99 lines
3.7 KiB
C++
99 lines
3.7 KiB
C++
/* -*-c++-*- OpenSceneGraph - Copyright (C) 1998-2006 Robert Osfield
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*
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* This library is open source and may be redistributed and/or modified under
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* the terms of the OpenSceneGraph Public License (OSGPL) version 0.0 or
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* (at your option) any later version. The full license is in LICENSE file
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* included with this distribution, and on the openscenegraph.org website.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* OpenSceneGraph Public License for more details.
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*/
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//osgIntrospection - Copyright (C) 2005 Marco Jez
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#ifndef OSGINTROSPECTION_VARIANT_CAST_
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#define OSGINTROSPECTION_VARIANT_CAST_
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#include <osgIntrospection/Value>
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#include <osgIntrospection/ReaderWriter>
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#include <sstream>
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namespace osgIntrospection
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{
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/// Tries to convert an instance of Value to an object of type T.
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/// If T is a plain type or a pointer type (either const or non-const),
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/// and it matches the type of the value contained in v, then the actual
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/// value of type T is returned. If T is a [const] reference type, and
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/// its base (non reference) type matches the internal value's type,
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/// then a [const] reference to the internal value is returned.
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/// If none of the above conditions are met, a conversion is attempted
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/// as described in Value::convert() and then variant_cast is called again
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/// with the converted value as parameter.
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/// If the conversion can't be completed, an exception is thrown.
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/// Conversions that attempt to make a const pointer non-const will fail.
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template<typename T> T variant_cast(const Value& v)
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{
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// return value
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Value::Instance<T> *i = dynamic_cast<Value::Instance<T> *>(v._inbox->inst_);
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if (i) return i->_data;
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// return reference to value
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i = dynamic_cast<Value::Instance<T> *>(v._inbox->_ref_inst);
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if (i) return i->_data;
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// return const reference to value
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i = dynamic_cast<Value::Instance<T> *>(v._inbox->_const_ref_inst);
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if (i) return i->_data;
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// try to convert v to type T and restart
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return variant_cast<T>(v.convertTo(typeof(T)));
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}
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/// Returns true if the Value passed as parameter can't be casted to
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/// the specified type without a (potentially slow) conversion.
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/// Returns false otherwise.
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template<typename T> bool requires_conversion(const Value& v)
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{
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// direct value
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Value::Instance<T> *i = dynamic_cast<Value::Instance<T> *>(v._inbox->inst_);
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if (i) return false;
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// reference to value
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i = dynamic_cast<Value::Instance<T> *>(v._inbox->_ref_inst);
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if (i) return false;
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// const reference to value
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i = dynamic_cast<Value::Instance<T> *>(v._inbox->_const_ref_inst);
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if (i) return false;
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return true;
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}
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/// Returns a typed pointer to the data contained in a Value
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/// instance. If the value's type is not identical to type T,
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/// a null pointer is returned.
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template<typename T> T* extract_raw_data(Value& v)
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{
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Value::Instance<T>* i = dynamic_cast<Value::Instance<T> *>(v._inbox->inst_);
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if (i) return &i->_data;
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return 0;
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}
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/// Returns a typed pointer to the data contained in a const Value
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/// instance. If the value's type is not identical to type T, a
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/// null pointer is returned.
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template<typename T> const T* extract_raw_data(const Value& v)
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{
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Value::Instance<T>* i = dynamic_cast<Value::Instance<T> *>(v._inbox->inst_);
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if (i) return &i->_data;
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return 0;
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}
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}
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#endif
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