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Diffstat (limited to 'indra/llui/lllazyvalue.h')
| -rw-r--r-- | indra/llui/lllazyvalue.h | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/indra/llui/lllazyvalue.h b/indra/llui/lllazyvalue.h new file mode 100644 index 0000000000..cf45214628 --- /dev/null +++ b/indra/llui/lllazyvalue.h @@ -0,0 +1,88 @@ +/** + * @file lllazyvalue.h + * @brief generic functor/value abstraction for lazy evaluation of a value + * parsing construction parameters from xml and LLSD + * + * $LicenseInfo:firstyear=2008&license=viewergpl$ + * + * Copyright (c) 2008-2009, Linden Research, Inc. + * + * Second Life Viewer Source Code + * The source code in this file ("Source Code") is provided by Linden Lab + * to you under the terms of the GNU General Public License, version 2.0 + * ("GPL"), unless you have obtained a separate licensing agreement + * ("Other License"), formally executed by you and Linden Lab. Terms of + * the GPL can be found in doc/GPL-license.txt in this distribution, or + * online at http://secondlifegrid.net/programs/open_source/licensing/gplv2 + * + * There are special exceptions to the terms and conditions of the GPL as + * it is applied to this Source Code. View the full text of the exception + * in the file doc/FLOSS-exception.txt in this software distribution, or + * online at + * http://secondlifegrid.net/programs/open_source/licensing/flossexception + * + * By copying, modifying or distributing this software, you acknowledge + * that you have read and understood your obligations described above, + * and agree to abide by those obligations. + * + * ALL LINDEN LAB SOURCE CODE IS PROVIDED "AS IS." LINDEN LAB MAKES NO + * WARRANTIES, EXPRESS, IMPLIED OR OTHERWISE, REGARDING ITS ACCURACY, + * COMPLETENESS OR PERFORMANCE. + * $/LicenseInfo$ + */ + +#ifndef LL_LAZY_VALUE_H +#define LL_LAZY_VALUE_H + +#include <boost/function.hpp> + +// Holds on to a value of type T *or* calls a functor to generate a value of type T +template<typename T> +class LLLazyValue +{ +public: + typedef typename boost::add_reference<typename boost::add_const<T>::type>::type T_const_ref; + typedef typename boost::function<T_const_ref (void)> function_type; + +public: + LLLazyValue(const function_type& value) + : mValueGetter(value) + {} + LLLazyValue(T_const_ref value) + : mValue(value) + {} + LLLazyValue() + : mValue() + {} + + void set(const LLLazyValue& val) + { + mValueGetter = val.mValueGetter; + } + + void set(T_const_ref val) + { + mValue = val; + mValueGetter = NULL; + } + + T_const_ref get() const + { + if (!mValueGetter.empty()) + { + return mValueGetter(); + } + return mValue; + } + + bool isUsingFunction() const + { + return mValueGetter != NULL; + } + +private: + function_type mValueGetter; + T mValue; +}; + +#endif // LL_LAZY_VALUE_H |