Hi all,
I'm updating a parser I wrote a couple of years ago, which parses a molecular
format called SMILES. Molecules contain atoms and bonds. The atoms include the
element name as an abbreviation.
Consider C and Cl as two such abbreviations. One is a prefix of the other. I had
is_raw_atom = (
#
'B' % raw_atom_B_5_action |
'C' % raw_atom_C_6_action |
'Cl' % raw_atom_Cl_17_action |
...
and that worked for what I was doing before, but now I'm trying to get error
handling to work. Suppose someone does "CQ". I want raw_atom_C_6_action to
occur and then an error.
Ragel doesn't do that. It reports the error at the 'C', because it never
transitions out from the end state.
What I did in my current update (in addition to changing the action names) is
this:
aliphatic_organic = (
'B' %is_aliphatic_B %err(is_aliphatic_B) |
'C' %is_aliphatic_C %err(is_aliphatic_C) |
'N' >is_aliphatic_N |
...
'Cl' %is_aliphatic_Cl %err(is_aliphatic_Cl) |
'Br' @is_aliphatic_Br |
...
);
It works, but is it correct and proper? I did see there was the |* ... *|
construct designed for things like this, but I didn't want the backtracking.
Best regards,
Andrew
[email protected]
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