Hi Josh;
I haven't looked at the grammar closely but as a note, are you using
Bison as both a lexer and parser? May I suggest that you separate lexing
from parsing and use flex and Bison rather than Bison alone? This does
nothing to solve your problem, but increases speed of execution,
decreases the size of tables, reduces the parsing statements, and makes
it easier to maintain.
art
On 11/12/2025 7:44 AM, Josh Meise wrote:
Hello,
I trust you are well.
I am working on building a LALR parser for ABNF grammars using Bison and am
running into shift/reduce conflicts pertaining to whitespace.
The rule that is causing this issue is the alternation rule (from the RFC
for ABNF <https://datatracker.ietf.org/doc/html/rfc5234>):
alternation = concatenation *(*c-wsp "/" *c-wsp concatenation)
concatenation = repetition *(1*c-wsp repetition) /* I have just set
repetition to be a character value for simplicity */
c-wsp = WSP / (c-nl WSP)
c-nl = comment / CRLF
comment = ";" *(WSP / VCHAR) CRLF
I have attached my current Bison grammar. I believe I know what is causing
the conflict but am having some trouble coming to a solution. Any advice
would be greatly appreciated.
Best,
Josh
