On Wed, Apr 23, 2014 at 09:21:04AM -0700, Asmus Freytag wrote: > > a parsing is good if it satisfies all conditions below: > > > > 0) Some delimiters in the string are marked as “non-matching”; the rest > > is broken into disjoint “matched” pairs; > > > > MATCH) A “matched” pair consists of an open-delimiter and matching close- > > delimiter (in this order in the string). > > > > NEST) “Matched” pairs are properly nested (meaning that 2 pairs cannot be > > positioned as Open1 Open2 Close1 Close2 in the string order). > > > > MINLEN) “Inside” a “matched” pair, every delimiter which could match > > elements > > of the pair but is marked as “non-matching” must nest inside > > some deeper-nested “matched” pair. > > > >(I hope that the meaning of the word “inside” in MINLEN is clear.) > > > > GREED) Given any close-delimiter marked as “non-matching”, its > > pre-context does not contain any open-delimiter which could > > match it. > > > > Here pre-context of a position is a concatenation of substrings of the > > initial string: > > • Take the most deeply nested “matched pair” containing the position > > (if none, the whole string); > > • take the part of the string inside this pair AND before the position; > > • remove all “matched” pairs completely contained insidde this > > substring > > together with what they enclose. > > This is a very nice formal definition. I'm surprised that your "GREED" > statement needs such a complex auxiliary concept (pre-context). > > Can you explain why, if you make "pre-context" simply the part of the > whole string that precedes the unmatched close-delimiter, the words > "which could match it" are insufficient?
Aha, this means that my description is INCOMPLETE: you got a wrong impression what “match” means! Everywhere, this word means exactly the same as in the MATCH rule: that Unicode codepoints match following Unicode properties. This is non-recursive definition. All rules are independent. Without complicated notion of pre-context, matching [] in ( [ ) ] would be an acceptable match. Thanks for your corrections, Ilya _______________________________________________ Unicode mailing list [email protected] http://unicode.org/mailman/listinfo/unicode
