grammar

I am starting to write BibTeX parser. The first thing I would like to do is to parse a braced item. A braced item could be an author field or a title for example. There might be nested braces within the field. The following code does not handle nested braces: use v6; my $str = q:to/END/; author={Belayneh, M. and Geiger, S. and Matth{\"{a}}i, S.K.}, END $str .= chomp; grammar ExtractBraced { rule TOP { 'author=' <braced-item> .* } rule braced-item { '{' <-[}]>* '}' } } ExtractBraced.parse( $str ).say; Output : ｢author={Belayneh, M. and Geiger, S. and Matth{\"{a}}i, S.K.},｣ braced-item => ｢

Given the following basic grammar I want to understand how I can handle comment lines. Missing is the handling of the <CR><LF> which usually terminates the comment line - the only exception is a last comment line before the EOF, e. g.: # comment abcd := 12 ; # comment eof without <CR><LF> grammar CommentLine1a; //========================================================== // Options //========================================================== //========================================================== // Lexer Rules //========================================================== Int : Digit+ ;

I'm very impressed by Prolog's DCG and how quickly I can produce all the possible structures that fit a particular grammar. But I'd like to combine this search with other constraints. For example, define a complex grammar and ask Prolog to generate all sentences with not more than 10 words. Or all sentences that don't repeat the same word twice. Is it possible to add extra constraints like this to a DCG grammer? Or do I basically have to translate the DCG back into normal Prolog clauses and start modifying them? If you only want to see all sentences that are generated, it is very convenient to

I would like to input a string and return a regular expression that can be used to describe the string's structure. The regex will be used to find more strings of the same structure as the first. This is intentionally ambiguous because I will certainly miss a case that someone in the SO community will catch. Please post any and all possible ways to do this. The trivial answer, and probably not what you want, is: return the input string (with regex special characters escaped). That is always a regular expression that matches the string. If you wish certain structures to be identified, you have