Fix data cycling the right way. Merged TomyLobo's test changes in.

src/main/java/com/sk89q/worldedit/data/BlockData.java

@@ -583,19 +583,24 @@ public final class BlockData {
      * @return the new data value for the block
      */
     public static int cycle(int type, int data, int increment) {
+        if (increment != -1 && increment != 1) {
+            throw new IllegalArgumentException("Increment must be 1 or -1.");
+        }
+
         int store;
         switch (type) {
         case BlockID.LOG:
         case BlockID.LONG_GRASS:
         case BlockID.STONE_BRICK:
         case BlockID.SILVERFISH_BLOCK:
-            return (data + increment) % 3;
+            if (data > 2) return -1;
+            return mod((data + increment), 3);
 
         case BlockID.TORCH:
         case BlockID.REDSTONE_TORCH_ON:
         case BlockID.REDSTONE_TORCH_OFF:
             if (data < 1 || data > 4) return -1;
-            return (data - 1 + increment) % 4 + 1;
+            return mod((data - 1 + increment), 4) + 1;
 
         case BlockID.WOODEN_STAIRS:
         case BlockID.COBBLESTONE_STAIRS:
@@ -603,31 +608,37 @@ public final class BlockData {
         case BlockID.STONE_BRICK_STAIRS:
         case BlockID.PUMPKIN:
         case BlockID.JACKOLANTERN:
-            return (data + increment) % 4;
+            if (data > 3) return -1;
+            return mod((data + increment), 4);
 
         case BlockID.STEP:
         case BlockID.DOUBLE_STEP:
         case BlockID.CAKE_BLOCK:
-            return (data + increment) % 6;
+            if (data > 5) return -1;
+            return mod((data + increment), 6);
 
         case BlockID.CROPS:
         case BlockID.PUMPKIN_STEM:
         case BlockID.MELON_STEM:
-            return (data + increment) % 7;
+            if (data > 6) return -1;
+            return mod((data + increment), 7);
 
         case BlockID.SOIL:
-        case BlockID.SNOW:
+            if (data > 8) return -1;
-            return (data + increment) % 9;
+            return mod((data + increment), 9);
 
         case BlockID.RED_MUSHROOM_CAP:
         case BlockID.BROWN_MUSHROOM_CAP:
-            return (data + increment) % 11;
+            if (data > 10) return -1;
+            return mod((data + increment), 11);
 
         case BlockID.CACTUS:
         case BlockID.REED:
         case BlockID.SIGN_POST:
         case BlockID.VINE:
-            return (data + increment) % 16;
+        case BlockID.SNOW:
+            if (data > 15) return -1;
+            return mod((data + increment), 16);
 
         case BlockID.FURNACE:
         case BlockID.BURNING_FURNACE:
@@ -635,31 +646,32 @@ public final class BlockData {
         case BlockID.WALL_SIGN:
         case BlockID.LADDER:
         case BlockID.CHEST:
-            return (data - 2 + increment) % 4 + 2;
+            if (data < 2 || data > 5) return -1;
+            return mod((data - 2 + increment), 4) + 2;
 
         case BlockID.REDSTONE_REPEATER_OFF:
         case BlockID.REDSTONE_REPEATER_ON:
         case BlockID.TRAP_DOOR:
         case BlockID.FENCE_GATE:
         case BlockID.LEAVES:
+            if (data > 7) return -1;
             store = data & ~0x3;
-            return ((data & 0x3) + increment) % 4 | store;
+            return mod(((data & 0x3) + increment), 4) | store;
 
         case BlockID.MINECART_TRACKS:
             if (data < 6 || data > 9) return -1;
-            return (data - 6 + increment) % 4 + 6;
+            return mod((data - 6 + increment), 4) + 6;
 
         case BlockID.SAPLING:
+            if ((data & 0x3) == 3 || data > 15) return -1;
             store = data & ~0x3;
-            return ((data & 0x3) + increment) % 3 | store;
+            return mod(((data & 0x3) + increment), 3) | store;
 
         case BlockID.CLOTH:
-            if (increment > 0) {
+            if (increment == 1) {
                 data = nextClothColor(data);
-            } else if (increment < 0) {
+            } else if (increment == -1) {
                 data = prevClothColor(data);
-            } else {
-                return -1; // shouldn't have a 0 increment anyway
             }
             return data;
 
@@ -668,6 +680,14 @@ public final class BlockData {
         }
     }
 
+    /**
+     * Better modulo, not just remainder.
+     */
+    private static int mod(int x, int y) {
+        int res = x % y;
+        return res < 0 ? res + y : res;
+    }
+
     /**
      * Returns the data value for the next color of cloth in the rainbow. This
      * should not be used if you want to just increment the data value.

src/test/java/com/sk89q/worldedit/data/BlockDataTest.java

@@ -19,6 +19,8 @@
 
 package com.sk89q.worldedit.data;
 
+import java.util.TreeSet;
+
 import org.junit.*;
 
 import com.sk89q.worldedit.CuboidClipboard.FlipDirection;
@@ -26,6 +28,9 @@ import com.sk89q.worldedit.blocks.BlockID;
 
 import static org.junit.Assert.*;
 
+/**
+ * @author TomyLobo
+ */
 public class BlockDataTest {
     @Test
     public void testRotateFlip() {
@@ -33,23 +38,36 @@ public class BlockDataTest {
             for (int data = 0; data < 16; ++data) {
                 final String message = type+"/"+data;
 
+                //Test r90(r-90(x))==x
                 assertEquals(message, data, BlockData.rotate90(type, BlockData.rotate90Reverse(type, data)));
+                //Test r-90(r90(x))==x
                 assertEquals(message, data, BlockData.rotate90Reverse(type, BlockData.rotate90(type, data)));
 
-                int flipped = BlockData.flip(type, BlockData.flip(type, data, FlipDirection.WEST_EAST), FlipDirection.NORTH_SOUTH);
+                final int flipped = BlockData.flip(type, BlockData.flip(type, data, FlipDirection.WEST_EAST), FlipDirection.NORTH_SOUTH);
 
+                //Test r90(r90(x))==flipNS(flipWE(x))
                 assertEquals(message, flipped, BlockData.rotate90(type, BlockData.rotate90(type, data)));
+                //Test r-90(r-90(x))==flipNS(flipWE(x))
                 assertEquals(message, flipped, BlockData.rotate90Reverse(type, BlockData.rotate90Reverse(type, data)));
 
+                //Test flipNS(flipNS(x))==x
                 assertEquals(message, data, BlockData.flip(type, BlockData.flip(type, data, FlipDirection.NORTH_SOUTH), FlipDirection.NORTH_SOUTH));
+                //Test flipWE(flipWE(x))==x
                 assertEquals(message, data, BlockData.flip(type, BlockData.flip(type, data, FlipDirection.WEST_EAST), FlipDirection.WEST_EAST));
+                //Test flipUD(flipUD(x))==x
                 assertEquals(message, data, BlockData.flip(type, BlockData.flip(type, data, FlipDirection.UP_DOWN), FlipDirection.UP_DOWN));
+
+                //Test r90(r90(r90(r90(x))))==x
+                assertEquals(message, data, BlockData.rotate90(type, BlockData.rotate90(type, BlockData.rotate90(type, BlockData.rotate90(type, data)))));
+                //Test r-90(r-90(r-90(r-90(x))))==x
+                assertEquals(message, data, BlockData.rotate90Reverse(type, BlockData.rotate90Reverse(type, BlockData.rotate90Reverse(type, BlockData.rotate90Reverse(type, data)))));
             }
         }
     }
 
     @Test
     public void testCycle() {
+        // Test monotony
         for (int type = 0; type < 256; ++type) {
             if (type == BlockID.CLOTH)
                 continue;
@@ -57,7 +75,7 @@ public class BlockDataTest {
             for (int data = 0; data < 16; ++data) {
                 final String message = type+"/"+data;
 
-                int cycled = BlockData.cycle(type, data, 1);
+                final int cycled = BlockData.cycle(type, data, 1);
 
                 if (cycled <= data) {
                     continue;
@@ -66,5 +84,56 @@ public class BlockDataTest {
                 assertEquals(message, data+1, cycled);
             }
         }
+
+        // Test cyclicity
+        final TreeSet<Integer> datasTemplate = new TreeSet<Integer>();
+        for (int data = 0; data < 16; ++data) {
+            datasTemplate.add(data);
+        }
+
+        // Forwards...
+        for (int type = 0; type < 256; ++type) {
+            @SuppressWarnings("unchecked")
+            final TreeSet<Integer> datas = (TreeSet<Integer>) datasTemplate.clone();
+            while (!datas.isEmpty()) {
+                final int start = datas.pollFirst();
+                String message = type+"/"+start;
+                int current = start;
+                boolean first = true;
+                while (true) {
+                    current = BlockData.cycle(type, current, 1);
+                    if (first && current == -1) break;
+                    first = false;
+                    message += "->"+current;
+                    assertTrue(message, current >= 0);
+                    assertTrue(message, current < 16);
+                    if (current == start) break;
+                    assertTrue(message, datas.remove(current));
                 }
             }
+        }
+        
+        // ...and backwards
+        for (int type = 0; type < 256; ++type) {
+            @SuppressWarnings("unchecked")
+            final TreeSet<Integer> datas = (TreeSet<Integer>) datasTemplate.clone();
+            while (!datas.isEmpty()) {
+                final int start = datas.pollFirst();
+                String message = type+"/"+start;
+                int current = start;
+                boolean first = true;
+                while (true) {
+                    current = BlockData.cycle(type, current, -1);
+                    if (first && current == -1) break;
+                    first = false;
+                    message += "->"+current;
+                    assertTrue(message, current >= 0);
+                    assertTrue(message, current < 16);
+                    if (current == start) break;
+                    assertTrue(message, datas.remove(current));
+                }
+            }
+        }
+    }
+}
+