Jeddic#6 Prevent illegal reuse of the curve builder (which would caus…

…e very weird behaviour)

src/main/java/com/epaga/particles/valuetypes/curvebuilder/CurveBuilderAtAnchor.java

@@ -3,11 +3,11 @@
 import com.epaga.particles.valuetypes.Curve;
 import com.jme3.math.Vector2f;
 
-public class CurveBuilderAtAnchor{
+public class CurveBuilderAtAnchor extends CurveBuilderPiece{
 
-  Curve curveBeingBuilt;
-  Vector2f controlPointIn;
-  Vector2f currentAnchor;
+  private final Curve curveBeingBuilt;
+  private final Vector2f controlPointIn;
+  private final Vector2f currentAnchor;
 
   public CurveBuilderAtAnchor(Curve curveBeingBuilt, Vector2f controlPointIn, Vector2f currentAnchor){
     this.curveBeingBuilt = curveBeingBuilt;
@@ -16,9 +16,9 @@ public CurveBuilderAtAnchor(Curve curveBeingBuilt, Vector2f controlPointIn, Vect
   }
 
   /**
-   * Adds a point that the curve will attempt to move towards but may not actually touch.
+   * Adds a point that the curve will attempt to move towards (but may not actually touch).
    *
-   * The 2 control points are used to define a cubic Bézier curve between 2 anchors
+   * The 2 control points are used to define a cubic Bézier-like curve between 2 anchors
    * @param x the next control point's x
    * @param y the next control point's y
    * @return a CurveBuilderAtControlPoint1 a part of the curve builder system
@@ -28,13 +28,14 @@ public CurveBuilderAtControlPoint1 controlPoint1( float x, float y ){
   }
 
   /**
-   * Adds a point that the curve will attempt to move towards but may not actually touch.
+   * Adds a point that the curve will attempt to move towards (but may not actually touch)
    *
-   * The 2 control points are used to define a cubic Bézier curve between 2 anchors
+   * The 2 control points are used to define a cubic Bézier-like curve between 2 anchors
    * @param nextControlPoint the control point
    * @return a CurveBuilderAtControlPoint1 a part of the curve builder system
    */
   public CurveBuilderAtControlPoint1 controlPoint1( Vector2f nextControlPoint ){
+    checkReuse();
     return new CurveBuilderAtControlPoint1(curveBeingBuilt, controlPointIn, currentAnchor, nextControlPoint);
   }
 
@@ -54,14 +55,17 @@ public CurveBuilderAtAnchor anchorPoint(float x, float y){
    * @return a CurveBuilderAtAnchor a part of the curve builder system
    */
   public CurveBuilderAtAnchor anchorPoint(Vector2f nextAnchor ){
+    //no checkReuse() as the call to controlPoint1 will do that
     //simulate a straight line using a Bézier curve
     Vector2f midOne = currentAnchor.mult(2f/3).add(nextAnchor.mult(1f/3));
     Vector2f midTwo = currentAnchor.mult(1f/3).add(nextAnchor.mult(2f/3));
     return controlPoint1(midOne).controlPoint2(midTwo).anchorPoint(nextAnchor);
   }
 
-  public Curve end(){
+  public Curve build(){
+    checkReuse();
     curveBeingBuilt.addControlPoint(controlPointIn, currentAnchor, null);
     return curveBeingBuilt;
   }
+
 }

src/main/java/com/epaga/particles/valuetypes/curvebuilder/CurveBuilderAtControlPoint1.java

@@ -3,7 +3,7 @@
 import com.epaga.particles.valuetypes.Curve;
 import com.jme3.math.Vector2f;
 
-public class CurveBuilderAtControlPoint1{
+public class CurveBuilderAtControlPoint1 extends CurveBuilderPiece{
 
   Curve curveBeingBuilt;
 
@@ -32,6 +32,7 @@ public CurveBuilderAtControlPoint2 controlPoint2( float x, float y ){
    * @return a CurveBuilderAtControlPoint1 a part of the curve builder system
    */
   public CurveBuilderAtControlPoint2 controlPoint2( Vector2f nextControlPoint ){
+    checkReuse();
     return new CurveBuilderAtControlPoint2(curveBeingBuilt, nextControlPoint);
   }
 }

src/main/java/com/epaga/particles/valuetypes/curvebuilder/CurveBuilderAtControlPoint2.java

@@ -3,7 +3,7 @@
 import com.epaga.particles.valuetypes.Curve;
 import com.jme3.math.Vector2f;
 
-public class CurveBuilderAtControlPoint2{
+public class CurveBuilderAtControlPoint2 extends CurveBuilderPiece{
 
   Curve curveBeingBuilt;
   Vector2f inControlPoint;
@@ -33,6 +33,7 @@ public CurveBuilderAtAnchor anchorPoint(float x, float y){
    * @return a CurveBuilderAtAnchor a part of the curve builder system
    */
   public CurveBuilderAtAnchor anchorPoint(Vector2f nextAnchor ){
+    checkReuse();
     return new CurveBuilderAtAnchor(curveBeingBuilt, inControlPoint, nextAnchor);
   }
 }

src/main/java/com/epaga/particles/valuetypes/curvebuilder/CurveBuilderPiece.java

@@ -0,0 +1,13 @@
+package com.epaga.particles.valuetypes.curvebuilder;
+
+public class CurveBuilderPiece{
+
+    boolean used = false;
+
+    protected void checkReuse(){
+        if (used){
+            throw new IllegalStateException("Curve builders must not be reused (As they actually build a single curve as they go along)");
+        }
+        used = true;
+    }
+}

src/main/java/com/epaga/particles/valuetypes/curvebuilder/CurveBuilderStart.java

@@ -4,7 +4,7 @@
 import com.jme3.math.Vector2f;
 import com.jme3.math.Vector3f;
 
-public class CurveBuilderStart{
+public class CurveBuilderStart extends CurveBuilderPiece{
 
   Curve curveBeingBuilt = new Curve();
 
@@ -17,6 +17,7 @@ public CurveBuilderAtAnchor anchorPoint(float x, float y){
    * @return CurveBuilderAtAnchor a part of the curve builder system
    */
   public CurveBuilderAtAnchor anchorPoint(Vector2f start){
+    checkReuse();
     return new CurveBuilderAtAnchor(curveBeingBuilt, null, start);
   }
 

src/test/java/com/epaga/particles/valuetypes/CurveTest.java

@@ -1,5 +1,6 @@
 package com.epaga.particles.valuetypes;
 
+import com.epaga.particles.valuetypes.curvebuilder.CurveBuilderAtAnchor;
 import org.junit.Test;
 
 import static org.junit.Assert.*;
@@ -11,7 +12,7 @@ public void builder_straightLine(){
         Curve curve = Curve.builder()
                 .anchorPoint(0,0)
                 .anchorPoint(1,10)
-                .end();
+                .build();
 
         assertEquals(0, curve.getValue(0f), 0.001);
         assertEquals(4, curve.getValue(0.4f), 0.001);
@@ -27,7 +28,7 @@ public void builder_doubleStraightLine(){
                 .anchorPoint(0,0)
                 .anchorPoint(0.4f,10)
                 .anchorPoint(1f, 10)
-                .end();
+                .build();
 
         assertEquals(0, curve.getValue(0f), 0.001);
         assertEquals(5, curve.getValue(0.2f), 0.001);
@@ -48,7 +49,7 @@ public void builder_curve(){
                 .controlPoint1(0.2f, 1)
                 .controlPoint2(0.8f, 0)
                 .anchorPoint(1,1)
-                .end();
+                .build();
 
         //expected values obtained using https://www.desmos.com/calculator/ebdtbxgbq0
 
@@ -71,4 +72,14 @@ public void builder_curve(){
         assertEquals(0.5, curve.getValue(0.5f), 0.001);
         assertEquals(1, curve.getValue(1), 0.001);
     }
-}
+
+    @Test(expected = IllegalStateException.class)
+    public void builder_reuseLeadsToException(){
+        CurveBuilderAtAnchor builder = Curve.builder()
+                .anchorPoint(0,0);
+
+        Curve legalUse = builder.build();
+        Curve illegalReuse = builder.build();
+    }
+
+}