Ruby Gem for the Mattermark Semantic Filter Language

Contains serializers and validators (and perhaps other) MSFL goodies

EBNF

MSFL is a context-free language. The context-free grammar is defined below.

I'm not actually sure this is correct, it is definitely not comprehensive as it skips over the shortcut functionality.

filter = range_op | binary_op | set_op
set_op = and | or
and = "{" "\"and\"" ":" list "}"
or = "{" "\"or\"" ":" list "}"
list = "[" filter? | (filter ("," filter)*) "]";
range_op = between;
between = "{" field ":" between_body | "{" "\"between\"" ":" between_body "}";
between_body = "{" "\"start\"" ":" between_start "," "\"end\"" ":" between_end "}";
between_start = integer | double | date | datetime | time;
between_end = integer | double | date | datetime | time;
binary_op = comparison | containment;
comparison = "{" field ":" "{" comparison_op ":" atom "}" "}";
field = "\"" ALPHANUMERIC+ "\"";
comparison_op = "lt" | "gt" | "lte" | "gte" | "eq";
containment = "{" field ":" "{" "\"in\"" ":" atom_list "}" "}";
atom = string | integer | double | boolean | date | datetime | time;
atom_list = "[" atom? | (atom ("," atom)*) "]";

Configuration

All configuration options should be set in a block passed to MSFL.configure { |c| c.datasets = [] }

Naturally you should provide an appropriate array of the datasets you are supporting.

As additional configuration settings are added they will be set similarly.

Converters

The MSFL converters provide convenience methods for transforming a parsed MSFL tree to a different structure that is logically equivalent. The intent is to enable consumers of MSFL to easily manipulate parsed MSFL filters into the form that most easily or efficiently allows adaptation to the storage mechanism upon which the filtering is being effected.

Note that the order in which converters are run is controlled by the constant MSFL::Converters::CONVERSIONS and cannot be manipulated through configuration. This behavior is currently necessary for ease of implementation but is unlikely to continue to be status quo.

Datasets

The consumer of the MSFL gem defines one or more datasets. The dataset definition enumerates the supported fields and their types.

Parsers

Currently there is only a parser for the JSON encoding of MSFL filters. Any additional parsers will also be placed under this directory.

Types

Because of the behavioral limitations imposed on certain types (currently Sets are the only example) there is a folder for types to be defined.

Validators

After parsing a MSFL filter it can be validated. Currently the validation is primitive. The intent is to enable semantic validation on a per dataset basis. This will allow per attribute validations to be setup by the consumer of this gem, which will be run automatically during validation.

Frameworks

Sinatra

There are several helper methods for using this gem with Sinatra. You can register the helpers in your Sinatra app by adding the following inside of your application's class.

# This should actually be Sinatra::MSFL but there are some namespacing issues with MSFL currently that prevented
# this from being the v0 implementation. This will change in the near future.
register MSFL::Sinatra