new: ForwardIterator

assira/src/main/java/net/ranides/assira/collection/iterators/ForwardIterator.java

@@ -0,0 +1,41 @@
+/*
+ * @author Ranides Atterwim <ranides@gmail.com>
+ * @copyright Ranides Atterwim
+ * @license WTFPL
+ * @url http://ranides.net/projects/assira
+ */
+package net.ranides.assira.collection.iterators;
+
+import java.util.Iterator;
+import java.util.NoSuchElementException;
+import java.util.function.Consumer;
+
+/**
+ *
+ * @author Ranides Atterwim <ranides@gmail.com>
+ */
+public abstract class ForwardIterator<T> implements Iterator<T> {
+    
+    private boolean ready = false;
+    private T last  = null;
+    
+    protected abstract boolean next(Consumer<? super T> action);
+
+    @Override
+    public boolean hasNext() {
+        return ready || (ready = next(v -> last = v));
+    }
+
+    @Override
+    public T next() {
+        if(ready) {
+            ready = false;
+            return last;
+        }
+        if(!next(v -> last = v)) {
+            throw new NoSuchElementException();
+        }
+        return last;
+    }
+    
+}