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Diffstat (limited to 'indra/llcommon/lllistenerwrapper.h')
| -rw-r--r-- | indra/llcommon/lllistenerwrapper.h | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/indra/llcommon/lllistenerwrapper.h b/indra/llcommon/lllistenerwrapper.h new file mode 100644 index 0000000000..e7bad1423a --- /dev/null +++ b/indra/llcommon/lllistenerwrapper.h @@ -0,0 +1,181 @@ +/** + * @file lllistenerwrapper.h + * @author Nat Goodspeed + * @date 2009-11-30 + * @brief Introduce LLListenerWrapper template + * + * $LicenseInfo:firstyear=2009&license=viewergpl$ + * Copyright (c) 2009, Linden Research, Inc. + * $/LicenseInfo$ + */ + +#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 LL_COMMON_API 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> LL_COMMON_API 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 LL_COMMON_API 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 LL_COMMON_API 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) */ |