From 7574a77482936bf2c56ee904f7d91d64571b0b12 Mon Sep 17 00:00:00 2001
From: Pacien TRAN-GIRARD
Date: Mon, 22 Feb 2016 16:39:45 +0100
Subject: Refactor neighbor computation using directional vectors

---
 src/ch/epfl/xblast/Cell.java           | 13 +------------
 src/ch/epfl/xblast/Direction.java      | 32 ++++++++++++++++++++++++++++++++
 src/ch/epfl/xblast/SubCell.java        | 13 +------------
 test/ch/epfl/xblast/DirectionTest.java | 26 ++++++++++++++++++--------
 4 files changed, 52 insertions(+), 32 deletions(-)

diff --git a/src/ch/epfl/xblast/Cell.java b/src/ch/epfl/xblast/Cell.java
index ef5ff60..9a17f6a 100644
--- a/src/ch/epfl/xblast/Cell.java
+++ b/src/ch/epfl/xblast/Cell.java
@@ -156,18 +156,7 @@ public final class Cell {
      * @return the neighboring Cell
      */
     public Cell neighbor(Direction dir) {
-        switch (dir) {
-            case N:
-                return new Cell(this.x, this.y - 1);
-            case S:
-                return new Cell(this.x, this.y + 1);
-            case E:
-                return new Cell(this.x + 1, this.y);
-            case W:
-                return new Cell(this.x - 1, this.y);
-            default:
-                return null;
-        }
+        return new Cell(this.x + dir.xVector(), this.y + dir.yVector());
     }
 
     /**
diff --git a/src/ch/epfl/xblast/Direction.java b/src/ch/epfl/xblast/Direction.java
index cd4822e..e9d5961 100644
--- a/src/ch/epfl/xblast/Direction.java
+++ b/src/ch/epfl/xblast/Direction.java
@@ -66,4 +66,36 @@ public enum Direction {
         return that == this || that == this.opposite();
     }
 
+    /**
+     * Returns the x-coordinate of the normed vector representation of the Direction.
+     *
+     * @return the x-coordinate
+     */
+    public int xVector() {
+        switch (this) {
+            case W:
+                return -1;
+            case E:
+                return +1;
+            default:
+                return 0;
+        }
+    }
+
+    /**
+     * Returns the x-coordinate of the normed vector representation of the Direction.
+     *
+     * @return the y-coordinate
+     */
+    public int yVector() {
+        switch (this) {
+            case N:
+                return -1;
+            case S:
+                return +1;
+            default:
+                return 0;
+        }
+    }
+
 }
diff --git a/src/ch/epfl/xblast/SubCell.java b/src/ch/epfl/xblast/SubCell.java
index 2731029..b4f9c91 100644
--- a/src/ch/epfl/xblast/SubCell.java
+++ b/src/ch/epfl/xblast/SubCell.java
@@ -109,18 +109,7 @@ public final class SubCell {
      * @return the neighboring SubCell
      */
     public SubCell neighbor(Direction dir) {
-        switch (dir) {
-            case N:
-                return new SubCell(this.x, this.y - 1);
-            case S:
-                return new SubCell(this.x, this.y + 1);
-            case E:
-                return new SubCell(this.x + 1, this.y);
-            case W:
-                return new SubCell(this.x - 1, this.y);
-            default:
-                return null;
-        }
+        return new SubCell(this.x + dir.xVector(), this.y + dir.yVector());
     }
 
     /**
diff --git a/test/ch/epfl/xblast/DirectionTest.java b/test/ch/epfl/xblast/DirectionTest.java
index a2ac9cd..0ebb3b7 100644
--- a/test/ch/epfl/xblast/DirectionTest.java
+++ b/test/ch/epfl/xblast/DirectionTest.java
@@ -1,21 +1,23 @@
 package ch.epfl.xblast;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
 import org.junit.Test;
 
+import static org.junit.Assert.*;
+
+/**
+ * @author EPFL
+ * @author Pacien TRAN-GIRARD (261948)
+ */
 public class DirectionTest {
     @Test
     public void oppositeOfOppositeIsIdentity() {
-        for (Direction d: Direction.values())
+        for (Direction d : Direction.values())
             assertEquals(d, d.opposite().opposite());
     }
 
     @Test
     public void oppositeIsTwoStepsAway() {
-        for (Direction d: Direction.values())
+        for (Direction d : Direction.values())
             assertEquals(2, Math.abs(d.ordinal() - d.opposite().ordinal()));
     }
 
@@ -29,8 +31,8 @@ public class DirectionTest {
 
     @Test
     public void isParallelIsTrueOnlyForOppositeAndSelf() {
-        for (Direction d1: Direction.values()) {
-            for (Direction d2: Direction.values()) {
+        for (Direction d1 : Direction.values()) {
+            for (Direction d2 : Direction.values()) {
                 if (d1 == d2 || d1 == d2.opposite())
                     assertTrue(d1.isParallelTo(d2));
                 else
@@ -38,4 +40,12 @@ public class DirectionTest {
             }
         }
     }
+
+    @Test
+    public void oppositeVectorSumIsNil() {
+        for (Direction d : Direction.values()) {
+            assertEquals(0, d.xVector() + d.opposite().xVector());
+            assertEquals(0, d.yVector() + d.opposite().yVector());
+        }
+    }
 }
-- 
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