// Stream buffer classes -*- C++ -*-

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

// 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 2, 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.

// You should have received a copy of the GNU General Public License along

// with this library; see the file COPYING.  If not, write to the Free

// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,

// USA.

// As a special exception, you may use this file as part of a free software

// library without restriction.  Specifically, if other files instantiate

// templates or use macros or inline functions from this file, or you compile

// this file and link it with other files to produce an executable, this

// file does not by itself cause the resulting executable to be covered by

// the GNU General Public License.  This exception does not however

// invalidate any other reasons why the executable file might be covered by

// the GNU General Public License.

//

// ISO C++ 14882: 27.5  Stream buffers

//

/** @file streambuf

 *  This is a Standard C++ Library header.  You should @c #include this header

 *  in your programs, rather than any of the "st[dl]_*.h" implementation files.

 */

#ifndef _CLIBXX_STREAMBUF

#define _CLIBXX_STREAMBUF 1

#pragma GCC system_header

#include <bits/c++config.h>

#include <iosfwd>

#include <bits/localefwd.h>

#include <bits/ios_base.h>

namespace std

{

  /**

   *  @if maint

   *  Does stuff.

   *  @endif

  */

  template<typename _CharT, typename _Traits>

    streamsize

    __copy_streambufs(basic_streambuf<_CharT, _Traits>* __sbin,

		      basic_streambuf<_CharT, _Traits>* __sbout);

  /**

   *  @brief  The actual work of input and output (interface).

   *

   *  This is a base class.  Derived stream buffers each control a

   *  pair of character sequences:  one for input, and one for output.

   *

   *  Section [27.5.1] of the standard describes the requirements and

   *  behavior of stream buffer classes.  That section (three paragraphs)

   *  is reproduced here, for simplicity and accuracy.

   *

   *  -# Stream buffers can impose various constraints on the sequences

   *     they control.  Some constraints are:

   *     - The controlled input sequence can be not readable.

   *     - The controlled output sequence can be not writable.

   *     - The controlled sequences can be associated with the contents of

   *       other representations for character sequences, such as external

   *       files.

   *     - The controlled sequences can support operations @e directly to or

   *       from associated sequences.

   *     - The controlled sequences can impose limitations on how the

   *       program can read characters from a sequence, write characters to

   *       a sequence, put characters back into an input sequence, or alter

   *       the stream position.

   *     .

   *  -# Each sequence is characterized by three pointers which, if non-null,

   *     all point into the same @c charT array object.  The array object

   *     represents, at any moment, a (sub)sequence of characters from the

   *     sequence.  Operations performed on a sequence alter the values

   *     stored in these pointers, perform reads and writes directly to or

   *     from associated sequences, and alter "the stream position" and

   *     conversion state as needed to maintain this subsequence relationship.

   *     The three pointers are:

   *     - the <em>beginning pointer</em>, or lowest element address in the

   *       array (called @e xbeg here);

   *     - the <em>next pointer</em>, or next element address that is a

   *       current candidate for reading or writing (called @e xnext here);

   *     - the <em>end pointer</em>, or first element address beyond the

   *       end of the array (called @e xend here).

   *     .

   *  -# The following semantic constraints shall always apply for any set

   *     of three pointers for a sequence, using the pointer names given

   *     immediately above:

   *     - If @e xnext is not a null pointer, then @e xbeg and @e xend shall

   *       also be non-null pointers into the same @c charT array, as

   *       described above; otherwise, @e xbeg and @e xend shall also be null.

   *     - If @e xnext is not a null pointer and @e xnext < @e xend for an

   *       output sequence, then a <em>write position</em> is available.

   *       In this case, @e *xnext shall be assignable as the next element

   *       to write (to put, or to store a character value, into the sequence).

   *     - If @e xnext is not a null pointer and @e xbeg < @e xnext for an

   *       input sequence, then a <em>putback position</em> is available.

   *       In this case, @e xnext[-1] shall have a defined value and is the

   *       next (preceding) element to store a character that is put back

   *       into the input sequence.

   *     - If @e xnext is not a null pointer and @e xnext< @e xend for an

   *       input sequence, then a <em>read position</em> is available.

   *       In this case, @e *xnext shall have a defined value and is the

   *       next element to read (to get, or to obtain a character value,

   *       from the sequence).

  */

  template<typename _CharT, typename _Traits>

    class basic_streambuf 

    {

    public:

      //@{

      /**

       *  These are standard types.  They permit a standardized way of

       *  referring to names of (or names dependant on) the template

       *  parameters, which are specific to the implementation.

      */

      typedef _CharT 					char_type;

      typedef _Traits 					traits_type;

      typedef typename traits_type::int_type 		int_type;

      typedef typename traits_type::pos_type 		pos_type;

      typedef typename traits_type::off_type 		off_type;

      //@}

      //@{

      /**

       *  @if maint

       *  This is a non-standard type.

       *  @endif

      */

      typedef basic_streambuf<char_type, traits_type>  	__streambuf_type;

      //@}

      friend class basic_ios<char_type, traits_type>;

      friend class basic_istream<char_type, traits_type>;

      friend class basic_ostream<char_type, traits_type>;

      friend class istreambuf_iterator<char_type, traits_type>;

      friend class ostreambuf_iterator<char_type, traits_type>;

      friend streamsize

      __copy_streambufs<>(__streambuf_type* __sbin,

			  __streambuf_type* __sbout);

    protected:

      //@{

      /**

       *  @if maint

       *  This is based on _IO_FILE, just reordered to be more consistent,

       *  and is intended to be the most minimal abstraction for an

       *  internal buffer.

       *  -  get == input == read

       *  -  put == output == write

       *  @endif

      */

      char_type* 		_M_in_beg;     // Start of get area. 

      char_type* 		_M_in_cur;     // Current read area. 

      char_type* 		_M_in_end;     // End of get area. 

      char_type* 		_M_out_beg;    // Start of put area. 

      char_type* 		_M_out_cur;    // Current put area. 

      char_type* 		_M_out_end;    // End of put area.

      /**

       *  @if maint

       *  Current locale setting.

       *  @endif

      */

      locale 			_M_buf_locale;	

  public:

      /// Destructor deallocates no buffer space.

      virtual 

      ~basic_streambuf() 

      { }

      // [27.5.2.2.1] locales

      /**

       *  @brief  Entry point for imbue().

       *  @param  loc  The new locale.

       *  @return  The previous locale.

       *

       *  Calls the derived imbue(loc).

      */

      locale 

      pubimbue(const locale &__loc)

      {

	locale __tmp(this->getloc());

	this->imbue(__loc);

	_M_buf_locale = __loc;

	return __tmp;

      }

      /**

       *  @brief  Locale access.

       *  @return  The current locale in effect.

       *

       *  If pubimbue(loc) has been called, then the most recent @c loc

       *  is returned.  Otherwise the global locale in effect at the time

       *  of construction is returned.

      */

      locale   

      getloc() const

      { return _M_buf_locale; } 

      // [27.5.2.2.2] buffer management and positioning

      //@{

      /**

       *  @brief  Entry points for derived buffer functions.

       *

       *  The public versions of @c pubfoo dispatch to the protected

       *  derived @c foo member functions, passing the arguments (if any)

       *  and returning the result unchanged.

      */

      __streambuf_type* 

      pubsetbuf(char_type* __s, streamsize __n) 

      { return this->setbuf(__s, __n); }

      pos_type 

      pubseekoff(off_type __off, ios_base::seekdir __way, 

		 ios_base::openmode __mode = ios_base::in | ios_base::out)

      { return this->seekoff(__off, __way, __mode); }

      pos_type 

      pubseekpos(pos_type __sp,

		 ios_base::openmode __mode = ios_base::in | ios_base::out)

      { return this->seekpos(__sp, __mode); }

      int 

      pubsync() { return this->sync(); }

      //@}

      // [27.5.2.2.3] get area

      /**

       *  @brief  Looking ahead into the stream.

       *  @return  The number of characters available.

       *

       *  If a read position is available, returns the number of characters

       *  available for reading before the buffer must be refilled.

       *  Otherwise returns the derived @c showmanyc().

      */

      streamsize 

      in_avail() 

      { 

	const streamsize __ret = this->egptr() - this->gptr();

	return __ret ? __ret : this->showmanyc();

      }

      /**

       *  @brief  Getting the next character.

       *  @return  The next character, or eof.

       *

       *  Calls @c sbumpc(), and if that function returns

       *  @c traits::eof(), so does this function.  Otherwise, @c sgetc().

      */

      int_type 

      snextc()

      {

	int_type __ret = traits_type::eof();

	if (__builtin_expect(!traits_type::eq_int_type(this->sbumpc(), 

						       __ret), true))

	  __ret = this->sgetc();

	return __ret;

      }

      /**

       *  @brief  Getting the next character.

       *  @return  The next character, or eof.

       *

       *  If the input read position is available, returns that character

       *  and increments the read pointer, otherwise calls and returns

       *  @c uflow().

      */

      int_type 

      sbumpc()

      {

	int_type __ret;

	if (__builtin_expect(this->gptr() < this->egptr(), true))

	  {

	    __ret = traits_type::to_int_type(*this->gptr());

	    this->gbump(1);

	  }

	else 

	  __ret = this->uflow();

	return __ret;

      }

      /**

       *  @brief  Getting the next character.

       *  @return  The next character, or eof.

       *

       *  If the input read position is available, returns that character,

       *  otherwise calls and returns @c underflow().  Does not move the 

       *  read position after fetching the character.

      */

      int_type 

      sgetc()

      {

	int_type __ret;

	if (__builtin_expect(this->gptr() < this->egptr(), true))

	  __ret = traits_type::to_int_type(*this->gptr());

	else 

	  __ret = this->underflow();

	return __ret;

      }

      /**

       *  @brief  Entry point for xsgetn.

       *  @param  s  A buffer area.

       *  @param  n  A count.

       *

       *  Returns xsgetn(s,n).  The effect is to fill @a s[0] through

       *  @a s[n-1] with characters from the input sequence, if possible.

      */

      streamsize 

      sgetn(char_type* __s, streamsize __n)

      { return this->xsgetn(__s, __n); }

      // [27.5.2.2.4] putback

      /**

       *  @brief  Pushing characters back into the input stream.

       *  @param  c  The character to push back.

       *  @return  The previous character, if possible.

       *

       *  Similar to sungetc(), but @a c is pushed onto the stream instead

       *  of "the previous character".  If successful, the next character

       *  fetched from the input stream will be @a c.

      */

      int_type 

      sputbackc(char_type __c)

      {

	int_type __ret;

	const bool __testpos = this->eback() < this->gptr();

	if (__builtin_expect(!__testpos || 

			     !traits_type::eq(__c, this->gptr()[-1]), false))

	  __ret = this->pbackfail(traits_type::to_int_type(__c));

	else 

	  {

	    this->gbump(-1);

	    __ret = traits_type::to_int_type(*this->gptr());

	  }

	return __ret;

      }

      /**

       *  @brief  Moving backwards in the input stream.

       *  @return  The previous character, if possible.

       *

       *  If a putback position is available, this function decrements the

       *  input pointer and returns that character.  Otherwise, calls and

       *  returns pbackfail().  The effect is to "unget" the last character

       *  "gotten".

      */

      int_type 

      sungetc()

      {

	int_type __ret;

	if (__builtin_expect(this->eback() < this->gptr(), true))

	  {

	    this->gbump(-1);

	    __ret = traits_type::to_int_type(*this->gptr());

	  }

	else 

	  __ret = this->pbackfail();

	return __ret;

      }

      // [27.5.2.2.5] put area

      /**

       *  @brief  Entry point for all single-character output functions.

       *  @param  c  A character to output.

       *  @return  @a c, if possible.

       *

       *  One of two public output functions.

       *

       *  If a write position is available for the output sequence (i.e.,

       *  the buffer is not full), stores @a c in that position, increments

       *  the position, and returns @c traits::to_int_type(c).  If a write

       *  position is not available, returns @c overflow(c).

      */

      int_type 

      sputc(char_type __c)

      {

	int_type __ret;

	if (__builtin_expect(this->pptr() < this->epptr(), true))

	  {

	    *this->pptr() = __c;

	    this->pbump(1);

	    __ret = traits_type::to_int_type(__c);

	  }

	else

	  __ret = this->overflow(traits_type::to_int_type(__c));

	return __ret;

      }

      /**

       *  @brief  Entry point for all single-character output functions.

       *  @param  s  A buffer read area.

       *  @param  n  A count.

       *

       *  One of two public output functions.

       *

       *

       *  Returns xsputn(s,n).  The effect is to write @a s[0] through

       *  @a s[n-1] to the output sequence, if possible.

      */

      streamsize 

      sputn(const char_type* __s, streamsize __n)

      { return this->xsputn(__s, __n); }

    protected:

      /**

       *  @brief  Base constructor.

       *

       *  Only called from derived constructors, and sets up all the

       *  buffer data to zero, including the pointers described in the

       *  basic_streambuf class description.  Note that, as a result,

       *  - the class starts with no read nor write positions available,

       *  - this is not an error

      */

      basic_streambuf()

      : _M_in_beg(0), _M_in_cur(0), _M_in_end(0), 

      _M_out_beg(0), _M_out_cur(0), _M_out_end(0),

      _M_buf_locale(locale()) 

      { }

      // [27.5.2.3.1] get area access

      //@{

      /**

       *  @brief  Access to the get area.

       *

       *  These functions are only available to other protected functions,

       *  including derived classes.

       *

       *  - eback() returns the beginning pointer for the input sequence

       *  - gptr() returns the next pointer for the input sequence

       *  - egptr() returns the end pointer for the input sequence

      */

      char_type* 

      eback() const { return _M_in_beg; }

      char_type* 

      gptr()  const { return _M_in_cur;  }

      char_type* 

      egptr() const { return _M_in_end; }

      //@}

      /**

       *  @brief  Moving the read position.

       *  @param  n  The delta by which to move.

       *

       *  This just advances the read position without returning any data.

      */

      void 

      gbump(int __n) { _M_in_cur += __n; }

      /**

       *  @brief  Setting the three read area pointers.

       *  @param  gbeg  A pointer.

       *  @param  gnext  A pointer.

       *  @param  gend  A pointer.

       *  @post  @a gbeg == @c eback(), @a gnext == @c gptr(), and

       *         @a gend == @c egptr()

      */

      void 

      setg(char_type* __gbeg, char_type* __gnext, char_type* __gend)

      {

	_M_in_beg = __gbeg;

	_M_in_cur = __gnext;

	_M_in_end = __gend;

      }

      // [27.5.2.3.2] put area access

      //@{

      /**

       *  @brief  Access to the put area.

       *

       *  These functions are only available to other protected functions,

       *  including derived classes.

       *

       *  - pbase() returns the beginning pointer for the output sequence

       *  - pptr() returns the next pointer for the output sequence

       *  - epptr() returns the end pointer for the output sequence

      */

      char_type* 

      pbase() const { return _M_out_beg; }

      char_type* 

      pptr() const { return _M_out_cur; }

      char_type* 

      epptr() const { return _M_out_end; }

      //@}

      /**

       *  @brief  Moving the write position.

       *  @param  n  The delta by which to move.

       *

       *  This just advances the write position without returning any data.

      */

      void 

      pbump(int __n) { _M_out_cur += __n; }

      /**

       *  @brief  Setting the three write area pointers.

       *  @param  pbeg  A pointer.

       *  @param  pend  A pointer.

       *  @post  @a pbeg == @c pbase(), @a pbeg == @c pptr(), and

       *         @a pend == @c epptr()

      */

      void 

      setp(char_type* __pbeg, char_type* __pend)

      { 

	_M_out_beg = _M_out_cur = __pbeg; 

	_M_out_end = __pend;