re PR libstdc++/28765 (__gnu_cxx::__vstring::clear() is slow)

2006-08-18  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/28765
	* include/ext/rc_string_base.h (_M_clear): New.
	* include/ext/sso_string_base.h (_M_clear): Likewise.
	* include/ext/vstring.h (clear): Use it.

From-SVN: r116240

libstdc++-v3/ChangeLog

+2006-08-18  Paolo Carlini  <pcarlini@suse.de>
+
+	PR libstdc++/28765
+	* include/ext/rc_string_base.h (_M_clear): New.
+	* include/ext/sso_string_base.h (_M_clear): Likewise.
+	* include/ext/vstring.h (clear): Use it.
+
 2006-08-15  Paolo Carlini  <pcarlini@suse.de>
 
 	* include/tr1/random (poisson_distribution<>::_M_initialize): Add.

libstdc++-v3/include/ext/rc_string_base.h

@@ -338,6 +338,10 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
       void
       _M_erase(size_type __pos, size_type __n);
 
+      void
+      _M_clear()
+      { _M_erase(size_type(0), _M_length()); }
+
       bool
       _M_compare(const __rc_string_base&) const
       { return false; }

libstdc++-v3/include/ext/sso_string_base.h

@@ -226,6 +226,10 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
       void
       _M_erase(size_type __pos, size_type __n);
 
+      void
+      _M_clear()
+      { _M_set_length(0); }
+
       bool
       _M_compare(const __sso_string_base&) const
       { return false; }

libstdc++-v3/include/ext/vstring.h

@@ -409,7 +409,7 @@ _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
        */
       void
       clear()
-      { this->_M_erase(size_type(0), this->size()); }
+      { this->_M_clear(); }
 
       /**
        *  Returns true if the %string is empty.  Equivalent to *this == "".