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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef IOS_CHROME_BROWSER_WEB_DOM_ALTERING_LOCK_H_
#define IOS_CHROME_BROWSER_WEB_DOM_ALTERING_LOCK_H_
#include "base/ios/block_types.h"
#import "base/ios/weak_nsobject.h"
#include "ios/web/public/web_state/web_state_user_data.h"
namespace web {
class WebState;
}
typedef void (^ProceduralBlockWithBool)(BOOL);
// This protocol must be implemented by all classes which may alter the DOM tree
// of a web page. Before altering the DOM, the class must call
// DOMAlteringLock::Acquire() and can only proceed if the lock is really
// acquired.
// After restoring the DOM tree, the class must call DOMAlteringLock::Release().
@protocol DOMAltering<NSObject>
// Method called when another class wants to acquire the lock.
// Return YES if the class is ready to restore the DOM tree to its initial state
// and release the lock. A call to |releaseDOMLockWithCompletionHandler:|
// will follow to do the actual cleaning.
// Return NO if the class wants to keep an exclusive access to the DOM tree.
// Other features must account for the fact that they may not be able to acquire
// a lock on the DOM and behave accordingly.
- (BOOL)canReleaseDOMLock;
// Method called when another class wants to acquire the lock.
// The class must restore the DOM tree, call DOMAlteringLock::Release() and then
// |completionHandler|.
- (void)releaseDOMLockWithCompletionHandler:(ProceduralBlock)completionHandler;
@end
class DOMAlteringLock : public web::WebStateUserData<DOMAlteringLock> {
public:
DOMAlteringLock(web::WebState* web_state);
// This method must be called before altering the DOM of the page. This will
// ensure that only one class tries to alter the page at a time.
// The completion handler is called with YES if the lock was acquired, or NO
// if it could not.
// This method must be called on the UI thread.
void Acquire(id<DOMAltering> feature, ProceduralBlockWithBool lockAction);
// Releases the lock on the DOM tree.
// The lock is always released, even if it was acquired multiple times.
// This method must be called on the UI thread.
void Release(id<DOMAltering> feature);
private:
// DOMAltering object currently having the lock.
base::WeakNSProtocol<id<DOMAltering>> current_dom_altering_feature_;
~DOMAlteringLock() override;
};
#endif // IOS_CHROME_BROWSER_WEB_DOM_ALTERING_LOCK_H_
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