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| -rw-r--r-- | slideshow/source/inc/listenercontainer.hxx | 418 |
1 files changed, 418 insertions, 0 deletions
diff --git a/slideshow/source/inc/listenercontainer.hxx b/slideshow/source/inc/listenercontainer.hxx new file mode 100644 index 000000000..8deb1be90 --- /dev/null +++ b/slideshow/source/inc/listenercontainer.hxx @@ -0,0 +1,418 @@ +/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */ +/* + * This file is part of the LibreOffice project. + * + * This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. + * + * This file incorporates work covered by the following license notice: + * + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed + * with this work for additional information regarding copyright + * ownership. The ASF licenses this file to you under the Apache + * License, Version 2.0 (the "License"); you may not use this file + * except in compliance with the License. You may obtain a copy of + * the License at http://www.apache.org/licenses/LICENSE-2.0 . + */ +#ifndef INCLUDED_SLIDESHOW_SOURCE_INC_LISTENERCONTAINER_HXX +#define INCLUDED_SLIDESHOW_SOURCE_INC_LISTENERCONTAINER_HXX + +#include <algorithm> +#include <memory> +#include <vector> +#include <iterator> + +namespace slideshow::internal { + +struct EmptyBase +{ + struct EmptyGuard{ explicit EmptyGuard(EmptyBase) {} }; + struct EmptyClearableGuard + { + explicit EmptyClearableGuard(EmptyBase) {} + static void clear() {} + }; + + typedef EmptyGuard Guard; + typedef EmptyClearableGuard ClearableGuard; +}; + +template< typename result_type, typename ListenerTargetT > struct FunctionApply +{ + template<typename FuncT> static bool apply( + FuncT func, + ListenerTargetT const& rArg ) + { + return func(rArg); + } +}; + +template<typename ListenerTargetT> struct FunctionApply<void,ListenerTargetT> +{ + template<typename FuncT> static bool apply( + FuncT func, + ListenerTargetT const& rArg ) + { + func(rArg); + return true; + } +}; + +template< typename ListenerT > struct ListenerOperations +{ + /// Notify a single one of the listeners + template< typename ContainerT, + typename FuncT > + static bool notifySingleListener( ContainerT& rContainer, + FuncT func ) + { + // true: a handler in this queue processed the event + // false: no handler in this queue finally processed the event + return std::any_of( rContainer.begin(), + rContainer.end(), + func ); + } + + /// Notify all listeners + template< typename ContainerT, + typename FuncT > + static bool notifyAllListeners( ContainerT& rContainer, + FuncT func ) + { + bool bRet(false); + for( const auto& rCurr : rContainer ) + { + if( FunctionApply< typename ::std::invoke_result< FuncT, const typename ContainerT::value_type& >::type, + typename ContainerT::value_type >::apply( + func, + rCurr) ) + { + bRet = true; + } + } + + // true: at least one handler returned true + // false: not a single handler returned true + return bRet; + } + + /// Prune container from deceased listeners + template< typename ContainerT > + static void pruneListeners( ContainerT&, size_t ) + { + } +}; + +template< typename ListenerTargetT > +struct ListenerOperations< std::weak_ptr<ListenerTargetT> > +{ + template< typename ContainerT, + typename FuncT > + static bool notifySingleListener( ContainerT& rContainer, + FuncT func ) + { + for( const auto& rCurr : rContainer ) + { + std::shared_ptr<ListenerTargetT> pListener( rCurr.lock() ); + + if( pListener && func(pListener) ) + return true; + } + + return false; + } + + template< typename ContainerT, + typename FuncT > + static bool notifyAllListeners( ContainerT& rContainer, + FuncT func ) + { + bool bRet(false); + for( const auto& rCurr : rContainer ) + { + std::shared_ptr<ListenerTargetT> pListener( rCurr.lock() ); + + if( pListener.get() && + FunctionApply<typename ::std::invoke_result<FuncT, std::shared_ptr<ListenerTargetT> const&>::type, + std::shared_ptr<ListenerTargetT> >::apply(func,pListener) ) + { + bRet = true; + } + } + + return bRet; + } + template< typename ContainerT > + static void pruneListeners( ContainerT& rContainer, + size_t nSizeThreshold ) + { + if( rContainer.size() <= nSizeThreshold ) + return; + + ContainerT aAliveListeners; + aAliveListeners.reserve(rContainer.size()); + + for( const auto& rCurr : rContainer ) + { + if( !rCurr.expired() ) + aAliveListeners.push_back( rCurr ); + } + + std::swap( rContainer, aAliveListeners ); + } +}; + +/** Container for objects that can be notified. + + This templatized container holds listener objects, then can get + notified (by calling certain methods on them). + + @tpl Listener + Type for the listener objects to be held + + @tpl ContainerT + Full type of the container to store the listener objects. Defaults + to std::vector<ListenerT> + + @tpl MaxDeceasedListenerUllage + Threshold, from which upwards the listener container gets + pruned. Avoids frequent copying of nearly empty containers. + + @attention internal class, not to be used. functionality is + incomplete, please use the Thread(Un)safeListenerContainer types + from below +*/ +template< typename ListenerT, + typename MutexHolderBaseT, + typename ContainerT=std::vector<ListenerT>, + size_t MaxDeceasedListenerUllage=16 > class ListenerContainerBase : public MutexHolderBaseT +{ + typedef typename MutexHolderBaseT::Guard Guard; + typedef typename MutexHolderBaseT::ClearableGuard ClearableGuard; + +public: + typedef ListenerT listener_type; + typedef ContainerT container_type; + + /** Check whether listener container is empty + + @return true, if currently no listeners registered. Note that + in a multi-threaded scenario, without external synchronisation + to this object, the return value might become wrong at any time. + */ + bool isEmpty() const + { + Guard aGuard(*this); + return maListeners.empty(); + } + + /** Check whether given listener is already added + + @return true, if given listener is already added. + */ + bool isAdded( listener_type const& rListener ) const + { + Guard aGuard(*this); + + const typename container_type::const_iterator aEnd( maListeners.end() ); + if( std::find( maListeners.begin(), + aEnd, + rListener ) != aEnd ) + { + return true; // already added + } + + return false; + } + + /** Add new listener + + @param rListener + Listener to add + */ + void add( listener_type const& rListener ) + { + Guard aGuard(*this); + + // ensure uniqueness + if( isAdded(rListener) ) + return; // already added + + maListeners.push_back( rListener ); + + ListenerOperations<ListenerT>::pruneListeners( + maListeners, + MaxDeceasedListenerUllage); + } + + /** Add new listener into sorted container + + The stored listeners are kept sorted (using this method + requires listener_type to have operator< defined on it). Make + sure to call addSorted() for <em>each</em> listener to add to + this container - sorting is performed under the assumption + that existing entries are already sorted. + + @param rListener + Listener to add + + @return false, if the listener is already added, true + otherwise + */ + bool addSorted( listener_type const& rListener ) + { + Guard aGuard(*this); + + // ensure uniqueness + if( isAdded(rListener) ) + return false; // already added + + maListeners.push_back( rListener ); + + // a single entry does not need to be sorted + if( maListeners.size() > 1 ) + { + std::inplace_merge( + maListeners.begin(), + std::prev(maListeners.end()), + maListeners.end() ); + } + + ListenerOperations<ListenerT>::pruneListeners( + maListeners, + MaxDeceasedListenerUllage); + + return true; + } + + /** Remove listener from container + + @param rListener + The listener to remove + + @return false, if listener not found in container, true + otherwise + */ + bool remove( listener_type const& rListener ) + { + Guard aGuard(*this); + + const typename container_type::iterator aEnd( maListeners.end() ); + typename container_type::iterator aIter; + if( (aIter=std::remove(maListeners.begin(), + aEnd, + rListener)) == aEnd ) + { + return false; // listener not found + } + + maListeners.erase( aIter, aEnd ); + + return true; + } + + /// Removes all listeners in one go + void clear() + { + Guard aGuard(*this); + + maListeners.clear(); + } + + /** Apply functor to one listener + + This method applies functor to one of the listeners. Starting + with the first entry of the container, the functor is called + with the listener entries, until it returns true. + + @param func + Given functor is called with listeners, until it returns true + + @return true, if functor was successfully applied to a + listener + */ + template< typename FuncT > bool apply( FuncT func ) const + { + ClearableGuard aGuard(*this); + + // generate a local copy of all handlers, to make method + // reentrant and thread-safe. + container_type const local( maListeners ); + aGuard.clear(); + + const bool bRet( + ListenerOperations<ListenerT>::notifySingleListener( + local, + func )); + + { + Guard aGuard2(*this); + ListenerOperations<ListenerT>::pruneListeners( + const_cast<container_type&>(maListeners), + MaxDeceasedListenerUllage); + } + + return bRet; + } + + /** Apply functor to all listeners + + This method applies functor to all of the listeners. Starting + with the first entry of the container, the functor is called + with the listener entries. + + @param func + Given functor is called with listeners. + + @return true, if functor was successfully applied to at least + one listener + */ + template< typename FuncT > bool applyAll( FuncT func ) const + { + ClearableGuard aGuard(*this); + + // generate a local copy of all handlers, to make method + // reentrant and thread-safe. + container_type const local( maListeners ); + aGuard.clear(); + + const bool bRet( + ListenerOperations<ListenerT>::notifyAllListeners( + local, + func )); + + { + Guard aGuard2(*this); + ListenerOperations<ListenerT>::pruneListeners( + const_cast<container_type&>(maListeners), + MaxDeceasedListenerUllage); + } + + return bRet; + } + +private: + ContainerT maListeners; +}; + + +/** ListenerContainer variant that does not serialize access + + This ListenerContainer version is not safe to use in a + multi-threaded scenario, but has less overhead. + */ +template< typename ListenerT, + typename ContainerT=std::vector<ListenerT> > +class ThreadUnsafeListenerContainer : public ListenerContainerBase<ListenerT, + EmptyBase, + ContainerT> +{ +}; + +} // namespace slideshow::internal + +#endif // INCLUDED_SLIDESHOW_SOURCE_INC_LISTENERCONTAINER_HXX + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |