Parser generator (+ Lexer) that actually works?
in [TCL]
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From: Gerald W. Lester on 5 Jun 2010 14:28 Fredrik Karlsson wrote: > Hi, > > I've been trying to get hold of a parser generator + lexer combination > that would give me a parser implemented in Tcl, that actually works. > > My experience so far: > > taccle + fickle - just outputs nothing. Even the demos fails to give > any ouput. > Yeti - I get bus error every time I use either the parser or the lexer > demos. > > I am using UTF-8 encoding.. Are there other options out there that I > should try before continuing my current work of rolling my own parser > from scratch? If you have control over the input language, how about using a safe interp and letting the Tcl parser parse it for you. You define the language elements as commands aliased back to your main interp (or that do things directly if that is what you want). I've seen an "compiler" written this way. From a language that Tcl's parser could parse it generated a binary output file that was then uploaded to a computer as its program (also was first uploaded to a simulator to verify the program did what it was supposed to do). From what I've been reading in the press, it sounds like the program will be retired later this year after the last use of the hardware. -- +------------------------------------------------------------------------+ | Gerald W. Lester, President, KNG Consulting LLC | | Email: Gerald.Lester(a)kng-consulting.net | +------------------------------------------------------------------------+
From: Will Duquette on 5 Jun 2010 15:48 On Jun 5, 11:28 am, "Gerald W. Lester" <Gerald.Les...(a)KnG- Consulting.net> wrote: > Fredrik Karlsson wrote: > > Hi, > > > I've been trying to get hold of a parser generator + lexer combination > > that would give me a parser implemented in Tcl, that actually works. > > > My experience so far: > > > taccle + fickle - just outputs nothing. Even the demos fails to give > > any ouput. > > Yeti - I get bus error every time I use either the parser or the lexer > > demos. > > > I am using UTF-8 encoding.. Are there other options out there that I > > should try before continuing my current work of rolling my own parser > > from scratch? > > If you have control over the input language, how about using a safe interp > and letting the Tcl parser parse it for you. > > You define the language elements as commands aliased back to your main > interp (or that do things directly if that is what you want). I've seen an > "compiler" written this way. From a language that Tcl's parser could parse > it generated a binary output file that was then uploaded to a computer as > its program (also was first uploaded to a simulator to verify the program > did what it was supposed to do). From what I've been reading in the press, > it sounds like the program will be retired later this year after the last > use of the hardware. > > -- > +------------------------------------------------------------------------+ > | Gerald W. Lester, President, KNG Consulting LLC | > | Email: Gerald.Les...(a)kng-consulting.net | > +------------------------------------------------------------------------+ This approach is close to being one of the most used techniques in my bag of tricks. I must have implemented hundreds of tiny, application specific languages for particular tasks in this manner.
From: tom.rmadilo on 6 Jun 2010 00:18 On Jun 5, 11:28 am, "Gerald W. Lester" <Gerald.Les...(a)KnG- Consulting.net> wrote: > Fredrik Karlsson wrote: > > Hi, > > > I've been trying to get hold of a parser generator + lexer combination > > that would give me a parser implemented in Tcl, that actually works. > > > My experience so far: > > > taccle + fickle - just outputs nothing. Even the demos fails to give > > any ouput. > > Yeti - I get bus error every time I use either the parser or the lexer > > demos. > > > I am using UTF-8 encoding.. Are there other options out there that I > > should try before continuing my current work of rolling my own parser > > from scratch? > > If you have control over the input language, how about using a safe interp > and letting the Tcl parser parse it for you. I don't understand, if the Tcl parser can parse the language, wouldn't it be Tcl? But even so, since the Tcl parser doesn't enforce command structure, how does this end up working? There must be a simple example of this concept, which would be very helpful if you don't really need a flex/bison type generator.
From: Uwe Klein on 6 Jun 2010 05:01 tom.rmadilo wrote: > On Jun 5, 11:28 am, "Gerald W. Lester" <Gerald.Les...(a)KnG- > Consulting.net> wrote: > >>Fredrik Karlsson wrote: >> >>>Hi, >> >>>I've been trying to get hold of a parser generator + lexer combination >>>that would give me a parser implemented in Tcl, that actually works. >> >>>My experience so far: >> >>>taccle + fickle - just outputs nothing. Even the demos fails to give >>>any ouput. >>>Yeti - I get bus error every time I use either the parser or the lexer >>>demos. >> >>>I am using UTF-8 encoding.. Are there other options out there that I >>>should try before continuing my current work of rolling my own parser >>>from scratch? >> >>If you have control over the input language, how about using a safe interp >>and letting the Tcl parser parse it for you. > > > I don't understand, if the Tcl parser can parse the language, wouldn't > it be Tcl? Sure. > But even so, since the Tcl parser doesn't enforce command > structure, how does this end up working? There must be a simple > example of this concept, which would be very helpful if you don't > really need a flex/bison type generator. The basic idea about tcl: Being a framework for most "domain specific language" instances you could need, uwe >
From: Will Duquette on 6 Jun 2010 11:03
On Jun 5, 9:18 pm, "tom.rmadilo" <tom.rmad...(a)gmail.com> wrote: > On Jun 5, 11:28 am, "Gerald W. Lester" <Gerald.Les...(a)KnG- > > > > > > Consulting.net> wrote: > > Fredrik Karlsson wrote: > > > Hi, > > > > I've been trying to get hold of a parser generator + lexer combination > > > that would give me a parser implemented in Tcl, that actually works. > > > > My experience so far: > > > > taccle + fickle - just outputs nothing. Even the demos fails to give > > > any ouput. > > > Yeti - I get bus error every time I use either the parser or the lexer > > > demos. > > > > I am using UTF-8 encoding.. Are there other options out there that I > > > should try before continuing my current work of rolling my own parser > > > from scratch? > > > If you have control over the input language, how about using a safe interp > > and letting the Tcl parser parse it for you. > > I don't understand, if the Tcl parser can parse the language, wouldn't > it be Tcl? But even so, since the Tcl parser doesn't enforce command > structure, how does this end up working? There must be a simple > example of this concept, which would be very helpful if you don't > really need a flex/bison type generator. The trick is, you define a set of Tcl commands that provide the functionality you're looking for. These commands do all necessary error checking. Then, you put these commands in a safe interpreter that contains only the commands in your little language, along with any standard Tcl commands you want to provide (like expr). As you say, the resulting language is Tcl--in just the same sense as little languages built on Lisp remain Lisp. But for many applications, that's fine. Which is why Gerald asked whether Fredrik had control of the input syntax or not. |