[ragel-users] short strings, including some which are 1-letter prefixes of other

[Adrian Thurston]

Hi Andrew,

Hmmm, that's an idea. Leaving actions executed on error ... I'm going to 
have to mull over that. Might be the right thing to do.

How is the aliphatic_organic used?

You may be able to do the following:

something = (
	aliphatic_organic @1 |
	any @0 @{raise error}
)**

Andrew Dalke wrote:
> 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
> 				dalke at dalkescientific.com
> 
> 
> 
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