std_sstream.h - patch

[Ryszard Kabatek <rysio@rumcajs.chemie.uni-halle.de>]

The attached patch contains two optimizations for basic_stringbuf<>:

1. In the default constructor I changed _M_str(__string_type()) to _M_str().

2. In setbuf I changed the return value type and I removed the
temporary __string_type object. Now if the new buffer length is smaller
than the old one no reallocation is necessary.

BTW. The basic_streambuf<>::setbuf in bits/std_streambuf.h
     does not return any value if 'if (false)' occurs.


1999-05-25  Ryszard Kabatek <kabatek@chemie.uni-halle.de>

	* bits/std_sstream.h:
          basic_stringbuf<>::basic_stringbuf: fix.
	  basic_stringbuf<>::setbuf: 
	  remove the temporary __string_type object,
	  remove the unnecessary dynymic_cast in the return value,
	  change the type of the returned value from __streambuf_type*
	  to basic_stringbuf<_CharT, _Traits, _Alloc>*.


Ryszard Kabatek
Martin-Luther University Halle-Wittenberg, Department of Physical Chemistry
Geusaer Str. 88, 06217 Merseburg, Germany
Tel. +49 3461 46 2487 (2466) Fax. +49 3461 46 2129
Index: bits/std_sstream.h
===================================================================
RCS file: /cvs/libstdc++/libstdc++/bits/std_sstream.h,v
retrieving revision 1.32
diff -c -2 -p -r1.32 std_sstream.h
*** std_sstream.h	1999/05/21 10:33:25	1.32
--- std_sstream.h	1999/05/25 11:45:20
*************** namespace std {
*** 60,64 ****
        explicit 
        basic_stringbuf(ios_base::openmode __mode = ios_base::in | ios_base::out)
!       : __streambuf_type(), _M_str(__string_type())
        { 
  	_M_mode = __mode;
--- 60,64 ----
        explicit 
        basic_stringbuf(ios_base::openmode __mode = ios_base::in | ios_base::out)
!       : __streambuf_type(), _M_str()
        { 
  	_M_mode = __mode;
*************** namespace std {
*** 104,114 ****
        overflow(int_type __c = traits_type::eof());
  
!       virtual __streambuf_type* 
        setbuf(char_type* __s, streamsize __n)
        { 
! 	__string_type __str(__s, __n);
! 	if (__str.size())
! 	  this->str(__str);
! 	return dynamic_cast<__streambuf_type*> (this); 
        } 
  
--- 104,115 ----
        overflow(int_type __c = traits_type::eof());
  
!       virtual basic_stringbuf<_CharT, _Traits, _Alloc>*
        setbuf(char_type* __s, streamsize __n)
        { 
!         if (__n) {
!           _M_str.assign(__s, __n);
!           this->sync();
!         }
!         return this;
        }