Hi Keith, Yes, it makes sense to add QStringRef::toInt/Float/Double. The entire point of QStringRef was to make things faster and having those apis will definitely be an improvement.
Girish On Wed, Jun 13, 2012 at 12:24 PM, Keith Gardner <kgard...@zebraimaging.com> wrote: > Sorry to backtrack this thread, but I have some performance information. > Just FYI, I haven't made any code changes to Qt, yet. > > To give some background information, I am parsing a single xml file with > 88,704 floating point values using the QXmlStreamReader. I am running in > Windows 7 x64 and am using an SSD to store the file. My compiler is Visual > Studio 2010 with a Win32 configuration. > > I would take the QStringRef for the argument, convert it to a string using > the toString() function and then use toFloat(). > > This method would parse the entire document in 608 milliseconds in > release mode. > stringRef.toString().toFloat() > Changing that code to use wcstod on the QStringRef resulted in parsing > the document in 467 millesconds. > wcstod((const wchar_t*)stringref.unicode(),0); > > In debug mode, this goes from 2814 milliseconds down to 1850 milliseconds. > > I would say that there is a big payout with changing what we currently have. > > Thanks, > Keith > > -----Original Message----- > From: Girish Ramakrishnan [mailto:gir...@forwardbias.in] > Sent: Monday, June 11, 2012 4:55 PM > To: Keith Gardner > Cc: development@qt-project.org > Subject: Re: [Development] QStringRef conversion functions > > Hi, > > On Mon, Jun 11, 2012 at 11:38 AM, Keith Gardner > <kgard...@zebraimaging.com> wrote: >> I was wondering if there would be a possibility of getting some of the >> conversion functions that are in QString implemented in QStringRef (toInt, >> toFloat, etc...). The reasoning behind this is that I am using the >> QXMLStreamReader to parse an XML file with over 88,704 floating point >> values. I am trying to improve the speed at which the file is parsed and I >> believe one of the bottlenecks is taking an attribute of QStringRef and >> copying its data into a QString in order to convert to a float. I would >> prefer that the copy never happen but that would require some more >> intelligence be added into the QStringRef class. >> > > I am tempted to say it's 5.1 material but it would be nice to see how > much gains you are getting out of these new apis and how intrusive the > new code is. Can you push your change to gerrit ? > > Thanks, > Girish _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
