// Input streams -*- C++ -*- // Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 // 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, // 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: 27.6.1 Input streams // /** @file istream * This is a Standard C++ Library header. */ #ifndef _GLIBCXX_ISTREAM #define _GLIBCXX_ISTREAM 1 #pragma GCC system_header #include <ios> #include <limits> // For numeric_limits _GLIBCXX_BEGIN_NAMESPACE(std) // [27.6.1.1] Template class basic_istream /** * @brief Controlling input. * * This is the base class for all input streams. It provides text * formatting of all builtin types, and communicates with any class * derived from basic_streambuf to do the actual input. */ template<typename _CharT, typename _Traits> class basic_istream : virtual public basic_ios<_CharT, _Traits> { public: // Types (inherited from basic_ios (27.4.4)): typedef _CharT char_type; typedef typename _Traits::int_type int_type; typedef typename _Traits::pos_type pos_type; typedef typename _Traits::off_type off_type; typedef _Traits traits_type; // Non-standard Types: typedef basic_streambuf<_CharT, _Traits> __streambuf_type; typedef basic_ios<_CharT, _Traits> __ios_type; typedef basic_istream<_CharT, _Traits> __istream_type; typedef num_get<_CharT, istreambuf_iterator<_CharT, _Traits> > __num_get_type; typedef ctype<_CharT> __ctype_type; template<typename _CharT2, typename _Traits2> friend basic_istream<_CharT2, _Traits2>& operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2&); template<typename _CharT2, typename _Traits2> friend basic_istream<_CharT2, _Traits2>& operator>>(basic_istream<_CharT2, _Traits2>&, _CharT2*); protected: // Data Members: /** * @if maint * The number of characters extracted in the previous unformatted * function; see gcount(). * @endif */ streamsize _M_gcount; public: // [27.6.1.1.1] constructor/destructor /** * @brief Base constructor. * * This ctor is almost never called by the user directly, rather from * derived classes' initialization lists, which pass a pointer to * their own stream buffer. */ explicit basic_istream(__streambuf_type* __sb): _M_gcount(streamsize(0)) { this->init(__sb); } /** * @brief Base destructor. * * This does very little apart from providing a virtual base dtor. */ virtual ~basic_istream() { _M_gcount = streamsize(0); } // [27.6.1.1.2] prefix/suffix class sentry; friend class sentry; // [27.6.1.2] formatted input // [27.6.1.2.3] basic_istream::operator>> //@{ /** * @brief Interface for manipulators. * * Manuipulators such as @c std::ws and @c std::dec use these * functions in constructs like "std::cin >> std::ws". For more * information, see the iomanip header. */ __istream_type& operator>>(__istream_type& (*__pf)(__istream_type&)) { return __pf(*this); } __istream_type& operator>>(__ios_type& (*__pf)(__ios_type&)) { __pf(*this); return *this; } __istream_type& operator>>(ios_base& (*__pf)(ios_base&)) { __pf(*this); return *this; } //@} // [27.6.1.2.2] arithmetic extractors /** * @name Arithmetic Extractors * * All the @c operator>> functions (aka <em>formatted input * functions</em>) have some common behavior. Each starts by * constructing a temporary object of type std::basic_istream::sentry * with the second argument (noskipws) set to false. This has several * effects, concluding with the setting of a status flag; see the * sentry documentation for more. * * If the sentry status is good, the function tries to extract * whatever data is appropriate for the type of the argument. * * If an exception is thrown during extraction, ios_base::badbit * will be turned on in the stream's error state without causing an * ios_base::failure to be thrown. The original exception will then * be rethrown. */ //@{ /** * @brief Basic arithmetic extractors * @param A variable of builtin type. * @return @c *this if successful * * These functions use the stream's current locale (specifically, the * @c num_get facet) to parse the input data. */ __istream_type& operator>>(bool& __n) { return _M_extract(__n); } __istream_type& operator>>(short& __n); __istream_type& operator>>(unsigned short& __n) { return _M_extract(__n); } __istream_type& operator>>(int& __n); __istream_type& operator>>(unsigned int& __n) { return _M_extract(__n); } __istream_type& operator>>(long& __n) { return _M_extract(__n); } __istream_type& operator>>(unsigned long& __n) { return _M_extract(__n); } #ifdef _GLIBCXX_USE_LONG_LONG __istream_type& operator>>(long long& __n) { return _M_extract(__n); } __istream_type& operator>>(unsigned long long& __n) { return _M_extract(__n); } #endif __istream_type& operator>>(float& __f) { return _M_extract(__f); } __istream_type& operator>>(double& __f) { return _M_extract(__f); } __istream_type& operator>>(long double& __f) { return _M_extract(__f); } __istream_type& operator>>(void*& __p) { return _M_extract(__p); } /** * @brief Extracting into another streambuf. * @param sb A pointer to a streambuf * * This function behaves like one of the basic arithmetic extractors, * in that it also constructs a sentry object and has the same error * handling behavior. * * If @a sb is NULL, the stream will set failbit in its error state. * * Characters are extracted from this stream and inserted into the * @a sb streambuf until one of the following occurs: * * - the input stream reaches end-of-file, * - insertion into the output buffer fails (in this case, the * character that would have been inserted is not extracted), or * - an exception occurs (and in this case is caught) * * If the function inserts no characters, failbit is set. */ __istream_type& operator>>(__streambuf_type* __sb); //@} // [27.6.1.3] unformatted input /** * @brief Character counting * @return The number of characters extracted by the previous * unformatted input function dispatched for this stream. */ streamsize gcount() const { return _M_gcount; } /** * @name Unformatted Input Functions * * All the unformatted input functions have some common behavior. * Each starts by constructing a temporary object of type * std::basic_istream::sentry with the second argument (noskipws) * set to true. This has several effects, concluding with the * setting of a status flag; see the sentry documentation for more. * * If the sentry status is good, the function tries to extract * whatever data is appropriate for the type of the argument. * * The number of characters extracted is stored for later retrieval * by gcount(). * * If an exception is thrown during extraction, ios_base::badbit * will be turned on in the stream's error state without causing an * ios_base::failure to be thrown. The original exception will then * be rethrown. */ //@{ /** * @brief Simple extraction. * @return A character, or eof(). * * Tries to extract a character. If none are available, sets failbit * and returns traits::eof(). */ int_type get(); /** * @brief Simple extraction. * @param c The character in which to store data. * @return *this * * Tries to extract a character and store it in @a c. If none are * available, sets failbit and returns traits::eof(). * * @note This function is not overloaded on signed char and * unsigned char. */ __istream_type& get(char_type& __c); /** * @brief Simple multiple-character extraction. * @param s Pointer to an array. * @param n Maximum number of characters to store in @a s. * @param delim A "stop" character. * @return *this * * Characters are extracted and stored into @a s until one of the * following happens: * * - @c n-1 characters are stored * - the input sequence reaches EOF * - the next character equals @a delim, in which case the character * is not extracted * * If no characters are stored, failbit is set in the stream's error * state. * * In any case, a null character is stored into the next location in * the array. * * @note This function is not overloaded on signed char and * unsigned char. */ __istream_type& get(char_type* __s, streamsize __n, char_type __delim); /** * @brief Simple multiple-character extraction. * @param s Pointer to an array. * @param n Maximum number of characters to store in @a s. * @return *this * * Returns @c get(s,n,widen('\n')). */ __istream_type& get(char_type* __s, streamsize __n) { return this->get(__s, __n, this->widen('\n')); } /** * @brief Extraction into another streambuf. * @param sb A streambuf in which to store data. * @param delim A "stop" character. * @return *this * * Characters are extracted and inserted into @a sb until one of the * following happens: * * - the input sequence reaches EOF * - insertion into the output buffer fails (in this case, the * character that would have been inserted is not extracted) * - the next character equals @a delim (in this case, the character * is not extracted) * - an exception occurs (and in this case is caught) * * If no characters are stored, failbit is set in the stream's error * state. */ __istream_type& get(__streambuf_type& __sb, char_type __delim); /** * @brief Extraction into another streambuf. * @param sb A streambuf in which to store data. * @return *this * * Returns @c get(sb,widen('\n')). */ __istream_type& get(__streambuf_type& __sb) { return this->get(__sb, this->widen('\n')); } /** * @brief String extraction. * @param s A character array in which to store the data. * @param n Maximum number of characters to extract. * @param delim A "stop" character. * @return *this * * Extracts and stores characters into @a s until one of the * following happens. Note that these criteria are required to be * tested in the order listed here, to allow an input line to exactly * fill the @a s array without setting failbit. * * -# the input sequence reaches end-of-file, in which case eofbit * is set in the stream error state * -# the next character equals @c delim, in which case the character * is extracted (and therefore counted in @c gcount()) but not stored * -# @c n-1 characters are stored, in which case failbit is set * in the stream error state * * If no characters are extracted, failbit is set. (An empty line of * input should therefore not cause failbit to be set.) * * In any case, a null character is stored in the next location in * the array. */ __istream_type& getline(char_type* __s, streamsize __n, char_type __delim); /** * @brief String extraction. * @param s A character array in which to store the data. * @param n Maximum number of characters to extract. * @return *this * * Returns @c getline(s,n,widen('\n')). */ __istream_type& getline(char_type* __s, streamsize __n) { return this->getline(__s, __n, this->widen('\n')); } /** * @brief Discarding characters * @param n Number of characters to discard. * @param delim A "stop" character. * @return *this * * Extracts characters and throws them away until one of the * following happens: * - if @a n @c != @c std::numeric_limits<int>::max(), @a n * characters are extracted * - the input sequence reaches end-of-file * - the next character equals @a delim (in this case, the character * is extracted); note that this condition will never occur if * @a delim equals @c traits::eof(). * * NB: Provide three overloads, instead of the single function * (with defaults) mandated by the Standard: this leads to a * better performing implementation, while still conforming to * the Standard. */ __istream_type& ignore(); __istream_type& ignore(streamsize __n); __istream_type& ignore(streamsize __n, int_type __delim); /** * @brief Looking ahead in the stream * @return The next character, or eof(). * * If, after constructing the sentry object, @c good() is false, * returns @c traits::eof(). Otherwise reads but does not extract * the next input character. */ int_type peek(); /** * @brief Extraction without delimiters. * @param s A character array. * @param n Maximum number of characters to store. * @return *this * * If the stream state is @c good(), extracts characters and stores * them into @a s until one of the following happens: * - @a n characters are stored * - the input sequence reaches end-of-file, in which case the error * state is set to @c failbit|eofbit. * * @note This function is not overloaded on signed char and * unsigned char. */ __istream_type& read(char_type* __s, streamsize __n); /** * @brief Extraction until the buffer is exhausted, but no more. * @param s A character array. * @param n Maximum number of characters to store. * @return The number of characters extracted. * * Extracts characters and stores them into @a s depending on the * number of characters remaining in the streambuf's buffer, * @c rdbuf()->in_avail(), called @c A here: * - if @c A @c == @c -1, sets eofbit and extracts no characters * - if @c A @c == @c 0, extracts no characters * - if @c A @c > @c 0, extracts @c min(A,n) * * The goal is to empty the current buffer, and to not request any * more from the external input sequence controlled by the streambuf. */ streamsize readsome(char_type* __s, streamsize __n); /** * @brief Unextracting a single character. * @param c The character to push back into the input stream. * @return *this * * If @c rdbuf() is not null, calls @c rdbuf()->sputbackc(c). * * If @c rdbuf() is null or if @c sputbackc() fails, sets badbit in * the error state. * * @note Since no characters are extracted, the next call to * @c gcount() will return 0, as required by DR 60. */ __istream_type& putback(char_type __c); /** * @brief Unextracting the previous character. * @return *this * * If @c rdbuf() is not null, calls @c rdbuf()->sungetc(c). * * If @c rdbuf() is null or if @c sungetc() fails, sets badbit in * the error state. * * @note Since no characters are extracted, the next call to * @c gcount() will return 0, as required by DR 60. */ __istream_type& unget(); /** * @brief Synchronizing the stream buffer. * @return 0 on success, -1 on failure * * If @c rdbuf() is a null pointer, returns -1. * * Otherwise, calls @c rdbuf()->pubsync(), and if that returns -1, * sets badbit and returns -1. * * Otherwise, returns 0. * * @note This function does not count the number of characters * extracted, if any, and therefore does not affect the next * call to @c gcount(). */ int sync(); /** * @brief Getting the current read position. * @return A file position object. * * If @c fail() is not false, returns @c pos_type(-1) to indicate * failure. Otherwise returns @c rdbuf()->pubseekoff(0,cur,in). * * @note This function does not count the number of characters * extracted, if any, and therefore does not affect the next * call to @c gcount(). */ pos_type tellg(); /** * @brief Changing the current read position. * @param pos A file position object. * @return *this * * If @c fail() is not true, calls @c rdbuf()->pubseekpos(pos). If * that function fails, sets failbit. * * @note This function does not count the number of characters * extracted, if any, and therefore does not affect the next * call to @c gcount(). */ __istream_type& seekg(pos_type); /** * @brief Changing the current read position. * @param off A file offset object. * @param dir The direction in which to seek. * @return *this * * If @c fail() is not true, calls @c rdbuf()->pubseekoff(off,dir). * If that function fails, sets failbit. * * @note This function does not count the number of characters * extracted, if any, and therefore does not affect the next * call to @c gcount(). */ __istream_type& seekg(off_type, ios_base::seekdir); //@} protected: explicit basic_istream(): _M_gcount(streamsize(0)) { } template<typename _ValueT> __istream_type& _M_extract(_ValueT& __v); }; // Explicit specialization declarations, defined in src/istream.cc. template<> basic_istream<char>& basic_istream<char>:: getline(char_type* __s, streamsize __n, char_type __delim); template<> basic_istream<char>& basic_istream<char>:: ignore(streamsize __n); template<> basic_istream<char>& basic_istream<char>:: ignore(streamsize __n, int_type __delim); #ifdef _GLIBCXX_USE_WCHAR_T template<> basic_istream<wchar_t>& basic_istream<wchar_t>:: getline(char_type* __s, streamsize __n, char_type __delim); template<> basic_istream<wchar_t>& basic_istream<wchar_t>:: ignore(streamsize __n); template<> basic_istream<wchar_t>& basic_istream<wchar_t>:: ignore(streamsize __n, int_type __delim); #endif /** * @brief Performs setup work for input streams. * * Objects of this class are created before all of the standard * extractors are run. It is responsible for "exception-safe prefix and * suffix operations," although only prefix actions are currently required * by the standard. Additional actions may be added by the * implementation, and we list them in * http://gcc.gnu.org/onlinedocs/libstdc++/17_intro/howto.html#5 * under [27.6] notes. */ template<typename _CharT, typename _Traits> class basic_istream<_CharT, _Traits>::sentry { public: /// Easy access to dependant types. typedef _Traits traits_type; typedef basic_streambuf<_CharT, _Traits> __streambuf_type; typedef basic_istream<_CharT, _Traits> __istream_type; typedef typename __istream_type::__ctype_type __ctype_type; typedef typename _Traits::int_type __int_type; /** * @brief The constructor performs all the work. * @param is The input stream to guard. * @param noskipws Whether to consume whitespace or not. * * If the stream state is good (@a is.good() is true), then the * following actions are performed, otherwise the sentry state is * false ("not okay") and failbit is set in the stream state. * * The sentry's preparatory actions are: * * -# if the stream is tied to an output stream, @c is.tie()->flush() * is called to synchronize the output sequence * -# if @a noskipws is false, and @c ios_base::skipws is set in * @c is.flags(), the sentry extracts and discards whitespace * characters from the stream. The currently imbued locale is * used to determine whether each character is whitespace. * * If the stream state is still good, then the sentry state becomes * true ("okay"). */ explicit sentry(basic_istream<_CharT, _Traits>& __is, bool __noskipws = false); /** * @brief Quick status checking. * @return The sentry state. * * For ease of use, sentries may be converted to booleans. The * return value is that of the sentry state (true == okay). */ operator bool() const { return _M_ok; } private: bool _M_ok; }; // [27.6.1.2.3] character extraction templates //@{ /** * @brief Character extractors * @param in An input stream. * @param c A character reference. * @return in * * Behaves like one of the formatted arithmetic extractors described in * std::basic_istream. After constructing a sentry object with good * status, this function extracts a character (if one is available) and * stores it in @a c. Otherwise, sets failbit in the input stream. */ template<typename _CharT, typename _Traits> basic_istream<_CharT, _Traits>& operator>>(basic_istream<_CharT, _Traits>& __in, _CharT& __c); template<class _Traits> inline basic_istream<char, _Traits>& operator>>(basic_istream<char, _Traits>& __in, unsigned char& __c) { return (__in >> reinterpret_cast<char&>(__c)); } template<class _Traits> inline basic_istream<char, _Traits>& operator>>(basic_istream<char, _Traits>& __in, signed char& __c) { return (__in >> reinterpret_cast<char&>(__c)); } //@} //@{ /** * @brief Character string extractors * @param in An input stream. * @param s A pointer to a character array. * @return in * * Behaves like one of the formatted arithmetic extractors described in * std::basic_istream. After constructing a sentry object with good * status, this function extracts up to @c n characters and stores them * into the array starting at @a s. @c n is defined as: * * - if @c width() is greater than zero, @c n is width() * - otherwise @c n is "the number of elements of the largest array of * @c char_type that can store a terminating @c eos." [27.6.1.2.3]/6 * * Characters are extracted and stored until one of the following happens: * - @c n-1 characters are stored * - EOF is reached * - the next character is whitespace according to the current locale * - the next character is a null byte (i.e., @c charT() ) * * @c width(0) is then called for the input stream. * * If no characters are extracted, sets failbit. */ template<typename _CharT, typename _Traits> basic_istream<_CharT, _Traits>& operator>>(basic_istream<_CharT, _Traits>& __in, _CharT* __s); // Explicit specialization declaration, defined in src/istream.cc. template<> basic_istream<char>& operator>>(basic_istream<char>& __in, char* __s); template<class _Traits> inline basic_istream<char, _Traits>& operator>>(basic_istream<char, _Traits>& __in, unsigned char* __s) { return (__in >> reinterpret_cast<char*>(__s)); } template<class _Traits> inline basic_istream<char, _Traits>& operator>>(basic_istream<char, _Traits>& __in, signed char* __s) { return (__in >> reinterpret_cast<char*>(__s)); } //@} // 27.6.1.5 Template class basic_iostream /** * @brief Merging istream and ostream capabilities. * * This class multiply inherits from the input and output stream classes * simply to provide a single interface. */ template<typename _CharT, typename _Traits> class basic_iostream : public basic_istream<_CharT, _Traits>, public basic_ostream<_CharT, _Traits> { public: // _GLIBCXX_RESOLVE_LIB_DEFECTS // 271. basic_iostream missing typedefs // Types (inherited): typedef _CharT char_type; typedef typename _Traits::int_type int_type; typedef typename _Traits::pos_type pos_type; typedef typename _Traits::off_type off_type; typedef _Traits traits_type; // Non-standard Types: typedef basic_istream<_CharT, _Traits> __istream_type; typedef basic_ostream<_CharT, _Traits> __ostream_type; /** * @brief Constructor does nothing. * * Both of the parent classes are initialized with the same * streambuf pointer passed to this constructor. */ explicit basic_iostream(basic_streambuf<_CharT, _Traits>* __sb) : __istream_type(), __ostream_type() { this->init(__sb); } /** * @brief Destructor does nothing. */ virtual ~basic_iostream() { } protected: explicit basic_iostream() : __istream_type(), __ostream_type() { } }; // [27.6.1.4] standard basic_istream manipulators /** * @brief Quick and easy way to eat whitespace * * This manipulator extracts whitespace characters, stopping when the * next character is non-whitespace, or when the input sequence is empty. * If the sequence is empty, @c eofbit is set in the stream, but not * @c failbit. * * The current locale is used to distinguish whitespace characters. * * Example: * @code * MyClass mc; * * std::cin >> std::ws >> mc; * @endcode * will skip leading whitespace before calling operator>> on cin and your * object. Note that the same effect can be achieved by creating a * std::basic_istream::sentry inside your definition of operator>>. */ template<typename _CharT, typename _Traits> basic_istream<_CharT, _Traits>& ws(basic_istream<_CharT, _Traits>& __is); _GLIBCXX_END_NAMESPACE #ifndef _GLIBCXX_EXPORT_TEMPLATE # include <bits/istream.tcc> #endif #endif /* _GLIBCXX_ISTREAM */