Add -dependencies option to reference grammars that their input grammars rely on

[0xedward]

Background

Currently it is not possible for a user to reference a rule from a grammar not in dharma/grammars unless they edit DharmaMachine.default_grammars to include the path to the grammar files they want to reference. In this patch, we add support for users to reference rules in other files or directories in their input grammar files using the -dependencies option. -dependencies accepts both files and directories of dharma grammar files. The -dependencies option prioritizes definitions in default_grammars over user defined dependent grammars to make resolving redefinition errors easier.

Example Usage

python3 -m dharma -g input_grammar.dg -d reference_grammar.dg

...
%section% := value

definition :=
    +reference_grammar:dependency+
...

...
%section% := value

dependency :=
    "This is a rule input_grammar references in its grammar"
...

[posidron]

I'm terribly sorry that I only write now here, it's been a complex ride every since I left Mozilla that I can not really (yet) publish my changes made here at Microsoft and the public version here did not receive the proper attention.

First of all, thanks for the contribution, really appreciated, however, you were already able to do that via the colon operator if you specify your other grammar on the CLI use the name of that grammar as reference. :-) Look at the end of the README.md, although the common.dg is always pre-loaded, the concept works in general for other grammars.