Added new history framework, visitors for history.

src/main/java/com/sk89q/worldedit/function/operation/ChangeSetExecutor.java

@@ -0,0 +1,80 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * 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.function.operation;
+
+import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.history.change.Change;
+import com.sk89q.worldedit.history.changeset.ChangeSet;
+import com.sk89q.worldedit.history.UndoContext;
+
+import java.util.Iterator;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+public class ChangeSetExecutor implements Operation {
+
+    public enum Type {UNDO, REDO}
+
+    private final Iterator<Change> iterator;
+    private final Type type;
+    private final UndoContext context;
+
+    private ChangeSetExecutor(ChangeSet changeSet, Type type, UndoContext context) {
+        checkNotNull(changeSet);
+        checkNotNull(type);
+        checkNotNull(context);
+
+        this.type = type;
+        this.context = context;
+
+        if (type == Type.UNDO) {
+            iterator = changeSet.backwardIterator();
+        } else {
+            iterator = changeSet.forwardIterator();
+        }
+    }
+
+    @Override
+    public Operation resume() throws WorldEditException {
+        while (iterator.hasNext()) {
+            Change change = iterator.next();
+            if (type == Type.UNDO) {
+                change.undo(context);
+            } else {
+                change.redo(context);
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    public void cancel() {
+    }
+
+    public static ChangeSetExecutor createUndo(ChangeSet changeSet, UndoContext context) {
+        return new ChangeSetExecutor(changeSet, Type.UNDO, context);
+    }
+
+    public static ChangeSetExecutor createRedo(ChangeSet changeSet, UndoContext context) {
+        return new ChangeSetExecutor(changeSet, Type.REDO, context);
+    }
+
+}