[Paraview] Possible bug in vtkFunctionParser?

[Berk Geveci]

Hi Takuya,

Can you please create an issue in the bug tracker and attach the patch there?

Thanks,
-berk


On Thu, Mar 27, 2008 at 9:41 AM, OSHIMA Takuya
<oshima at eng.niigata-u.ac.jp> wrote:
> Hi,
>
>  Sorry to bother you again, but does anyone have a comment?
>  This time I had a look through the bug tracker but could not find the issue.
>
>  Takuya
>
>  From: OSHIMA Takuya <oshima at eng.niigata-u.ac.jp>
>  Date: Sat, 22 Mar 2008 14:41:17 +0900
>
>
>
>  Hi,
>
>  I have a dataset which contains an array with the name say "A/B,"
>  which in turn contains a character that may be interpreted as a
>  mathematical operator '/'. If I try to run Filter->Calculator and to
>  evaluate an expression "A/B + A/B" over the dataset, I can't get the
>  expected result (an array with all components doubled).
>
>  I'm not sure this should be called as a bug since the array name is
>  itself confusing, but anyway what I found out was that finding the
>  first occurrence of the array name within the given expression is not
>  enough in vtkFunctionParser::OperatorWithinVariable(). I think at
>  least the array name should be searched until the location of idx even
>  if there was an occurrence prior to the location.
>
>  Here I attach a patch that worked for me. I know this is far from
>  perfect as a fix (there are still many possible cases that can't be
>  properly detected). Please take it just as a clarification of a
>  solution that worked for me.
>
>  Regards,
>  Takuya
>
>  --- vtkFunctionParser.cxx.orig  2007-12-22 03:55:56.000000000 +0900
>  +++ vtkFunctionParser.cxx       2008-03-22 12:26:51.320000000 +0900
>  @@ -1342,14 +1342,21 @@
>      {
>      if (strchr(this->ScalarVariableNames[i], this->Function[idx]) != 0)
>        {
>  -      tmpString = strstr(this->Function, this->ScalarVariableNames[i]);
>  -      if (tmpString)
>  +      for(end = 0; end <= idx;)
>          {
>  -        start = static_cast<int>(tmpString - this->Function);
>  -        end = start + strlen(this->ScalarVariableNames[i]);
>  -        if (start <= idx && end >= idx)
>  +        tmpString = strstr(this->Function + end, this->ScalarVariableNames[i]);
>  +        if (tmpString)
>            {
>  -          return 1;
>  +          start = static_cast<int>(tmpString - this->Function);
>  +          end = start + strlen(this->ScalarVariableNames[i]);
>  +          if (start <= idx && end > idx)
>  +            {
>  +            return 1;
>  +            }
>  +          }
>  +        else
>  +          {
>  +          break;
>            }
>          }
>        }
>  @@ -1358,14 +1365,21 @@
>      {
>      if (strchr(this->VectorVariableNames[i], this->Function[idx]) != 0)
>        {
>  -      tmpString = strstr(this->Function, this->VectorVariableNames[i]);
>  -      if (tmpString)
>  +      for(end = 0; end <= idx;)
>          {
>  -        start = static_cast<int>(tmpString - this->Function);
>  -        end = start + strlen(this->VectorVariableNames[i]);
>  -        if (start <= idx && end >= idx)
>  +        tmpString = strstr(this->Function + end, this->VectorVariableNames[i]);
>  +        if (tmpString)
>  +          {
>  +          start = static_cast<int>(tmpString - this->Function);
>  +          end = start + strlen(this->VectorVariableNames[i]);
>  +          if (start <= idx && end > idx)
>  +            {
>  +            return 1;
>  +            }
>  +          }
>  +        else
>            {
>  -          return 1;
>  +          break;
>            }
>          }
>        }
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