On Friday 16 of October 2009 at 04:02:02, Andrew Dalke wrote: > On Oct 14, 2009, at 4:42 PM, matio wrote: > > to implement an 'if', do you have to use 'ast' like in GardenSnake > > GardenSnake was something I wrote years ago. It uses the ast because > GardenSnake ends up generating Python byte code and I could leverage > existing Python data structures and byte code generation to help with > that. > > Implementing an 'if' can be done in many ways, so there's no way to > answer than without a lot more context. > > Based on your postings, you still have a lot to go before you > understand PLY and how it works, You posted a snippet of code (with > t_ccode_lbrace and t_ccode_rbrace) and asked what it does. It comes > from the PLY documentation, and with a description in the paragraph > before the code. > > But to understand that description you have to know why lexers (being > regular grammars) can't on their own handle balanced braces. And to > get that requires some theory background that can be hard for people > to pick up on their own. > > I cannot help you there. I learned this through university course > work and a lot of work on my own. There are books on the topic, but > then you'll have to learn how to convert from the syntax used in the > book to using PLY, which isn't always direct. Nor do I have advice on > which books to even look at to get a better understanding.
I can recommend a book called Parsing Techniques - A Practical Guide. It describes grammars and parsing and is very useful if you want to learn what is under the hood (and why your grammar doesn't work sometimes). It is freely available at http://www.cs.vu.nl/~dick/PTAPG.html (check the Availability section for direct download links). Best regards, Oldrich. > Best regards, > > Andrew > [email protected] > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "ply-hack" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/ply-hack?hl=en -~----------~----~----~----~------~----~------~--~---
