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418 lines
9.4 KiB
C++
418 lines
9.4 KiB
C++
#ifndef XAPIAN_INCLUDED_INTRUSIVE_PTR_H
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#define XAPIAN_INCLUDED_INTRUSIVE_PTR_H
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//
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// Based on Boost's intrusive_ptr.hpp
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//
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// Copyright (c) 2001, 2002 Peter Dimov
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// Copyright (c) 2011,2013,2014,2015 Olly Betts
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//
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// Distributed under the Boost Software License, Version 1.0.
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//
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// Boost Software License - Version 1.0 - August 17th, 2003
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//
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// Permission is hereby granted, free of charge, to any person or organization
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// obtaining a copy of the software and accompanying documentation covered by
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// this license (the "Software") to use, reproduce, display, distribute,
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// execute, and transmit the Software, and to prepare derivative works of the
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// Software, and to permit third-parties to whom the Software is furnished to
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// do so, all subject to the following:
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//
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// The copyright notices in the Software and this entire statement, including
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// the above license grant, this restriction and the following disclaimer,
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// must be included in all copies of the Software, in whole or in part, and
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// all derivative works of the Software, unless such copies or derivative
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// works are solely in the form of machine-executable object code generated by
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// a source language processor.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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// DEALINGS IN THE SOFTWARE.
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//
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// See http://www.boost.org/libs/smart_ptr/intrusive_ptr.html for documentation.
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//
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#if !defined XAPIAN_IN_XAPIAN_H && !defined XAPIAN_LIB_BUILD
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# error Never use <xapian/intrusive_ptr.h> directly; include <xapian.h> instead.
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#endif
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#include <xapian/visibility.h>
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namespace Xapian {
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namespace Internal {
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/// Base class for objects managed by intrusive_ptr.
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class intrusive_base {
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/// Prevent copying.
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intrusive_base(const intrusive_base&);
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/// Prevent assignment.
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void operator=(const intrusive_base&);
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public:
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/** Construct with no references.
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*
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* The references get added if/when this object is put into an
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* intrusive_ptr.
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*/
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intrusive_base() : _refs(0) { }
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/* There's no need for a virtual destructor here as we never delete a
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* subclass of intrusive_base by calling delete on intrusive_base*.
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*/
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/** Reference count.
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*
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* This needs to be mutable so we can add/remove references through const
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* pointers.
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*/
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mutable unsigned _refs;
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};
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//
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// intrusive_ptr
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//
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/// A smart pointer that uses intrusive reference counting.
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template<class T> class intrusive_ptr
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{
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private:
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typedef intrusive_ptr this_type;
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public:
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intrusive_ptr(): px( 0 )
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{
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}
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intrusive_ptr( T * p): px( p )
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{
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if( px != 0 ) ++px->_refs;
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}
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template<class U>
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intrusive_ptr( intrusive_ptr<U> const & rhs )
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: px( rhs.get() )
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{
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if( px != 0 ) ++px->_refs;
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}
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intrusive_ptr(intrusive_ptr const & rhs): px( rhs.px )
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{
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if( px != 0 ) ++px->_refs;
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}
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~intrusive_ptr()
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{
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if( px != 0 && --px->_refs == 0 ) delete px;
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}
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#ifdef XAPIAN_MOVE_SEMANTICS
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intrusive_ptr(intrusive_ptr && rhs) : px( rhs.px )
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{
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rhs.px = 0;
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}
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intrusive_ptr & operator=(intrusive_ptr && rhs)
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{
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this_type( static_cast< intrusive_ptr && >( rhs ) ).swap(*this);
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return *this;
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}
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template<class U> friend class intrusive_ptr;
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template<class U>
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intrusive_ptr(intrusive_ptr<U> && rhs) : px( rhs.px )
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{
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rhs.px = 0;
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}
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template<class U>
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intrusive_ptr & operator=(intrusive_ptr<U> && rhs)
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{
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this_type( static_cast< intrusive_ptr<U> && >( rhs ) ).swap(*this);
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return *this;
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}
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#endif
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intrusive_ptr & operator=(intrusive_ptr const & rhs)
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{
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this_type(rhs).swap(*this);
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return *this;
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}
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intrusive_ptr & operator=(T * rhs)
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{
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this_type(rhs).swap(*this);
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return *this;
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}
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T * get() const
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{
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return px;
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}
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T & operator*() const
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{
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return *px;
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}
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T * operator->() const
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{
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return px;
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}
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void swap(intrusive_ptr & rhs)
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{
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T * tmp = px;
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px = rhs.px;
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rhs.px = tmp;
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}
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private:
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T * px;
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};
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template<class T, class U> inline bool operator==(intrusive_ptr<T> const & a, intrusive_ptr<U> const & b)
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{
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return a.get() == b.get();
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}
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template<class T, class U> inline bool operator!=(intrusive_ptr<T> const & a, intrusive_ptr<U> const & b)
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{
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return a.get() != b.get();
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}
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template<class T, class U> inline bool operator==(intrusive_ptr<T> const & a, U * b)
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{
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return a.get() == b;
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}
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template<class T, class U> inline bool operator!=(intrusive_ptr<T> const & a, U * b)
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{
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return a.get() != b;
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}
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template<class T, class U> inline bool operator==(T * a, intrusive_ptr<U> const & b)
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{
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return a == b.get();
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}
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template<class T, class U> inline bool operator!=(T * a, intrusive_ptr<U> const & b)
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{
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return a != b.get();
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}
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/// Base class for objects managed by opt_intrusive_ptr.
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class XAPIAN_VISIBILITY_DEFAULT opt_intrusive_base {
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public:
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opt_intrusive_base(const opt_intrusive_base&) : _refs(0) { }
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opt_intrusive_base& operator=(const opt_intrusive_base&) {
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// Don't touch _refs.
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return *this;
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}
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/** Construct object which is initially not reference counted.
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*
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* The reference counting starts if release() is called.
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*/
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opt_intrusive_base() : _refs(0) { }
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/* Subclasses of opt_intrusive_base may be deleted by calling delete on a
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* pointer to opt_intrusive_base.
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*/
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virtual ~opt_intrusive_base() { }
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void ref() const {
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if (_refs == 0)
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_refs = 2;
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else
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++_refs;
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}
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void unref() const {
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if (--_refs == 1)
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delete this;
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}
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/** Reference count.
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*
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* This needs to be mutable so we can add/remove references through const
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* pointers.
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*/
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mutable unsigned _refs;
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protected:
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/** Start reference counting.
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*
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* The object is constructed with _refs set to 0, meaning it isn't being
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* reference counted.
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*
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* Calling release() sets _refs to 1 if it is 0, and from then
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* opt_intrusive_ptr will increment and decrement _refs. If it is
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* decremented to 1, the object is deleted.
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*/
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void release() const {
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if (_refs == 0)
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_refs = 1;
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}
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};
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//
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// opt_intrusive_ptr
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//
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/// A smart pointer that optionally uses intrusive reference counting.
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template<class T> class opt_intrusive_ptr
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{
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private:
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typedef opt_intrusive_ptr this_type;
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public:
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opt_intrusive_ptr(): px( 0 ), counting( false )
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{
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}
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opt_intrusive_ptr( T * p): px( p ), counting( px != 0 && px->_refs )
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{
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if( counting ) ++px->_refs;
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}
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template<class U>
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opt_intrusive_ptr( opt_intrusive_ptr<U> const & rhs )
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: px( rhs.get() ), counting( rhs.counting )
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{
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if( counting ) ++px->_refs;
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}
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opt_intrusive_ptr(opt_intrusive_ptr const & rhs)
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: px( rhs.px ), counting( rhs.counting )
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{
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if( counting ) ++px->_refs;
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}
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~opt_intrusive_ptr()
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{
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if( counting && --px->_refs == 1 ) delete px;
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}
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#ifdef XAPIAN_MOVE_SEMANTICS
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opt_intrusive_ptr(opt_intrusive_ptr && rhs)
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: px( rhs.px ), counting( rhs.counting )
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{
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rhs.px = 0;
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rhs.counting = 0;
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}
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opt_intrusive_ptr & operator=(opt_intrusive_ptr && rhs)
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{
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this_type( static_cast< opt_intrusive_ptr && >( rhs ) ).swap(*this);
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return *this;
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}
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template<class U> friend class opt_intrusive_ptr;
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template<class U>
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opt_intrusive_ptr(opt_intrusive_ptr<U> && rhs)
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: px( rhs.px ), counting( rhs.counting )
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{
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rhs.px = 0;
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rhs.counting = 0;
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}
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template<class U>
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opt_intrusive_ptr & operator=(opt_intrusive_ptr<U> && rhs)
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{
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this_type( static_cast< opt_intrusive_ptr<U> && >( rhs ) ).swap(*this);
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return *this;
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}
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#endif
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opt_intrusive_ptr & operator=(opt_intrusive_ptr const & rhs)
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{
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this_type(rhs).swap(*this);
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return *this;
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}
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opt_intrusive_ptr & operator=(T * rhs)
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{
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this_type(rhs).swap(*this);
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return *this;
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}
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T * get() const
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{
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return px;
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}
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T & operator*() const
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{
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return *px;
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}
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T * operator->() const
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{
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return px;
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}
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void swap(opt_intrusive_ptr & rhs)
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{
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T * tmp = px;
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px = rhs.px;
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rhs.px = tmp;
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bool tmp2 = counting;
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counting = rhs.counting;
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rhs.counting = tmp2;
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}
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private:
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T * px;
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bool counting;
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};
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template<class T, class U> inline bool operator==(opt_intrusive_ptr<T> const & a, opt_intrusive_ptr<U> const & b)
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{
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return a.get() == b.get();
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}
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template<class T, class U> inline bool operator!=(opt_intrusive_ptr<T> const & a, opt_intrusive_ptr<U> const & b)
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{
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return a.get() != b.get();
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}
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template<class T, class U> inline bool operator==(opt_intrusive_ptr<T> const & a, U * b)
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{
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return a.get() == b;
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}
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template<class T, class U> inline bool operator!=(opt_intrusive_ptr<T> const & a, U * b)
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{
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return a.get() != b;
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}
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template<class T, class U> inline bool operator==(T * a, opt_intrusive_ptr<U> const & b)
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{
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return a == b.get();
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}
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template<class T, class U> inline bool operator!=(T * a, opt_intrusive_ptr<U> const & b)
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{
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return a != b.get();
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}
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}
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}
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#endif // XAPIAN_INCLUDED_INTRUSIVE_PTR_H
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