re PR libstdc++/22515 (operator>>(istream, string/CharT*) can be faster)

2005-07-24  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/22515
	* include/bits/basic_string.h: Declare the specialization
	operator>>(basic_istream<char>&, basic_string<char>&).
	* include/std/std_istream.h: Declate the specialization
	operator>>(basic_istream<char>&, char*).
	* include/std/std_streambuf.h (basic_streambuf): Add friend
	declarations for the above.
	* src/istream.cc: Define the above.
	* testsuite/27_io/basic_istream/extractors_character/char/4.cc: New.
	* testsuite/27_io/basic_istream/extractors_character/wchar_t/4.cc:
	Likewise.
	* testsuite/performance/27_io/ifstream_extract_chars.cc: Likewise.

From-SVN: r102353

1 files changed, 151 insertions, 0 deletions

diff --git a/libstdc++-v3/src/istream.cc b/libstdc++-v3/src/istream.cc
index e8da16c..15ff41a 100644
--- a/libstdc++-v3/src/istream.cc
+++ b/libstdc++-v3/src/istream.cc
@@ -185,6 +185,157 @@ namespace std
 
   template<>
     basic_istream<char>&
+    operator>>(basic_istream<char>& __in, char* __s)
+    {
+      typedef basic_istream<char>       	__istream_type;
+      typedef __istream_type::int_type		__int_type;
+      typedef __istream_type::char_type		__char_type;
+      typedef __istream_type::traits_type	__traits_type;
+      typedef __istream_type::__streambuf_type  __streambuf_type;
+      typedef __istream_type::__ctype_type	__ctype_type;
+
+      streamsize __extracted = 0;
+      ios_base::iostate __err = ios_base::iostate(ios_base::goodbit);
+      __istream_type::sentry __cerb(__in, false);
+      if (__cerb)
+	{
+	  try
+	    {
+	      // Figure out how many characters to extract.
+	      streamsize __num = __in.width();
+	      if (__num <= 0)
+		__num = numeric_limits<streamsize>::max();
+
+	      const __ctype_type& __ct = use_facet<__ctype_type>(__in.getloc());
+
+	      const __int_type __eof = __traits_type::eof();
+	      __streambuf_type* __sb = __in.rdbuf();
+	      __int_type __c = __sb->sgetc();
+
+	      while (__extracted < __num - 1
+		     && !__traits_type::eq_int_type(__c, __eof)
+		     && !__ct.is(ctype_base::space,
+				 __traits_type::to_char_type(__c)))
+		{
+		  streamsize __size = std::min(streamsize(__sb->egptr()
+							  - __sb->gptr()),
+					       streamsize(__num - __extracted
+							  - 1));
+		  if (__size > 1)
+		    {
+		      __size = (__ct.scan_is(ctype_base::space,
+					     __sb->gptr() + 1,
+					     __sb->gptr() + __size)
+				- __sb->gptr());
+		      __traits_type::copy(__s, __sb->gptr(), __size);
+		      __s += __size;
+		      __sb->gbump(__size);
+		      __extracted += __size;
+		      __c = __sb->sgetc();
+		    }
+		  else
+		    {
+		      *__s++ = __traits_type::to_char_type(__c);
+		      ++__extracted;
+		      __c = __sb->snextc();
+		    }
+		}
+
+	      if (__traits_type::eq_int_type(__c, __eof))
+		__err |= ios_base::eofbit;
+
+	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+	      // 68.  Extractors for char* should store null at end
+	      *__s = __char_type();
+	      __in.width(0);
+	    }
+	  catch(...)
+	    { __in._M_setstate(ios_base::badbit); }
+	}
+      if (!__extracted)
+	__err |= ios_base::failbit;
+      if (__err)
+	__in.setstate(__err);
+      return __in;
+    }
+
+  template<>
+    basic_istream<char>&
+    operator>>(basic_istream<char>& __in, basic_string<char>& __str)
+    {
+      typedef basic_istream<char>       	__istream_type;
+      typedef __istream_type::int_type		__int_type;
+      typedef __istream_type::char_type		__char_type;
+      typedef __istream_type::traits_type	__traits_type;
+      typedef __istream_type::__streambuf_type  __streambuf_type;
+      typedef __istream_type::__ctype_type	__ctype_type;
+      typedef basic_string<char>        	__string_type;
+      typedef __string_type::size_type		__size_type;
+
+      __size_type __extracted = 0;
+      ios_base::iostate __err = ios_base::iostate(ios_base::goodbit);
+      __istream_type::sentry __cerb(__in, false);
+      if (__cerb)
+	{
+	  try
+	    {
+	      __str.erase();
+	      const streamsize __w = __in.width();
+	      const __size_type __n = __w > 0 ? static_cast<__size_type>(__w)
+		                              : __str.max_size();
+	      const __ctype_type& __ct = use_facet<__ctype_type>(__in.getloc());
+	      const __int_type __eof = __traits_type::eof();
+	      __streambuf_type* __sb = __in.rdbuf();
+	      __int_type __c = __sb->sgetc();
+
+	      while (__extracted < __n
+		     && !__traits_type::eq_int_type(__c, __eof)
+		     && !__ct.is(ctype_base::space,
+				 __traits_type::to_char_type(__c)))
+		{
+		  streamsize __size = std::min(streamsize(__sb->egptr()
+							  - __sb->gptr()),
+					       streamsize(__n - __extracted));
+		  if (__size > 1)
+		    {
+		      __size = (__ct.scan_is(ctype_base::space,
+					     __sb->gptr() + 1,
+					     __sb->gptr() + __size)
+				- __sb->gptr());
+		      __str.append(__sb->gptr(), __size);
+		      __sb->gbump(__size);
+		      __extracted += __size;
+		      __c = __sb->sgetc();
+		    }
+		  else
+		    {
+		      __str += __traits_type::to_char_type(__c);
+		      ++__extracted;
+		      __c = __sb->snextc();
+		    }		  
+		}
+
+	      if (__traits_type::eq_int_type(__c, __eof))
+		__err |= ios_base::eofbit;
+	      __in.width(0);
+	    }
+	  catch(...)
+	    {
+	      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+	      // 91. Description of operator>> and getline() for string<>
+	      // might cause endless loop
+	      __in._M_setstate(ios_base::badbit);
+	    }
+	}
+      if (!__extracted)
+	__err |= ios_base::failbit;
+      if (__err)
+	__in.setstate(__err);
+      return __in;
+    }
+
+  template<>
+    basic_istream<char>&
     getline(basic_istream<char>& __in, basic_string<char>& __str,
 	    char __delim)
     {