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82 lines
2.0 KiB
C++
82 lines
2.0 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is dual licensed under the MIT and the University of Illinois Open
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// Source Licenses. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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// <istream>
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// basic_istream<charT,traits>& unget();
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#include <istream>
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#include <cassert>
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template <class CharT>
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struct testbuf
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: public std::basic_streambuf<CharT>
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{
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typedef std::basic_string<CharT> string_type;
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typedef std::basic_streambuf<CharT> base;
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private:
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string_type str_;
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public:
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testbuf() {}
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testbuf(const string_type& str)
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: str_(str)
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{
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base::setg(const_cast<CharT*>(str_.data()),
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const_cast<CharT*>(str_.data()),
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const_cast<CharT*>(str_.data()) + str_.size());
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}
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CharT* eback() const {return base::eback();}
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CharT* gptr() const {return base::gptr();}
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CharT* egptr() const {return base::egptr();}
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};
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int main()
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{
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{
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testbuf<char> sb(" 123456789");
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std::istream is(&sb);
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is.get();
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is.get();
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is.get();
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.bad());
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assert(is.gcount() == 0);
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}
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{
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testbuf<wchar_t> sb(L" 123456789");
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std::wistream is(&sb);
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is.get();
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is.get();
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is.get();
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.good());
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assert(is.gcount() == 0);
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is.unget();
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assert(is.bad());
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assert(is.gcount() == 0);
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}
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}
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