Added LayerVisitor and LayerFunction.

src/main/java/com/sk89q/worldedit/function/LayerFunction.java

@@ -0,0 +1,48 @@
+/*
+ * 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;
+
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.WorldEditException;
+
+/**
+ * A function that accepts layers of blocks.
+ */
+public interface LayerFunction {
+
+    /**
+     * Returns whether the given block should be "passed through" when
+     * conducting the ground search.
+     *
+     * @param position return whether the given block is the ground
+     * @return true if the search should stop
+     */
+    boolean isGround(Vector position);
+
+    /**
+     * Apply the function to the given position.
+     *
+     * @param position the position
+     * @param depth the depth as a number starting from 0
+     * @return true whether this method should be called for further layers
+     * @throws com.sk89q.worldedit.WorldEditException thrown on an error
+     */
+    boolean apply(Vector position, int depth) throws WorldEditException;
+}

src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java

@@ -0,0 +1,123 @@
+/*
+ * 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.visitor;
+
+import com.sk89q.worldedit.Vector;
+import com.sk89q.worldedit.Vector2D;
+import com.sk89q.worldedit.WorldEditException;
+import com.sk89q.worldedit.function.LayerFunction;
+import com.sk89q.worldedit.function.operation.Operation;
+import com.sk89q.worldedit.masks.DummyMask2D;
+import com.sk89q.worldedit.masks.Mask2D;
+import com.sk89q.worldedit.regions.FlatRegion;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Visits the layers within a region.
+ * </p>
+ * This class works by iterating over all the columns in a {@link FlatRegion},
+ * finding the first ground block in each column (searching from a given
+ * maximum Y down to a minimum Y), and then applies a {@link LayerFunction} to
+ * each layer.
+ */
+public class LayerVisitor implements Operation {
+
+    private final FlatRegion flatRegion;
+    private final LayerFunction function;
+    private Mask2D mask = new DummyMask2D();
+    private int minY;
+    private int maxY;
+
+    /**
+     * Create a new visitor.
+     *
+     * @param flatRegion the flat region to visit
+     * @param minY the minimum Y to stop the search at
+     * @param maxY the maximum Y to begin the search at
+     * @param function the layer function to apply t blocks
+     */
+    public LayerVisitor(FlatRegion flatRegion, int minY, int maxY, LayerFunction function) {
+        checkNotNull(flatRegion);
+        checkArgument(minY <= maxY, "minY <= maxY required");
+        checkNotNull(function);
+
+        this.flatRegion = flatRegion;
+        this.minY = minY;
+        this.maxY = maxY;
+        this.function = function;
+    }
+
+    /**
+     * Get the mask that determines which columns within the flat region
+     * will be visited.
+     *
+     * @return a 2D mask
+     */
+    public Mask2D getMask() {
+        return mask;
+    }
+
+    /**
+     * Set the mask that determines which columns within the flat region
+     * will be visited.
+     *
+     * @param mask a 2D mask
+     */
+    public void setMask(Mask2D mask) {
+        checkNotNull(mask);
+        this.mask = mask;
+    }
+
+    @Override
+    public Operation resume() throws WorldEditException {
+        for (Vector2D column : flatRegion.asFlatRegion()) {
+            // Abort if we are underground
+            if (function.isGround(column.toVector(maxY + 1))) {
+                return null;
+            }
+
+            boolean found = false;
+            int groundY = 0;
+            for (int y = maxY; y >= minY; --y) {
+                Vector test = column.toVector(y);
+                if (!found) {
+                    if (function.isGround(test)) {
+                        found = true;
+                        groundY = y;
+                    }
+                }
+
+                if (found) {
+                    if (!function.apply(test, groundY - y)) {
+                        break;
+                    }
+                }
+            }
+        }
+
+        return null;
+    }
+
+    @Override
+    public void cancel() {
+    }
+}