One of the things that blocks wider acceptance of the excellent CQL code is the limited scope of the common query language. In GeoTools we have a more relaxed view of a filter; and it would be nice to make a TXT format that matches what we can do!
Here is what our new TXT format needs to do (over and beyond the current abilities of CQL):
- support for spatial and comparison filters between any two expressions (CQL is limited to: propertyName OP expr)
- CQL: propertyName contains geometry
- TXT: geometry contains geometry
- support for the Id filters as defined by Filter 1.0 specification
- CQL: n/q
- TXT: #road.1, #road.2
This request is for a new grammar (called TXT) that extends the CQL BNF to account for these ideas. The new format should be presented as a seperate facade class (even though behind the scenes it will share a lot of code with the normal CQL implementation classes).
The new TXT grammar facade class is method compatible with CQL facade class:
Existing specificaitons like CAT2 allow the specificaiton of a queryLanguage; if an application wishes to make this format available to the public it is advised that "txt" be a more expressive alternative queryLanaguage to "cql".
Here are some technical notes from Mauricio:
Here are some examples (requested from Maria):
- area( the_geom ) > 30,000
- #road.1,#road.2, #road.47