damn you guys speak in a language I am not aware of :D Looks like I have reading to do.
Anyway regex worked fin for converting pharo messages to python method calls and assignment / reading variables . Regex was actually quite simple to learn. Now for classes I dont know if RBParser would be an overkill or not, probably its good. I have asked before and I was shown how nodes works with AST but I have not used that information yet. I dont care about a full python parser, thats not my goal. Its not my goal to take pharo code and fully convert it to python code, only make it easy for pharoers to use python libraries. So I move in small steps , instead of trying to create a whole parser. Though a full python parser would not be a bad idea either. So I am definitely interested to what you saying. On Tue, Sep 23, 2014 at 3:20 PM, Thierry Goubier <thierry.goub...@gmail.com> wrote: > > > 2014-09-23 13:57 GMT+02:00 Udo Schneider <udo.schnei...@homeaddress.de>: > >> > yeap noway I compare Regex with PettitParser. I will probably give a >> > PettitParser a try, because I try to parse Pharo syntax to Python, I >> > want now to parse Pharo classes to python class and that will be a >> > nightmare with regex, so time to give PettitParser a serious try. >> Without wanting to go too deep into theory... Parsing Pharo or Python >> would definitely need a Chromsky Type 2 language (Context free grammar). So >> you'd be out of luck parsing Smalltalk or Python code with Regular >> Expressions (Chromsky Type 3) only - except maybe for some very simple >> expressions. >> > > Confirmed in even a better way: given how convoluted and hacky is writing > a full Python Parser, it is probably not even a Context Free Grammar. > > That is: the Python grammar is LALR which is a subset of Context Free > Grammar (but already more than a type 3 Chomsky grammar), but the Lexer is > a fair bit more than usual (dedent tokens come to mind; special handling of > end of lines as well). > > I think you need a fair bit of special magic in PetitParser to parse > Python. > > Luckily, Python is well documented in that regard. > > Thierry > > >> >> CU, >> >> Udo >> >> >> On 23.09.14 13:35, kilon alios wrote: >> >>> yeap noway I compare Regex with PettitParser. I will probably give a >>> PettitParser a try, because I try to parse Pharo syntax to Python, I >>> want now to parse Pharo classes to python class and that will be a >>> nightmare with regex, so time to give PettitParser a serious try. >>> >>> On Tue, Sep 23, 2014 at 1:10 PM, Udo Schneider >>> <udo.schnei...@homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>> wrote: >>> >>> > I have not used PettitParser yet, looks powerful but I find it a >>> bit >>> > weird in design. On the other hand regex is quite ugly and >>> understanding >>> > complex regex a pain. >>> I normally encounter two issues with RegExps: >>> >>> 1) The syntax between different apps/libs/frameworks differs >>> sligtly. Esp. for character classes or greediness. This drove me >>> crazy more than one time. >>> 2) Often enough I realize (while developing the RegExp) that I need >>> something more capable than a Chomsky Type 3 parser (which RegExps >>> are in a way). So I have to use "a bigger gun" - e.g. PetitParser. >>> >>> CU, >>> >>> Udo >>> >>> >>> On 23.09.14 10:15, kilon alios wrote: >>> >>> it reminds a lot of Kent's Beck Smalltalk Practice Patterns >>> where it >>> removes all ifs and replaces them with regular unary messages . >>> It is >>> definitely an elegant way of coding making the code just flow. >>> >>> I have not used PettitParser yet, looks powerful but I find it a >>> bit >>> weird in design. On the other hand regex is quite ugly and >>> understanding >>> complex regex a pain. >>> >>> On Tue, Sep 23, 2014 at 11:07 AM, Udo Schneider >>> <udo.schnei...@homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de> >>> <mailto:udo.schneider@__homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>>> >>> wrote: >>> >>> > just as it is black magic for me now :D >>> The nice thing about this approach is the fact that it >>> "just" >>> piggybacks the normal Smalltalk message sending. So you can >>> step >>> through it using the Debugger - it's Smalltalk all the way >>> down. >>> >>> I still remember my first shock when (having no formal >>> background on >>> parsing theory at that time) I saw the parsing tables >>> generated by >>> T-Gen. Of course it was Smalltalk ... but understanding >>> those tables >>> was a nightmare. >>> >>> PetitParser is the gold standard here IMHO. It is able to >>> parse >>> arbitrary input (compared to my block expressions only). >>> And you can >>> still use the Debugger to step through the parsing process >>> *and >>> still understand what's going on!* >>> >>> CU, >>> >>> Udo >>> >>> On 23.09.14 09:54, kilon alios wrote: >>> >>> just as it is black magic for me now :D >>> >>> At least I get the general feeling. I am new to parsing >>> too, so >>> far I >>> have only played with regex parsing. Not the most >>> smalltalkish >>> way but >>> it works well so far. >>> >>> On Tue, Sep 23, 2014 at 9:39 AM, Udo Schneider >>> <udo.schnei...@homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de> >>> <mailto:udo.schneider@__homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>> >>> <mailto:udo.schneider@ >>> <mailto:udo.schneider@>__homead__dress.de <http://homeaddress.de >>> > >>> >>> >>> <mailto:udo.schneider@__homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>>>> >>> wrote: >>> >>> Hi Estaban, >>> >>> I think the first time I saw this pattern was in >>> ReStore on >>> Dolphin >>> Smalltalk. I didn't understand it's implementation >>> back then. I >>> assume that it's similar to what I described >>> though. But >>> having a >>> Smalltalk block automagically creating the >>> equivalent SQL >>> SELECT >>> expression was like black magic at that time :-) >>> >>> CU, >>> >>> Udo >>> >>> >>> >>> >>> On 23.09.14 04:15, Esteban A. Maringolo wrote: >>> >>> Excellent article. >>> >>> I think GLORP uses a similar technique to >>> setup its >>> expressions, and >>> also have issues with #and:/#or: selectors due >>> to >>> inlining, so >>> it uses >>> AND:/#OR: instead. >>> >>> Regards! >>> >>> Esteban A. Maringolo >>> >>> pd: Your blog and it's choosen topic made me >>> remember >>> http://use-the-index-luke.com/ >>> >>> 2014-09-22 20:48 GMT-03:00 Udo Schneider >>> <udo.schnei...@homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de> >>> <mailto:udo.schneider@__homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>> >>> <mailto:udo.schneider@ >>> <mailto:udo.schneider@>__homead__dress.de <http://homeaddress.de >>> > >>> <mailto:udo.schneider@__homeaddress.de >>> <mailto:udo.schnei...@homeaddress.de>>>>__: >>> >>> >>> All, >>> >>> I just finished a blog entry. It shows how >>> to use >>> Smalltalk >>> blocks as parsers/translators. E.g. >>> translating a Block >>> >>> [:customer | (customer joinDate >>> year is: Date >>> today year)] >>> >>> into an SQL-like String >>> >>> (YEAR(customers.joinDate) = 2014) >>> >>> The SQL stuff is just an example - you can >>> create >>> nearly any >>> output. >>> >>> Check out >>> http://readthesourceluke.__blo____gspot.de/2014/09/block-___ >>> ___translators-parsing-magic.html >>> <http://blo__gspot.de/2014/09/block-____translators-parsing- >>> magic.html> >>> >>> <http://blogspot.de/2014/09/__block-__translators-parsing-__ >>> magic.html >>> <http://blogspot.de/2014/09/block-__translators-parsing- >>> magic.html>> >>> >>> >>> <http://readthesourceluke.__bl__ogspot.de/2014/09/block-____ >>> translators-parsing-magic.html >>> <http://blogspot.de/2014/09/block-__translators-parsing- >>> magic.html> >>> >>> <http://readthesourceluke.__blogspot.de/2014/09/block-__ >>> translators-parsing-magic.html >>> <http://readthesourceluke.blogspot.de/2014/09/block- >>> translators-parsing-magic.html>__>__> >>> >>> Maybe that's old stuff for some of you - >>> but I hope >>> it's >>> interesting for some at least :-) >>> >>> Comments and feedback appreciated. >>> >>> CU, >>> >>> Udo >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >> >> >
