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       1             : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
       2             : /* vim: set ts=8 sts=2 et sw=2 tw=80: */
       3             : /* This Source Code Form is subject to the terms of the Mozilla Public
       4             :  * License, v. 2.0. If a copy of the MPL was not distributed with this
       5             :  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
       6             : 
       7             : #ifndef mozilla_dom_XMLHttpRequestString_h
       8             : #define mozilla_dom_XMLHttpRequestString_h
       9             : 
      10             : #include "mozilla/Mutex.h"
      11             : #include "nsString.h"
      12             : 
      13             : namespace mozilla {
      14             : namespace dom {
      15             : 
      16             : class DOMString;
      17             : class XMLHttpRequestStringBuffer;
      18             : class XMLHttpRequestStringSnapshot;
      19             : class XMLHttpRequestStringWriterHelper;
      20             : class XMLHttpRequestStringSnapshotReaderHelper;
      21             : 
      22             : // We want to avoid the dup of strings when XHR in workers has access to
      23             : // responseText for events dispatched during the loading state. For this reason
      24             : // we use this class, able to create snapshots of the current size of itself
      25             : // without making extra copies.
      26             : class XMLHttpRequestString final
      27             : {
      28             :   friend class XMLHttpRequestStringWriterHelper;
      29             : 
      30             : public:
      31             :   XMLHttpRequestString();
      32             :   ~XMLHttpRequestString();
      33             : 
      34             :   void Truncate();
      35             : 
      36             :   uint32_t Length() const;
      37             : 
      38             :   void Append(const nsAString& aString);
      39             : 
      40             :   // This method should be called only when the string is really needed because
      41             :   // it can cause the duplication of the strings in case the loading of the XHR
      42             :   // is not completed yet.
      43             :   MOZ_MUST_USE bool GetAsString(nsAString& aString) const;
      44             : 
      45             :   size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;
      46             : 
      47             :   const char16_t* Data() const;
      48             : 
      49             :   bool IsEmpty() const;
      50             : 
      51             :   void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot);
      52             : 
      53             : private:
      54             :   XMLHttpRequestString(const XMLHttpRequestString&) = delete;
      55             :   XMLHttpRequestString& operator=(const XMLHttpRequestString&) = delete;
      56             :   XMLHttpRequestString& operator=(const XMLHttpRequestString&&) = delete;
      57             : 
      58             :   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
      59             : };
      60             : 
      61             : // This class locks the buffer and allows the callee to write data into it.
      62           3 : class MOZ_STACK_CLASS XMLHttpRequestStringWriterHelper final
      63             : {
      64             : public:
      65             :   explicit XMLHttpRequestStringWriterHelper(XMLHttpRequestString& aString);
      66             : 
      67             :   bool
      68             :   AddCapacity(int32_t aCapacity);
      69             : 
      70             :   char16_t*
      71             :   EndOfExistingData();
      72             : 
      73             :   void
      74             :   AddLength(int32_t aLength);
      75             : 
      76             : private:
      77             :   XMLHttpRequestStringWriterHelper(const XMLHttpRequestStringWriterHelper&) = delete;
      78             :   XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&) = delete;
      79             :   XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&&) = delete;
      80             : 
      81             :   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
      82             :   MutexAutoLock mLock;
      83             : };
      84             : 
      85             : // This class is the internal XMLHttpRequestStringBuffer of the
      86             : // XMLHttpRequestString plus the current length. GetAsString will return the
      87             : // string with that particular length also if the XMLHttpRequestStringBuffer is
      88             : // grown in the meantime.
      89             : class XMLHttpRequestStringSnapshot final
      90             : {
      91             :   friend class XMLHttpRequestStringBuffer;
      92             :   friend class XMLHttpRequestStringSnapshotReaderHelper;
      93             : 
      94             : public:
      95             :   XMLHttpRequestStringSnapshot();
      96             :   ~XMLHttpRequestStringSnapshot();
      97             : 
      98             :   XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&);
      99             : 
     100          17 :   void Reset()
     101             :   {
     102          17 :     ResetInternal(false /* isVoid */);
     103          17 :   }
     104             : 
     105           0 :   void SetVoid()
     106             :   {
     107           0 :     ResetInternal(true /* isVoid */);
     108           0 :   }
     109             : 
     110          17 :   bool IsVoid() const
     111             :   {
     112          17 :     return mVoid;
     113             :   }
     114             : 
     115           0 :   bool IsEmpty() const
     116             :   {
     117           0 :     return !mLength;
     118             :   }
     119             : 
     120             :   MOZ_MUST_USE bool GetAsString(DOMString& aString) const;
     121             : 
     122             : private:
     123             :   XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;
     124             :   XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&&) = delete;
     125             : 
     126             :   void Set(XMLHttpRequestStringBuffer* aBuffer, uint32_t aLength);
     127             : 
     128             :   void ResetInternal(bool aIsVoid);
     129             : 
     130             :   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
     131             :   uint32_t mLength;
     132             :   bool mVoid;
     133             : };
     134             : 
     135             : // This class locks the buffer and allows the callee to read data from it.
     136           0 : class MOZ_STACK_CLASS XMLHttpRequestStringSnapshotReaderHelper final
     137             : {
     138             : public:
     139             :   explicit XMLHttpRequestStringSnapshotReaderHelper(XMLHttpRequestStringSnapshot& aSnapshot);
     140             : 
     141             :   const char16_t*
     142             :   Buffer() const;
     143             : 
     144             :   uint32_t
     145             :   Length() const;
     146             : 
     147             : private:
     148             :   XMLHttpRequestStringSnapshotReaderHelper(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
     149             :   XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;
     150             :   XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&&) = delete;
     151             : 
     152             :   RefPtr<XMLHttpRequestStringBuffer> mBuffer;
     153             :   MutexAutoLock mLock;
     154             : };
     155             : 
     156             : } // dom namespace
     157             : } // mozilla namespace
     158             : 
     159             : #endif // mozilla_dom_XMLHttpRequestString_h