Decouple object subclassing. #245
There are no files selected for viewing
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| /* | ||
| * Copyright (c) 2015-present, Parse, LLC. | ||
| * All rights reserved. | ||
| * | ||
| * This source code is licensed under the BSD-style license found in the | ||
| * LICENSE file in the root directory of this source tree. An additional grant | ||
| * of patent rights can be found in the PATENTS file in the same directory. | ||
| */ | ||
| package com.parse; | ||
|
|
||
| import java.lang.reflect.Constructor; | ||
| import java.lang.reflect.Modifier; | ||
| import java.util.HashMap; | ||
| import java.util.Map; | ||
|
|
||
| /* package */ class ParseObjectSubclassingController { | ||
| private final Object mutex = new Object(); | ||
| private final Map<String, Constructor<? extends ParseObject>> registeredSubclasses = new HashMap<>(); | ||
|
|
||
| /* package */ String getClassName(Class<? extends ParseObject> clazz) { | ||
| ParseClassName info = clazz.getAnnotation(ParseClassName.class); | ||
| if (info == null) { | ||
| throw new IllegalArgumentException("No ParseClassName annotation provided on " + clazz); | ||
| } | ||
| return info.value(); | ||
| } | ||
|
|
||
| /* package */ boolean isSubclassValid(String className, Class<? extends ParseObject> clazz) { | ||
| Constructor<? extends ParseObject> constructor = null; | ||
|
|
||
| synchronized (mutex) { | ||
| constructor = registeredSubclasses.get(className); | ||
| } | ||
|
|
||
| return constructor == null | ||
| ? clazz == ParseObject.class | ||
| : constructor.getDeclaringClass() == clazz; | ||
| } | ||
|
|
||
| /* package */ void registerSubclass(Class<? extends ParseObject> clazz) { | ||
| if (!ParseObject.class.isAssignableFrom(clazz)) { | ||
| throw new IllegalArgumentException("Cannot register a type that is not a subclass of ParseObject"); | ||
| } | ||
|
|
||
| String className = getClassName(clazz); | ||
| Constructor<? extends ParseObject> previousConstructor = null; | ||
|
|
||
| synchronized (mutex) { | ||
| previousConstructor = registeredSubclasses.get(className); | ||
| if (previousConstructor != null) { | ||
| Class<? extends ParseObject> previousClass = previousConstructor.getDeclaringClass(); | ||
| if (clazz.isAssignableFrom(previousClass)) { | ||
| // Previous subclass is more specific or equal to the current type, do nothing. | ||
| return; | ||
|
There was a problem hiding this comment. any reason why we have return here but not in the next condition? |
||
| } else if (previousClass.isAssignableFrom(clazz)) { | ||
| // Previous subclass is parent of new child subclass, fallthrough and actually | ||
| // register this class. | ||
| /* Do nothing */ | ||
| } else { | ||
| throw new IllegalArgumentException( | ||
| "Tried to register both " + previousClass.getName() + " and " + clazz.getName() + | ||
| " as the ParseObject subclass of " + className + ". " + "Cannot determine the right " + | ||
| "class to use because neither inherits from the other." | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| try { | ||
| registeredSubclasses.put(className, getConstructor(clazz)); | ||
| } catch (NoSuchMethodException ex) { | ||
| throw new IllegalArgumentException( | ||
| "Cannot register a type that does not implement the default constructor!" | ||
| ); | ||
| } catch (IllegalAccessException ex) { | ||
| throw new IllegalArgumentException( | ||
| "Default constructor for " + clazz + " is not accessible." | ||
| ); | ||
| } | ||
| } | ||
|
|
||
| if (previousConstructor != null) { | ||
| // TODO: This is super tightly coupled. Let's remove it when automatic registration is in. | ||
| // NOTE: Perform this outside of the mutex, to prevent any potential deadlocks. | ||
| if (className.equals(getClassName(ParseUser.class))) { | ||
| ParseUser.getCurrentUserController().clearFromMemory(); | ||
| } else if (className.equals(getClassName(ParseInstallation.class))) { | ||
| ParseInstallation.getCurrentInstallationController().clearFromMemory(); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| /* package */ void unregisterSubclass(Class<? extends ParseObject> clazz) { | ||
| String className = getClassName(clazz); | ||
|
|
||
| synchronized (mutex) { | ||
| registeredSubclasses.remove(className); | ||
| } | ||
| } | ||
|
|
||
| /* package */ ParseObject newInstance(String className) { | ||
| Constructor<? extends ParseObject> constructor = null; | ||
|
|
||
| synchronized (mutex) { | ||
| constructor = registeredSubclasses.get(className); | ||
| } | ||
|
|
||
| try { | ||
| return constructor != null | ||
| ? constructor.newInstance() | ||
| : new ParseObject(className); | ||
| } catch (RuntimeException e) { | ||
| throw e; | ||
| } catch (Exception e) { | ||
| throw new RuntimeException("Failed to create instance of subclass.", e); | ||
| } | ||
| } | ||
|
|
||
| private static Constructor<? extends ParseObject> getConstructor(Class<? extends ParseObject> clazz) throws NoSuchMethodException, IllegalAccessException { | ||
| Constructor<? extends ParseObject> constructor = clazz.getDeclaredConstructor(); | ||
| if (constructor == null) { | ||
| throw new NoSuchMethodException(); | ||
| } | ||
| int modifiers = constructor.getModifiers(); | ||
| if (Modifier.isPublic(modifiers) || (clazz.getPackage().getName().equals("com.parse") && | ||
| !(Modifier.isProtected(modifiers) || Modifier.isPrivate(modifiers)))) { | ||
| return constructor; | ||
| } | ||
| throw new IllegalAccessException(); | ||
| } | ||
| } | ||
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Could we ever hit this condition? We have strong typing already in the method signature that
clazzhas toextend ParseObjectThere was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Theoretically yes, especially if we go the route of runtime searching for automatic registration. It's mostly just a sanity check, though.