InputStreamLengthHelper.h

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/* -*- 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_InputStreamLengthHelper_h

#define mozilla_InputStreamLengthHelper_h

#include <functional>

#include "nsISupportsImpl.h"

#include "nsIInputStreamLength.h"

#include "nsThreadUtils.h"

class nsIInputStream;

namespace mozilla {

// This class helps to retrieve the stream's length.

class InputStreamLengthHelper final : public Runnable,

                                      public nsIInputStreamLengthCallback {

 public:

  NS_DECL_ISUPPORTS_INHERITED

  // This is one of the 2 entry points of this class. It returns false if the

  // length cannot be taken synchronously.

  static bool GetSyncLength(nsIInputStream* aStream, int64_t* aLength);

  // This is one of the 2 entry points of this class. The callback is executed

  // asynchronously when the length is known.

  static void GetAsyncLength(

      nsIInputStream* aStream,

      const std::function<void(int64_t aLength)>& aCallback);

 private:

  NS_DECL_NSIINPUTSTREAMLENGTHCALLBACK

  InputStreamLengthHelper(

      nsIInputStream* aStream,

      const std::function<void(int64_t aLength)>& aCallback);

  ~InputStreamLengthHelper();

  NS_IMETHOD

  Run() override;

  void ExecCallback(int64_t aLength);

  nsCOMPtr<nsIInputStream> mStream;

  std::function<void(int64_t aLength)> mCallback;

};

}  // namespace mozilla

#endif  // mozilla_InputStreamLengthHelper_h