// SGI's rope class -*- C++ -*-

// Copyright (C) 2001-2018 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library.  This library 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 3, or (at your option)
// any later version.

// This library 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.

// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.

// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
// <http://www.gnu.org/licenses/>.

/*
 * Copyright (c) 1997
 * Silicon Graphics Computer Systems, Inc.
 *
 * 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.  Silicon Graphics makes no
 * representations about the suitability of this software for any
 * purpose.  It is provided "as is" without express or implied warranty.
 */

/** @file ext/rope
 *  This file is a GNU extension to the Standard C++ Library (possibly
 *  containing extensions from the HP/SGI STL subset). 
 */

#ifndef _ROPE
#define _ROPE 1

#pragma GCC system_header

#include <algorithm>
#include <iosfwd>
#include <bits/stl_construct.h>
#include <bits/stl_uninitialized.h>
#include <bits/stl_function.h>
#include <bits/stl_numeric.h>
#include <bits/allocator.h>
#include <bits/gthr.h>
#include <tr1/functional>

# ifdef __GC
#   define __GC_CONST const
# else
#   define __GC_CONST   // constant except for deallocation
# endif

#include <ext/memory> // For uninitialized_copy_n

namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION

  namespace __detail
  {
    enum { _S_max_rope_depth = 45 };
    enum _Tag {_S_leaf, _S_concat, _S_substringfn, _S_function};
  } // namespace __detail

  using std::size_t;
  using std::ptrdiff_t;
  using std::allocator;
  using std::_Destroy;

  // See libstdc++/36832.
  template<typename _ForwardIterator, typename _Allocator>
    void
    _Destroy_const(_ForwardIterator __first,
		   _ForwardIterator __last, _Allocator __alloc)
    {
      for (; __first != __last; ++__first)
	__alloc.destroy(&*__first);
    }

  template<typename _ForwardIterator, typename _Tp>
    inline void
    _Destroy_const(_ForwardIterator __first,
		   _ForwardIterator __last, allocator<_Tp>)
    { _Destroy(__first, __last); }

  // The _S_eos function is used for those functions that
  // convert to/from C-like strings to detect the end of the string.
  
  // The end-of-C-string character.
  // This is what the draft standard says it should be.
  template <class _CharT>
    inline _CharT
    _S_eos(_CharT*)
    { return _CharT(); }

  // Test for basic character types.
  // For basic character types leaves having a trailing eos.
  template <class _CharT>
    inline bool
    _S_is_basic_char_type(_CharT*)
    { return false; }
  
  template <class _CharT>
    inline bool
    _S_is_one_byte_char_type(_CharT*)
    { return false; }

  inline bool
  _S_is_basic_char_type(char*)
  { return true; }
  
  inline bool
  _S_is_one_byte_char_type(char*)
  { return true; }
  
  inline bool
  _S_is_basic_char_type(wchar_t*)
  { return true; }

  // Store an eos iff _CharT is a basic character type.
  // Do not reference _S_eos if it isn't.
  template <class _CharT>
    inline void
    _S_cond_store_eos(_CharT&) { }

  inline void
  _S_cond_store_eos(char& __c)
  { __c = 0; }

  inline void
  _S_cond_store_eos(wchar_t& __c)
  { __c = 0; }

  // char_producers are logically functions that generate a section of
  // a string.  These can be converted to ropes.  The resulting rope
  // invokes the char_producer on demand.  This allows, for example,
  // files to be viewed as ropes without reading the entire file.
  template <class _CharT>
    class char_producer
    {
    public:
      virtual ~char_producer() { }

      virtual void
      operator()(size_t __start_pos, size_t __len,
		 _CharT* __buffer) = 0;
      // Buffer should really be an arbitrary output iterator.
      // That way we could flatten directly into an ostream, etc.
      // This is thoroughly impossible, since iterator types don't
      // have runtime descriptions.
    };

  // Sequence buffers:
  //
  // Sequence must provide an append operation that appends an
  // array to the sequence.  Sequence buffers are useful only if
  // appending an entire array is cheaper than appending element by element.
  // This is true for many string representations.
  // This should  perhaps inherit from ostream<sequence::value_type>
  // and be implemented correspondingly, so that they can be used
  // for formatted.  For the sake of portability, we don't do this yet.
  //
  // For now, sequence buffers behave as output iterators.  But they also
  // behave a little like basic_ostringstream<sequence::value_type> and a
  // little like containers.

  template<class _Sequence, size_t _Buf_sz = 100>
    class sequence_buffer
    : public std::iterator<std::output_iterator_tag, void, void, void, void>
    {
    public:
      typedef typename _Sequence::value_type value_type;
    protected:
      _Sequence* _M_prefix;
      value_type _M_buffer[_Buf_sz];
      size_t     _M_buf_count;
    public:

      void
      flush()
      {
	_M_prefix->append(_M_buffer, _M_buffer + _M_buf_count);
	_M_buf_count = 0;
      }
      
      ~sequence_buffer()
      { flush(); }
      
      sequence_buffer()
      : _M_prefix(0), _M_buf_count(0) { }

      sequence_buffer(const sequence_buffer& __x)
      {
	_M_prefix = __x._M_prefix;
	_M_buf_count = __x._M_buf_count;
	std::copy(__x._M_buffer, __x._M_buffer + __x._M_buf_count, _M_buffer);
      }
      
      sequence_buffer(sequence_buffer& __x)
      {
	__x.flush();
	_M_prefix = __x._M_prefix;
	_M_buf_count = 0;
      }
      
      sequence_buffer(_Sequence& __s)
      : _M_prefix(&__s), _M_buf_count(0) { }
      
      sequence_buffer&
      operator=(sequence_buffer& __x)
      {
	__x.flush();
	_M_prefix = __x._M_prefix;
	_M_buf_count = 0;
	return *this;
      }

      sequence_buffer&
      operator=(const sequence_buffer& __x)
      {
	_M_prefix = __x._M_prefix;
	_M_buf_count = __x._M_buf_count;
	std::copy(__x._M_buffer, __x._M_buffer + __x._M_buf_count, _M_buffer);
	return *this;
      }
      
      void
      push_back(value_type __x)
      {
	if (_M_buf_count < _Buf_sz)
	  {
	    _M_buffer[_M_buf_count] = __x;
	    ++_M_buf_count;
	  }
	else
	  {
	    flush();
	    _M_buffer[0] = __x;
	    _M_buf_count = 1;
	  }
      }
      
      void
      append(value_type* __s, size_t __len)
      {
	if (__len + _M_buf_count <= _Buf_sz)
	  {
	    size_t __i = _M_buf_count;
	    for (size_t __j = 0; __j < __len; __i++, __j++)
	      _M_buffer[__i] = __s[__j];
	    _M_buf_count += __len;
	  }
	else if (0 == _M_buf_count)
	  _M_prefix->append(__s, __s + __len);
	else
	  {
	    flush();
	    append(__s, __len);
	  }
      }

      sequence_buffer&
      write(value_type* __s, size_t __len)
      {
	append(__s, __len);
	return *this;
      }
      
      sequence_buffer&
      put(value_type __x)
      {
	push_back(__x);
	return *this;
      }
      
      sequence_buffer&
      operator=(const value_type& __rhs)
      {
	push_back(__rhs);
	return *this;
      }
      
      sequence_buffer&
      operator*()
      { return *this; }
      
      sequence_buffer&
      operator++()
      { return *this; }
      
      sequence_buffer
      operator++(int)
      { return *this; }
    };
  
  // The following should be treated as private, at least for now.
  template<class _CharT>
    class _Rope_char_consumer
    {
    public:
      // If we had member templates, these should not be virtual.
      // For now we need to use run-time parametrization where
      // compile-time would do.  Hence this should all be private
      // for now.
      // The symmetry with char_producer is accidental and temporary.
      virtual ~_Rope_char_consumer() { }
  
      virtual bool
      operator()(const _CharT* __buffer, size_t __len) = 0;
    };
  
  // First a lot of forward declarations.  The standard seems to require
  // much stricter "declaration before use" than many of the implementations
  // that preceded it.
  template<class _CharT, class _Alloc = allocator<_CharT> >
    class rope;
  
  template<class _CharT, class _Alloc>
    struct _Rope_RopeConcatenation;

  template<class _CharT, class _Alloc>
    struct _Rope_RopeLeaf;
  
  template<class _CharT, class _Alloc>
    struct _Rope_RopeFunction;
  
  template<class _CharT, class _Alloc>
    struct _Rope_RopeSubstring;
  
  template<class _CharT, class _Alloc>
    class _Rope_iterator;
  
  template<class _CharT, class _Alloc>
    class _Rope_const_iterator;
  
  template<class _CharT, class _Alloc>
    class _Rope_char_ref_proxy;
  
  template<class _CharT, class _Alloc>
    class _Rope_char_ptr_proxy;

  template<class _CharT, class _Alloc>
    bool
    operator==(const _Rope_char_ptr_proxy<_CharT, _Alloc>& __x,
	       const _Rope_char_ptr_proxy<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    _Rope_const_iterator<_CharT, _Alloc>
    operator-(const _Rope_const_iterator<_CharT, _Alloc>& __x,
	      ptrdiff_t __n);

  template<class _CharT, class _Alloc>
    _Rope_const_iterator<_CharT, _Alloc>
    operator+(const _Rope_const_iterator<_CharT, _Alloc>& __x,
	      ptrdiff_t __n);

  template<class _CharT, class _Alloc>
    _Rope_const_iterator<_CharT, _Alloc>
    operator+(ptrdiff_t __n,
	      const _Rope_const_iterator<_CharT, _Alloc>& __x);

  template<class _CharT, class _Alloc>
    bool
    operator==(const _Rope_const_iterator<_CharT, _Alloc>& __x,
	       const _Rope_const_iterator<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    bool
    operator<(const _Rope_const_iterator<_CharT, _Alloc>& __x,
	      const _Rope_const_iterator<_CharT, _Alloc>& __y);
  
  template<class _CharT, class _Alloc>
    ptrdiff_t
    operator-(const _Rope_const_iterator<_CharT, _Alloc>& __x,
	      const _Rope_const_iterator<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    _Rope_iterator<_CharT, _Alloc>
    operator-(const _Rope_iterator<_CharT, _Alloc>& __x, ptrdiff_t __n);

  template<class _CharT, class _Alloc>
    _Rope_iterator<_CharT, _Alloc>
    operator+(const _Rope_iterator<_CharT, _Alloc>& __x, ptrdiff_t __n);

  template<class _CharT, class _Alloc>
    _Rope_iterator<_CharT, _Alloc>
    operator+(ptrdiff_t __n, const _Rope_iterator<_CharT, _Alloc>& __x);

  template<class _CharT, class _Alloc>
    bool
    operator==(const _Rope_iterator<_CharT, _Alloc>& __x,
	       const _Rope_iterator<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    bool
    operator<(const _Rope_iterator<_CharT, _Alloc>& __x,
	      const _Rope_iterator<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    ptrdiff_t
    operator-(const _Rope_iterator<_CharT, _Alloc>& __x,
	      const _Rope_iterator<_CharT, _Alloc>& __y);

  template<class _CharT, class _Alloc>
    rope<_CharT, _Alloc>
    operator+(const rope<_CharT, _Alloc>& __left,
	      const rope<_CharT, _Alloc>& __right);

  template<class _CharT, class _Alloc>
    rope<_CharT, _Alloc>
    operator+(const rope<_CharT, _Alloc>& __left, const _CharT* __right);

  template<class _CharT, class _Alloc>
    rope<_CharT, _Alloc>
    operator+(const rope<_CharT, _Alloc>& __left, _CharT __right);

  // Some helpers, so we can use power on ropes.
  // See below for why this isn't local to the implementation.
  
  // This uses a nonstandard refcount convention.
  // The result has refcount 0.
  template<class _CharT, class _Alloc>
    struct _Rope_Concat_fn
    : public std::binary_function<rope<_CharT, _Alloc>, rope<_CharT, _Alloc>,
				  rope<_CharT, _Alloc> >
    {
      rope<_CharT, _Alloc>
      operator()(const rope<_CharT, _Alloc>& __x,
		 const rope<_CharT, _Alloc>& __y)
      { return __x + __y; }
    };

  template <class _CharT, class _Alloc>
    inline rope<_CharT, _Alloc>
    identity_element(_Rope_Concat_fn<_CharT, _Alloc>)
    { return rope<_CharT, _Alloc>(); }

  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