Re: [Help-smalltalk] Which parser to use to parse the gnu-smalltalk code

[Holger Freyther]

> On 12 Apr 2015, at 16:56, Junsong Li <address@hidden> wrote:
> 
> Thanks. Basically what I want is just a method that compile the .st file, 
> give me the root node of the AST, then I can traverse the AST and print out 
> each kind of expression. I have tried _various_ classes in STInST, none of 
> them works. Here is what I got. There are basically Drivers and Parsers for 
> parsing:

The general approach is to look at the testcases. E.g. to parse a class the
first thing I found is:

> (STInST.STParsingDriver new parseSmalltalkStream: 'Object subclass: Test [ 
> method [ ^1 ] ]' readStream 
>   with: STInST.GSTFileInParser) parser

Did you have a look at the test cases? E.g. the STClassLoader? And did you look
at scripts/Convert.st which is using STInST to parse and re-format? At the same
also at the STCompiler which inherits from the RBProgramNodeVisitor?

The STInST.STParsingDriver hierarchy will load the code and call >>#evaluate:
on each node. So you don’t get an AST of ASTs with this.

But if you start the other way around. E.g. with the RBParser you can parse 
simple
expressions like STInST.RBParser parseExpression: '3+3’ or even entire methods
using STInST.RBBracketedMethodParser parseMethod: 'abc [ ^ 3]’ which will give
you RBMethodNode.

But starting from the STFileInparser subclass you need to provide a driver that
will be called whenever something has been parsed. It is then up to you to 
decide
what to do with the RB nodes.



> 
> Then I am stuck on getting AST out. It appears to having no methods to return 
> the AST node.  Anything wrong with it?

You looked at the driver. IIRC they go through the classes but don’t store 
them. E.g. the
STClassLoader loads a class and you can access a representation of the class 
then.