Make writable arrays and maps only shallowly writable

Summary:
@public

The `WritableArray` and `WritableMap` interfaces currently require that nested arrays and maps also be writable. Nothing in our code actually relies on this, so we can relax this restriction and get useful properties.

For instance, it is now possible to construct a `JavaOnlyMap` (or array) that reuses `ReadableMap` and `ReadableArray` values by reference ( = structural sharing) instead of forcing a deep copy.

Reviewed By: kathryngray

Differential Revision: D16132580

fbshipit-source-id: 9f41189ebea2a82e775a7a4da8c357a5ce9c5b9d

ReactAndroid/src/main/java/com/facebook/react/bridge/JavaOnlyArray.java

@@ -101,8 +101,8 @@ public class JavaOnlyArray implements ReadableArray, WritableArray {
   }
 
   @Override
-  public JavaOnlyArray getArray(int index) {
-    return (JavaOnlyArray) mBackingList.get(index);
+  public ReadableArray getArray(int index) {
+    return (ReadableArray) mBackingList.get(index);
   }
 
   @Override
@@ -111,8 +111,8 @@ public class JavaOnlyArray implements ReadableArray, WritableArray {
   }
 
   @Override
-  public JavaOnlyMap getMap(int index) {
-    return (JavaOnlyMap) mBackingList.get(index);
+  public ReadableMap getMap(int index) {
+    return (ReadableMap) mBackingList.get(index);
   }
 
   @Override
@@ -161,12 +161,12 @@ public class JavaOnlyArray implements ReadableArray, WritableArray {
   }
 
   @Override
-  public void pushArray(@Nullable WritableArray array) {
+  public void pushArray(@Nullable ReadableArray array) {
     mBackingList.add(array);
   }
 
   @Override
-  public void pushMap(@Nullable WritableMap map) {
+  public void pushMap(@Nullable ReadableMap map) {
     mBackingList.add(map);
   }
 

ReactAndroid/src/main/java/com/facebook/react/bridge/JavaOnlyMap.java

@@ -116,8 +116,8 @@ public class JavaOnlyMap implements ReadableMap, WritableMap {
   }
 
   @Override
-  public JavaOnlyArray getArray(@Nonnull String name) {
-    return (JavaOnlyArray) mBackingMap.get(name);
+  public ReadableArray getArray(@Nonnull String name) {
+    return (ReadableArray) mBackingMap.get(name);
   }
 
   @Override
@@ -196,7 +196,7 @@ public class JavaOnlyMap implements ReadableMap, WritableMap {
   }
 
   @Override
-  public void putMap(@Nonnull String key, @Nullable WritableMap value) {
+  public void putMap(@Nonnull String key, @Nullable ReadableMap value) {
     mBackingMap.put(key, value);
   }
 
@@ -213,7 +213,7 @@ public class JavaOnlyMap implements ReadableMap, WritableMap {
   }
 
   @Override
-  public void putArray(@Nonnull String key, @Nullable WritableArray value) {
+  public void putArray(@Nonnull String key, @Nullable ReadableArray value) {
     mBackingMap.put(key, value);
   }
 

ReactAndroid/src/main/java/com/facebook/react/bridge/WritableArray.java

@@ -21,7 +21,7 @@ public interface WritableArray extends ReadableArray {
 
   void pushString(@Nullable String value);
 
-  void pushArray(@Nullable WritableArray array);
+  void pushArray(@Nullable ReadableArray array);
 
-  void pushMap(@Nullable WritableMap map);
+  void pushMap(@Nullable ReadableMap map);
 }

ReactAndroid/src/main/java/com/facebook/react/bridge/WritableMap.java

@@ -22,9 +22,9 @@ public interface WritableMap extends ReadableMap {
 
   void putString(@Nonnull String key, @Nullable String value);
 
-  void putArray(@Nonnull String key, @Nullable WritableArray value);
+  void putArray(@Nonnull String key, @Nullable ReadableArray value);
 
-  void putMap(@Nonnull String key, @Nullable WritableMap value);
+  void putMap(@Nonnull String key, @Nullable ReadableMap value);
 
   void merge(@Nonnull ReadableMap source);
 

ReactAndroid/src/main/java/com/facebook/react/bridge/WritableNativeArray.java

@@ -42,7 +42,7 @@ public class WritableNativeArray extends ReadableNativeArray implements Writable
 
   // Note: this consumes the map so do not reuse it.
   @Override
-  public void pushArray(@Nullable WritableArray array) {
+  public void pushArray(@Nullable ReadableArray array) {
     Assertions.assertCondition(
         array == null || array instanceof WritableNativeArray, "Illegal type provided");
     pushNativeArray((WritableNativeArray) array);
@@ -50,7 +50,7 @@ public class WritableNativeArray extends ReadableNativeArray implements Writable
 
   // Note: this consumes the map so do not reuse it.
   @Override
-  public void pushMap(@Nullable WritableMap map) {
+  public void pushMap(@Nullable ReadableMap map) {
     Assertions.assertCondition(
         map == null || map instanceof WritableNativeMap, "Illegal type provided");
     pushNativeMap((WritableNativeMap) map);

ReactAndroid/src/main/java/com/facebook/react/bridge/WritableNativeMap.java

@@ -40,7 +40,7 @@ public class WritableNativeMap extends ReadableNativeMap implements WritableMap
 
   // Note: this consumes the map so do not reuse it.
   @Override
-  public void putMap(@Nonnull String key, @Nullable WritableMap value) {
+  public void putMap(@Nonnull String key, @Nullable ReadableMap value) {
     Assertions.assertCondition(
         value == null || value instanceof WritableNativeMap, "Illegal type provided");
     putNativeMap(key, (WritableNativeMap) value);
@@ -48,7 +48,7 @@ public class WritableNativeMap extends ReadableNativeMap implements WritableMap
 
   // Note: this consumes the map so do not reuse it.
   @Override
-  public void putArray(@Nonnull String key, @Nullable WritableArray value) {
+  public void putArray(@Nonnull String key, @Nullable ReadableArray value) {
     Assertions.assertCondition(
         value == null || value instanceof WritableNativeArray, "Illegal type provided");
     putNativeArray(key, (WritableNativeArray) value);