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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H
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#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H
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#include "base/base_export.h"
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#include "base/event_types.h"
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// Dispatcher is used during a nested invocation of Run to dispatch events when
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// |RunLoop(dispatcher).Run()| is used. If |RunLoop().Run()| is invoked,
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// MessageLoop does not dispatch events (or invoke TranslateMessage), rather
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// every message is passed to Dispatcher's Dispatch method for dispatch. It is
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// up to the Dispatcher whether or not to dispatch the event.
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// The nested loop is exited by either posting a quit, or setting the
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// POST_DISPATCH_QUIT_LOOP flag on the return value from Dispatch.
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class BASE_EXPORT MessagePumpDispatcher {
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enum PostDispatchAction {
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POST_DISPATCH_NONE = 0x0,
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POST_DISPATCH_QUIT_LOOP = 0x1,
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POST_DISPATCH_PERFORM_DEFAULT = 0x2,
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virtual ~MessagePumpDispatcher() {}
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// Dispatches the event. The return value can have more than one
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// PostDispatchAction flags OR'ed together. If POST_DISPATCH_PERFORM_DEFAULT
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// is set in the returned value, then the message-pump performs the default
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// action. If POST_DISPATCH_QUIT_LOOP is set, in the return value, then the
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// nested loop exits immediately.
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virtual uint32_t Dispatch(const NativeEvent& event) = 0;
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#endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_DISPATCHER_H