From 7dc81f83508c7c588de9870993e256a69e1003f5 Mon Sep 17 00:00:00 2001
From: sk89q <the.sk89q@gmail.com>
Date: Sun, 30 Mar 2014 13:48:15 -0700
Subject: [PATCH] Added preconditions to BreadthFirstSearch and subclasses.

---
 .../worldedit/function/visitor/BreadthFirstSearch.java   | 5 ++++-
 .../worldedit/function/visitor/DownwardVisitor.java      | 3 +++
 .../sk89q/worldedit/function/visitor/LayerVisitor.java   | 1 -
 .../worldedit/function/visitor/RecursiveVisitor.java     | 9 +++++++++
 4 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/sk89q/worldedit/function/visitor/BreadthFirstSearch.java b/src/main/java/com/sk89q/worldedit/function/visitor/BreadthFirstSearch.java
index 153882333..95f099a67 100644
--- a/src/main/java/com/sk89q/worldedit/function/visitor/BreadthFirstSearch.java
+++ b/src/main/java/com/sk89q/worldedit/function/visitor/BreadthFirstSearch.java
@@ -27,6 +27,8 @@ import com.sk89q.worldedit.function.RegionFunction;
 
 import java.util.*;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 /**
  * Performs a breadth-first search starting from points added with
  * {@link #visit(com.sk89q.worldedit.Vector)}. The search continues
@@ -51,7 +53,8 @@ public abstract class BreadthFirstSearch implements Operation {
      *
      * @param function the function to apply to visited blocks
      */
-    public BreadthFirstSearch(RegionFunction function) {
+    protected BreadthFirstSearch(RegionFunction function) {
+        checkNotNull(function);
         this.function = function;
         addAxes();
     }
diff --git a/src/main/java/com/sk89q/worldedit/function/visitor/DownwardVisitor.java b/src/main/java/com/sk89q/worldedit/function/visitor/DownwardVisitor.java
index 3533eba0e..16072b243 100644
--- a/src/main/java/com/sk89q/worldedit/function/visitor/DownwardVisitor.java
+++ b/src/main/java/com/sk89q/worldedit/function/visitor/DownwardVisitor.java
@@ -25,6 +25,8 @@ import com.sk89q.worldedit.function.mask.Mask;
 
 import java.util.List;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 /**
  * Visits adjacent points on the same X-Z plane as long as the points
  * pass the given mask, and then executes the provided region
@@ -45,6 +47,7 @@ public class DownwardVisitor extends RecursiveVisitor {
      */
     public DownwardVisitor(Mask mask, RegionFunction function, int baseY) {
         super(mask, function);
+        checkNotNull(mask);
 
         this.baseY = baseY;
 
diff --git a/src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java b/src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java
index a51bbc719..3437ec6d0 100644
--- a/src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java
+++ b/src/main/java/com/sk89q/worldedit/function/visitor/LayerVisitor.java
@@ -19,7 +19,6 @@
 
 package com.sk89q.worldedit.function.visitor;
 
-import com.sk89q.worldedit.EditSession;
 import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.Vector2D;
 import com.sk89q.worldedit.WorldEditException;
diff --git a/src/main/java/com/sk89q/worldedit/function/visitor/RecursiveVisitor.java b/src/main/java/com/sk89q/worldedit/function/visitor/RecursiveVisitor.java
index 3bb013f6a..d6531b933 100644
--- a/src/main/java/com/sk89q/worldedit/function/visitor/RecursiveVisitor.java
+++ b/src/main/java/com/sk89q/worldedit/function/visitor/RecursiveVisitor.java
@@ -23,6 +23,8 @@ import com.sk89q.worldedit.Vector;
 import com.sk89q.worldedit.function.RegionFunction;
 import com.sk89q.worldedit.function.mask.Mask;
 
+import static com.google.common.base.Preconditions.checkNotNull;
+
 /**
  * An implementation of an {@link BreadthFirstSearch} that uses a mask to
  * determine where a block should be visited.
@@ -31,8 +33,15 @@ public class RecursiveVisitor extends BreadthFirstSearch {
 
     private final Mask mask;
 
+    /**
+     * Create a new recursive visitor.
+     *
+     * @param mask the mask
+     * @param function the function
+     */
     public RecursiveVisitor(Mask mask, RegionFunction function) {
         super(function);
+        checkNotNull(mask);
         this.mask = mask;
     }