update Filtering/CQL to Part 3, 1.0.0-draft.2

[cportele]

Part 3, 1.0.0-draft.2 (in public review): https://portal.ogc.org/files/?artifact_id=96288&version=2

• The BNF has been updated in general and we should sync with the current grammar. Updated BNF: https://github.com/opengeospatial/ogcapi-features/blob/master/extensions/cql/standard/schema/cql.bnf. Important changes in predicates:
  • LIKE operator has additional options and by default comparisons are case insensitive
  • Array expressions have been added: https://docs.ogc.org/DRAFTS/19-079r1.html#arrays
  • Support double quoted identifiers (doubleQuote)
  • A boolean literal has been added
  • axis order of coordinates in ENVELOPE has changed (to align with bbox parameter)
  • Note: We won't implement any other parts of CQL that were excluded in the initial implementation
• Keywords in the BNF grammar are case-insensitive. I.e., "and", "AND", "aNd" etc. all match "AND". This is a general rule for ABNF grammars. Currently, they the implementation is case sensitive.
• A query parameter filter-crs must be supported: https://docs.ogc.org/DRAFTS/19-079r1.html#filter-filter-crs

[azahnen]

Implementation tasks:

• case insensitive keywords
  • define keywords in CqlLexer.g4 as described here
• filter-crs
  • our CQL text parser already accepts a CRS parameter, currently it is always set to CRS84
  • add read method with additional CRS parameter in Cql/CqlImpl, pass to CqlTextParser.parse
  • add QueryParameterFilterCrs, read and pass to CQL.read in FeatureQueryImpl
• double quoted identifiers
  • adjust grammar in CqlLexer.g4`
• axis order of coordinates in ENVELOPE has changed
  • adjust grammar in CqlParser.g4`
• LIKE operator has additional options
  • adjust grammar in CqlParser.g4` and domain model
• Array expressions TBD
• general
  • the BNF definition has changed significantly, but I am not sure to which extent that really changes the resulting grammar, so I would follow these steps:
  • check the current CQL text examples, adjust the existing tests in CqlTextSpec, add missing tests
  • adjust the grammar to make the tests pass

[cportele]

the BNF definition has changed significantly, but I am not sure to which extent that really changes the resulting grammar

In general, it should be the same (except in the cases that I have identified, although I may have missed something). The changes we mainly required for consistency between the BNF grammar and the schema for the JSON encoding, which required a re-factoring: opengeospatial/ogcapi-features#460.

[cportele]

I also noticed that ANYINTERACTS is not implemented, but it is mandatory, so this needs to be supported, too.

In general, we should implement all the temporal operators and align the implementation with the spec, but this can be a second step. For example, After only works with instants or TOverlaps is not the operator specified in the spec.

[cportele]

I found another difference. Currently predicates where both operands are property references (e.g. height < floors) are not supported, but this is required by CQL.

[cportele]

We should decouple array predicates from this issue, I have created #431.

[cportele]

closed by #423

[cportele]

Open issues are in #432.