string.hpp

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//////////////////////////////////////////////////////////////////////////////
//
// (C) Copyright Ion Gaztanaga 2005-2008. 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)
//
// See http://www.boost.org/libs/interprocess for documentation.
//
//////////////////////////////////////////////////////////////////////////////
//
// This file comes from SGI's string file. Modified by Ion Gaztanaga 2004-2008
// Renaming, isolating and porting to generic algorithms. Pointer typedef 
// set to allocator::pointer to allow placing it in shared memory.
//
///////////////////////////////////////////////////////////////////////////////
// Copyright (c) 1994
// Hewlett-Packard Company
// 
// Permission to use, copy, modify, distribute and sell this software
// and its documentation for any purpose is hereby granted without fee,
// provided that the above copyright notice appear in all copies and
// that both that copyright notice and this permission notice appear
// in supporting documentation.  Hewlett-Packard Company makes no
// representations about the suitability of this software for any
// purpose.  It is provided "as is" without express or implied warranty.

#ifndef BOOST_INTERPROCESS_STRING_HPP
#define BOOST_INTERPROCESS_STRING_HPP

#include <boost/interprocess/detail/config_begin.hpp>
#include <boost/interprocess/detail/workaround.hpp>

#include <boost/interprocess/detail/workaround.hpp>
#include <boost/interprocess/interprocess_fwd.hpp>
#include <boost/interprocess/detail/utilities.hpp>
#include <boost/interprocess/detail/algorithms.hpp>
#include <boost/interprocess/detail/min_max.hpp>
#include <boost/interprocess/detail/iterators.hpp>
#include <boost/interprocess/detail/version_type.hpp>
#include <boost/interprocess/allocators/allocation_type.hpp>
#include <boost/interprocess/detail/mpl.hpp>
#include <boost/interprocess/detail/move.hpp>
#include <boost/static_assert.hpp>

#include <functional>
#include <string>
#include <stdexcept>      
#include <utility>  
#include <iterator>
#include <memory>
#include <algorithm>
#include <iosfwd>
#include <istream>
#include <ostream>
#include <ios>
#include <locale>
#include <cstddef>
#include <climits>
#include <boost/interprocess/detail/type_traits.hpp>
#include <boost/detail/no_exceptions_support.hpp>
#include <boost/type_traits/has_trivial_destructor.hpp>

namespace boost {
namespace interprocess {
namespace detail {

/// @cond
// ------------------------------------------------------------
// Class basic_string_base.  

// basic_string_base is a helper class that makes it it easier to write
// an exception-safe version of basic_string.  The constructor allocates,
// but does not initialize, a block of memory.  The destructor
// deallocates, but does not destroy elements within, a block of
// memory.  The destructor assumes that the memory either is the internal buffer, 
// or else points to a block of memory that was allocated using _String_base's 
// allocator and whose size is this->m_storage.
template <class A>
class basic_string_base
{
   basic_string_base();
 public:
   typedef A allocator_type;
   //! The stored allocator type
   typedef allocator_type                          stored_allocator_type;
   typedef typename A::pointer     pointer;
   typedef typename A::value_type  value_type;
   typedef typename A::size_type   size_type;

   basic_string_base(const allocator_type& a)
      : members_(a)
   {  init(); }

   basic_string_base(const allocator_type& a, std::size_t n)
      : members_(a)
   {  
      this->init(); 
      this->allocate_initial_block(n);
   }

   #ifndef BOOST_INTERPROCESS_RVALUE_REFERENCE
   basic_string_base(const detail::moved_object<basic_string_base<A> >& b)
      :  members_(b.get().members_)
   {  
      init();
      this->swap(b.get()); 
   }
   #else
   basic_string_base(basic_string_base<A> && b)
      :  members_(b.members_)
   {  
      init();
      this->swap(b); 
   }
   #endif

   ~basic_string_base() 
   {  
      this->deallocate_block(); 
      if(!this->is_short()){
         static_cast<long_t*>(static_cast<void*>(&this->members_.m_repr.r))->~long_t();
      }
   }

   private:

   //This is the structure controlling a long string 
   struct long_t
   {
      size_type      is_short  : 1;
      size_type      length    : (sizeof(size_type)*CHAR_BIT - 1);
      size_type      storage;
      pointer        start;

      long_t()
      {}

      long_t(const long_t &other)
      {
         this->is_short = other.is_short;
         length   = other.length;
         storage  = other.storage;
         start    = other.start;
      }

      long_t &operator =(const long_t &other)
      {
         this->is_short = other.is_short;
         length   = other.length;
         storage  = other.storage;
         start    = other.start;
         return *this;
      }
   };

   //This basic type should have the same alignment as long_t
//iG   typedef typename type_with_alignment<detail::alignment_of<long_t>::value>::type
//      long_alignment_type;
   typedef void *long_alignment_type;
   BOOST_STATIC_ASSERT((detail::alignment_of<long_alignment_type>::value % 
                        detail::alignment_of<long_t>::value) == 0);


   //This type is the first part of the structure controlling a short string
   //The "data" member stores
   struct short_header
   {
      unsigned char  is_short  : 1;
      unsigned char  length    : (CHAR_BIT - 1);
   };

   //This type has the same alignment and size as long_t but it's POD
   //so, unlike long_t, it can be placed in a union
   struct long_raw_t
   {
      long_alignment_type  a;
      unsigned char        b[sizeof(long_t) - sizeof(long_alignment_type)];
   };

   protected:
   static const size_type  MinInternalBufferChars = 8;
   static const size_type  AlignmentOfValueType =
      alignment_of<value_type>::value;
   static const size_type  ShortDataOffset =
      detail::ct_rounded_size<sizeof(short_header),  AlignmentOfValueType>::value;
   static const size_type  ZeroCostInternalBufferChars =
      (sizeof(long_t) - ShortDataOffset)/sizeof(value_type);
   static const size_type  UnalignedFinalInternalBufferChars = 
      (ZeroCostInternalBufferChars > MinInternalBufferChars) ?
                ZeroCostInternalBufferChars : MinInternalBufferChars;

   struct short_t
   {
      short_header   h; 
      value_type     data[UnalignedFinalInternalBufferChars];
   };

   union repr_t
   {
      long_raw_t  r;
      short_t     s;

      short_t &short_repr() const
      {  return *const_cast<short_t *>(&s);  }

      long_t &long_repr() const
      {  return *static_cast<long_t*>(const_cast<void*>(static_cast<const void*>(&r)));  }
   };

   struct members_holder
      :  public A
   {
      members_holder(const A &a)
         :  A(a)
      {}

      repr_t m_repr;
   } members_;

   const A &alloc() const
   {  return members_;  }

   A &alloc()
   {  return members_;  }

   static const size_type InternalBufferChars = (sizeof(repr_t) - ShortDataOffset)/sizeof(value_type);

   private:

   static const size_type MinAllocation = InternalBufferChars*2;

   protected:
   bool is_short() const
   {  return static_cast<bool>(this->members_.m_repr.s.h.is_short != 0);  }

   void is_short(bool yes)
   {  
      if(yes && !this->is_short()){
         static_cast<long_t*>(static_cast<void*>(&this->members_.m_repr.r))->~long_t();
      }
      else{
         new(static_cast<void*>(&this->members_.m_repr.r))long_t();
      }
      this->members_.m_repr.s.h.is_short = yes;
   }

   private:
   void init()
   {
      this->members_.m_repr.s.h.is_short = 1;
      this->members_.m_repr.s.h.length   = 0;
   }

   protected:

   typedef detail::integral_constant<unsigned, 1>      allocator_v1;
   typedef detail::integral_constant<unsigned, 2>      allocator_v2;
   typedef detail::integral_constant<unsigned,
      boost::interprocess::detail::version<A>::value> alloc_version;

   std::pair<pointer, bool>
      allocation_command(allocation_type command,
                         size_type limit_size, 
                         size_type preferred_size,
                         size_type &received_size, pointer reuse = 0)
   {
      if(this->is_short() && (command & (expand_fwd | expand_bwd)) ){
         reuse = pointer(0);
         command &= ~(expand_fwd | expand_bwd);
      }
      return this->allocation_command
         (command, limit_size, preferred_size, received_size, reuse, alloc_version());
   }

   std::pair<pointer, bool>
      allocation_command(allocation_type command,
                         size_type limit_size, 
                         size_type preferred_size,
                         size_type &received_size,
                         const pointer &reuse,
                         allocator_v1)
   {
      (void)limit_size;
      (void)reuse;
      if(!(command & allocate_new))
         return std::pair<pointer, bool>(pointer(0), 0);
      received_size = preferred_size;
      return std::make_pair(this->alloc().allocate(received_size), false);
   }

   std::pair<pointer, bool>
      allocation_command(allocation_type command,
                         size_type limit_size, 
                         size_type preferred_size,
                         size_type &received_size,
                         pointer reuse,
                         allocator_v2)
   {
      return this->alloc().allocation_command(command, limit_size, preferred_size, 
                                              received_size, reuse);
   }

   size_type next_capacity(size_type additional_objects) const
   {  return get_next_capacity(this->alloc().max_size(), this->priv_storage(), additional_objects);  }

   void deallocate(pointer p, std::size_t n) 
   {  
      if (p && (n > InternalBufferChars))
         this->alloc().deallocate(p, n);
   }

   void construct(pointer p, const value_type &value = value_type())
   {  new((void*)detail::get_pointer(p)) value_type(value);   }

   void destroy(pointer p, size_type n)
   {
      for(; n--; ++p)
         detail::get_pointer(p)->~value_type();
   }

   void destroy(pointer p)
   {  detail::get_pointer(p)->~value_type(); }

   void allocate_initial_block(std::size_t n)
   {
      if (n <= this->max_size()) {
         if(n > InternalBufferChars){
            size_type new_cap = this->next_capacity(n);
            pointer p = this->allocation_command(allocate_new, n, new_cap, new_cap).first;
            this->is_short(false);
            this->priv_addr(p);
            this->priv_size(0);
            this->priv_storage(new_cap);
         }
      }
      else
         throw_length_error();
   }

   void deallocate_block() 
   {  this->deallocate(this->priv_addr(), this->priv_storage());  }
      
   std::size_t max_size() const
   {  return this->alloc().max_size() - 1; }

   // Helper functions for exception handling.
   void throw_length_error() const
   {  throw(std::length_error("basic_string"));  }

   void throw_out_of_range() const
   {  throw(std::out_of_range("basic_string"));  }

   protected:
   size_type priv_capacity() const
   { return this->priv_storage() - 1; }

   pointer priv_addr() const
   {  return this->is_short() ? pointer(&this->members_.m_repr.short_repr().data[0]) : this->members_.m_repr.long_repr().start;  }