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// Components for manipulating sequences of characters -*- C++ -*-

// Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,

// 2006, 2007, 2008, 2009, 2010, 2011

// 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

// .

/** @file bits/basic_string.tcc

 *  This is an internal header file, included by other library headers.

 *  Do not attempt to use it directly. @headername{string}

 */

//

// ISO C++ 14882: 21  Strings library

//

// Written by Jason Merrill based upon the specification by Takanori Adachi

// in ANSI X3J16/94-0013R2.  Rewritten by Nathan Myers to ISO-14882.

#ifndef _BASIC_STRING_TCC

#define _BASIC_STRING_TCC 1

#pragma GCC system_header

#include 

namespace std _GLIBCXX_VISIBILITY(default)

{

_GLIBCXX_BEGIN_NAMESPACE_VERSION

  template

    const typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    _Rep::_S_max_size = (((npos - sizeof(_Rep_base))/sizeof(_CharT)) - 1) / 4;

  template

    const _CharT

    basic_string<_CharT, _Traits, _Alloc>::

    _Rep::_S_terminal = _CharT();

  template

    const typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::npos;

  // Linker sets _S_empty_rep_storage to all 0s (one reference, empty string)

  // at static init time (before static ctors are run).

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::_Rep::_S_empty_rep_storage[

    (sizeof(_Rep_base) + sizeof(_CharT) + sizeof(size_type) - 1) /

      sizeof(size_type)];

  // NB: This is the special case for Input Iterators, used in

  // istreambuf_iterators, etc.

  // Input Iterators have a cost structure very different from

  // pointers, calling for a different coding style.

  template

    template

      _CharT*

      basic_string<_CharT, _Traits, _Alloc>::

      _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,

                   input_iterator_tag)

      {

#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0

        if (__beg == __end && __a == _Alloc())

          return _S_empty_rep()._M_refdata();

#endif

        // Avoid reallocation for common case.

        _CharT __buf[128];

        size_type __len = 0;

        while (__beg != __end && __len < sizeof(__buf) / sizeof(_CharT))

          {

            __buf[__len++] = *__beg;

            ++__beg;

          }

        _Rep* __r = _Rep::_S_create(__len, size_type(0), __a);

        _M_copy(__r->_M_refdata(), __buf, __len);

        __try

          {

            while (__beg != __end)

              {

                if (__len == __r->_M_capacity)

                  {

                    // Allocate more space.

                    _Rep* __another = _Rep::_S_create(__len + 1, __len, __a);

                    _M_copy(__another->_M_refdata(), __r->_M_refdata(), __len);

                    __r->_M_destroy(__a);

                    __r = __another;

                  }

                __r->_M_refdata()[__len++] = *__beg;

                ++__beg;

              }

          }

        __catch(...)

          {

            __r->_M_destroy(__a);

            __throw_exception_again;

          }

        __r->_M_set_length_and_sharable(__len);

        return __r->_M_refdata();

      }

  template

    template 

      _CharT*

      basic_string<_CharT, _Traits, _Alloc>::

      _S_construct(_InIterator __beg, _InIterator __end, const _Alloc& __a,

                   forward_iterator_tag)

      {

#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0

        if (__beg == __end && __a == _Alloc())

          return _S_empty_rep()._M_refdata();

#endif

        // NB: Not required, but considered best practice.

        if (__gnu_cxx::__is_null_pointer(__beg) && __beg != __end)

          __throw_logic_error(__N("basic_string::_S_construct null not valid"));

        const size_type __dnew = static_cast(std::distance(__beg,

                                                                      __end));

        // Check for out_of_range and length_error exceptions.

        _Rep* __r = _Rep::_S_create(__dnew, size_type(0), __a);

        __try

          { _S_copy_chars(__r->_M_refdata(), __beg, __end); }

        __catch(...)

          {

            __r->_M_destroy(__a);

            __throw_exception_again;

          }

        __r->_M_set_length_and_sharable(__dnew);

        return __r->_M_refdata();

      }

  template

    _CharT*

    basic_string<_CharT, _Traits, _Alloc>::

    _S_construct(size_type __n, _CharT __c, const _Alloc& __a)

    {

#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0

      if (__n == 0 && __a == _Alloc())

        return _S_empty_rep()._M_refdata();

#endif

      // Check for out_of_range and length_error exceptions.

      _Rep* __r = _Rep::_S_create(__n, size_type(0), __a);

      if (__n)

        _M_assign(__r->_M_refdata(), __n, __c);

      __r->_M_set_length_and_sharable(__n);

      return __r->_M_refdata();

    }

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const basic_string& __str)

    : _M_dataplus(__str._M_rep()->_M_grab(_Alloc(__str.get_allocator()),

                                          __str.get_allocator()),

                  __str.get_allocator())

    { }

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const _Alloc& __a)

    : _M_dataplus(_S_construct(size_type(), _CharT(), __a), __a)

    { }

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const basic_string& __str, size_type __pos, size_type __n)

    : _M_dataplus(_S_construct(__str._M_data()

                               + __str._M_check(__pos,

                                                "basic_string::basic_string"),

                               __str._M_data() + __str._M_limit(__pos, __n)

                               + __pos, _Alloc()), _Alloc())

    { }

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const basic_string& __str, size_type __pos,

                 size_type __n, const _Alloc& __a)

    : _M_dataplus(_S_construct(__str._M_data()

                               + __str._M_check(__pos,

                                                "basic_string::basic_string"),

                               __str._M_data() + __str._M_limit(__pos, __n)

                               + __pos, __a), __a)

    { }

  // TBD: DPG annotate

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const _CharT* __s, size_type __n, const _Alloc& __a)

    : _M_dataplus(_S_construct(__s, __s + __n, __a), __a)

    { }

  // TBD: DPG annotate

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(const _CharT* __s, const _Alloc& __a)

    : _M_dataplus(_S_construct(__s, __s ? __s + traits_type::length(__s) :

                               __s + npos, __a), __a)

    { }

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(size_type __n, _CharT __c, const _Alloc& __a)

    : _M_dataplus(_S_construct(__n, __c, __a), __a)

    { }

  // TBD: DPG annotate

  template

    template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(_InputIterator __beg, _InputIterator __end, const _Alloc& __a)

    : _M_dataplus(_S_construct(__beg, __end, __a), __a)

    { }

#if __cplusplus >= 201103L

  template

    basic_string<_CharT, _Traits, _Alloc>::

    basic_string(initializer_list<_CharT> __l, const _Alloc& __a)

    : _M_dataplus(_S_construct(__l.begin(), __l.end(), __a), __a)

    { }

#endif

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    assign(const basic_string& __str)

    {

      if (_M_rep() != __str._M_rep())

        {

          // XXX MT

          const allocator_type __a = this->get_allocator();

          _CharT* __tmp = __str._M_rep()->_M_grab(__a, __str.get_allocator());

          _M_rep()->_M_dispose(__a);

          _M_data(__tmp);

        }

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    assign(const _CharT* __s, size_type __n)

    {

      __glibcxx_requires_string_len(__s, __n);

      _M_check_length(this->size(), __n, "basic_string::assign");

      if (_M_disjunct(__s) || _M_rep()->_M_is_shared())

        return _M_replace_safe(size_type(0), this->size(), __s, __n);

      else

        {

          // Work in-place.

          const size_type __pos = __s - _M_data();

          if (__pos >= __n)

            _M_copy(_M_data(), __s, __n);

          else if (__pos)

            _M_move(_M_data(), __s, __n);

          _M_rep()->_M_set_length_and_sharable(__n);

          return *this;

        }

     }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    append(size_type __n, _CharT __c)

    {

      if (__n)

        {

          _M_check_length(size_type(0), __n, "basic_string::append");

          const size_type __len = __n + this->size();

          if (__len > this->capacity() || _M_rep()->_M_is_shared())

            this->reserve(__len);

          _M_assign(_M_data() + this->size(), __n, __c);

          _M_rep()->_M_set_length_and_sharable(__len);

        }

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    append(const _CharT* __s, size_type __n)

    {

      __glibcxx_requires_string_len(__s, __n);

      if (__n)

        {

          _M_check_length(size_type(0), __n, "basic_string::append");

          const size_type __len = __n + this->size();

          if (__len > this->capacity() || _M_rep()->_M_is_shared())

            {

              if (_M_disjunct(__s))

                this->reserve(__len);

              else

                {

                  const size_type __off = __s - _M_data();

                  this->reserve(__len);

                  __s = _M_data() + __off;

                }

            }

          _M_copy(_M_data() + this->size(), __s, __n);

          _M_rep()->_M_set_length_and_sharable(__len);

        }

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    append(const basic_string& __str)

    {

      const size_type __size = __str.size();

      if (__size)

        {

          const size_type __len = __size + this->size();

          if (__len > this->capacity() || _M_rep()->_M_is_shared())

            this->reserve(__len);

          _M_copy(_M_data() + this->size(), __str._M_data(), __size);

          _M_rep()->_M_set_length_and_sharable(__len);

        }

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    append(const basic_string& __str, size_type __pos, size_type __n)

    {

      __str._M_check(__pos, "basic_string::append");

      __n = __str._M_limit(__pos, __n);

      if (__n)

        {

          const size_type __len = __n + this->size();

          if (__len > this->capacity() || _M_rep()->_M_is_shared())

            this->reserve(__len);

          _M_copy(_M_data() + this->size(), __str._M_data() + __pos, __n);

          _M_rep()->_M_set_length_and_sharable(__len);

        }

      return *this;

    }

   template

     basic_string<_CharT, _Traits, _Alloc>&

     basic_string<_CharT, _Traits, _Alloc>::

     insert(size_type __pos, const _CharT* __s, size_type __n)

     {

       __glibcxx_requires_string_len(__s, __n);

       _M_check(__pos, "basic_string::insert");

       _M_check_length(size_type(0), __n, "basic_string::insert");

       if (_M_disjunct(__s) || _M_rep()->_M_is_shared())

         return _M_replace_safe(__pos, size_type(0), __s, __n);

       else

         {

           // Work in-place.

           const size_type __off = __s - _M_data();

           _M_mutate(__pos, 0, __n);

           __s = _M_data() + __off;

           _CharT* __p = _M_data() + __pos;

           if (__s  + __n <= __p)

             _M_copy(__p, __s, __n);

           else if (__s >= __p)

             _M_copy(__p, __s + __n, __n);

           else

             {

               const size_type __nleft = __p - __s;

               _M_copy(__p, __s, __nleft);

               _M_copy(__p + __nleft, __p + __n, __n - __nleft);

             }

           return *this;

         }

     }

   template

     typename basic_string<_CharT, _Traits, _Alloc>::iterator

     basic_string<_CharT, _Traits, _Alloc>::

     erase(iterator __first, iterator __last)

     {

       _GLIBCXX_DEBUG_PEDASSERT(__first >= _M_ibegin() && __first <= __last

                                && __last <= _M_iend());

       // NB: This isn't just an optimization (bail out early when

       // there is nothing to do, really), it's also a correctness

       // issue vs MT, see libstdc++/40518.

       const size_type __size = __last - __first;

       if (__size)

         {

           const size_type __pos = __first - _M_ibegin();

           _M_mutate(__pos, __size, size_type(0));

           _M_rep()->_M_set_leaked();

           return iterator(_M_data() + __pos);

         }

       else

         return __first;

     }

   template

     basic_string<_CharT, _Traits, _Alloc>&

     basic_string<_CharT, _Traits, _Alloc>::

     replace(size_type __pos, size_type __n1, const _CharT* __s,

             size_type __n2)

     {

       __glibcxx_requires_string_len(__s, __n2);

       _M_check(__pos, "basic_string::replace");

       __n1 = _M_limit(__pos, __n1);

       _M_check_length(__n1, __n2, "basic_string::replace");

       bool __left;

       if (_M_disjunct(__s) || _M_rep()->_M_is_shared())

         return _M_replace_safe(__pos, __n1, __s, __n2);

       else if ((__left = __s + __n2 <= _M_data() + __pos)

                || _M_data() + __pos + __n1 <= __s)

         {

           // Work in-place: non-overlapping case.

           size_type __off = __s - _M_data();

           __left ? __off : (__off += __n2 - __n1);

           _M_mutate(__pos, __n1, __n2);

           _M_copy(_M_data() + __pos, _M_data() + __off, __n2);

           return *this;

         }

       else

         {

           // Todo: overlapping case.

           const basic_string __tmp(__s, __n2);

           return _M_replace_safe(__pos, __n1, __tmp._M_data(), __n2);

         }

     }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::_Rep::

    _M_destroy(const _Alloc& __a) throw ()

    {

      const size_type __size = sizeof(_Rep_base) +

                               (this->_M_capacity + 1) * sizeof(_CharT);

      _Raw_bytes_alloc(__a).deallocate(reinterpret_cast(this), __size);

    }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::

    _M_leak_hard()

    {

#if _GLIBCXX_FULLY_DYNAMIC_STRING == 0

      if (_M_rep() == &_S_empty_rep())

        return;

#endif

      if (_M_rep()->_M_is_shared())

        _M_mutate(0, 0, 0);

      _M_rep()->_M_set_leaked();

    }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::

    _M_mutate(size_type __pos, size_type __len1, size_type __len2)

    {

      const size_type __old_size = this->size();

      const size_type __new_size = __old_size + __len2 - __len1;

      const size_type __how_much = __old_size - __pos - __len1;

      if (__new_size > this->capacity() || _M_rep()->_M_is_shared())

        {

          // Must reallocate.

          const allocator_type __a = get_allocator();

          _Rep* __r = _Rep::_S_create(__new_size, this->capacity(), __a);

          if (__pos)

            _M_copy(__r->_M_refdata(), _M_data(), __pos);

          if (__how_much)

            _M_copy(__r->_M_refdata() + __pos + __len2,

                    _M_data() + __pos + __len1, __how_much);

          _M_rep()->_M_dispose(__a);

          _M_data(__r->_M_refdata());

        }

      else if (__how_much && __len1 != __len2)

        {

          // Work in-place.

          _M_move(_M_data() + __pos + __len2,

                  _M_data() + __pos + __len1, __how_much);

        }

      _M_rep()->_M_set_length_and_sharable(__new_size);

    }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::

    reserve(size_type __res)

    {

      if (__res != this->capacity() || _M_rep()->_M_is_shared())

        {

          // Make sure we don't shrink below the current size

          if (__res < this->size())

            __res = this->size();

          const allocator_type __a = get_allocator();

          _CharT* __tmp = _M_rep()->_M_clone(__a, __res - this->size());

          _M_rep()->_M_dispose(__a);

          _M_data(__tmp);

        }

    }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::

    swap(basic_string& __s)

    {

      if (_M_rep()->_M_is_leaked())

        _M_rep()->_M_set_sharable();

      if (__s._M_rep()->_M_is_leaked())

        __s._M_rep()->_M_set_sharable();

      if (this->get_allocator() == __s.get_allocator())

        {

          _CharT* __tmp = _M_data();

          _M_data(__s._M_data());

          __s._M_data(__tmp);

        }

      // The code below can usually be optimized away.

      else

        {

          const basic_string __tmp1(_M_ibegin(), _M_iend(),

                                    __s.get_allocator());

          const basic_string __tmp2(__s._M_ibegin(), __s._M_iend(),

                                    this->get_allocator());

          *this = __tmp2;

          __s = __tmp1;

        }

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::_Rep*

    basic_string<_CharT, _Traits, _Alloc>::_Rep::

    _S_create(size_type __capacity, size_type __old_capacity,

              const _Alloc& __alloc)

    {

      // _GLIBCXX_RESOLVE_LIB_DEFECTS

      // 83.  String::npos vs. string::max_size()

      if (__capacity > _S_max_size)

        __throw_length_error(__N("basic_string::_S_create"));

      // The standard places no restriction on allocating more memory

      // than is strictly needed within this layer at the moment or as

      // requested by an explicit application call to reserve().

      // Many malloc implementations perform quite poorly when an

      // application attempts to allocate memory in a stepwise fashion

      // growing each allocation size by only 1 char.  Additionally,

      // it makes little sense to allocate less linear memory than the

      // natural blocking size of the malloc implementation.

      // Unfortunately, we would need a somewhat low-level calculation

      // with tuned parameters to get this perfect for any particular

      // malloc implementation.  Fortunately, generalizations about

      // common features seen among implementations seems to suffice.

      // __pagesize need not match the actual VM page size for good

      // results in practice, thus we pick a common value on the low

      // side.  __malloc_header_size is an estimate of the amount of

      // overhead per memory allocation (in practice seen N * sizeof

      // (void*) where N is 0, 2 or 4).  According to folklore,

      // picking this value on the high side is better than

      // low-balling it (especially when this algorithm is used with

      // malloc implementations that allocate memory blocks rounded up

      // to a size which is a power of 2).

      const size_type __pagesize = 4096;

      const size_type __malloc_header_size = 4 * sizeof(void*);

      // The below implements an exponential growth policy, necessary to

      // meet amortized linear time requirements of the library: see

      // http://gcc.gnu.org/ml/libstdc++/2001-07/msg00085.html.

      // It's active for allocations requiring an amount of memory above

      // system pagesize. This is consistent with the requirements of the

      // standard: http://gcc.gnu.org/ml/libstdc++/2001-07/msg00130.html

      if (__capacity > __old_capacity && __capacity < 2 * __old_capacity)

        __capacity = 2 * __old_capacity;

      // NB: Need an array of char_type[__capacity], plus a terminating

      // null char_type() element, plus enough for the _Rep data structure.

      // Whew. Seemingly so needy, yet so elemental.

      size_type __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);

      const size_type __adj_size = __size + __malloc_header_size;

      if (__adj_size > __pagesize && __capacity > __old_capacity)

        {

          const size_type __extra = __pagesize - __adj_size % __pagesize;

          __capacity += __extra / sizeof(_CharT);

          // Never allocate a string bigger than _S_max_size.

          if (__capacity > _S_max_size)

            __capacity = _S_max_size;

          __size = (__capacity + 1) * sizeof(_CharT) + sizeof(_Rep);

        }

      // NB: Might throw, but no worries about a leak, mate: _Rep()

      // does not throw.

      void* __place = _Raw_bytes_alloc(__alloc).allocate(__size);

      _Rep *__p = new (__place) _Rep;

      __p->_M_capacity = __capacity;

      // ABI compatibility - 3.4.x set in _S_create both

      // _M_refcount and _M_length.  All callers of _S_create

      // in basic_string.tcc then set just _M_length.

      // In 4.0.x and later both _M_refcount and _M_length

      // are initialized in the callers, unfortunately we can

      // have 3.4.x compiled code with _S_create callers inlined

      // calling 4.0.x+ _S_create.

      __p->_M_set_sharable();

      return __p;

    }

  template

    _CharT*

    basic_string<_CharT, _Traits, _Alloc>::_Rep::

    _M_clone(const _Alloc& __alloc, size_type __res)

    {

      // Requested capacity of the clone.

      const size_type __requested_cap = this->_M_length + __res;

      _Rep* __r = _Rep::_S_create(__requested_cap, this->_M_capacity,

                                  __alloc);

      if (this->_M_length)

        _M_copy(__r->_M_refdata(), _M_refdata(), this->_M_length);

      __r->_M_set_length_and_sharable(this->_M_length);

      return __r->_M_refdata();

    }

  template

    void

    basic_string<_CharT, _Traits, _Alloc>::

    resize(size_type __n, _CharT __c)

    {

      const size_type __size = this->size();

      _M_check_length(__size, __n, "basic_string::resize");

      if (__size < __n)

        this->append(__n - __size, __c);

      else if (__n < __size)

        this->erase(__n);

      // else nothing (in particular, avoid calling _M_mutate() unnecessarily.)

    }

  template

    template

      basic_string<_CharT, _Traits, _Alloc>&

      basic_string<_CharT, _Traits, _Alloc>::

      _M_replace_dispatch(iterator __i1, iterator __i2, _InputIterator __k1,

                          _InputIterator __k2, __false_type)

      {

        const basic_string __s(__k1, __k2);

        const size_type __n1 = __i2 - __i1;

        _M_check_length(__n1, __s.size(), "basic_string::_M_replace_dispatch");

        return _M_replace_safe(__i1 - _M_ibegin(), __n1, __s._M_data(),

                               __s.size());

      }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    _M_replace_aux(size_type __pos1, size_type __n1, size_type __n2,

                   _CharT __c)

    {

      _M_check_length(__n1, __n2, "basic_string::_M_replace_aux");

      _M_mutate(__pos1, __n1, __n2);

      if (__n2)

        _M_assign(_M_data() + __pos1, __n2, __c);

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>&

    basic_string<_CharT, _Traits, _Alloc>::

    _M_replace_safe(size_type __pos1, size_type __n1, const _CharT* __s,

                    size_type __n2)

    {

      _M_mutate(__pos1, __n1, __n2);

      if (__n2)

        _M_copy(_M_data() + __pos1, __s, __n2);

      return *this;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>

    operator+(const _CharT* __lhs,

              const basic_string<_CharT, _Traits, _Alloc>& __rhs)

    {

      __glibcxx_requires_string(__lhs);

      typedef basic_string<_CharT, _Traits, _Alloc> __string_type;

      typedef typename __string_type::size_type   __size_type;

      const __size_type __len = _Traits::length(__lhs);

      __string_type __str;

      __str.reserve(__len + __rhs.size());

      __str.append(__lhs, __len);

      __str.append(__rhs);

      return __str;

    }

  template

    basic_string<_CharT, _Traits, _Alloc>

    operator+(_CharT __lhs, const basic_string<_CharT, _Traits, _Alloc>& __rhs)

    {

      typedef basic_string<_CharT, _Traits, _Alloc> __string_type;

      typedef typename __string_type::size_type   __size_type;

      __string_type __str;

      const __size_type __len = __rhs.size();

      __str.reserve(__len + 1);

      __str.append(__size_type(1), __lhs);

      __str.append(__rhs);

      return __str;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    copy(_CharT* __s, size_type __n, size_type __pos) const

    {

      _M_check(__pos, "basic_string::copy");

      __n = _M_limit(__pos, __n);

      __glibcxx_requires_string_len(__s, __n);

      if (__n)

        _M_copy(__s, _M_data() + __pos, __n);

      // 21.3.5.7 par 3: do not append null.  (good.)

      return __n;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      const size_type __size = this->size();

      const _CharT* __data = _M_data();

      if (__n == 0)

        return __pos <= __size ? __pos : npos;

      if (__n <= __size)

        {

          for (; __pos <= __size - __n; ++__pos)

            if (traits_type::eq(__data[__pos], __s[0])

                && traits_type::compare(__data + __pos + 1,

                                        __s + 1, __n - 1) == 0)

              return __pos;

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT

    {

      size_type __ret = npos;

      const size_type __size = this->size();

      if (__pos < __size)

        {

          const _CharT* __data = _M_data();

          const size_type __n = __size - __pos;

          const _CharT* __p = traits_type::find(__data + __pos, __n, __c);

          if (__p)

            __ret = __p - __data;

        }

      return __ret;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    rfind(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      const size_type __size = this->size();

      if (__n <= __size)

        {

          __pos = std::min(size_type(__size - __n), __pos);

          const _CharT* __data = _M_data();

          do

            {

              if (traits_type::compare(__data + __pos, __s, __n) == 0)

                return __pos;

            }

          while (__pos-- > 0);

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    rfind(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT

    {

      size_type __size = this->size();

      if (__size)

        {

          if (--__size > __pos)

            __size = __pos;

          for (++__size; __size-- > 0; )

            if (traits_type::eq(_M_data()[__size], __c))

              return __size;

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_first_of(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      for (; __n && __pos < this->size(); ++__pos)

        {

          const _CharT* __p = traits_type::find(__s, __n, _M_data()[__pos]);

          if (__p)

            return __pos;

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_last_of(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      size_type __size = this->size();

      if (__size && __n)

        {

          if (--__size > __pos)

            __size = __pos;

          do

            {

              if (traits_type::find(__s, __n, _M_data()[__size]))

                return __size;

            }

          while (__size-- != 0);

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_first_not_of(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      for (; __pos < this->size(); ++__pos)

        if (!traits_type::find(__s, __n, _M_data()[__pos]))

          return __pos;

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_first_not_of(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT

    {

      for (; __pos < this->size(); ++__pos)

        if (!traits_type::eq(_M_data()[__pos], __c))

          return __pos;

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_last_not_of(const _CharT* __s, size_type __pos, size_type __n) const

    {

      __glibcxx_requires_string_len(__s, __n);

      size_type __size = this->size();

      if (__size)

        {

          if (--__size > __pos)

            __size = __pos;

          do

            {

              if (!traits_type::find(__s, __n, _M_data()[__size]))

                return __size;

            }

          while (__size--);

        }

      return npos;

    }

  template

    typename basic_string<_CharT, _Traits, _Alloc>::size_type

    basic_string<_CharT, _Traits, _Alloc>::

    find_last_not_of(_CharT __c, size_type __pos) const _GLIBCXX_NOEXCEPT

    {

      size_type __size = this->size();

      if (__size)

        {

          if (--__size > __pos)

            __size = __pos;

          do

            {

              if (!traits_type::eq(_M_data()[__size], __c))

                return __size;

            }

          while (__size--);

        }

      return npos;

    }

  template

    int

    basic_string<_CharT, _Traits, _Alloc>::

    compare(size_type __pos, size_type __n, const basic_string& __str) const

    {

      _M_check(__pos, "basic_string::compare");

      __n = _M_limit(__pos, __n);

      const size_type __osize = __str.size();

      const size_type __len = std::min(__n, __osize);

      int __r = traits_type::compare(_M_data() + __pos, __str.data(), __len);

      if (!__r)

        __r = _S_compare(__n, __osize);

      return __r;

    }

  template

    int