Added new method in RandomUtil + Added AABBBlockGroup to ease manipulation of collection of AABBBlocks

Core/src/main/java/fr/pandacube/lib/core/util/IteratorIterator.java

@@ -0,0 +1,65 @@
+package fr.pandacube.lib.core.util;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+
+public class IteratorIterator<T> implements Iterator<T> {
+
+	public static <T> IteratorIterator<T> ofCollectionOfIterable(Collection<Iterable<T>> coll) {
+		return new IteratorIterator<>(coll.stream().map(i -> i.iterator()).iterator());
+	}
+	
+	public static <T> IteratorIterator<T> ofCollectionOfIterator(Collection<Iterator<T>> coll) {
+		return new IteratorIterator<>(new ArrayList<>(coll).iterator());
+	}
+
+	@SafeVarargs
+	public static <T> IteratorIterator<T> ofArrayOfIterable(Iterable<T>... arr) {
+		return new IteratorIterator<>(Arrays.stream(arr).map(i -> i.iterator()).iterator());
+	}
+	
+	@SafeVarargs
+	public static <T> IteratorIterator<T> ofArrayOfIterator(Iterator<T>... arr) {
+		return new IteratorIterator<>(Arrays.asList(arr).iterator());
+	}
+	
+	private Iterator<Iterator<T>> iterators;
+	
+	private Iterator<T> currentIterator = null;
+	
+	private IteratorIterator(Iterator<Iterator<T>> iterators) {
+		this.iterators = iterators;
+	}
+	
+	private void fixCurrentIterator() {
+		if (currentIterator != null && !currentIterator.hasNext()) {
+			currentIterator = null;
+		}
+	}
+	private void fixState() {
+		fixCurrentIterator();
+		while (currentIterator == null) {
+			if (iterators.hasNext()) {
+				currentIterator = iterators.next();
+				fixCurrentIterator();
+			}
+		}
+	}
+	
+	@Override
+	public boolean hasNext() {
+		fixState();
+		return currentIterator != null && currentIterator.hasNext();
+	}
+	
+	@Override
+	public T next() {
+		if (!hasNext())
+			throw new NoSuchElementException("No next value found in iterator.");
+		return currentIterator.next();
+	}
+	
+}

Core/src/main/java/fr/pandacube/lib/core/util/RandomUtil.java

@@ -42,5 +42,31 @@ public class RandomUtil {
 		}
 		throw new RuntimeException("Should never go to this line of code");
 	}
+	
+	/**
+	 * Return a value between 0 and the number of parameter minus 1, using the provided frequencies.
+	 * 
+	 * The probability of each value to be returned depends of the frequencies provided.
+	 * @param frequencies the frequencies of each entries
+	 * @return the index of an entry, or -1 if it is unable to pick anything (all the frequencies are 0 or there is not provided frequency)
+	 */
+	public static int randomIndexOfFrequencies(double... frequencies) {
+		if (frequencies == null)
+			return -1;
+		double sum = 0;
+		for (double f : frequencies)
+			sum += f;
+		if (sum == 0)
+			return -1;
+		double r = rand.nextDouble() * sum;
+		int i = -1;
+		double limit = frequencies[++i];
+		while (i < frequencies.length) {
+			if (r < limit)
+				return i;
+			limit += frequencies[++i];
+		}
+		return frequencies.length - 1;
+	}
 
 }