It's because of the fws in between hosts and the fws? inside field. You
could lower the priority of the inner one and raise the priority of the
outer one to resolve the ambiguity.
wsp = [ \t];
fws = ( ( wsp* crlf )? wsp+ ) ;
opt_fws = ( fws? )$(fws,0);
sep_fws = ( fws )$(fws,1);
field = (opt_fws alpha+ opt_fws);
host = (field ('.' field)*) >mark %print;
main := host (sep_fws host)*;
-Adrian
Husam Senussi wrote:
Hi,
I'm trying to use ragel to write parser for RFC2822 but I found some ambiguity
in the grammar so just want to see if
is solve it using priories.
Below is sample I found in the grammar with ambiguity
wsp = [ \t];
fws = ( ( wsp* crlf )? wsp+ )
field = (fws? alpha+ fws?);
host = (field ('.' field)*) >mark %print;
main := host (fws host)*;
The problem I found with input like this "a.mydomain.com b.mydomain.com" end
up calling print 3 times
1. "a.mydomain.com"
2. "a.mydomain.com "
3. "b.mydomain.com"
where I was expecting:
2. "a.mydomain.com "
3. "b.mydomain.com"
I'm assuming the problem is having fws? in end of field and one in main between
host, so is there
anyway solve this without breaking the grammar.
Sorry if this sounds like basic question I just started using Ragel.
Thanks
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