Added RegionMaskFilter to filter a RegionFunction.

src/main/java/com/sk89q/worldedit/operation/RegionMaskFilter.java

@@ -0,0 +1,57 @@
+/*
+ * 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.operation;
+
+import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.masks.Mask;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Passes positions that match the given mask onto the provided function.
+ */
+public class RegionMaskFilter implements RegionFunction {
+
+    private final EditSession editSession;
+    private final Mask mask;
+    private final RegionFunction function;
+
+    public RegionMaskFilter(EditSession editSession, Mask mask, RegionFunction function) {
+        checkNotNull(function, "function must not be null");
+        checkNotNull(editSession, "editSession must not be null");
+        checkNotNull(mask, "mask must not be null");
+
+        this.editSession = editSession;
+        this.mask = mask;
+        this.function = function;
+    }
+
+    @Override
+    public boolean apply(Vector position) throws WorldEditException {
+        if (mask.matches(editSession, position)) {
+            return function.apply(position);
+        } else {
+            return false;
+        }
+    }
+
+}