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| Date: | -- (:) |
| From: | Alan Schmitt <alan.schmitt@p...> |
| Subject: | [Caml-list] a few lexing questions |
Hi,
I am writing a parser / pretty-printer for the iCalendar file format,
and I have a few questions.
First of all, there are some times when I need to differentiate lexing
according to the first letter of what I am lexing. As I want to reuse
the lexing code, I did the following:
and alt_lang_xparam = parse
| 'A' { lexbuf.Lexing.lex_curr_pos <- Lexing.lexeme_start lexbuf;
Altrepparam (altrepparam lexbuf) }
| 'X' { lexbuf.Lexing.lex_curr_pos <- Lexing.lexeme_start lexbuf;
Xparam (xparam lexbuf) }
| 'L' { lexbuf.Lexing.lex_curr_pos <- Lexing.lexeme_start lexbuf;
Langparam (languageparam lexbuf) }
Is it buggy ? Bad style ? Is there a nicer way to do it ?
A second question is about integration this code with other lexing code
or streams. An iCalendar file cannot have a line that is longer than 75
bytes, excluding line break. A line may be broken anywhere as long as
there is a space at the beginning of the next line, as in:
this is a very lo
ng line
represents "this is a very long line". As this break may occur anywhere
(even inside keywords), I assume when writing the lexer these kind of
lines have been already merged together. I know how to implement the
merging using a temp file, but I'm looking for a nicer solution (like
using a stream, or using one lexer to feed the current lexer). Any
suggestion ?
I'd also like to have some advice on doing the symmetric transformation
(breaking long lines when necessary) ... Would streams be a good
solution here ?
Thanks a lot,
Alan Schmitt
--
The hacker: someone who figured things out and made something cool happen.
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