//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// <istream>
// basic_istream<charT,traits>& seekg(off_type off, ios_base::seekdir dir);
#include <istream>
#include <cassert>
#include "test_macros.h"
int seekoff_called = 0;
template <class CharT>
struct testbuf
: public std::basic_streambuf<CharT>
{
typedef std::basic_string<CharT> string_type;
typedef std::basic_streambuf<CharT> base;
private:
string_type str_;
public:
testbuf() {}
testbuf(const string_type& str)
: str_(str)
{
base::setg(const_cast<CharT*>(str_.data()),
const_cast<CharT*>(str_.data()),
const_cast<CharT*>(str_.data()) + str_.size());
}
CharT* eback() const {return base::eback();}
CharT* gptr() const {return base::gptr();}
CharT* egptr() const {return base::egptr();}
protected:
typename base::pos_type seekoff(typename base::off_type off,
std::ios_base::seekdir,
std::ios_base::openmode which)
{
assert(which == std::ios_base::in);
++seekoff_called;
return off;
}
};
int main(int, char**)
{
{
testbuf<char> sb(" 123456789");
std::istream is(&sb);
is.seekg(5, std::ios_base::cur);
assert(is.good());
assert(seekoff_called == 1);
is.seekg(-1, std::ios_base::beg);
assert(is.fail());
assert(seekoff_called == 2);
}
#ifndef TEST_HAS_NO_WIDE_CHARACTERS
{
testbuf<wchar_t> sb(L" 123456789");
std::wistream is(&sb);
is.seekg(5, std::ios_base::cur);
assert(is.good());
assert(seekoff_called == 3);
is.seekg(-1, std::ios_base::beg);
assert(is.fail());
assert(seekoff_called == 4);
}
#endif
{
testbuf<char> sb(" 123456789");
std::istream is(&sb);
is.setstate(std::ios_base::eofbit);
assert(is.eof());
is.seekg(5, std::ios_base::beg);
assert(is.good());
assert(!is.eof());
}
return 0;
}