EIC code displayed by LXR master/​include/​boost/​xpressive/​detail/​utility/​tracking_ptr.hpp	Source navigation Diff markup Identifier search General search
	Version: master test Revert   Change

File indexing completed on 2025-01-18 09:53:52

 ///////////////////////////////////////////////////////////////////////////////
 // tracking_ptr.hpp
 //
 //  Copyright 2008 Eric Niebler. Distributed under the Boost
 //  Software License, Version 1.0. (See accompanying file
 //  LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 #ifndef BOOST_XPRESSIVE_DETAIL_UTILITY_TRACKING_PTR_HPP_EAN_10_04_2005
 #define BOOST_XPRESSIVE_DETAIL_UTILITY_TRACKING_PTR_HPP_EAN_10_04_2005
 
 // MS compatible compilers support #pragma once
 #if defined(_MSC_VER)
 # pragma once
 #endif
 
 #ifdef BOOST_XPRESSIVE_DEBUG_TRACKING_POINTER
 # include <iostream>
 #endif
 #include <set>
 #include <functional>
 #include <boost/config.hpp>
 #include <boost/assert.hpp>
 #include <boost/weak_ptr.hpp>
 #include <boost/shared_ptr.hpp>
 #include <boost/mpl/assert.hpp>
 #include <boost/intrusive_ptr.hpp>
 #include <boost/detail/workaround.hpp>
 #include <boost/detail/atomic_count.hpp>
 #include <boost/iterator/iterator_facade.hpp>
 #include <boost/iterator/filter_iterator.hpp>
 #include <boost/type_traits/is_base_and_derived.hpp>
 
 namespace boost { namespace xpressive { namespace detail
 {
 
 template<typename Type>
 struct tracking_ptr;
 
 template<typename Derived>
 struct enable_reference_tracking;
 
 ///////////////////////////////////////////////////////////////////////////////
 // weak_iterator
 //  steps through a set of weak_ptr, converts to shared_ptrs on the fly and
 //  removes from the set the weak_ptrs that have expired.
 template<typename Derived>
 struct weak_iterator
   : iterator_facade
     <
         weak_iterator<Derived>
       , shared_ptr<Derived> const
       , std::forward_iterator_tag
     >
 {
     typedef std::set<weak_ptr<Derived> > set_type;
     typedef typename set_type::iterator base_iterator;
 
     weak_iterator()
       : cur_()
       , iter_()
       , set_(0)
     {
     }
 
     weak_iterator(base_iterator iter, set_type *set)
       : cur_()
       , iter_(iter)
       , set_(set)
     {
         this->satisfy_();
     }
 
 private:
     friend class boost::iterator_core_access;
 
     shared_ptr<Derived> const &dereference() const
     {
         return this->cur_;
     }
 
     void increment()
     {
         ++this->iter_;
         this->satisfy_();
     }
 
     bool equal(weak_iterator<Derived> const &that) const
     {
         return this->iter_ == that.iter_;
     }
 
     void satisfy_()
     {
         while(this->iter_ != this->set_->end())
         {
             this->cur_ = this->iter_->lock();
             if(this->cur_)
                 return;
             base_iterator tmp = this->iter_++;
             this->set_->erase(tmp);
         }
         this->cur_.reset();
     }
 
     shared_ptr<Derived> cur_;
     base_iterator iter_;
     set_type *set_;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 // filter_self
 //  for use with a filter_iterator to filter a node out of a list of dependencies
 template<typename Derived>
 struct filter_self
 {
     typedef shared_ptr<Derived> argument_type;
     typedef bool result_type;
 
     filter_self(enable_reference_tracking<Derived> *self)
       : self_(self)
     {
     }
 
     bool operator ()(shared_ptr<Derived> const &that) const
     {
         return this->self_ != that.get();
     }
 
 private:
     enable_reference_tracking<Derived> *self_;
 };
 
 ///////////////////////////////////////////////////////////////////////////////
 // swap without bringing in std::swap -- must be found by ADL.
 template<typename T>
 void adl_swap(T &t1, T &t2)
 {
     swap(t1, t2);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 // enable_reference_tracking
 //   inherit from this type to enable reference tracking for a type. You can
 //   then use tracking_ptr (below) as a holder for derived objects.
 //
 template<typename Derived>
 struct enable_reference_tracking
 {
     typedef std::set<shared_ptr<Derived> > references_type;
     typedef std::set<weak_ptr<Derived> > dependents_type;
 
     void tracking_copy(Derived const &that)
     {
         if(&this->derived_() != &that)
         {
             this->raw_copy_(that);
             this->tracking_update();
         }
     }
 
     void tracking_clear()
     {
         this->raw_copy_(Derived());
     }
 
     // called automatically as a result of a tracking_copy(). Must be called explicitly
     // if you change the references without calling tracking_copy().
     void tracking_update()
     {
         // add "this" as a dependency to all the references
         this->update_references_();
         // notify our dependencies that we have new references
         this->update_dependents_();
     }
 
     void track_reference(enable_reference_tracking<Derived> &that)
     {
         // avoid some unbounded memory growth in certain circumstances by
         // opportunistically removing stale dependencies from "that"
         that.purge_stale_deps_();
         // add "that" as a reference
         this->refs_.insert(that.self_);
         // also inherit that's references
         this->refs_.insert(that.refs_.begin(), that.refs_.end());
     }
 
     long use_count() const
     {
         return this->cnt_;
     }
 
     void add_ref()
     {
         ++this->cnt_;
     }
 
     void release()
     {
         BOOST_ASSERT(0 < this->cnt_);
         if(0 == --this->cnt_)
         {
             this->refs_.clear();
             this->self_.reset();
         }
     }
 
     //{{AFX_DEBUG
     #ifdef BOOST_XPRESSIVE_DEBUG_TRACKING_POINTER
     friend std::ostream &operator <<(std::ostream &sout, enable_reference_tracking<Derived> const &that)
     {
         that.dump_(sout);
         return sout;
     }
     #endif
     //}}AFX_DEBUG
 
 protected:
 
     enable_reference_tracking()
       : refs_()
       , deps_()
       , self_()
       , cnt_(0)
     {
     }
 
     enable_reference_tracking(enable_reference_tracking<Derived> const &that)
       : refs_()
       , deps_()
       , self_()
       , cnt_(0)
     {
         this->operator =(that);
     }
 
     enable_reference_tracking<Derived> &operator =(enable_reference_tracking<Derived> const &that)
     {
         references_type(that.refs_).swap(this->refs_);
         return *this;
     }
 
     void swap(enable_reference_tracking<Derived> &that)
     {
         this->refs_.swap(that.refs_);
     }
 
 private:
     friend struct tracking_ptr<Derived>;
 
     Derived &derived_()
     {
         return *static_cast<Derived *>(this);
     }
 
     void raw_copy_(Derived that)
     {
         detail::adl_swap(this->derived_(), that);
     }
 
     bool has_deps_() const
     {
         return !this->deps_.empty();
     }
 
     void update_references_()
     {
         typename references_type::iterator cur = this->refs_.begin();
         typename references_type::iterator end = this->refs_.end();
         for(; cur != end; ++cur)
         {
             // for each reference, add this as a dependency
             (*cur)->track_dependency_(*this);
         }
     }
 
     void update_dependents_()
     {
         // called whenever this regex object changes (i.e., is assigned to). it walks
         // the list of dependent regexes and updates *their* lists of references,
         // thereby spreading out the reference counting responsibility evenly.
         weak_iterator<Derived> cur(this->deps_.begin(), &this->deps_);
         weak_iterator<Derived> end(this->deps_.end(), &this->deps_);
 
         for(; cur != end; ++cur)
         {
             (*cur)->track_reference(*this);
         }
     }
 
     void track_dependency_(enable_reference_tracking<Derived> &dep)
     {
         if(this == &dep) // never add ourself as a dependency
             return;
 
         // add dep as a dependency
         this->deps_.insert(dep.self_);
 
         filter_self<Derived> not_self(this);
         weak_iterator<Derived> begin(dep.deps_.begin(), &dep.deps_);
         weak_iterator<Derived> end(dep.deps_.end(), &dep.deps_);
 
         // also inherit dep's dependencies
         this->deps_.insert(
             make_filter_iterator(not_self, begin, end)
           , make_filter_iterator(not_self, end, end)
         );
     }
 
     void purge_stale_deps_()
     {
         weak_iterator<Derived> cur(this->deps_.begin(), &this->deps_);
         weak_iterator<Derived> end(this->deps_.end(), &this->deps_);
 
         for(; cur != end; ++cur)
             ;
     }
 
     //{{AFX_DEBUG
     #ifdef BOOST_XPRESSIVE_DEBUG_TRACKING_POINTER
     void dump_(std::ostream &sout) const;
     #endif
     //}}AFX_DEBUG
 
     references_type refs_;
     dependents_type deps_;
     shared_ptr<Derived> self_;
     boost::detail::atomic_count cnt_;
 };
 
 template<typename Derived>
 inline void intrusive_ptr_add_ref(enable_reference_tracking<Derived> *p)
 {
     p->add_ref();
 }
 
 template<typename Derived>
 inline void intrusive_ptr_release(enable_reference_tracking<Derived> *p)
 {
     p->release();
 }
 
 //{{AFX_DEBUG
 #ifdef BOOST_XPRESSIVE_DEBUG_TRACKING_POINTER
 ///////////////////////////////////////////////////////////////////////////////
 // dump_
 //
 template<typename Derived>
 inline void enable_reference_tracking<Derived>::dump_(std::ostream &sout) const
 {
     shared_ptr<Derived> this_ = this->self_;
     sout << "0x" << (void*)this << " cnt=" << this_.use_count()-1 << " refs={";
     typename references_type::const_iterator cur1 = this->refs_.begin();
     typename references_type::const_iterator end1 = this->refs_.end();
     for(; cur1 != end1; ++cur1)
     {
         sout << "0x" << (void*)&**cur1 << ',';
     }
     sout << "} deps={";
     typename dependents_type::const_iterator cur2 = this->deps_.begin();
     typename dependents_type::const_iterator end2 = this->deps_.end();
     for(; cur2 != end2; ++cur2)
     {
         // ericne, 27/nov/05: CW9_4 doesn't like if(shared_ptr x = y)
         shared_ptr<Derived> dep = cur2->lock();
         if(dep.get())
         {
             sout << "0x" << (void*)&*dep << ',';
         }
     }
     sout << '}';
 }
 #endif
 //}}AFX_DEBUG
 
 ///////////////////////////////////////////////////////////////////////////////
 // tracking_ptr
 //   holder for a reference-tracked type. Does cycle-breaking, lazy initialization
 //   and copy-on-write. TODO: implement move semantics.
 //
 template<typename Type>
 struct tracking_ptr
 {
     BOOST_MPL_ASSERT((is_base_and_derived<enable_reference_tracking<Type>, Type>));
     typedef Type element_type;
 
     tracking_ptr()
       : impl_()
     {
     }
 
     tracking_ptr(tracking_ptr<element_type> const &that)
       : impl_()
     {
         this->operator =(that);
     }
 
     tracking_ptr<element_type> &operator =(tracking_ptr<element_type> const &that)
     {
         // Note: the copy-and-swap idiom doesn't work here if has_deps_()==true
         // because it invalidates references to the element_type object.
         if(this != &that)
         {
             if(that)
             {
                 if(that.has_deps_() || this->has_deps_())
                 {
                     this->fork_(); // deep copy, forks data if necessary
                     this->impl_->tracking_copy(*that);
                 }
                 else
                 {
                     this->impl_ = that.impl_; // shallow, copy-on-write
                 }
             }
             else if(*this)
             {
                 this->impl_->tracking_clear();
             }
         }
         return *this;
     }
 
     // NOTE: this does *not* do tracking. Can't provide a non-throwing swap that tracks references
     void swap(tracking_ptr<element_type> &that) // throw()
     {
         this->impl_.swap(that.impl_);
     }
 
     // calling this forces this->impl_ to fork.
     shared_ptr<element_type> const &get() const
     {
         if(intrusive_ptr<element_type> impl = this->fork_())
         {
             this->impl_->tracking_copy(*impl);
         }
         return this->impl_->self_;
     }
 
     // smart-pointer operators
     #if defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x530)
 
     operator bool() const
     {
         return this->impl_;
     }
 
     #else
 
     typedef intrusive_ptr<element_type> tracking_ptr::* unspecified_bool_type;
 
     operator unspecified_bool_type() const
     {
         return this->impl_ ? &tracking_ptr::impl_ : 0;
     }
 
     #endif
 
     bool operator !() const
     {
         return !this->impl_;
     }
 
     // Since this does not un-share the data, it returns a ptr-to-const
     element_type const *operator ->() const
     {
         return get_pointer(this->impl_);
     }
 
     // Since this does not un-share the data, it returns a ref-to-const
     element_type const &operator *() const
     {
         return *this->impl_;
     }
 
 private:
 
     // calling this forces impl_ to fork.
     intrusive_ptr<element_type> fork_() const
     {
         intrusive_ptr<element_type> impl;
         if(!this->impl_ || 1 != this->impl_->use_count())
         {
             impl = this->impl_;
             BOOST_ASSERT(!this->has_deps_());
             shared_ptr<element_type> simpl(new element_type);
             this->impl_ = get_pointer(simpl->self_ = simpl);
         }
         return impl;
     }
 
     // does anybody have a dependency on us?
     bool has_deps_() const
     {
         return this->impl_ && this->impl_->has_deps_();
     }
 
     // mutable to allow lazy initialization
     mutable intrusive_ptr<element_type> impl_;
 };
 
 }}} // namespace boost::xpressive::detail
 
 #endif

This page was automatically generated by the 2.3.7 LXR engine. The LXR team