// Position types -*- C++ -*- // Copyright (C) 1997, 1998, 1999, 2000, 2001, 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: 27.4.1 - Types // ISO C++ 14882: 27.4.3 - Template class fpos // /** @file postypes.h * This is an internal header file, included by other library headers. * You should not attempt to use it directly. */ #ifndef _GLIBCXX_POSTYPES_H #define _GLIBCXX_POSTYPES_H 1 #pragma GCC system_header #include <cwchar> // For mbstate_t #ifdef _GLIBCXX_HAVE_STDINT_H #include <stdint.h> // For int64_t #endif namespace std { // The types streamoff, streampos and wstreampos and the class // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2, // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbage, the // behaviour of these types is mostly implementation defined or // unspecified. The behaviour in this implementation is as noted // below. /** * @brief Type used by fpos, char_traits<char>, and char_traits<wchar_t>. * * @if maint * In clauses 21.1.3.1 and 27.4.1 streamoff is described as an * implementation defined type. * Note: In versions of GCC up to and including GCC 3.3, streamoff * was typedef long. * @endif */ #ifdef _GLIBCXX_HAVE_INT64_T typedef int64_t streamoff; #else typedef long long streamoff; #endif /// Integral type for I/O operation counts and buffer sizes. typedef ptrdiff_t streamsize; // Signed integral type template<typename _StateT> class fpos; /** * @brief Class representing stream positions. * * The standard places no requirements upon the template parameter StateT. * In this implementation StateT must be DefaultConstructible, * CopyConstructible and Assignable. The standard only requires that fpos * should contain a member of type StateT. In this implementation it also * contains an offset stored as a signed integer. * * @param StateT Type passed to and returned from state(). */ template<typename _StateT> class fpos { private: streamoff _M_off; _StateT _M_state; public: // The standard doesn't require that fpos objects can be default // constructed. This implementation provides a default // constructor that initializes the offset to 0 and default // constructs the state. fpos() : _M_off(0), _M_state() { } // The standard requires that fpos objects can be constructed // from streamoff objects using the constructor syntax, and // fails to give any meaningful semantics. In this // implementation implicit conversion is also allowed, and this // constructor stores the streamoff as the offset and default // constructs the state. /// Construct position from offset. fpos(streamoff __off) : _M_off(__off), _M_state() { } /// Convert to streamoff. operator streamoff() const { return _M_off; } /// Remember the value of @a st. void state(_StateT __st) { _M_state = __st; } /// Return the last set value of @a st. _StateT state() const { return _M_state; } // The standard only requires that operator== must be an // equivalence relation. In this implementation two fpos<StateT> // objects belong to the same equivalence class if the contained // offsets compare equal. /// Test if equivalent to another position. bool operator==(const fpos& __other) const { return _M_off == __other._M_off; } /// Test if not equivalent to another position. bool operator!=(const fpos& __other) const { return _M_off != __other._M_off; } // The standard requires that this operator must be defined, but // gives no semantics. In this implemenation it just adds it's // argument to the stored offset and returns *this. /// Add offset to this position. fpos& operator+=(streamoff __off) { _M_off += __off; return *this; } // The standard requires that this operator must be defined, but // gives no semantics. In this implemenation it just subtracts // it's argument from the stored offset and returns *this. /// Subtract offset from this position. fpos& operator-=(streamoff __off) { _M_off -= __off; return *this; } // The standard requires that this operator must be defined, but // defines it's semantics only in terms of operator-. In this // implementation it constructs a copy of *this, adds the // argument to that copy using operator+= and then returns the // copy. /// Add position and offset. fpos operator+(streamoff __off) const { fpos __pos(*this); __pos += __off; return __pos; } // The standard requires that this operator must be defined, but // defines it's semantics only in terms of operator+. In this // implementation it constructs a copy of *this, subtracts the // argument from that copy using operator-= and then returns the // copy. /// Subtract offset from position. fpos operator-(streamoff __off) const { fpos __pos(*this); __pos -= __off; return __pos; } // The standard requires that this operator must be defined, but // defines it's semantics only in terms of operator+. In this // implementation it returns the difference between the offset // stored in *this and in the argument. /// Subtract position to return offset. streamoff operator-(const fpos& __other) const { return _M_off - __other._M_off; } }; // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos // as implementation defined types, but clause 27.2 requires that // they must both be typedefs for fpos<mbstate_t> /// File position for char streams. typedef fpos<mbstate_t> streampos; /// File position for wchar_t streams. typedef fpos<mbstate_t> wstreampos; } // namespace std #endif