/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_dom_XMLHttpRequestString_h

#define mozilla_dom_XMLHttpRequestString_h

#include "mozilla/Mutex.h"

#include "nsString.h"

namespace mozilla {

namespace dom {

class DOMString;

class XMLHttpRequestStringBuffer;

class XMLHttpRequestStringSnapshot;

class XMLHttpRequestStringWriterHelper;

class XMLHttpRequestStringSnapshotReaderHelper;

// We want to avoid the dup of strings when XHR in workers has access to

// responseText for events dispatched during the loading state. For this reason

// we use this class, able to create snapshots of the current size of itself

// without making extra copies.

class XMLHttpRequestString final

{

  friend class XMLHttpRequestStringWriterHelper;

public:

  XMLHttpRequestString();

  ~XMLHttpRequestString();

  void Truncate();

  uint32_t Length() const;

  void Append(const nsAString& aString);

  // This method should be called only when the string is really needed because

  // it can cause the duplication of the strings in case the loading of the XHR

  // is not completed yet.

  MOZ_MUST_USE bool GetAsString(nsAString& aString) const;

  size_t SizeOfThis(MallocSizeOf aMallocSizeOf) const;

  const char16_t* Data() const;

  bool IsEmpty() const;

  void CreateSnapshot(XMLHttpRequestStringSnapshot& aSnapshot);

private:

  XMLHttpRequestString(const XMLHttpRequestString&) = delete;

  XMLHttpRequestString& operator=(const XMLHttpRequestString&) = delete;

  XMLHttpRequestString& operator=(const XMLHttpRequestString&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;

};

// This class locks the buffer and allows the callee to write data into it.

class MOZ_STACK_CLASS XMLHttpRequestStringWriterHelper final

{

public:

  explicit XMLHttpRequestStringWriterHelper(XMLHttpRequestString& aString);

  /**

   * The existing length of the string. Do not call during BulkWrite().

   */

  uint32_t

  Length() const;

  mozilla::BulkWriteHandle<char16_t>

  BulkWrite(uint32_t aCapacity, nsresult& aRv);

private:

  XMLHttpRequestStringWriterHelper(const XMLHttpRequestStringWriterHelper&) = delete;

  XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&) = delete;

  XMLHttpRequestStringWriterHelper& operator=(const XMLHttpRequestStringWriterHelper&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;

  MutexAutoLock mLock;

};

// This class is the internal XMLHttpRequestStringBuffer of the

// XMLHttpRequestString plus the current length. GetAsString will return the

// string with that particular length also if the XMLHttpRequestStringBuffer is

// grown in the meantime.

class XMLHttpRequestStringSnapshot final

{

  friend class XMLHttpRequestStringBuffer;

  friend class XMLHttpRequestStringSnapshotReaderHelper;

public:

  XMLHttpRequestStringSnapshot();

  ~XMLHttpRequestStringSnapshot();

  XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&);

  void Reset()

  {

    ResetInternal(false /* isVoid */);

  }

  void SetVoid()

  {

    ResetInternal(true /* isVoid */);

  }

  bool IsVoid() const

  {

    return mVoid;

  }

  bool IsEmpty() const

  {

    return !mLength;

  }

  MOZ_MUST_USE bool GetAsString(DOMString& aString) const;

private:

  XMLHttpRequestStringSnapshot(const XMLHttpRequestStringSnapshot&) = delete;

  XMLHttpRequestStringSnapshot& operator=(const XMLHttpRequestStringSnapshot&&) = delete;

  void Set(XMLHttpRequestStringBuffer* aBuffer, uint32_t aLength);

  void ResetInternal(bool aIsVoid);

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;

  uint32_t mLength;

  bool mVoid;

};

// This class locks the buffer and allows the callee to read data from it.

class MOZ_STACK_CLASS XMLHttpRequestStringSnapshotReaderHelper final

{

public:

  explicit XMLHttpRequestStringSnapshotReaderHelper(XMLHttpRequestStringSnapshot& aSnapshot);

  const char16_t*

  Buffer() const;

  uint32_t

  Length() const;

private:

  XMLHttpRequestStringSnapshotReaderHelper(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;

  XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&) = delete;

  XMLHttpRequestStringSnapshotReaderHelper& operator=(const XMLHttpRequestStringSnapshotReaderHelper&&) = delete;

  RefPtr<XMLHttpRequestStringBuffer> mBuffer;

  MutexAutoLock mLock;

};

} // dom namespace

} // mozilla namespace

#endif // mozilla_dom_XMLHttpRequestString_h