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      1 /*
      2  * libjingle
      3  * Copyright 2004--2005, Google Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions are met:
      7  *
      8  *  1. Redistributions of source code must retain the above copyright notice,
      9  *     this list of conditions and the following disclaimer.
     10  *  2. Redistributions in binary form must reproduce the above copyright notice,
     11  *     this list of conditions and the following disclaimer in the documentation
     12  *     and/or other materials provided with the distribution.
     13  *  3. The name of the author may not be used to endorse or promote products
     14  *     derived from this software without specific prior written permission.
     15  *
     16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
     17  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
     18  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
     19  * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     20  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     21  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
     22  * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
     23  * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
     24  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
     25  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     26  */
     27 
     28 #ifndef _moduleimpl_h_
     29 #define _moduleimpl_h_
     30 
     31 #include "talk/xmpp/xmppengine.h"
     32 #include "talk/xmpp/module.h"
     33 
     34 namespace buzz {
     35 
     36 //! This is the base implementation class for extension modules.
     37 //! An engine is registered with the module and the module then hooks the
     38 //! appropriate parts of the engine to implement that set of features.  It is
     39 //! important to unregister modules before destructing the engine.
     40 class XmppModuleImpl {
     41 protected:
     42   XmppModuleImpl();
     43   virtual ~XmppModuleImpl();
     44 
     45   //! Register the engine with the module.  Only one engine can be associated
     46   //! with a module at a time.  This method will return an error if there is
     47   //! already an engine registered.
     48   XmppReturnStatus RegisterEngine(XmppEngine* engine);
     49 
     50   //! Gets the engine that this module is attached to.
     51   XmppEngine* engine();
     52 
     53   //! Process the given stanza.
     54   //! The module must return true if it has handled the stanza.
     55   //! A false return value causes the stanza to be passed on to
     56   //! the next registered handler.
     57   virtual bool HandleStanza(const XmlElement *) { return false; };
     58 
     59 private:
     60 
     61   //! The ModuleSessionHelper nested class allows the Module
     62   //! to hook into and get stanzas and events from the engine.
     63   class ModuleStanzaHandler : public XmppStanzaHandler {
     64     friend class XmppModuleImpl;
     65 
     66     ModuleStanzaHandler(XmppModuleImpl* module) :
     67       module_(module) {
     68     }
     69 
     70     bool HandleStanza(const XmlElement* stanza) {
     71       return module_->HandleStanza(stanza);
     72     }
     73 
     74     XmppModuleImpl* module_;
     75   };
     76 
     77   friend class ModuleStanzaHandler;
     78 
     79   XmppEngine* engine_;
     80   ModuleStanzaHandler stanza_handler_;
     81 };
     82 
     83 
     84 // This macro will implement the XmppModule interface for a class
     85 // that derives from both XmppModuleImpl and XmppModule
     86 #define IMPLEMENT_XMPPMODULE \
     87   XmppReturnStatus RegisterEngine(XmppEngine* engine) { \
     88     return XmppModuleImpl::RegisterEngine(engine); \
     89   }
     90 
     91 }
     92 
     93 #endif
     94