Update

3 files changed, 102 insertions, 17 deletions

diff --git a/base/src/main/java/bjc/utils/funcdata/FunctionalList.java b/base/src/main/java/bjc/utils/funcdata/FunctionalList.java
index c730424..6953bd0 100644
--- a/base/src/main/java/bjc/utils/funcdata/FunctionalList.java
+++ b/base/src/main/java/bjc/utils/funcdata/FunctionalList.java
@@ -169,6 +169,33 @@ public class FunctionalList<E> implements Cloneable, IList<E> {
 	}
 
 	@Override
+	public E last() {
+		if(wrapped.size() < 1) throw new NoSuchElementException("Attempted to get last element of empty list");
+
+		return wrapped.get(wrapped.size() - 1);
+	}
+
+	@Override
+	public E popFirst() {
+		if(wrapped.size() < 1) throw new NoSuchElementException("Attempted to pop first element of empty list");
+
+		E head = first();
+		wrapped.remove(0);
+
+		return head;
+	}
+
+	@Override
+	public E popLast() {
+		if(wrapped.size() < 1) throw new NoSuchElementException("Attempted to pop last element of empty list");
+
+		E tail = last();
+		wrapped.remove(wrapped.size() - 1);
+
+		return tail;
+	}
+
+	@Override
 	public <T> IList<T> flatMap(final Function<E, IList<T>> expander) {
 		if(expander == null) throw new NullPointerException("Expander must not be null");
 
diff --git a/base/src/main/java/bjc/utils/funcdata/IList.java b/base/src/main/java/bjc/utils/funcdata/IList.java
index cfda68d..12eaf2f 100644
--- a/base/src/main/java/bjc/utils/funcdata/IList.java
+++ b/base/src/main/java/bjc/utils/funcdata/IList.java
@@ -160,6 +160,16 @@ public interface IList<ContainedType> extends Iterable<ContainedType> {
 	ContainedType first();
 
 	/**
+	 * Get the last element in the list.
+	 *
+	 * @return The last element in this list.
+	 */
+	ContainedType last();
+
+	ContainedType popFirst();
+	ContainedType popLast();
+
+	/**
 	 * Apply a function to each member of the list, then flatten the
 	 * results.
 	 *
diff --git a/base/src/main/java/bjc/utils/gen/WeightedRandom.java b/base/src/main/java/bjc/utils/gen/WeightedRandom.java
index c9bdad8..405d685 100644
--- a/base/src/main/java/bjc/utils/gen/WeightedRandom.java
+++ b/base/src/main/java/bjc/utils/gen/WeightedRandom.java
@@ -5,6 +5,7 @@ import java.util.Random;
 import bjc.utils.data.IHolder;
 import bjc.utils.data.IPair;
 import bjc.utils.data.Identity;
+import bjc.utils.data.Pair;
 import bjc.utils.funcdata.FunctionalList;
 import bjc.utils.funcdata.IList;
 
@@ -18,10 +19,7 @@ import bjc.utils.funcdata.IList;
  *        The type of values that are randomly selected.
  */
 public class WeightedRandom<E> {
-	/* The list of probabilities for each result */
-	private final IList<Integer> probabilities;
-	/* The list of possible results to pick from */
-	private final IList<E> results;
+	private final IList<IPair<Integer, E>> values;
 
 	/* The source for any needed random numbers */
 	private Random source;
@@ -30,6 +28,7 @@ public class WeightedRandom<E> {
 
 	private final static Random BASE = new Random();
 
+	private boolean exhaust;
 	/**
 	 * Create a new weighted random generator with the specified source of
 	 * randomness.
@@ -38,8 +37,7 @@ public class WeightedRandom<E> {
 	 *        The source of randomness to use.
 	 */
 	public WeightedRandom(Random src) {
-		probabilities = new FunctionalList<>();
-		results       = new FunctionalList<>();
+		values = new FunctionalList<>();
 
 		if(src == null) throw new NullPointerException("Source of randomness must not be null");
 
@@ -52,6 +50,15 @@ public class WeightedRandom<E> {
 	public WeightedRandom() {
 		this(BASE);
 	}
+
+	private WeightedRandom(Random src, IList<IPair<Integer, E>> vals, int chance) {
+		source = src;
+
+		values = vals;
+
+		totalChance = chance;
+	}
+
 	/**
 	 * Add a probability for a specific result to be given.
 	 *
@@ -62,8 +69,7 @@ public class WeightedRandom<E> {
 	 *        The result to get when the chance comes up.
 	 */
 	public void addProbability(final int chance, final E result) {
-		probabilities.add(chance);
-		results.add(result);
+		values.add(new Pair<>(chance, result));
 
 		totalChance += chance;
 	}
@@ -81,14 +87,23 @@ public class WeightedRandom<E> {
 		int target = rn.nextInt(totalChance);
 		int i = 0;
 
-		for(int prob : probabilities) {
-			if(target < prob) return results.getByIndex(i);
+		for(IPair<Integer, E> val : values) {
+			int prob = val.getLeft();
+
+			if(target < prob) {
+				if(exhaust) {
+					totalChance -= val.getLeft();
+					values.removeMatching(val);
+				}
+
+				return val.getRight();
+			}
 
 			target -= prob;
 			i      += 1;
 		}
 
-		throw new NullPointerException("Fell off the end of the results list");
+		return null;
 	}
 	/**
 	 * Return a list of values that can be generated by this generator
@@ -96,7 +111,7 @@ public class WeightedRandom<E> {
 	 * @return A list of all the values that can be generated
 	 */
 	public IList<E> getResults() {
-		return results;
+		return values.map(IPair::getRight);
 	}
 
 	/**
@@ -106,7 +121,7 @@ public class WeightedRandom<E> {
 	 * @return A list of pairs of values and value probabilities
 	 */
 	public IList<IPair<Integer, E>> getValues() {
-		return probabilities.pairWith(results);
+		return values;
 	}
 
 	public E getDescent(int factor) {
@@ -114,13 +129,24 @@ public class WeightedRandom<E> {
 	}
 
 	public E getDescent(int factor, Random rn) {
-		for(E res : results) {
+		if(values.getSize() == 0) return null;
+
+		for(IPair<Integer, E> val : values) {
 			if(rn.nextInt(factor) == 0) continue;
 
-			return res;
+			if(exhaust) {
+				totalChance -= val.getLeft();
+
+				values.removeMatching(val);
+			}
+
+			return val.getRight();
 		}
 
-		return results.getByIndex(results.getSize() - 1);
+		IPair<Integer, E> val = values.getByIndex(values.getSize() - 1);
+		if(exhaust) values.removeMatching(val);
+
+		return val.getRight();
 	}
 
 	public E getBinomial(int target, int bound, int trials) {
@@ -128,6 +154,8 @@ public class WeightedRandom<E> {
 	}
 
 	public E getBinomial(int target, int bound, int trials, Random rn) {
+		if(values.getSize() == 0) return null;
+
 		int numSuc = 0;
 
 		for(int i = 0; i < trials; i++) {
@@ -145,6 +173,26 @@ public class WeightedRandom<E> {
 		}
 
 		//System.err.printf("\tTRACE: got %d success for binomial trials (%d <= 1d%d, %d times)\n", numSuc, target, bound, trials);
-		return results.getByIndex(Math.min(numSuc, results.getSize() - 1));
+		IPair<Integer, E> val = values.getByIndex(Math.min(numSuc, values.getSize() - 1));
+		if(exhaust) {
+			totalChance -= val.getLeft();
+
+			values.removeMatching(val);
+		}
+
+		return val.getRight();
+	}
+
+	public WeightedRandom<E> exhaustible() {
+		IList<IPair<Integer, E>> lst = new FunctionalList<>();
+		for(IPair<Integer, E> val : values) {
+			lst.add(val);
+		}
+
+		WeightedRandom<E> res = new WeightedRandom<>(source, lst, totalChance);
+
+		res.exhaust = true;
+
+		return res;
 	}
 }