/indra/llcommon/lllistenerwrapper.h
C++ Header | 198 lines | 96 code | 18 blank | 84 comment | 2 complexity | e286efc55950535cfd85de1808687d51 MD5 | raw file
Possible License(s): LGPL-2.1
- /**
- * @file lllistenerwrapper.h
- * @author Nat Goodspeed
- * @date 2009-11-30
- * @brief Introduce LLListenerWrapper template
- *
- * $LicenseInfo:firstyear=2009&license=viewerlgpl$
- * Second Life Viewer Source Code
- * Copyright (C) 2010, Linden Research, Inc.
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation;
- * version 2.1 of the License only.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- *
- * Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
- * $/LicenseInfo$
- */
- #if ! defined(LL_LLLISTENERWRAPPER_H)
- #define LL_LLLISTENERWRAPPER_H
- #include "llevents.h" // LLListenerWrapperBase
- #include <boost/visit_each.hpp>
- /**
- * Template base class for coding wrappers for LLEventPump listeners.
- *
- * Derive your listener wrapper from LLListenerWrapper. You must use
- * LLLISTENER_WRAPPER_SUBCLASS() so your subclass will play nicely with
- * boost::visit_each (q.v.). That way boost::signals2 can still detect
- * derivation from LLEventTrackable, and so forth.
- */
- template <typename LISTENER>
- class LLListenerWrapper: public LLListenerWrapperBase
- {
- public:
- /// Wrap an arbitrary listener object
- LLListenerWrapper(const LISTENER& listener):
- mListener(listener)
- {}
- /// call
- virtual bool operator()(const LLSD& event)
- {
- return mListener(event);
- }
- /// Allow boost::visit_each() to peek at our mListener.
- template <class V>
- void accept_visitor(V& visitor) const
- {
- using boost::visit_each;
- visit_each(visitor, mListener, 0);
- }
- private:
- LISTENER mListener;
- };
- /**
- * Specialize boost::visit_each() (leveraging ADL) to peek inside an
- * LLListenerWrapper<T> to traverse its LISTENER. We borrow the
- * accept_visitor() pattern from boost::bind(), avoiding the need to make
- * mListener public.
- */
- template <class V, typename T>
- void visit_each(V& visitor, const LLListenerWrapper<T>& wrapper, int)
- {
- wrapper.accept_visitor(visitor);
- }
- /// use this (sigh!) for each subclass of LLListenerWrapper<T> you write
- #define LLLISTENER_WRAPPER_SUBCLASS(CLASS) \
- template <class V, typename T> \
- void visit_each(V& visitor, const CLASS<T>& wrapper, int) \
- { \
- visit_each(visitor, static_cast<const LLListenerWrapper<T>&>(wrapper), 0); \
- } \
- \
- /* Have to state this explicitly, rather than using LL_TEMPLATE_CONVERTIBLE, */ \
- /* because the source type is itself a template. */ \
- template <typename T> \
- struct ll_template_cast_impl<const LLListenerWrapperBase*, const CLASS<T>*> \
- { \
- const LLListenerWrapperBase* operator()(const CLASS<T>* wrapper) \
- { \
- return wrapper; \
- } \
- }
- /**
- * Make an instance of a listener wrapper. Every wrapper class must be a
- * template accepting a listener object of arbitrary type. In particular, the
- * type of a boost::bind() expression is deliberately undocumented. So we
- * can't just write Wrapper<CorrectType>(boost::bind(...)). Instead we must
- * write llwrap<Wrapper>(boost::bind(...)).
- */
- template <template<typename> class WRAPPER, typename T>
- WRAPPER<T> llwrap(const T& listener)
- {
- return WRAPPER<T>(listener);
- }
- /**
- * This LLListenerWrapper template subclass is used to report entry/exit to an
- * event listener, by changing this:
- * @code
- * someEventPump.listen("MyClass",
- * boost::bind(&MyClass::method, ptr, _1));
- * @endcode
- * to this:
- * @code
- * someEventPump.listen("MyClass",
- * llwrap<LLCoutListener>(
- * boost::bind(&MyClass::method, ptr, _1)));
- * @endcode
- */
- template <class LISTENER>
- class LLCoutListener: public LLListenerWrapper<LISTENER>
- {
- typedef LLListenerWrapper<LISTENER> super;
- public:
- /// Wrap an arbitrary listener object
- LLCoutListener(const LISTENER& listener):
- super(listener)
- {}
- /// call
- virtual bool operator()(const LLSD& event)
- {
- std::cout << "Entering listener " << *super::mName << " with " << event << std::endl;
- bool handled = super::operator()(event);
- std::cout << "Leaving listener " << *super::mName;
- if (handled)
- {
- std::cout << " (handled)";
- }
- std::cout << std::endl;
- return handled;
- }
- };
- LLLISTENER_WRAPPER_SUBCLASS(LLCoutListener);
- /**
- * This LLListenerWrapper template subclass is used to log entry/exit to an
- * event listener, by changing this:
- * @code
- * someEventPump.listen("MyClass",
- * boost::bind(&MyClass::method, ptr, _1));
- * @endcode
- * to this:
- * @code
- * someEventPump.listen("MyClass",
- * llwrap<LLLogListener>(
- * boost::bind(&MyClass::method, ptr, _1)));
- * @endcode
- */
- template <class LISTENER>
- class LLLogListener: public LLListenerWrapper<LISTENER>
- {
- typedef LLListenerWrapper<LISTENER> super;
- public:
- /// Wrap an arbitrary listener object
- LLLogListener(const LISTENER& listener):
- super(listener)
- {}
- /// call
- virtual bool operator()(const LLSD& event)
- {
- LL_DEBUGS("LLLogListener") << "Entering listener " << *super::mName << " with " << event << LL_ENDL;
- bool handled = super::operator()(event);
- LL_DEBUGS("LLLogListener") << "Leaving listener " << *super::mName;
- if (handled)
- {
- LL_CONT << " (handled)";
- }
- LL_CONT << LL_ENDL;
- return handled;
- }
- };
- LLLISTENER_WRAPPER_SUBCLASS(LLLogListener);
- #endif /* ! defined(LL_LLLISTENERWRAPPER_H) */