Any source code for converting an infix filter to a WFS filter?

Question

A WFS GetFeature query looks something like this:

http://hname/arcgis/services/sname/MapServer/WFSServer?SERVICE=WFS&REQUEST=GetFeature&VERSION=1.0.0&MAXFEATURES=1001&FILTER=%3CFilter%3E%3CPropertyIsEqualTo%3E%3CPropertyName%3EADDRKEY%3C/PropertyName%3E%3CLiteral%3E1001%3C/Literal%3E%3C/PropertyIsEqualTo%3E%3C/Filter%3E&TYPENAME=Addresses

But users would want to enter something like "ADDRKEY = 1001" so it becomes necessary to convert the infix expression to a AST and then into a WFS filter.

Are there any reusable solutions for converting an CQL filter into a OGC filter?

• "A=b" is converted into
• "<PropertyIsEqualTo><PropertyName>A</PropertyName><Literal>b</Literal></PropertyIsEqualTo>"

Answer 1

One approach would be to use the OGC Common Query Language (CQL) to generate your expressions and then use the OpenLayers CQL parser to convert to an OGC Filter. A description of the process can be found here.

Answer 2

A similar question was posted on stackoverflow (http://stackoverflow.com/questions/8053221/does-a-net-cql-parser-exist) pointing to this project (http://ncql.codeplex.com/). It's built with Antlr, difficult to read and large (2696 lines of code in NCqlParser.cs).