[e-lang] AST view of E program

[Kevin Reid]

On Sep 29, 2008, at 7:49, Marcelo D. Ré wrote:

>    I am working in a module to support E in NetBeans. Currently it
> sopport code highlight, braces completion, run e from the ide, and are
> developping the syntax check.
>    The question is: how to grab an AST from an E file? is it posible?

   def makeEParser := <import:org.erights.e.elang.syntax.makeEParser>

   makeEParser.run(theFile.getTwine())

The result of this is an AST of type ENode.

All of this can be accessed from Java too.

There is one caveat: in E-on-Java, there is no reified AST for un- 
expanded E syntax, only for Kernel-E. This may be sufficient,  
particularly as, provided that the source is a Twine (not a String),  
every ENode carries the line and column number of the source text  
corresponding to it (getOptSpan).


If it isn't, you can supply your own EBuilder (or is it ENodeBuilder?  
One's a class and the other's an interface) to EParser and get  
messages corresponding to the full syntax.

Another option is to use the grammar from E-on-CL, which is actually  
written in Java (generated by ANTLR), which provides an unexpanded AST.

> I have problem parsing the line
>
>              match [] { println(uri) }
>
>    in the counter-example.e.
>
>    I don't find a clause that parse the "println" statement.


This is an ordinary function call. The Kernel-E AST for this is

EMatcher
   ListPattern
     (no children)
   CallExpr
     NounExpr
       "println"
     "run"
     NounExpr
       "uri"

The unexpanded AST for this in E-on-CL is

EMatcher
   ListPattern
     (no children)
   FunCallExpr
     NounExpr
       "println"
     NounExpr
       "uri"

-- 
Kevin Reid                            <http://homepage.mac.com/kpreid/>