Generating predicates from alternating chained grammars

[yichao-liang]

When generating predicates from _ChainPredicateGrammar with alternate=True, such as here when CFG.grammar_search_grammar_use_diff_features=True.

The enumeration seems to stop before grammar_search_max_predicates amount of predicates are generated, as one of the grammars runs out. In my experiment, it generated a total of 17 candidates when the hyperparameter is set to 200.

[tomsilver]

Thanks @yichao-liang , that's a very good catch. Do you have the bandwidth to implement a fix?