Create AbstractForwardSequentialList util class

util/src/main/java/org/jf/util/AbstractForwardSequentialList.java

@@ -0,0 +1,118 @@
+/*
+ * Copyright 2012, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+package org.jf.util;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.AbstractSequentialList;
+import java.util.Iterator;
+import java.util.ListIterator;
+import java.util.NoSuchElementException;
+
+public abstract class AbstractForwardSequentialList<T> extends AbstractSequentialList<T> {
+
+    @Nonnull private Iterator<T> iterator(int index) {
+        if (index < 0) {
+            throw new NoSuchElementException();
+        }
+
+        Iterator<T> it = iterator();
+        for (int i=0; i<index; i++) {
+            it.next();
+        }
+        return it;
+    }
+
+    @Override @Nonnull public abstract Iterator<T> iterator();
+
+    @Override @Nonnull public ListIterator<T> listIterator(final int initialIndex) {
+
+        final Iterator<T> initialIterator;
+        try {
+            initialIterator = iterator(initialIndex);
+        } catch (NoSuchElementException ex) {
+            throw new IndexOutOfBoundsException();
+        }
+
+        return new AbstractListIterator<T>() {
+            private int index = initialIndex - 1;
+            @Nullable private Iterator<T> forwardIterator = initialIterator;
+
+            @Nonnull
+            private Iterator<T> getForwardIterator() {
+                if (forwardIterator == null) {
+                    try {
+                        forwardIterator = iterator(index+1);
+                    } catch (IndexOutOfBoundsException ex) {
+                        throw new NoSuchElementException();
+                    }
+                }
+                return forwardIterator;
+            }
+
+            @Override public boolean hasNext() {
+                return getForwardIterator().hasNext();
+            }
+
+            @Override public boolean hasPrevious() {
+                return index >= 0;
+            }
+
+            @Override public T next() {
+                T ret = getForwardIterator().next();
+                index++;
+                return ret;
+            }
+
+            @Override public int nextIndex() {
+                return index+1;
+            }
+
+            @Override public T previous() {
+                forwardIterator = null;
+                try {
+                    return iterator(index--).next();
+                } catch (IndexOutOfBoundsException ex) {
+                    throw new NoSuchElementException();
+                }
+            }
+
+            @Override public int previousIndex() {
+                return index;
+            }
+        };
+    }
+
+    @Override @Nonnull public ListIterator<T> listIterator() {
+        return listIterator(0);
+    }
+}