forked from OSchip/llvm-project
Partial implementation of N3665. This paper was not voted into the C++1y draft. However I was looking at it and with some experimentation realized that I could partially implement it, and at the same time offer a performance optimization to cout. I simply added an xsputn override to the cout filebuf. The override does nothing special at all if there is a non-trivial codecvt installed. However if the codecvt returns true for always_noconv(), then this function can dump an entire string to fwrite, instead of doing it a character at a time under overflow(). This just makes sense. I stopped short of a full implementation of N3665 because in order to do so, xsputn would have to allocate a buffer when always_noconv() returned false, and I don't want to go to that expense.
llvm-svn: 188077
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@ -233,6 +233,7 @@ public:
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protected:
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protected:
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virtual int_type overflow (int_type __c = traits_type::eof());
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virtual int_type overflow (int_type __c = traits_type::eof());
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virtual streamsize xsputn(const char_type* __s, streamsize __n);
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virtual int sync();
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virtual int sync();
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virtual void imbue(const locale& __loc);
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virtual void imbue(const locale& __loc);
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@ -308,6 +309,19 @@ __stdoutbuf<_CharT>::overflow(int_type __c)
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return traits_type::not_eof(__c);
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return traits_type::not_eof(__c);
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}
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}
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template <class _CharT>
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streamsize
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__stdoutbuf<_CharT>::xsputn(const char_type* __s, streamsize __n)
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{
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if (__always_noconv_)
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return fwrite(__s, sizeof(char_type), __n, __file_);
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streamsize __i = 0;
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for (; __i < __n; ++__i, ++__s)
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if (overflow(traits_type::to_int_type(*__s)) == traits_type::eof())
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break;
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return __i;
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}
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template <class _CharT>
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template <class _CharT>
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int
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int
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__stdoutbuf<_CharT>::sync()
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__stdoutbuf<_CharT>::sync()
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