[mapserver-dev] ms rfc 48: adding a type keyword to the styleblock

[Tamas Szekeres]

2008/11/6 thomas bonfort <thomas.bonfort at gmail.com>:
>
> Why do you want to add the "geom" argument to the expressions ?
>

This is just a notation to denote the input geometry in the
expression. It would probably be replaced with the actual feature of
the layer when the expression is evaluated.
However we might want to use here the same style as for the attribute
binding, like:

GEOMETRYEXPRESSION   "centroid([geom])"


> as for the implementation, I don't feel upto writing a parser capable
> of understanding the more complex of your examples, but I guess that
> could be done in a second step while keeping the same global concept.
>

In the first stage you could make a simple parser to recognize the
individual functions, however I think it would not be too difficult to
parse a complex expression into a proper structure in a more general
fashion.
I'm sure Steve will have some idea in this regard by using the current
lexer/parser capabilities but using a simple custom solution would
also be comfortable to implement. I could also help to find out the
actual implementation if needed.

Best regards,

Tamas