libstdc++
sstream
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00001 // String based streams -*- C++ -*-
00002 
00003 // Copyright (C) 1997-2013 Free Software Foundation, Inc.
00004 //
00005 // This file is part of the GNU ISO C++ Library.  This library is free
00006 // software; you can redistribute it and/or modify it under the
00007 // terms of the GNU General Public License as published by the
00008 // Free Software Foundation; either version 3, or (at your option)
00009 // any later version.
00010 
00011 // This library is distributed in the hope that it will be useful,
00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00014 // GNU General Public License for more details.
00015 
00016 // Under Section 7 of GPL version 3, you are granted additional
00017 // permissions described in the GCC Runtime Library Exception, version
00018 // 3.1, as published by the Free Software Foundation.
00019 
00020 // You should have received a copy of the GNU General Public License and
00021 // a copy of the GCC Runtime Library Exception along with this program;
00022 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
00023 // <http://www.gnu.org/licenses/>.
00024 
00025 /** @file include/sstream
00026  *  This is a Standard C++ Library header.
00027  */
00028 
00029 //
00030 // ISO C++ 14882: 27.7  String-based streams
00031 //
00032 
00033 #ifndef _GLIBCXX_SSTREAM
00034 #define _GLIBCXX_SSTREAM 1
00035 
00036 #pragma GCC system_header
00037 
00038 #include <istream>
00039 #include <ostream>
00040 
00041 namespace std _GLIBCXX_VISIBILITY(default)
00042 {
00043 _GLIBCXX_BEGIN_NAMESPACE_VERSION
00044 
00045   // [27.7.1] template class basic_stringbuf
00046   /**
00047    *  @brief  The actual work of input and output (for std::string).
00048    *  @ingroup io
00049    *
00050    *  @tparam _CharT  Type of character stream.
00051    *  @tparam _Traits  Traits for character type, defaults to
00052    *                   char_traits<_CharT>.
00053    *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
00054    *
00055    *  This class associates either or both of its input and output sequences
00056    *  with a sequence of characters, which can be initialized from, or made
00057    *  available as, a @c std::basic_string.  (Paraphrased from [27.7.1]/1.)
00058    *
00059    *  For this class, open modes (of type @c ios_base::openmode) have
00060    *  @c in set if the input sequence can be read, and @c out set if the
00061    *  output sequence can be written.
00062   */
00063   template<typename _CharT, typename _Traits, typename _Alloc>
00064     class basic_stringbuf : public basic_streambuf<_CharT, _Traits>
00065     {
00066     public:
00067       // Types:
00068       typedef _CharT                    char_type;
00069       typedef _Traits                   traits_type;
00070       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00071       // 251. basic_stringbuf missing allocator_type
00072       typedef _Alloc                        allocator_type;
00073       typedef typename traits_type::int_type        int_type;
00074       typedef typename traits_type::pos_type        pos_type;
00075       typedef typename traits_type::off_type        off_type;
00076 
00077       typedef basic_streambuf<char_type, traits_type>   __streambuf_type;
00078       typedef basic_string<char_type, _Traits, _Alloc>  __string_type;
00079       typedef typename __string_type::size_type     __size_type;
00080 
00081     protected:
00082       /// Place to stash in || out || in | out settings for current stringbuf.
00083       ios_base::openmode    _M_mode;
00084 
00085       // Data Members:
00086       __string_type         _M_string;
00087 
00088     public:
00089       // Constructors:
00090       /**
00091        *  @brief  Starts with an empty string buffer.
00092        *  @param  __mode  Whether the buffer can read, or write, or both.
00093        *
00094        *  The default constructor initializes the parent class using its
00095        *  own default ctor.
00096       */
00097       explicit
00098       basic_stringbuf(ios_base::openmode __mode = ios_base::in | ios_base::out)
00099       : __streambuf_type(), _M_mode(__mode), _M_string()
00100       { }
00101 
00102       /**
00103        *  @brief  Starts with an existing string buffer.
00104        *  @param  __str  A string to copy as a starting buffer.
00105        *  @param  __mode  Whether the buffer can read, or write, or both.
00106        *
00107        *  This constructor initializes the parent class using its
00108        *  own default ctor.
00109       */
00110       explicit
00111       basic_stringbuf(const __string_type& __str,
00112               ios_base::openmode __mode = ios_base::in | ios_base::out)
00113       : __streambuf_type(), _M_mode(), _M_string(__str.data(), __str.size())
00114       { _M_stringbuf_init(__mode); }
00115 
00116       // Get and set:
00117       /**
00118        *  @brief  Copying out the string buffer.
00119        *  @return  A copy of one of the underlying sequences.
00120        *
00121        *  <em>If the buffer is only created in input mode, the underlying
00122        *  character sequence is equal to the input sequence; otherwise, it
00123        *  is equal to the output sequence.</em> [27.7.1.2]/1
00124       */
00125       __string_type
00126       str() const
00127       {
00128     __string_type __ret;
00129     if (this->pptr())
00130       {
00131         // The current egptr() may not be the actual string end.
00132         if (this->pptr() > this->egptr())
00133           __ret = __string_type(this->pbase(), this->pptr());
00134         else
00135           __ret = __string_type(this->pbase(), this->egptr());
00136       }
00137     else
00138       __ret = _M_string;
00139     return __ret;
00140       }
00141 
00142       /**
00143        *  @brief  Setting a new buffer.
00144        *  @param  __s  The string to use as a new sequence.
00145        *
00146        *  Deallocates any previous stored sequence, then copies @a s to
00147        *  use as a new one.
00148       */
00149       void
00150       str(const __string_type& __s)
00151       {
00152     // Cannot use _M_string = __s, since v3 strings are COW.
00153     _M_string.assign(__s.data(), __s.size());
00154     _M_stringbuf_init(_M_mode);
00155       }
00156 
00157     protected:
00158       // Common initialization code goes here.
00159       void
00160       _M_stringbuf_init(ios_base::openmode __mode)
00161       {
00162     _M_mode = __mode;
00163     __size_type __len = 0;
00164     if (_M_mode & (ios_base::ate | ios_base::app))
00165       __len = _M_string.size();
00166     _M_sync(const_cast<char_type*>(_M_string.data()), 0, __len);
00167       }
00168 
00169       virtual streamsize
00170       showmanyc()
00171       { 
00172     streamsize __ret = -1;
00173     if (_M_mode & ios_base::in)
00174       {
00175         _M_update_egptr();
00176         __ret = this->egptr() - this->gptr();
00177       }
00178     return __ret;
00179       }
00180 
00181       virtual int_type
00182       underflow();
00183 
00184       virtual int_type
00185       pbackfail(int_type __c = traits_type::eof());
00186 
00187       virtual int_type
00188       overflow(int_type __c = traits_type::eof());
00189 
00190       /**
00191        *  @brief  Manipulates the buffer.
00192        *  @param  __s  Pointer to a buffer area.
00193        *  @param  __n  Size of @a __s.
00194        *  @return  @c this
00195        *
00196        *  If no buffer has already been created, and both @a __s and @a __n are
00197        *  non-zero, then @c __s is used as a buffer; see
00198        *  http://gcc.gnu.org/onlinedocs/libstdc++/manual/bk01pt11ch25s02.html
00199        *  for more.
00200       */
00201       virtual __streambuf_type*
00202       setbuf(char_type* __s, streamsize __n)
00203       {
00204     if (__s && __n >= 0)
00205       {
00206         // This is implementation-defined behavior, and assumes
00207         // that an external char_type array of length __n exists
00208         // and has been pre-allocated. If this is not the case,
00209         // things will quickly blow up.
00210         
00211         // Step 1: Destroy the current internal array.
00212         _M_string.clear();
00213         
00214         // Step 2: Use the external array.
00215         _M_sync(__s, __n, 0);
00216       }
00217     return this;
00218       }
00219 
00220       virtual pos_type
00221       seekoff(off_type __off, ios_base::seekdir __way,
00222           ios_base::openmode __mode = ios_base::in | ios_base::out);
00223 
00224       virtual pos_type
00225       seekpos(pos_type __sp,
00226           ios_base::openmode __mode = ios_base::in | ios_base::out);
00227 
00228       // Internal function for correctly updating the internal buffer
00229       // for a particular _M_string, due to initialization or re-sizing
00230       // of an existing _M_string.
00231       void
00232       _M_sync(char_type* __base, __size_type __i, __size_type __o);
00233 
00234       // Internal function for correctly updating egptr() to the actual
00235       // string end.
00236       void
00237       _M_update_egptr()
00238       {
00239     const bool __testin = _M_mode & ios_base::in;
00240     if (this->pptr() && this->pptr() > this->egptr())
00241       {
00242         if (__testin)
00243           this->setg(this->eback(), this->gptr(), this->pptr());
00244         else
00245           this->setg(this->pptr(), this->pptr(), this->pptr());
00246       }
00247       }
00248 
00249       // Works around the issue with pbump, part of the protected
00250       // interface of basic_streambuf, taking just an int.
00251       void
00252       _M_pbump(char_type* __pbeg, char_type* __pend, off_type __off);
00253     };
00254 
00255 
00256   // [27.7.2] Template class basic_istringstream
00257   /**
00258    *  @brief  Controlling input for std::string.
00259    *  @ingroup io
00260    *
00261    *  @tparam _CharT  Type of character stream.
00262    *  @tparam _Traits  Traits for character type, defaults to
00263    *                   char_traits<_CharT>.
00264    *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
00265    *
00266    *  This class supports reading from objects of type std::basic_string,
00267    *  using the inherited functions from std::basic_istream.  To control
00268    *  the associated sequence, an instance of std::basic_stringbuf is used,
00269    *  which this page refers to as @c sb.
00270   */
00271   template<typename _CharT, typename _Traits, typename _Alloc>
00272     class basic_istringstream : public basic_istream<_CharT, _Traits>
00273     {
00274     public:
00275       // Types:
00276       typedef _CharT                    char_type;
00277       typedef _Traits                   traits_type;
00278       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00279       // 251. basic_stringbuf missing allocator_type
00280       typedef _Alloc                        allocator_type;
00281       typedef typename traits_type::int_type        int_type;
00282       typedef typename traits_type::pos_type        pos_type;
00283       typedef typename traits_type::off_type        off_type;
00284 
00285       // Non-standard types:
00286       typedef basic_string<_CharT, _Traits, _Alloc>     __string_type;
00287       typedef basic_stringbuf<_CharT, _Traits, _Alloc>  __stringbuf_type;
00288       typedef basic_istream<char_type, traits_type> __istream_type;
00289 
00290     private:
00291       __stringbuf_type  _M_stringbuf;
00292 
00293     public:
00294       // Constructors:
00295       /**
00296        *  @brief  Default constructor starts with an empty string buffer.
00297        *  @param  __mode  Whether the buffer can read, or write, or both.
00298        *
00299        *  @c ios_base::in is automatically included in @a __mode.
00300        *
00301        *  Initializes @c sb using @c __mode|in, and passes @c &sb to the base
00302        *  class initializer.  Does not allocate any buffer.
00303        *
00304        *  That's a lie.  We initialize the base class with NULL, because the
00305        *  string class does its own memory management.
00306       */
00307       explicit
00308       basic_istringstream(ios_base::openmode __mode = ios_base::in)
00309       : __istream_type(), _M_stringbuf(__mode | ios_base::in)
00310       { this->init(&_M_stringbuf); }
00311 
00312       /**
00313        *  @brief  Starts with an existing string buffer.
00314        *  @param  __str  A string to copy as a starting buffer.
00315        *  @param  __mode  Whether the buffer can read, or write, or both.
00316        *
00317        *  @c ios_base::in is automatically included in @a mode.
00318        *
00319        *  Initializes @c sb using @a str and @c mode|in, and passes @c &sb
00320        *  to the base class initializer.
00321        *
00322        *  That's a lie.  We initialize the base class with NULL, because the
00323        *  string class does its own memory management.
00324       */
00325       explicit
00326       basic_istringstream(const __string_type& __str,
00327               ios_base::openmode __mode = ios_base::in)
00328       : __istream_type(), _M_stringbuf(__str, __mode | ios_base::in)
00329       { this->init(&_M_stringbuf); }
00330 
00331       /**
00332        *  @brief  The destructor does nothing.
00333        *
00334        *  The buffer is deallocated by the stringbuf object, not the
00335        *  formatting stream.
00336       */
00337       ~basic_istringstream()
00338       { }
00339 
00340       // Members:
00341       /**
00342        *  @brief  Accessing the underlying buffer.
00343        *  @return  The current basic_stringbuf buffer.
00344        *
00345        *  This hides both signatures of std::basic_ios::rdbuf().
00346       */
00347       __stringbuf_type*
00348       rdbuf() const
00349       { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
00350 
00351       /**
00352        *  @brief  Copying out the string buffer.
00353        *  @return  @c rdbuf()->str()
00354       */
00355       __string_type
00356       str() const
00357       { return _M_stringbuf.str(); }
00358 
00359       /**
00360        *  @brief  Setting a new buffer.
00361        *  @param  __s  The string to use as a new sequence.
00362        *
00363        *  Calls @c rdbuf()->str(s).
00364       */
00365       void
00366       str(const __string_type& __s)
00367       { _M_stringbuf.str(__s); }
00368     };
00369 
00370 
00371   // [27.7.3] Template class basic_ostringstream
00372   /**
00373    *  @brief  Controlling output for std::string.
00374    *  @ingroup io
00375    *
00376    *  @tparam _CharT  Type of character stream.
00377    *  @tparam _Traits  Traits for character type, defaults to
00378    *                   char_traits<_CharT>.
00379    *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
00380    *
00381    *  This class supports writing to objects of type std::basic_string,
00382    *  using the inherited functions from std::basic_ostream.  To control
00383    *  the associated sequence, an instance of std::basic_stringbuf is used,
00384    *  which this page refers to as @c sb.
00385   */
00386   template <typename _CharT, typename _Traits, typename _Alloc>
00387     class basic_ostringstream : public basic_ostream<_CharT, _Traits>
00388     {
00389     public:
00390       // Types:
00391       typedef _CharT                    char_type;
00392       typedef _Traits                   traits_type;
00393       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00394       // 251. basic_stringbuf missing allocator_type
00395       typedef _Alloc                        allocator_type;
00396       typedef typename traits_type::int_type        int_type;
00397       typedef typename traits_type::pos_type        pos_type;
00398       typedef typename traits_type::off_type        off_type;
00399 
00400       // Non-standard types:
00401       typedef basic_string<_CharT, _Traits, _Alloc>     __string_type;
00402       typedef basic_stringbuf<_CharT, _Traits, _Alloc>  __stringbuf_type;
00403       typedef basic_ostream<char_type, traits_type> __ostream_type;
00404 
00405     private:
00406       __stringbuf_type  _M_stringbuf;
00407 
00408     public:
00409       // Constructors/destructor:
00410       /**
00411        *  @brief  Default constructor starts with an empty string buffer.
00412        *  @param  __mode  Whether the buffer can read, or write, or both.
00413        *
00414        *  @c ios_base::out is automatically included in @a mode.
00415        *
00416        *  Initializes @c sb using @c mode|out, and passes @c &sb to the base
00417        *  class initializer.  Does not allocate any buffer.
00418        *
00419        *  That's a lie.  We initialize the base class with NULL, because the
00420        *  string class does its own memory management.
00421       */
00422       explicit
00423       basic_ostringstream(ios_base::openmode __mode = ios_base::out)
00424       : __ostream_type(), _M_stringbuf(__mode | ios_base::out)
00425       { this->init(&_M_stringbuf); }
00426 
00427       /**
00428        *  @brief  Starts with an existing string buffer.
00429        *  @param  __str  A string to copy as a starting buffer.
00430        *  @param  __mode  Whether the buffer can read, or write, or both.
00431        *
00432        *  @c ios_base::out is automatically included in @a mode.
00433        *
00434        *  Initializes @c sb using @a str and @c mode|out, and passes @c &sb
00435        *  to the base class initializer.
00436        *
00437        *  That's a lie.  We initialize the base class with NULL, because the
00438        *  string class does its own memory management.
00439       */
00440       explicit
00441       basic_ostringstream(const __string_type& __str,
00442               ios_base::openmode __mode = ios_base::out)
00443       : __ostream_type(), _M_stringbuf(__str, __mode | ios_base::out)
00444       { this->init(&_M_stringbuf); }
00445 
00446       /**
00447        *  @brief  The destructor does nothing.
00448        *
00449        *  The buffer is deallocated by the stringbuf object, not the
00450        *  formatting stream.
00451       */
00452       ~basic_ostringstream()
00453       { }
00454 
00455       // Members:
00456       /**
00457        *  @brief  Accessing the underlying buffer.
00458        *  @return  The current basic_stringbuf buffer.
00459        *
00460        *  This hides both signatures of std::basic_ios::rdbuf().
00461       */
00462       __stringbuf_type*
00463       rdbuf() const
00464       { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
00465 
00466       /**
00467        *  @brief  Copying out the string buffer.
00468        *  @return  @c rdbuf()->str()
00469       */
00470       __string_type
00471       str() const
00472       { return _M_stringbuf.str(); }
00473 
00474       /**
00475        *  @brief  Setting a new buffer.
00476        *  @param  __s  The string to use as a new sequence.
00477        *
00478        *  Calls @c rdbuf()->str(s).
00479       */
00480       void
00481       str(const __string_type& __s)
00482       { _M_stringbuf.str(__s); }
00483     };
00484 
00485 
00486   // [27.7.4] Template class basic_stringstream
00487   /**
00488    *  @brief  Controlling input and output for std::string.
00489    *  @ingroup io
00490    *
00491    *  @tparam _CharT  Type of character stream.
00492    *  @tparam _Traits  Traits for character type, defaults to
00493    *                   char_traits<_CharT>.
00494    *  @tparam _Alloc  Allocator type, defaults to allocator<_CharT>.
00495    *
00496    *  This class supports reading from and writing to objects of type
00497    *  std::basic_string, using the inherited functions from
00498    *  std::basic_iostream.  To control the associated sequence, an instance
00499    *  of std::basic_stringbuf is used, which this page refers to as @c sb.
00500   */
00501   template <typename _CharT, typename _Traits, typename _Alloc>
00502     class basic_stringstream : public basic_iostream<_CharT, _Traits>
00503     {
00504     public:
00505       // Types:
00506       typedef _CharT                    char_type;
00507       typedef _Traits                   traits_type;
00508       // _GLIBCXX_RESOLVE_LIB_DEFECTS
00509       // 251. basic_stringbuf missing allocator_type
00510       typedef _Alloc                        allocator_type;
00511       typedef typename traits_type::int_type        int_type;
00512       typedef typename traits_type::pos_type        pos_type;
00513       typedef typename traits_type::off_type        off_type;
00514 
00515       // Non-standard Types:
00516       typedef basic_string<_CharT, _Traits, _Alloc>     __string_type;
00517       typedef basic_stringbuf<_CharT, _Traits, _Alloc>  __stringbuf_type;
00518       typedef basic_iostream<char_type, traits_type>    __iostream_type;
00519 
00520     private:
00521       __stringbuf_type  _M_stringbuf;
00522 
00523     public:
00524       // Constructors/destructors
00525       /**
00526        *  @brief  Default constructor starts with an empty string buffer.
00527        *  @param  __m  Whether the buffer can read, or write, or both.
00528        *
00529        *  Initializes @c sb using the mode from @c __m, and passes @c
00530        *  &sb to the base class initializer.  Does not allocate any
00531        *  buffer.
00532        *
00533        *  That's a lie.  We initialize the base class with NULL, because the
00534        *  string class does its own memory management.
00535       */
00536       explicit
00537       basic_stringstream(ios_base::openmode __m = ios_base::out | ios_base::in)
00538       : __iostream_type(), _M_stringbuf(__m)
00539       { this->init(&_M_stringbuf); }
00540 
00541       /**
00542        *  @brief  Starts with an existing string buffer.
00543        *  @param  __str  A string to copy as a starting buffer.
00544        *  @param  __m  Whether the buffer can read, or write, or both.
00545        *
00546        *  Initializes @c sb using @a __str and @c __m, and passes @c &sb
00547        *  to the base class initializer.
00548        *
00549        *  That's a lie.  We initialize the base class with NULL, because the
00550        *  string class does its own memory management.
00551       */
00552       explicit
00553       basic_stringstream(const __string_type& __str,
00554              ios_base::openmode __m = ios_base::out | ios_base::in)
00555       : __iostream_type(), _M_stringbuf(__str, __m)
00556       { this->init(&_M_stringbuf); }
00557 
00558       /**
00559        *  @brief  The destructor does nothing.
00560        *
00561        *  The buffer is deallocated by the stringbuf object, not the
00562        *  formatting stream.
00563       */
00564       ~basic_stringstream()
00565       { }
00566 
00567       // Members:
00568       /**
00569        *  @brief  Accessing the underlying buffer.
00570        *  @return  The current basic_stringbuf buffer.
00571        *
00572        *  This hides both signatures of std::basic_ios::rdbuf().
00573       */
00574       __stringbuf_type*
00575       rdbuf() const
00576       { return const_cast<__stringbuf_type*>(&_M_stringbuf); }
00577 
00578       /**
00579        *  @brief  Copying out the string buffer.
00580        *  @return  @c rdbuf()->str()
00581       */
00582       __string_type
00583       str() const
00584       { return _M_stringbuf.str(); }
00585 
00586       /**
00587        *  @brief  Setting a new buffer.
00588        *  @param  __s  The string to use as a new sequence.
00589        *
00590        *  Calls @c rdbuf()->str(s).
00591       */
00592       void
00593       str(const __string_type& __s)
00594       { _M_stringbuf.str(__s); }
00595     };
00596 
00597 _GLIBCXX_END_NAMESPACE_VERSION
00598 } // namespace
00599 
00600 #include <bits/sstream.tcc>
00601 
00602 #endif /* _GLIBCXX_SSTREAM */