00001 // Position types -*- C++ -*- 00002 00003 // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 00004 // 2006, 2007, 2008 00005 // Free Software Foundation, Inc. 00006 // 00007 // This file is part of the GNU ISO C++ Library. This library is free 00008 // software; you can redistribute it and/or modify it under the 00009 // terms of the GNU General Public License as published by the 00010 // Free Software Foundation; either version 2, or (at your option) 00011 // any later version. 00012 00013 // This library is distributed in the hope that it will be useful, 00014 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00015 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00016 // GNU General Public License for more details. 00017 00018 // You should have received a copy of the GNU General Public License along 00019 // with this library; see the file COPYING. If not, write to the Free 00020 // Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 00021 // USA. 00022 00023 // As a special exception, you may use this file as part of a free software 00024 // library without restriction. Specifically, if other files instantiate 00025 // templates or use macros or inline functions from this file, or you compile 00026 // this file and link it with other files to produce an executable, this 00027 // file does not by itself cause the resulting executable to be covered by 00028 // the GNU General Public License. This exception does not however 00029 // invalidate any other reasons why the executable file might be covered by 00030 // the GNU General Public License. 00031 00032 /** @file postypes.h 00033 * This is an internal header file, included by other library headers. 00034 * You should not attempt to use it directly. 00035 */ 00036 00037 // 00038 // ISO C++ 14882: 27.4.1 - Types 00039 // ISO C++ 14882: 27.4.3 - Template class fpos 00040 // 00041 00042 #ifndef _GLIBCXX_POSTYPES_H 00043 #define _GLIBCXX_POSTYPES_H 1 00044 00045 #pragma GCC system_header 00046 00047 #include <cwchar> // For mbstate_t 00048 00049 #ifdef _GLIBCXX_HAVE_STDINT_H 00050 #include <stdint.h> // For int64_t 00051 #endif 00052 00053 _GLIBCXX_BEGIN_NAMESPACE(std) 00054 00055 // The types streamoff, streampos and wstreampos and the class 00056 // template fpos<> are described in clauses 21.1.2, 21.1.3, 27.1.2, 00057 // 27.2, 27.4.1, 27.4.3 and D.6. Despite all this verbiage, the 00058 // behaviour of these types is mostly implementation defined or 00059 // unspecified. The behaviour in this implementation is as noted 00060 // below. 00061 00062 /** 00063 * @brief Type used by fpos, char_traits<char>, and char_traits<wchar_t>. 00064 * 00065 * In clauses 21.1.3.1 and 27.4.1 streamoff is described as an 00066 * implementation defined type. 00067 * Note: In versions of GCC up to and including GCC 3.3, streamoff 00068 * was typedef long. 00069 */ 00070 #ifdef _GLIBCXX_HAVE_INT64_T 00071 typedef int64_t streamoff; 00072 #else 00073 typedef long long streamoff; 00074 #endif 00075 00076 /// Integral type for I/O operation counts and buffer sizes. 00077 typedef ptrdiff_t streamsize; // Signed integral type 00078 00079 /** 00080 * @brief Class representing stream positions. 00081 * 00082 * The standard places no requirements upon the template parameter StateT. 00083 * In this implementation StateT must be DefaultConstructible, 00084 * CopyConstructible and Assignable. The standard only requires that fpos 00085 * should contain a member of type StateT. In this implementation it also 00086 * contains an offset stored as a signed integer. 00087 * 00088 * @param StateT Type passed to and returned from state(). 00089 */ 00090 template<typename _StateT> 00091 class fpos 00092 { 00093 private: 00094 streamoff _M_off; 00095 _StateT _M_state; 00096 00097 public: 00098 // The standard doesn't require that fpos objects can be default 00099 // constructed. This implementation provides a default 00100 // constructor that initializes the offset to 0 and default 00101 // constructs the state. 00102 fpos() 00103 : _M_off(0), _M_state() { } 00104 00105 // The standard requires that fpos objects can be constructed 00106 // from streamoff objects using the constructor syntax, and 00107 // fails to give any meaningful semantics. In this 00108 // implementation implicit conversion is also allowed, and this 00109 // constructor stores the streamoff as the offset and default 00110 // constructs the state. 00111 /// Construct position from offset. 00112 fpos(streamoff __off) 00113 : _M_off(__off), _M_state() { } 00114 00115 /// Convert to streamoff. 00116 operator streamoff() const { return _M_off; } 00117 00118 /// Remember the value of @a st. 00119 void 00120 state(_StateT __st) 00121 { _M_state = __st; } 00122 00123 /// Return the last set value of @a st. 00124 _StateT 00125 state() const 00126 { return _M_state; } 00127 00128 // The standard requires that this operator must be defined, but 00129 // gives no semantics. In this implementation it just adds its 00130 // argument to the stored offset and returns *this. 00131 /// Add offset to this position. 00132 fpos& 00133 operator+=(streamoff __off) 00134 { 00135 _M_off += __off; 00136 return *this; 00137 } 00138 00139 // The standard requires that this operator must be defined, but 00140 // gives no semantics. In this implementation it just subtracts 00141 // its argument from the stored offset and returns *this. 00142 /// Subtract offset from this position. 00143 fpos& 00144 operator-=(streamoff __off) 00145 { 00146 _M_off -= __off; 00147 return *this; 00148 } 00149 00150 // The standard requires that this operator must be defined, but 00151 // defines its semantics only in terms of operator-. In this 00152 // implementation it constructs a copy of *this, adds the 00153 // argument to that copy using operator+= and then returns the 00154 // copy. 00155 /// Add position and offset. 00156 fpos 00157 operator+(streamoff __off) const 00158 { 00159 fpos __pos(*this); 00160 __pos += __off; 00161 return __pos; 00162 } 00163 00164 // The standard requires that this operator must be defined, but 00165 // defines its semantics only in terms of operator+. In this 00166 // implementation it constructs a copy of *this, subtracts the 00167 // argument from that copy using operator-= and then returns the 00168 // copy. 00169 /// Subtract offset from position. 00170 fpos 00171 operator-(streamoff __off) const 00172 { 00173 fpos __pos(*this); 00174 __pos -= __off; 00175 return __pos; 00176 } 00177 00178 // The standard requires that this operator must be defined, but 00179 // defines its semantics only in terms of operator+. In this 00180 // implementation it returns the difference between the offset 00181 // stored in *this and in the argument. 00182 /// Subtract position to return offset. 00183 streamoff 00184 operator-(const fpos& __other) const 00185 { return _M_off - __other._M_off; } 00186 }; 00187 00188 // The standard only requires that operator== must be an 00189 // equivalence relation. In this implementation two fpos<StateT> 00190 // objects belong to the same equivalence class if the contained 00191 // offsets compare equal. 00192 /// Test if equivalent to another position. 00193 template<typename _StateT> 00194 inline bool 00195 operator==(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs) 00196 { return streamoff(__lhs) == streamoff(__rhs); } 00197 00198 template<typename _StateT> 00199 inline bool 00200 operator!=(const fpos<_StateT>& __lhs, const fpos<_StateT>& __rhs) 00201 { return streamoff(__lhs) != streamoff(__rhs); } 00202 00203 // Clauses 21.1.3.1 and 21.1.3.2 describe streampos and wstreampos 00204 // as implementation defined types, but clause 27.2 requires that 00205 // they must both be typedefs for fpos<mbstate_t> 00206 /// File position for char streams. 00207 typedef fpos<mbstate_t> streampos; 00208 /// File position for wchar_t streams. 00209 typedef fpos<mbstate_t> wstreampos; 00210 00211 _GLIBCXX_END_NAMESPACE 00212 00213 #endif