block.hpp

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/*
 * $Id: block.hpp 313 2014-02-22 14:29:57Z jdl3 $
 * Copyright (C) 2010, 2011, 2012, 2014, 2024 John D Lamb
 * Enum copyright (C) 1996, 1997, 1998, 1999, 2000, 2007 Gerard Jungman, Brian Gough
 *
 * 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 CCGSL_BLOCK_HPP
#define CCGSL_BLOCK_HPP
 
#include<gsl/gsl_block.h>
#include<new>
#include<iterator>
#include<cstring>
#include<cstddef>
#ifdef __GXX_EXPERIMENTAL_CXX0X__
#include<initializer_list>
#endif
 
#include"exception.hpp"
 
// This file is used as a template
 
namespace gsl {
  class block {
  public:
    block(){
      ccgsl_pointer = 0;
      count = 0; // initially nullptr will do
    }
    // Refines random access container
    // Refines assignable
    explicit block( size_t const n ){
      if( n > 0 )
    ccgsl_pointer = gsl_block_alloc( n );
      else {
    ccgsl_pointer = new gsl_block;
    ccgsl_pointer->size = 0;
    ccgsl_pointer->data = 0;
      }
      // just plausibly we could allocate block but not count
      try { count = new size_t; } catch( std::bad_alloc& e ){
    // try to tidy up before rethrowing
    if( n > 0 ) gsl_block_free( ccgsl_pointer );
    else delete ccgsl_pointer;
    throw e;
      }
      *count = 1; // initially there is just one reference to ccgsl_pointer
    }
    explicit block( gsl_block* v ){
      ccgsl_pointer = v;
      // 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 ccgsl_pointer
    }
#ifdef __GXX_EXPERIMENTAL_CXX0X__
    block( std::initializer_list<double> initializer_list ){
      size_t const n = initializer_list.size();
      ccgsl_pointer = gsl_block_alloc( n );
      // just plausibly we could allocate vector but not count
      try { count = new size_t; } catch( std::bad_alloc& e ){
    // try to tidy up before rethrowing
    if( n > 0 ) gsl_block_free( ccgsl_pointer );
    else delete ccgsl_pointer;
    throw e;
      }
      *count = 1; // initially there is just one reference to ccgsl_pointer
      // now copy
      auto p = begin();
      for( auto x : initializer_list ){ *p = x; ++p; }
    }
#endif
    // copy constructor
    block( block const& v ) : ccgsl_pointer( v.ccgsl_pointer ), count( v.count ){
      if( count != 0 ) ++*count; // block is now shared.
    }
    // assignment operator
    block& operator=( block const& v ){
      // first, possibly delete anything pointed to by this
      if( count == 0 or --*count == 0 ){
    if( ccgsl_pointer != 0 ){
      if( ccgsl_pointer->size > 0 ) gsl_block_free( ccgsl_pointer );
      else delete ccgsl_pointer; }
    delete count;
      }
      // Then copy
      ccgsl_pointer = v.ccgsl_pointer;
      count = v.count;
      if( count != 0 ) ++*count; // block is now shared.
      return *this;
    }
    // clone()
    block clone() const {
      block copy( ccgsl_pointer->size );
      // Now copy
      memcpy( copy.ccgsl_pointer->data, ccgsl_pointer->data, ccgsl_pointer->size * sizeof( double ) );
      // return new object
      return copy;
    }
    // destructor
    ~block(){
      if( count == 0 or --*count == 0 ){
    // could have allocated null pointer
    if( ccgsl_pointer != 0 ){
      if( ccgsl_pointer->size > 0 ) gsl_block_free( ccgsl_pointer );
      else delete ccgsl_pointer; }
    delete count;
      }
    }
    void reset(){ block().swap( *this ); }
#ifdef __GXX_EXPERIMENTAL_CXX0X__
    block( block&& v ) : ccgsl_pointer( v.ccgsl_pointer ), count( nullptr ){
      std::swap( count, v.count );
      v.ccgsl_pointer = nullptr;
    }
    block& operator=( block&& v ){
      block( std::move( v ) ).swap( *this );
      return *this;
    }
#endif
    // Refines equality comparable
    // == operator
    bool operator==( block const& v ) const {
      // trivially equal if gsl_block*s are identical
      if( ccgsl_pointer == v.ccgsl_pointer ) return true;
      // trivially not equal if one is zero: != should be same as xor here
      if( (ccgsl_pointer == 0) != (v.ccgsl_pointer == 0 ) ) return false;
      // trivially not equal if sizes are different
      if( ccgsl_pointer->size != v.ccgsl_pointer->size ) return false;
      // check elementwise for equality
      for( size_t i = 0; i < ccgsl_pointer->size; ++i )
    if( ccgsl_pointer->data[i] != v.ccgsl_pointer->data[i] ) return false; 
      return true;
    }
    // != operator
    bool operator!=( block const& v ) const { return not operator==( v ); }
    // Refines forward container
    // Refines less than comparable
    // operator<
    bool operator<( block const& v ) const {
      // null block comes first
      if( ccgsl_pointer == 0 ) return v.ccgsl_pointer != 0;
      // if v is null then this > v
      if( v.ccgsl_pointer == 0 ) return false;
      // Now compare elementwise
      size_t const  size = ccgsl_pointer->size;
      size_t const  v_size = v.ccgsl_pointer->size;
      size_t const min = size > v_size ? size : v_size;
      for( size_t i = 0; i < min; ++i ){
    double const t = ccgsl_pointer->data[i];
    double const u =v.ccgsl_pointer->data[i];
    if( t < u ) return true;
    if( u < t ) return false;
      }
      // elements match.
      return size < v_size;
    }
    // operator>
    bool operator>( block const& v ) const {
      // null block comes first
      if( ccgsl_pointer == 0 ) return false;
      // if v is null then this > v
      if( v.ccgsl_pointer == 0 ) return true;
      // Now compare elementwise
      size_t const  size = ccgsl_pointer->size;
      size_t const  v_size = v.ccgsl_pointer->size;
      size_t const min = size > v_size ? size : v_size;
      for( size_t i = 0; i < min; ++i ){
    double const t = ccgsl_pointer->data[i];
    double const u =v.ccgsl_pointer->data[i];
    if( t > u ) return true;
    if( u > t ) return false;
      }
      // elements match.
      return size > v_size;
    }
    // operator<=
    bool operator<=( block const& v ) const {
      return operator<( v ) or operator==( v );
    }
    // operator>=
    bool operator>=( block const& v ) const {
      return operator>( v ) or operator==( v );
    }
    // Refines container
    // type value_type
    typedef double value_type;
    // type reference
    typedef value_type& reference;
    // type const_reference
    typedef value_type const& const_reference;
    // type pointer
    typedef value_type* pointer;
    // type const_pointer
    typedef value_type const* const_pointer;
    // type iterator
  private:
    template<typename container, typename content, bool reverse> class iterator_base {
      friend class block;
    public:
      typedef std::random_access_iterator_tag iterator_category;
      typedef double value_type;
      typedef value_type* pointer;
      typedef value_type& reference;
      // // type iterator_traits<block>::difference_type
      typedef ptrdiff_t difference_type;
    public:
      // // operator*
      reference operator*() const {
    // Always try to return something
    static content something = 0;
    // First check that iterator is initialised.
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAULT );
      return something;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAULT );
      return something;
    }
    // Check that position make sense
    if( position >= static_cast<difference_type>( v->size() ) ){
      gsl_error( "trying to dereference beyond rbegin()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    }
    if( position <= -1 ){
      gsl_error( "trying to dereference beyond begin()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    }
    // position and v are valid: return data
    return *(v->ccgsl_pointer->data + position);
      }
      // // operator->
      pointer operator->() const {
    // First check that iterator is initialised.
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    // Check that position make sense
    if( position >= static_cast<difference_type>( v->size() ) ){
      gsl_error( "trying to dereference end()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    if( position <= -1 ){
      gsl_error( "trying to dereference rend()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    // position and v are valid: return data
    return v->ccgsl_pointer->data + position;
      }
      // // operator[]
      reference operator[]( difference_type const n ) const {
    // Always try to return something
    static content something = 0;
    // First check that iterator is initialised.
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    }
    // Check that position make sense
    difference_type const p = reverse ? position - n : position + n;
    if( p >= static_cast<difference_type>( v->size() ) ){
      gsl_error( "trying to dereference beyond rbegin()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    }
    if( p <= -1 ){
      gsl_error( "trying to dereference beyond begin()", __FILE__, __LINE__, exception::GSL_EFAILED );
      return something;
    }
    // p is a valid position
    return *(v->ccgsl_pointer->data + p);
      }
      // // operator-: find distance between two iterators
      difference_type operator-( iterator_base<container,content,reverse> const& i ) const {
    // Warn if either iterator undefined
    if( v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    } else if( v->ccgsl_pointer == 0 or i.v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    // Warn if iterators do not point to same block
    if( v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return 0;
    }
    return reverse ? i.position - position : position - i.position;
      }
      // // operator!=
      // // operator<
      bool operator==( iterator_base<container,content,reverse> const& i ) const {
    return this->v == i.v and this->position == i.position;
      }
      bool operator!=( iterator_base<container,content,reverse> const& i ) const {
    return not this->operator==( i );
      }
      bool operator<( iterator_base<container,content,reverse> const& i ) const {
    // Warn if either iterator undefined
    if( v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return false;
    }
    // Warn if iterators do not point to same block
    if( v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return false;
    }
    return reverse ? i.position < position : position < i.position;
      }
    protected:
      void increment(){
    // Only makes sense if v points to a block
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    }
    // increment position and check against size
    if( reverse ){ if( position >= 0 ) --position; }
    else { if( position < static_cast<difference_type>( v->size() ) ) ++position; }
      }
      void decrement(){
    // Only makes sense if v points to a block
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    }
    // decrement position and check against size
    if( reverse ){ if( position < static_cast<difference_type>( v->size() ) ) ++position; }
    else { if( position >= 0 ) --position; }
      }
      void shift( difference_type const n ){
    // Warn if iterator undefined
    if( v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    } else if( v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return;
    }
    position += reverse ? -n : n;
      }
      iterator_base(){ v = 0; }
      iterator_base( container* v, difference_type position )
    : v( v ), position( position ){}
      container* v;
      difference_type position;
    };
    // Need to know about const_iterator_t
    template<bool reverse> class const_iterator_t;
    template<bool reverse> class iterator_t : public iterator_base<block,double,reverse>{
    public:
      // // Refines output iterator
      // // operator=
      iterator_t<reverse>& operator=( iterator_t<reverse> const& i ){
    iterator_base<block,double,reverse>::v = i.v;
    iterator_base<block,double,reverse>::position = i.position;
    return *this;
      }
      // // Refines forward iterator
      // // operator++ (both)
      iterator_t<reverse>& operator++(){
    iterator_base<block,double,reverse>::increment();
    return *this;
      }
      iterator_t<reverse> operator++( int ){
    // return value
    iterator_t<reverse> result( *this );
    iterator_base<block,double,reverse>::increment();
    return result;
      }
      // // Refines bidirectional iterator
      // // operator-- (both)
      iterator_t<reverse>& operator--(){
    iterator_base<block,double,reverse>::decrement();
    return *this;
      }
      iterator_t<reverse> operator--( int ){
    // return value
    iterator_t<reverse> result( *this );
    iterator_base<block,double,reverse>::decrement();
    return result;
      }
      typedef typename iterator_base<block,double,reverse>::difference_type
    difference_type;
      // // operator+=
      iterator_t<reverse>& operator+=( difference_type const n ){
    this->shift( n );
    return *this;
      }
      // // operator-=
      iterator_t<reverse>& operator-=( difference_type const n ){
    this->shift( -n );
    return *this;
      }
      // // operator+ (n+i)(i+n)
      iterator_t<reverse> operator+( difference_type const n ) const {
    iterator_t<reverse> result( *this );
    result.shift( n );
    return result;
      }
      // // operator- (n-i)(i-n)(i-j)
      iterator_t<reverse> operator-( difference_type const n ) const {
    iterator_t<reverse> result( *this );
    result.shift( -n );
    return result;
      }
      difference_type operator-( iterator_t<reverse> const& i ) const {
    return iterator_base<block,double,reverse>::operator-( i );
      }
      difference_type operator-( const_iterator_t<reverse> const& i ) const {
    // Warn if either iterator undefined
    if( this->v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    } else if( this->v->ccgsl_pointer == 0 or i.v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    // Warn if iterators do not point to same block
    if( this->v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return 0;
    }
    return reverse ? i.position - this->position : this->position - i.position;
      }
      bool operator==( const_iterator_t<reverse> const& i ) const {
        return this->v == i.v and this->position == i.position;
      }
      bool operator!=( const_iterator_t<reverse> const& i ) const {
        return not this->operator==( i );
      }
      bool operator<( const_iterator_t<reverse> const& i ) const {
    // Warn if either iterator undefined
    if( this->v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return false;
    }
    // Warn if iterators do not point to same block
    if( this->v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return false;
    }
    return reverse ? i.position < this->position : this->position < i.position;
      }
      iterator_t() : iterator_base<block,double,reverse>(){}
    protected:
      friend class block;
      // We need a constructor for block
      iterator_t( block* v, difference_type position )
      : iterator_base<block,double,reverse>( v, position ){}
    };
    template<bool reverse> class const_iterator_t
      : public iterator_base<block const,double,reverse>{
    public:
      // // Refines output iterator
      // // operator=
      const_iterator_t& operator=( const_iterator_t<reverse> const& i ){
    iterator_base<block const,double,reverse>::v = i.v;
    iterator_base<block const,double,reverse>::position = i.position;
    return *this;
      }
      // // Refines forward iterator
      // // operator++ (both)
      const_iterator_t<reverse>& operator++(){
    iterator_base<block const,double,reverse>::increment();
    return *this;
      }
      const_iterator_t<reverse> operator++( int ){
    // return value
    const_iterator_t<reverse> result( *this );
    iterator_base<block const,double,reverse>::increment();
    return result;
      }
      // // Refines bidirectional iterator
      // // operator-- (both)
      const_iterator_t<reverse>& operator--(){
    iterator_base<block const,double,reverse>::decrement();
    return *this;
      }
      const_iterator_t<reverse> operator--( int ){
    // return value
    const_iterator_t<reverse> result( *this );
    iterator_base<block const,double,reverse>::decrement();
    return result;
      }
      typedef typename iterator_base<block const,double,reverse>::difference_type
    difference_type;
      // // operator+=
      const_iterator_t<reverse>& operator+=( difference_type const n ){
    this->shift( n );
    return *this;
      }
      // // operator-=
      const_iterator_t<reverse>& operator-=( difference_type const n ){
    this->shift( -n );
    return *this;
      }
      // // operator+ (n+i)(i+n)
      const_iterator_t<reverse> operator+( difference_type const n ) const {
    const_iterator_t<reverse> result( *this );
    result += n;
    return result;
      }
      // // operator- (n-i)(i-n)(i-j)
      const_iterator_t<reverse> operator-( difference_type const n ) const {
    const_iterator_t<reverse> result( *this );
    result -= n;
    return result;
      }
      difference_type operator-( const_iterator_t<reverse> const& i ) const {
    return iterator_base<block const,double,reverse>::operator-( i );
      }
      difference_type operator-( iterator_t<reverse> const& i ) const {
    // Warn if either iterator undefined
    if( this->v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    } else if( this->v->ccgsl_pointer == 0 or i.v->ccgsl_pointer == 0 ){
      gsl_error( "block not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return 0;
    }
    // Warn if iterators do not point to same block
    if( this->v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return 0;
    }
    return reverse ? i.position - this->position : this->position - i.position;
      }
      const_iterator_t() : iterator_base<block,double,reverse>(){}
      const_iterator_t( iterator_t<reverse> const&i ){
    const_iterator_t<reverse>::v = i.v;
    const_iterator_t<reverse>::position = i.position;
      }
      bool operator==( iterator_t<reverse> const& i ) const {
        return this->v == i.v and this->position == i.position;
      }
      bool operator!=( iterator_t<reverse> const& i ) const {
        return not this->operator==( i );
      }
      bool operator<( iterator_t<reverse> const& i ) const {
    // Warn if either iterator undefined
    if( this->v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return false;
    }
    // Warn if iterators do not point to same block
    if( this->v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return false;
    }
    return reverse ? i.position < this->position : this->position < i.position;
      }
      bool operator==( const_iterator_t<reverse> const& i ) const {
        return this->v == i.v and this->position == i.position;
      }
      bool operator!=( const_iterator_t<reverse> const& i ) const {
        return not this->operator==( i );
      }
      bool operator<( const_iterator_t<reverse> const& i ) const {
    // Warn if either iterator undefined
    if( this->v == 0 or i.v == 0 ){
      gsl_error( "iterator not initialised", __FILE__, __LINE__, exception::GSL_EFAILED );
      return false;
    }
    // Warn if iterators do not point to same block
    if( this->v->ccgsl_pointer != i.v->ccgsl_pointer ){
      gsl_error( "trying to take difference of iterators for different blocks", __FILE__, __LINE__,
             exception::GSL_EFAILED );
      return false;
    }
    return reverse ? i.position < this->position : this->position < i.position;
      }
    protected:
      // We need a constructor for block
      friend class block;
      const_iterator_t( block const* v, difference_type position )
      : iterator_base<block const,double,reverse>( v, position ){}
    };
  public:
    typedef const_iterator_t<false> const_iterator;
    typedef iterator_t<false> iterator;
    typedef const_iterator_t<true> const_reverse_iterator;
    typedef iterator_t<true> reverse_iterator;
    // type difference_type
    typedef const_iterator::difference_type difference_type;
    // type size_type
    typedef size_t size_type;
    // begin()
    iterator begin(){
      return iterator( this, 0 );
    }
    const_iterator begin() const {
      return const_iterator( this, 0 );
    }
    // end()
    iterator end(){
      if( ccgsl_pointer == 0 ) return iterator( this, 0 );
      return iterator( this, size() );
    }
    const_iterator end() const {
      if( ccgsl_pointer == 0 ) return const_iterator( this, 0 );
      return const_iterator( this, size() );
    }
    // size()
    size_type size() const { return ccgsl_pointer->size; }
    double* data() {
      if( ccgsl_pointer == 0 ) gsl_error( "null block", __FILE__, __LINE__, GSL_EFAULT );
      return ccgsl_pointer->data; }
    double const* data() const {
      if( ccgsl_pointer == 0 ) gsl_error( "null block", __FILE__, __LINE__, GSL_EFAULT );
      return ccgsl_pointer->data; }
    // max_size()
    size_type max_size() const { return ccgsl_pointer->size; }
    // empty()
    bool empty() const { return ccgsl_pointer == 0 or ccgsl_pointer->size == 0; }
    // swap() --- should work even if sizes don't match
    void swap( block& v ){
      std::swap( ccgsl_pointer, v.ccgsl_pointer );
      std::swap( count, v.count );
    }
    // Refines reversible container
    // rbegin()
    reverse_iterator rbegin(){
      if( ccgsl_pointer ==0 ) return reverse_iterator( this, 0 );
      return reverse_iterator( this, size() - 1 );
    }
    const_reverse_iterator rbegin() const {
      if( ccgsl_pointer ==0 ) return const_reverse_iterator( this, 0 );
      return const_reverse_iterator( this, size() - 1 );
    }
    // rend()
    reverse_iterator rend(){
      return reverse_iterator( this, -1 );
    }
    const_reverse_iterator rend() const {
      return const_reverse_iterator( this, -1 );
    }
    // operator[]
    double& operator[]( size_t const n ){
      // Always try to return something
      static double something = 0;
      // First check that iterator is initialised.
      if( ccgsl_pointer == 0 ){
    gsl_error( "block is null", __FILE__, __LINE__, exception::GSL_EFAULT );
    return something;
      }
#ifndef GSL_RANGE_CHECK_OFF
      // Check that position make sense
      if( n >= size() ){
    gsl_error( "trying to read beyond end of block", __FILE__, __LINE__, exception::GSL_EINVAL );
    return something;
      }
      // n is a valid position
#endif
      return *(ccgsl_pointer->data + n);
    }
    double const& operator[]( size_t const n ) const {
      // Always try to return something
      static double something = 0;
      // First check that iterator is initialised.
      if( ccgsl_pointer == 0 ){
    gsl_error( "block is null", __FILE__, __LINE__, exception::GSL_EFAULT );
    return something;
      }
#ifndef GSL_RANGE_CHECK_OFF
      // Check that position make sense
      if( n >= size() ){
    gsl_error( "trying to read beyond end of block", __FILE__, __LINE__, exception::GSL_EINVAL );
    return something;
      }
      // n is a valid position
#endif
      return *(ccgsl_pointer->data + n);
    }
  private:
    gsl_block* ccgsl_pointer;
    size_t* count;
  public:
    // shared reference functions
    gsl_block* get() const { return ccgsl_pointer; }
    bool unique() const { return count != 0 and *count == 1; }
    size_t use_count() const { return count == 0 ? 0 : *count; }
#ifdef __GXX_EXPERIMENTAL_CXX0X__
    explicit
#endif
    operator bool() const { return ccgsl_pointer != 0; }
  };
  
  // gsl functions
  
  inline block::iterator operator+
  ( block::iterator::difference_type const n,
                  block::iterator const& i ){
    return i + n;
  }
  
  inline block::const_iterator operator+
  ( block::const_iterator::difference_type const n,
                    block::const_iterator const& i ){
    return i + n;
  }
  
  inline block::reverse_iterator operator+
  ( block::reverse_iterator::difference_type const n,
                  block::reverse_iterator const& i ){
    return i + n;
  }
  
  inline block::const_reverse_iterator operator+
  ( block::const_reverse_iterator::difference_type const n,
                  block::const_reverse_iterator const& i ){
    return i + n;
  }
  
}
 
#endif