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git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@7879 a592a061-630c-0410-9148-cb99ea01b6c8
108 lines
2.4 KiB
C++
108 lines
2.4 KiB
C++
// -*- C++ -*-
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/**
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* \file copied_ptr.h
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* This file is part of LyX, the document processor.
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* Licence details can be found in the file COPYING.
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*
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* \author Angus Leeming
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*
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* A templated class that can serve as a pointer to an object, with the
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* property that when the copied_ptr is copied, it creates its own copy
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* of the object pointed to as well.
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*
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* The implementation was based originally on Yonat Sharon's copied_ptr templated
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* class, as described at http://ootips.org/yonat/, but has evolved toward's
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* Herb Sutter's HolderPtr, as described at http://www.gotw.ca/gotw/062.htm.
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* (Note, HolderPtr became ValuePtr in his book, More Exceptional C++.)
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*
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* Warning: if the class stores 'Base * ptr_', but the actual object pointed to
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* belongs to a derived class, then you must specialise memory_traits<Base> so that
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* its clone and destroy member functions do the right thing. Otherwise, you'll
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* end up slicing the data.
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*/
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#ifndef COPIED_PTR_H
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#define COPIED_PTR_H
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namespace lyx {
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namespace support {
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template <typename T>
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struct memory_traits {
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static T * clone(T const * ptr) { return new T(*ptr); }
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static void destroy(T * ptr) { delete ptr; }
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};
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template <typename T, typename Traits=memory_traits<T> >
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class copied_ptr {
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public:
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explicit copied_ptr(T * = 0);
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copied_ptr(copied_ptr const &);
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~copied_ptr();
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copied_ptr & operator=(copied_ptr const &);
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T & operator*() const;
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T * operator->() const;
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T * get() const;
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private:
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T * ptr_;
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};
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template <typename T, typename Traits>
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copied_ptr<T, Traits>::copied_ptr(T * p)
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: ptr_(p)
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{}
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template <typename T, typename Traits>
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copied_ptr<T, Traits>::copied_ptr(copied_ptr const & other)
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: ptr_(other.ptr_ ? Traits::clone(other.ptr_) : 0)
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{}
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template <typename T, typename Traits>
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copied_ptr<T, Traits>::~copied_ptr()
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{
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Traits::destroy(ptr_);
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}
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template <typename T, typename Traits>
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copied_ptr<T, Traits> & copied_ptr<T, Traits>::operator=(copied_ptr const & other)
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{
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if (&other != this) {
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copied_ptr temp(other);
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std::swap(ptr_, temp.ptr_);
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}
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return *this;
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}
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template <typename T, typename Traits>
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T & copied_ptr<T, Traits>::operator*() const
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{
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return *ptr_;
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}
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template <typename T, typename Traits>
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T * copied_ptr<T, Traits>::operator->() const
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{
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return ptr_;
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}
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template <typename T, typename Traits>
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T * copied_ptr<T, Traits>::get() const
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{
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return ptr_;
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}
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} // namespace support
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} // namespace lyx
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#endif // NOT COPIED_PTR_H
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