Cosmetic changes to PEG grammar. #2
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added 11 commits
January 26, 2011 00:09
This change is consistent with operand-start, which doesn't group these rules together. This change is consistent with all other rules in operand-3, which don't try to share common-substructure. This change moves an ordered choice from the inside one choice out to the loop with the other choices. Since ordered choice is something that can be checked in parallel, this change allows more simultaneous threads to try parsing operand-3 at once.
The two choices in statement-2 differ only by the final element in the outermost optional clause. The first choice does not have statement-2, the second choice does. This can be expressed by another '?' operator, removing one ordered choice. If this rule was constructed this way in order to avoid a bug in the RATS! parser, please ignore this change.
This rule include one choice which is "a b c" and one choice which is "a b" That is the same as saying "a b c?", so combine these two choices.
This is the only choice in sumti-6 separated into it's own production. I'm not sure why it is pulled out, it is only referenced in sumti-6. If you were doing this because you wanted the parse tree shaped a particular way, please ignore this change. Otherwise, this change is more consistent with the rest of the grammar.
|b c / a b c| is the same as saying |a? b c|, except in conditions that make |a b c| never match (i.e., if |b c| always matches the same input as |a b c|). That is not the case here, these two choices can be folded into one by making the first clause optional.
space-interval contains the rule |a / b / a b|. Since the first matching choice is always taken, the last choice will never match, since a substring of that match is contained in a previous choice. reorder this rule to be |a b? / b|, which is equivalent to the *intent* to match a, or b, or a b.
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e326dff is a legitimate bug: the third choice in the ordered choice will never be matched. This probably needs to have a higher priority than the other stuff. |
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This is a list of mostly cosmetic changes to the PEG grammar.