I see there's a mu::ParserInt class in
https://github.com/beltoforion/muparser/blob/master/include/muParserInt.h
, that we don't use in GDAL. A bit strange it wasn't mentionned in [1].
Perhaps because of this comment: "This version of the parser handles
only integer numbers. It disables the built in operators thus it
is slower than muParser. Integer values are stored in the double
value_type and converted if needed."
Le 03/12/2025 à 21:07, Daniel Baston via gdal-dev a écrit :
Hugh,
My read of this discussion [1] is that bitwise operators are not
supported and we would need to add them as a GDAL extension. This is
pretty easy to do: see [2]. Alternatively, bitwise operators are
probably supported by the ExprTk expression parser [3] (supported by
GDAL) or this pull request [4].
Dan
[1]
https://github.com/beltoforion/muparser/discussions/154#discussioncomment-13104418
[2] https://github.com/OSGeo/gdal/pull/13187/files
[3] https://www.partow.net/programming/exprtk/
[4] https://github.com/OSGeo/gdal/pull/13470
On Wed, Dec 3, 2025 at 2:58 PM Hugh Graham via gdal-dev
<[email protected]> wrote:
Hi,
I am using VRT muparser expressions for bitwise operations when
creating masks and wanted to understand why I can't get the
/bitwise & /operator working? My current solution is to use fmod
which is fine (and I think equivalent) but using "&" would be
convenient and a bit easier to read...
To illustrate, the following file works:
https://gist.github.com/h-a-graham/6db16e70e064ae8173f1052537c59761#file-fmask-fmodmask-vrt
the expression used here is:"(fmod(Fmask, 16) >= 8) ||
(fmod(Fmask, 8) >= 4) ? 0 : 1"
```
gdal convert
"/vsicurl/https://gist.githubusercontent.com/h-a-graham/6db16e70e064ae8173f1052537c59761/raw/c48b15852bcc7c5252cae4b906c14b9a3205a33d/fmask-fmodmask.vrt";
"test.tif"
```
However, the following file fails:
https://gist.github.com/h-a-graham/6db16e70e064ae8173f1052537c59761#file-fmask-bitmask-vrt
the expression parsed as: "((Fmask & 8) > 0 || (Fmask &
4) > 0) ? 0 : 1" in the XML but provided as (to my xml parser):
"((Fmask & 8) > 0 || (Fmask & 4) > 0) ? 0 : 1"
```
gdal convert
"/vsicurl/https://gist.githubusercontent.com/h-a-graham/6db16e70e064ae8173f1052537c59761/raw/c48b15852bcc7c5252cae4b906c14b9a3205a33d/fmask-bitmask.vrt";
"test.tif"
0...10...20..ERROR 1: Unexpected token "& 8) > 0 || (Fmask & 4) >
0) ? 0 : 1 " found at position 8.
```
So, is using "&" possible, or should I just stick with fmod and
not worry about it?
Any help would be much appreciated.
Hugh
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
--
http://www.spatialys.com
My software is free, but my time generally not.
_______________________________________________
gdal-dev mailing list
[email protected]
https://lists.osgeo.org/mailman/listinfo/gdal-dev
