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| -rw-r--r-- | indra/llcommon/lleventfilter.h | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/indra/llcommon/lleventfilter.h b/indra/llcommon/lleventfilter.h index ff8fc9bc7f..8e7c075581 100644 --- a/indra/llcommon/lleventfilter.h +++ b/indra/llcommon/lleventfilter.h @@ -32,6 +32,7 @@ #include "llevents.h" #include "stdtypes.h" #include "lltimer.h" +#include "llsdutil.h" #include <boost/function.hpp> /** @@ -376,4 +377,54 @@ private: std::size_t mBatchSize; }; +/** + * LLStoreListener self-registers on the LLEventPump of interest, and + * unregisters on destruction. As long as it exists, a particular element is + * extracted from every event that comes through the upstream LLEventPump and + * stored into the target variable. + * + * This is implemented as a subclass of LLEventFilter, though strictly + * speaking it isn't really a "filter" at all: it never passes incoming events + * to its own listeners, if any. + * + * TBD: A variant based on output iterators that stores and then increments + * the iterator. Useful with boost::coroutine2! + */ +template <typename T> +class LLStoreListener: public LLEventFilter +{ +public: + // pass target and optional path to element + LLStoreListener(T& target, const LLSD& path=LLSD(), bool consume=false): + LLEventFilter("store"), + mTarget(target), + mPath(path), + mConsume(consume) + {} + // construct and connect + LLStoreListener(LLEventPump& source, T& target, const LLSD& path=LLSD(), bool consume=false): + LLEventFilter(source, "store"), + mTarget(target), + mPath(path), + mConsume(consume) + {} + + // Calling post() with an LLSD event extracts the element indicated by + // path, then stores it to mTarget. + virtual bool post(const LLSD& event) + { + // Extract the element specified by 'mPath' from 'event'. To perform a + // generic type-appropriate store through mTarget, construct an + // LLSDParam<T> and store that, thus engaging LLSDParam's custom + // conversions. + mTarget = LLSDParam<T>(llsd::drill(event, mPath)); + return mConsume; + } + +private: + T& mTarget; + const LLSD mPath; + const bool mConsume; +}; + #endif /* ! defined(LL_LLEVENTFILTER_H) */ |