[PATCH] let QString::lower() assume lower case input to avoid real_detach()

[Roger Larsson]

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As it said in the earlier comments "could do this only when we find a chang=
e"
This version does it like that.

upper could be optimized in the same way, but there it is questionable
if the all upper case in common enough...

It compiles but I have not tested it yet - Monday earliest.

My assumption is that this will speed up history loading.

/RogerL

=2D-=20
Roger Larsson
Skellefte=E5
Sweden

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Index: qstring.cpp
===================================================================
RCS file: /home/kde/qt-copy/src/tools/qstring.cpp,v
retrieving revision 1.51
diff -u -3 -p -r1.51 qstring.cpp
--- qstring.cpp	17 Dec 2002 15:04:18 -0000	1.51
+++ qstring.cpp	19 Jan 2003 01:39:26 -0000
@@ -15004,13 +15004,36 @@ QString QString::lower() const
     QString s(*this);
     int l=length();
     if ( l ) {
-	s.real_detach(); // could do this only when we find a change
-	register QChar *p=s.d->unicode;
+	QChar *p=s.d->unicode;
 	if ( p ) {
-	    while ( l-- ) {
-		*p = ::lower( *p );
+	    // check if all are lower already
+	    while ( l )
+	    {
+		QChar c_anycase = *p;
+		QChar c_lower = ::lower( c_anycase );
+
+		if (c_anycase != c_lower) { // !__builtin_expect
+		    s.real_detach(); // only when we found a change
+
+		    // p might have moved due to the detach, recalculate it
+		    // then update the mismatching char
+		    p=s.d->unicode + length() - l;  // might have moved, note the remaining l(ength)
+		    *p = c_lower;
+
+		    while ( --l ) {
+			*p = ::lower( *p );
+			p++;
+		    }
+
+		    break;
+		}
+
+                // more logical to do it in the same place
+		// and probably optimized better (decrement before test)
 		p++;
+		l--; 
 	    }
+
 	}
     }
     return s;

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