Switched history's hash maps to double array lists; operations 18x faster.

src/com/sk89q/worldedit/DoubleArrayList.java

@@ -0,0 +1,129 @@
+// $Id$
+/*
+ * WorldEdit
+ * Copyright (C) 2010 sk89q <http://www.sk89q.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package com.sk89q.worldedit;
+
+import java.util.List;
+import java.util.ArrayList;
+import java.util.Map;
+import java.util.Iterator;
+import java.util.ListIterator;
+import java.util.NoSuchElementException;
+
+/**
+ * Double array lists to work like a Map, but not really.
+ *
+ * @author sk89q
+ */
+public class DoubleArrayList<A,B> implements Iterable<Map.Entry<A,B>> {
+    /**
+     * First list.
+     */
+    private List<A> listA = new ArrayList<A>();
+    /**
+     * Second list.
+     */
+    private List<B> listB = new ArrayList<B>();
+
+    /**
+     * Add an item.
+     * 
+     * @param a
+     * @param b
+     */
+    public void put(A a, B b) {
+        listA.add(a);
+        listB.add(b);
+    }
+
+    /**
+     * Get size.
+     * @return
+     */
+    public int size() {
+        return listA.size();
+    }
+
+    /**
+     * Get an entry set.
+     *
+     * @return
+     */
+    public Iterator<Map.Entry<A,B>> iterator() {
+        return new EntryIterator<Map.Entry<A,B>>(
+                listA.listIterator(listA.size()),
+                listB.listIterator(listB.size()));
+    }
+
+    /**
+     * Entry iterator.
+     * 
+     * @param <A>
+     * @param <B>
+     */
+    public class EntryIterator<T extends Map.Entry> implements Iterator<Map.Entry<A,B>> {
+        private ListIterator<A> keyIterator;
+        private ListIterator<B> valueIterator;
+
+        public EntryIterator(ListIterator<A> keyIterator, ListIterator<B> valueIterator) {
+            this.keyIterator = keyIterator;
+            this.valueIterator = valueIterator;
+        }
+
+        public boolean hasNext() {
+            return keyIterator.hasPrevious();
+        }
+
+        public Map.Entry<A,B> next() throws NoSuchElementException {
+            return new Entry<A,B>(keyIterator.previous(), valueIterator.previous());
+        }
+
+        public void remove() {
+            throw new UnsupportedOperationException();
+        }
+    }
+
+    /**
+     * Class to masquerade as Map.Entry.
+     * 
+     * @param <A>
+     * @param <B>
+     */
+    public class Entry<A,B> implements Map.Entry<A,B> {
+        private A key;
+        private B value;
+
+        private Entry(A key, B value) {
+            this.key = key;
+            this.value = value;
+        }
+
+        public A getKey() {
+            return key;
+        }
+
+        public B getValue() {
+            return value;
+        }
+
+        public B setValue(B value) {
+            throw new UnsupportedOperationException();
+        }
+    }
+}