SharedFunctionPtr.hpp

Go to the documentation of this file.

/*
 * $Id: SharedFunctionPtr.hpp 135 2013-06-29 15:09:42Z jdl3 $
 * Copyright (C) 2010, 2011, 2013 John D Lamb
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifndef IPO_DETAIL_SHAREDFUNCTIONPTR_HPP
#define IPO_DETAIL_SHAREDFUNCTIONPTR_HPP

#include<new>
#include"../../ipo_function/Function.hpp"

namespace ipo {
  namespace detail {
    class SharedFunctionPtr {
    public:
      SharedFunctionPtr(){
    pointer = 0;
    count = 0; // initially nullptr will do
    owner = false;
      }
      // Refines assignable
      explicit SharedFunctionPtr( ipo_function::Function* function ){
    pointer = function;
    // just plausibly we could allocate Function but not count
    try { count = new size_t; } catch( std::bad_alloc& e ){
      // try to tidy up before rethrowing
      delete pointer;
      throw e;
    }
    *count = 1; // initially there is just one reference to pointer
    owner = true;
      }
      explicit SharedFunctionPtr( ipo_function::Function& function ){
    pointer = &function;
    // just plausibly we could fail to allocate count: no further action needed.
    count = new size_t;
    *count = 1; // initially there is just one reference to pointer
    owner = false;
      }
      // copy constructor
      SharedFunctionPtr( SharedFunctionPtr const& v ){ pointer = v.pointer;
    count = v.count; if( count != 0 ) ++*count; owner = v.owner; }
      // assignment operator
      SharedFunctionPtr& operator=( SharedFunctionPtr const& v ){
    // first, possibly delete anything pointed to by this
    if( count == 0 or --*count == 0 ){
      if( pointer != 0 and true == owner  ) delete pointer;
      delete count;
    } // Then copy
    pointer = v.pointer; count = v.count; if( count != 0 ) ++*count; owner = v.owner;
    return *this;
      }
      // destructor
      ~SharedFunctionPtr(){
    if( count == 0 or --*count == 0 ){
      // could have allocated null pointer
      if( pointer != 0 and true == owner ) delete pointer;
      delete count;
    }
      }
      // Refines equality comparable
      SharedFunctionPtr( SharedFunctionPtr&& v ) : pointer( v.pointer ), count( nullptr ){
    std::swap( count, v.count );
    v.pointer = nullptr;
    v.count = 0;
    v.owner = false;
      }
      SharedFunctionPtr& operator=( SharedFunctionPtr&& v ){
    SharedFunctionPtr( std::move( v ) ).swap( *this );
    return *this;
      }
      // == operator
      bool operator==( SharedFunctionPtr const& v ) const { return pointer == v.pointer; }
      // != operator
      bool operator!=( SharedFunctionPtr const& v ) const { return not operator==( v ); }
      // Refines forward container
      void swap( SharedFunctionPtr& v ){
    std::swap( pointer, v.pointer );
    std::swap( count, v.count );
      }
      ipo_function::Function& operator*() const { return *pointer; }
      ipo_function::Function* operator->() const { return pointer; }
    private:
      ipo_function::Function* pointer;
      size_t* count;
      bool owner;
    public:
      // shared reference functions
      ipo_function::Function* get() const { return pointer; }
      bool unique() const { return count != 0 and *count == 1; }
      size_t use_count() const { return count == 0 ? 0 : *count; }
      explicit operator bool() const { return pointer != 0; }
    };
  }
}

#endif