empty list iterator

platform/util-rt/src/com/intellij/util/containers/EmptyListIterator.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2000-2012 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.util.containers;
+
+import java.util.ListIterator;
+import java.util.NoSuchElementException;
+
+public class EmptyListIterator<E> extends EmptyIterator<E> implements ListIterator<E> {
+  private static final EmptyListIterator<Object> INSTANCE = new EmptyListIterator<Object>();
+
+  public static <E> EmptyListIterator<E> getInstance() {
+    //noinspection unchecked
+    return (EmptyListIterator<E>)INSTANCE;
+  }
+
+  @Override
+  public boolean hasPrevious() {
+    return false;
+  }
+
+  @Override
+  public E previous() {
+    throw new NoSuchElementException();
+  }
+
+  @Override
+  public int nextIndex() {
+    return 0;
+  }
+
+  @Override
+  public int previousIndex() {
+    return -1;
+  }
+
+  @Override
+  public void set(E e) {
+    throw new IllegalStateException();
+  }
+
+  @Override
+  public void add(E e) {
+    throw new UnsupportedOperationException();
+  }
+}