPath ret = basicpaths.get(methodName);
			if(ret==null) {
				methodName = methodName.intern();
				basicpaths.put(methodName, ret = new BasicPath(methodName, intArray));
			}
			return ret;
		}
	}
	
	static final CanonicalIntArray EMPTY_ARRAY = new CanonicalIntArray(new int[0]);
	
	static CanonicalIntArray intern(int[] array)
	{
		CanonicalIntArray ret = EMPTY_ARRAY;
		for(int i : array)
			ret = ret.extend(i);
		return ret;
	}
	
	static CanonicalIntArray intern(Iterable<Integer> list)
	{
		CanonicalIntArray ret = EMPTY_ARRAY;
		for(Integer i : list)
			ret = ret.extend(i);
		return ret;
	}

}