2015-04-02 11:49 GMT+02:00 phil@highoctane.be <phil@highoctane.be>:
Sure works.

Regex

'((XXX Logical Channel) ([0-9])) on (((Upstream)|(Downstream)) ([0-9])) on ((chassis) ([0-9])), ((slot) ([0-9])), ((mac) ([0-9]))' asRegex

But in PP, things were more comple and there were a lot of them, so:

line
^ temperatureStatusDescrEntry token asParser
/ temperatureStatusValueEntry token asParser
/ temperatureThresholdEntry token asParser
/ temperatureLastShutdownEntry token asParser
/ temperatureStateEntry token asParser
and things like

temperatureStatusDescrEntry ^ temperatureStatusDescrOidPrefix, oidIndex, space, equals, space, stringType, space, displayStringValue.

made my day much easier.

Especially when I had all the tokens I needed:

gauge32Type ^'Gauge32:' asParser flatten ==> [:str | #gauge32].


Not sure it would have been as flexible with a SmaCC (I am not familiar with SmaCC but used Lex/Yacc|Bison in another life).

SmaCC is a lot (and I mean a lot) simpler than Flex/bison, especially for the interaction between Flex and Bison (in short, SmaCC infer all the token/keyword stuff as well as the api between the two objects, behaving like a scannerless system).

For everything like keywords, for example, you don't even bother with the token:

Gauge32Type: "Gauge32:" { #gauge32 } ;

And of course you would:

TemperatureStatusDescrEntry : TemperatureStatusDescrOidPrefix OidIndex Space "=" Space StringType Space DisplayStringValue

(Everytime I read PetitParser code, I see the SmaCC grammar, usually in a more verbose form (asParser, asToken)... )

Some of the benefits of SmaCC are not that obvious in fact. Coming from the Flex/Bison world, what is striking is the multithreading ability of the SmaCC parser infrastructure: they have no global/shared space and you can create as many instances of them as you like, as often as you like... A second benefit, but harder to use, is the AST node automatic generation, with the api, an equality and visitors: this makes all the code appearing behind an SmaCC parser very regular.

However, if you derive on a regular basis grammars, the SmaCC API is not designed for that. It could do it (you could maybe include other grammars, for example), but nobody has expressed that need :)

Thierry