Merge pull request #10 from sjanarth/dev

Added CollatingIterator Sample

Author: sjanarth

.idea/encodings.xml

@@ -1,10 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <module org.jetbrains.idea.maven.project.MavenProjectsManager.isMavenModule="true" type="JAVA_MODULE" version="4">
   <component name="NewModuleRootManager" LANGUAGE_LEVEL="JDK_1_8">
-    <output url="file://$MODULE_DIR$/target/classes" />
-    <output-test url="file://$MODULE_DIR$/target/test-classes" />
+    <output url="file://$MODULE_DIR$/${project.build.directory}/classes" />
+    <output-test url="file://$MODULE_DIR$/${project.build.directory}/test-classes" />
     <content url="file://$MODULE_DIR$">
       <sourceFolder url="file://$MODULE_DIR$/src/main/java" isTestSource="false" />
+      <excludeFolder url="file://$MODULE_DIR$/${project.build.directory}/classes" />
+      <excludeFolder url="file://$MODULE_DIR$/${project.build.directory}/test-classes" />
       <excludeFolder url="file://$MODULE_DIR$/target" />
     </content>
     <orderEntry type="inheritedJdk" />

dsutils.iml

@@ -2,24 +2,38 @@
 
 import java.util.*;
 
+/**
+ * Given a list of Iterators that produce an non-decreasing sequence, the CollatingIterator
+ * can produce a collated, non-decreasing sequence without dropping any values from the
+ * underling iterators.
+ *
+ * @param <E> Type - could be a primitive or a custom class
+ */
 public class CollatingIterator<E> implements Iterator<E>
 {
-	private PriorityQueue<E> pq;
-	private List<Iterator<E>> allIterators;
-	private Map<E, Iterator<E>> waitingValues;
-	
+	/**
+	 * Constructs an empty instance.
+	 */
 	public CollatingIterator () {
 		pq = new PriorityQueue<E>();
-		allIterators = new ArrayList<Iterator<E>>();
-		waitingValues = new HashMap<E, Iterator<E>>();
+		allIterators = new ArrayList<>();
+		waitingValues = new HashMap<>();
 	}
 
+	/**
+	 * Constructs an empty instance with a Comparator
+	 * @param comparator Comparator instance to compare elements.
+	 */
 	public CollatingIterator (Comparator<? super E> comparator) {
 		pq = new PriorityQueue<E>(comparator);
-		allIterators = new ArrayList<Iterator<E>>();
-		waitingValues = new HashMap<E, Iterator<E>>();
+		allIterators = new ArrayList<>();
+		waitingValues = new HashMap<>();
 	}
 
+	/**
+	 * Adds the given iterator to an internal list of iterators.
+	 * @param it Iterator instance to add to the list.
+	 */
 	public void addIterator(Iterator<E> it) {
 		allIterators.add(it);
 	}
@@ -59,33 +73,7 @@ private void pullFrom(Iterator<E> it)	{
 		}
 	}
 
-	public static void main(String[] args) {
-		CollatingIterator<Integer> ci = new CollatingIterator<>();
-		ci.addIterator(new RandomIncreasingIterator());
-		ci.addIterator(new RandomIncreasingIterator());
-		ci.addIterator(new RandomIncreasingIterator());
-		for (int i = 0; i < 10; i++)	
-			System.out.println(ci.next());
-	}
-	
-	private static class RandomIncreasingIterator implements Iterator<Integer> 	{
-		public RandomIncreasingIterator() {}
-		private Integer lastValue = null;
-		@Override
-		public boolean hasNext() {
-			return true;
-		}
-		@Override
-		public Integer next() {
-			Integer value = (int) (Math.random() * 10.0);
-			//System.out.println("value="+value+", lastValue="+lastValue);
-			if (lastValue == null)	{
-				lastValue = value;
-				return value;
-			} else {
-				lastValue = lastValue + value;
-				return lastValue;
-			}
-		}
-	}
-}
+	private PriorityQueue<E> pq;
+	private List<Iterator<E>> allIterators;
+	private Map<E, Iterator<E>> waitingValues;
+}

src/main/java/com/sjanarth/dsutils/CollatingIterator.java

@@ -0,0 +1,36 @@
+package com.sjanarth.dsutils.samples;
+
+import java.util.Iterator;
+
+public class CollatingIterator
+{
+    public static void main (String[] args) {
+        com.sjanarth.dsutils.CollatingIterator<Integer> ci = new com.sjanarth.dsutils.CollatingIterator<>();
+        ci.addIterator(new RandomIncreasingIterator());
+        ci.addIterator(new RandomIncreasingIterator());
+        ci.addIterator(new RandomIncreasingIterator());
+        for (int i = 0; i < 10; i++)
+            System.out.println(ci.next());
+    }
+
+    private static class RandomIncreasingIterator implements Iterator<Integer> {
+        public RandomIncreasingIterator() {}
+        private Integer lastValue = null;
+        @Override
+        public boolean hasNext() {
+            return true;
+        }
+        @Override
+        public Integer next() {
+            Integer value = (int) (Math.random() * 10.0);
+            //System.out.println("value="+value+", lastValue="+lastValue);
+            if (lastValue == null)	{
+                lastValue = value;
+                return value;
+            } else {
+                lastValue = lastValue + value;
+                return lastValue;
+            }
+        }
+    }
+}