Add support for side-effect actions (pull request)

[jwcraftsman]

This pull request was spawned as a result of the discussion in #51.

This branch divides grammar actions into two groups, based on whether their purpose is to 1) construct a parse result (e.g. AST tree nodes) or 2) manipulate external state for use by recognizers or dynamic filters. If the purpose is manipulate external state, then the action is a side-effect action, otherwise it is a standard action.

A new keyword argument "side_actions" was added to the Parser constructor. Support for a _side_actions.py file was also added to grammar.py.

The option added in #45 was removed, as it is no longer necessary, since side_actions are processed regardless of whether build_tree is true or false.

[coveralls]

Coverage decreased (-2.7%) to 82.937% when pulling 136430f3486186571f012770769cc4f69b8c2fc5 on codecraftingtools:side-effects into c6e4d8ac778a8029d63edbd59fbafa0a80ef60e2 on igordejanovic:master.

[coveralls]

Coverage decreased (-0.4%) to 85.526% when pulling 3228904c08521516a6d266e8ee37e1a529740ea5 on codecraftingtools:side-effects into 39927c4ce4aabe78d9ad72e51dd2366947abffa0 on igordejanovic:master.

[jwcraftsman]

How does this implementation look? It seems to be working for me. Please let me know if this in on the right track. Thanks.

[igordejanovic]

I haven't had a change for a deeper look into it. I'll get to that probably after finishing current rework around error reporting. The thing that I don't like with the current side-effect implementation is that a lot of code is copy-pasted from plain actions. I would like to integrate/generalize that so it would be easier to maintain. I could provide more info when get back to it in the next week or two probably.

[jwcraftsman]

Yes, I agree that the duplicated code should be minimized. Thanks.