C++ concepts: UnformattedInputFunction

Requirements

An UnformattedInputFunction is a stream input function that performs the following:

• Constructs an object of type basic_istream::sentry with automatic storage duration and with the noskipws argument set to true, which performs the following
• if eofbit or badbit are set on the input stream, sets the failbit as well, and if exceptions on failbit are enabled in this input stream's exception mask, throws ios_base::failure.
• flushes the tie()'d output stream, if applicable
• Checks the status of the sentry by calling sentry::operator bool(), which is equivalent to basic_ios::good.
• If the sentry returned false or sentry's constructor threw an exception:
• sets the number of extracted characters (gcount) in the input stream to zero
• if the function was called to write to an array of CharT, writes CharT() (the null character) to the first location of the array
• If the sentry returned true, performs the input as if by calling rdbuf()->sbumpc() or rdbuf()->sgetc().
• if the end of the stream is reached (the call to rdbuf()->sbumpc() or rdbuf()->sgetc() returns Traits::eof(), sets eofbit. If exceptions on eofbit are enabled in this stream's exception mask, throws ios_base::failure.
• if an exception is thrown during input, sets badbit in the input stream. If exceptions on badbit are enabled in this stream's exception mask, the exception is also rethrown.
• If no exception was thrown during input, sets the number of extracted characters (gcount) in the input stream.
• In any event, whether terminating by exception or returning, the sentry's destructor is called before leaving this function.

Standard library

The following standard library functions are UnformattedInputFunctions.

• std::getline, except that it does not modify gcount.
• basic_istream::operator>>(basic_streambuf*)
• basic_istream::get
• basic_istream::getline
• basic_istream::ignore
• basic_istream::peek
• basic_istream::read
• basic_istream::readsome
• basic_istream::putback, except that it first clears eofbit
• basic_istream::unget, except that it first clears eofbit
• basic_istream::sync, except that it does not modify gcount
• basic_istream::tellg, except that it does not modify gcount
• basic_istream::seekg, except that it first clears eofbit and does not modify gcount
• std::ws, except that it does not modify gcount