Now internally ensures that ControllerChangeHandlers aren't reused, u…

…nless they're specifically designed to be safe for reuse

Made ControllerChangeHandler's copy() method public
Fixes #179

conductor/src/main/java/com/bluelinelabs/conductor/ControllerChangeHandler.java

@@ -29,6 +29,8 @@ public abstract class ControllerChangeHandler {
 
     private boolean forceRemoveViewOnPush;
 
+    boolean hasBeenUsed;
+
     /**
      * Responsible for swapping Views from one Controller to another.
      *
@@ -73,6 +75,16 @@ public void onAbortPush(@NonNull ControllerChangeHandler newHandler, @Nullable C
      */
     public void completeImmediately() { }
 
+    /**
+     * Returns a copy of this ControllerChangeHandler. This method is internally used by the library, so
+     * ensure it will return an exact copy of your handler if overriding. If not overriding, the handler
+     * will be saved and restored from the Bundle format.
+     */
+    @NonNull
+    public ControllerChangeHandler copy() {
+        return fromBundle(toBundle());
+    }
+
     @NonNull
     final Bundle toBundle() {
         Bundle bundle = new Bundle();
@@ -85,11 +97,6 @@ final Bundle toBundle() {
         return bundle;
     }
 
-    @NonNull
-    final ControllerChangeHandler copy() {
-        return fromBundle(toBundle());
-    }
-
     private void ensureDefaultConstructor() {
         try {
             getClass().getConstructor();
@@ -135,7 +142,15 @@ public static void executeChange(@Nullable final Controller to, @Nullable final
 
     public static void executeChange(@Nullable final Controller to, @Nullable final Controller from, final boolean isPush, @Nullable final ViewGroup container, @Nullable final ControllerChangeHandler inHandler, @NonNull final List<ControllerChangeListener> listeners) {
         if (container != null) {
-            final ControllerChangeHandler handler = inHandler != null ? inHandler : new SimpleSwapChangeHandler();
+            final ControllerChangeHandler handler;
+            if (inHandler == null) {
+                handler = new SimpleSwapChangeHandler();
+            } else if (inHandler.hasBeenUsed) {
+                handler = inHandler.copy();
+            } else {
+                handler = inHandler;
+            }
+            handler.hasBeenUsed = true;
 
             if (isPush && to != null) {
                 inProgressPushHandlers.put(to.getInstanceId(), handler);

conductor/src/main/java/com/bluelinelabs/conductor/Router.java

@@ -172,7 +172,7 @@ public void replaceTopController(@NonNull RouterTransaction transaction) {
             final boolean newHandlerRemovesViews = handler == null || handler.removesFromViewOnPush();
             if (!oldHandlerRemovedViews && newHandlerRemovesViews) {
                 for (RouterTransaction visibleTransaction : getVisibleTransactions(backstack.iterator())) {
-                    performControllerChange(null, visibleTransaction.controller, true, handler != null ? handler.copy() : new SimpleSwapChangeHandler());
+                    performControllerChange(null, visibleTransaction.controller, true, handler);
                 }
             }
         }
@@ -368,22 +368,19 @@ public void setBackstack(@NonNull List<RouterTransaction> newBackstack, @Nullabl
             }
 
             if (visibleTransactionsChanged) {
-                ControllerChangeHandler handler = changeHandler != null ? changeHandler : new SimpleSwapChangeHandler();
-
                 Controller rootController = oldVisibleTransactions.size() > 0 ? oldVisibleTransactions.get(0).controller : null;
-                performControllerChange(newVisibleTransactions.get(0).controller, rootController, true, handler);
+                performControllerChange(newVisibleTransactions.get(0).controller, rootController, true, changeHandler);
 
                 for (int i = oldVisibleTransactions.size() - 1; i > 0; i--) {
                     RouterTransaction transaction = oldVisibleTransactions.get(i);
-                    ControllerChangeHandler localHandler = handler.copy();
+                    ControllerChangeHandler localHandler = changeHandler != null ? changeHandler.copy() : new SimpleSwapChangeHandler();
                     localHandler.setForceRemoveViewOnPush(true);
                     performControllerChange(null, transaction.controller, true, localHandler);
                 }
 
                 for (int i = 1; i < newVisibleTransactions.size(); i++) {
                     RouterTransaction transaction = newVisibleTransactions.get(i);
-                    handler = transaction.pushChangeHandler() != null ? transaction.pushChangeHandler().copy() : new SimpleSwapChangeHandler();
-                    performControllerChange(transaction.controller, newVisibleTransactions.get(i - 1).controller, true, handler);
+                    performControllerChange(transaction.controller, newVisibleTransactions.get(i - 1).controller, true, transaction.pushChangeHandler());
                 }
             }
         }
@@ -631,7 +628,7 @@ private void performControllerChange(@Nullable RouterTransaction to, @Nullable R
         } else if (from != null) {
             changeHandler = from.popChangeHandler();
         } else {
-            changeHandler = new SimpleSwapChangeHandler();
+            changeHandler = null;
         }
 
         Controller toController = to != null ? to.controller : null;

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/AutoTransitionChangeHandler.java

@@ -9,6 +9,8 @@
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+
 /**
  * A change handler that will use an AutoTransition.
  */
@@ -20,4 +22,9 @@ protected Transition getTransition(@NonNull ViewGroup container, @Nullable View
         return new AutoTransition();
     }
 
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        return new AutoTransitionChangeHandler();
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/FadeChangeHandler.java

@@ -8,6 +8,8 @@
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+
 /**
  * An {@link AnimatorChangeHandler} that will cross fade two views
  */
@@ -45,4 +47,10 @@ protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from
     protected void resetFromView(@NonNull View from) {
         from.setAlpha(1);
     }
+
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        return new FadeChangeHandler(getAnimationDuration(), removesFromViewOnPush());
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/HorizontalChangeHandler.java

@@ -8,6 +8,8 @@
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+
 /**
  * An {@link AnimatorChangeHandler} that will slide the views left or right, depending on if it's a push or pop.
  */
@@ -54,4 +56,10 @@ protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from
     protected void resetFromView(@NonNull View from) {
         from.setTranslationX(0);
     }
+
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        return new HorizontalChangeHandler(getAnimationDuration(), removesFromViewOnPush());
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/SimpleSwapChangeHandler.java

@@ -102,4 +102,10 @@ public void onViewAttachedToWindow(@NonNull View v) {
 
     @Override
     public void onViewDetachedFromWindow(@NonNull View v) { }
+
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        return new SimpleSwapChangeHandler(removesFromViewOnPush());
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/TransitionChangeHandler.java

@@ -81,4 +81,5 @@ public void onTransitionResume(Transition transition) { }
     public final boolean removesFromViewOnPush() {
         return true;
     }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/TransitionChangeHandlerCompat.java

@@ -69,4 +69,13 @@ public boolean removesFromViewOnPush() {
         return changeHandler.removesFromViewOnPush();
     }
 
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
+            return new TransitionChangeHandlerCompat((TransitionChangeHandler)changeHandler.copy(), null);
+        } else {
+            return new TransitionChangeHandlerCompat(null, changeHandler.copy());
+        }
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/changehandler/VerticalChangeHandler.java

@@ -8,6 +8,8 @@
 import android.view.View;
 import android.view.ViewGroup;
 
+import com.bluelinelabs.conductor.ControllerChangeHandler;
+
 import java.util.ArrayList;
 import java.util.List;
 
@@ -49,4 +51,9 @@ protected Animator getAnimator(@NonNull ViewGroup container, @Nullable View from
     @Override
     protected void resetFromView(@NonNull View from) { }
 
+    @Override @NonNull
+    public ControllerChangeHandler copy() {
+        return new VerticalChangeHandler(getAnimationDuration(), removesFromViewOnPush());
+    }
+
 }

conductor/src/main/java/com/bluelinelabs/conductor/internal/NoOpControllerChangeHandler.java

@@ -14,4 +14,9 @@ public void performChange(@NonNull ViewGroup container, @Nullable View from, @Nu
         changeListener.onChangeCompleted();
     }
 
+    @NonNull
+    @Override
+    public ControllerChangeHandler copy() {
+        return new NoOpControllerChangeHandler();
+    }
 }

demo/src/main/java/com/bluelinelabs/conductor/demo/controllers/TextController.java

@@ -1,5 +1,6 @@
 package com.bluelinelabs.conductor.demo.controllers;
 
+import android.os.Bundle;
 import android.support.annotation.NonNull;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -8,6 +9,7 @@
 
 import com.bluelinelabs.conductor.demo.R;
 import com.bluelinelabs.conductor.demo.controllers.base.BaseController;
+import com.bluelinelabs.conductor.demo.util.BundleBuilder;
 
 import butterknife.BindView;
 
@@ -18,10 +20,14 @@ public class TextController extends BaseController {
     @BindView(R.id.text_view) TextView textView;
 
     public TextController(String text) {
-//        this(new BundleBuilder(new Bundle())
-//                .putString(KEY_TEXT, text)
-//                .build()
-//        );
+        this(new BundleBuilder(new Bundle())
+                .putString(KEY_TEXT, text)
+                .build()
+        );
+    }
+
+    public TextController(Bundle args) {
+        super(args);
     }
 
     @NonNull