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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef nsBaseContentStream_h__
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#define nsBaseContentStream_h__
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#include "nsIAsyncInputStream.h"
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#include "nsIEventTarget.h"
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#include "nsCOMPtr.h"
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//-----------------------------------------------------------------------------
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// nsBaseContentStream is designed to be subclassed with the intention of being
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// used to satisfy the nsBaseChannel::OpenContentStream method.
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//
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// The subclass typically overrides the default Available, ReadSegments and
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// CloseWithStatus methods. By default, Read is implemented in terms of
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// ReadSegments, and Close is implemented in terms of CloseWithStatus. If
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// CloseWithStatus is overriden, then the subclass will usually want to call
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// the base class' CloseWithStatus method before returning.
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//
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// If the stream is non-blocking, then readSegments may return the exception
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// NS_BASE_STREAM_WOULD_BLOCK if there is no data available and the stream is
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// not at the "end-of-file" or already closed. This error code must not be
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// returned from the Available implementation. When the caller receives this
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// error code, he may choose to call the stream's AsyncWait method, in which
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// case the base stream will have a non-null PendingCallback. When the stream
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// has data or encounters an error, it should be sure to dispatch a pending
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// callback if one exists (see DispatchCallback). The implementation of the
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// base stream's CloseWithStatus (and Close) method will ensure that any
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// pending callback is dispatched. It is the responsibility of the subclass
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// to ensure that the pending callback is dispatched when it wants to have its
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// ReadSegments method called again.
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class nsBaseContentStream : public nsIAsyncInputStream {
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public:
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NS_DECL_THREADSAFE_ISUPPORTS
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NS_DECL_NSIINPUTSTREAM
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NS_DECL_NSIASYNCINPUTSTREAM
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explicit nsBaseContentStream(bool nonBlocking)
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: mStatus(NS_OK), mNonBlocking(nonBlocking) {}
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nsresult Status() { return mStatus; }
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bool IsNonBlocking() { return mNonBlocking; }
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bool IsClosed() { return NS_FAILED(mStatus); }
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// Called to test if the stream has a pending callback.
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bool HasPendingCallback() { return mCallback != nullptr; }
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// The current dispatch target (may be null) for the pending callback if any.
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nsIEventTarget* CallbackTarget() { return mCallbackTarget; }
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// Called to dispatch a pending callback. If there is no pending callback,
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// then this function does nothing. Pass true to this function to cause the
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// callback to occur asynchronously; otherwise, the callback will happen
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// before this function returns.
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void DispatchCallback(bool async = true);
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// Helper function to make code more self-documenting.
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void DispatchCallbackSync() { DispatchCallback(false); }
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protected:
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virtual ~nsBaseContentStream() = default;
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private:
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// Called from the base stream's AsyncWait method when a pending callback
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// is installed on the stream.
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virtual void OnCallbackPending() {}
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private:
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nsCOMPtr<nsIInputStreamCallback> mCallback;
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nsCOMPtr<nsIEventTarget> mCallbackTarget;
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nsresult mStatus;
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bool mNonBlocking;
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};
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#endif // nsBaseContentStream_h__