[antlr-interest] C++ as a target - FAQ questions...

[Ric Klaren]

Hi,

On Wed, Sep 22, 2004 at 11:19:14AM -0400, Bryan Ewbank wrote:
> I've just started to use ANTLR, and seem to be in the minority because I
> have C++ as my target language, rather than java.  I've been able to compile
> an executable with my language it in (hurrah!), but am having a hard time
> sorting out what is Java and what is ANTLR in a specific file.
>
> Is there a place where someone that knows compilers well (theory and
> application) can find information on what is available in the actions and
> surrounding code for a C++ target?   The LL(k) versus LALR stuff wasn't much
> of a problem - though lexing REAL versus INTEGER is annoying - but figuring
> out the class hierarchy and what magic incantation to use to get what I want
> seems to be hard.
>
> For example, I know that C++ uses "->" in most(?) places where the Java uses
> "."; likewise, "::" instead of "." seemed to resolve some other problems.

The "->" appears for all the reference counted stuff.
- Tokens  (RefToken)
- AST nodes (RefAST)
- LexerSharedInputState
- ParserSharedInputState

For all places where the dots appear for namespace qualification the C++
parts use "::".

In general all the action code is pure C++. Though the filtering that is
done on the code inside the action code to translate the tree
building/referencing is somewhat crude at times (lacking in error feedback,
but that's a general antlr problem)

You also can generate documentation of the support library with doxygen.

In case of doubt it really helps to look at the generated code. But that's
a general idiom for antlr.

> Now I'm at one that stumped me.  In the "Debugging and Testing Grammars"
> discussion on the web, there are several calls to "super.<xxyyzz>"; however,
> I don't know the name of the superclass to use when translating this to C++,
> so can't precisely implement this on my own.

You mean you're trying to port the ParseTreeDebugParser stuff from java to
C++ ? If you get it working I'd welcome the files then I can include them
in the C++ support library.

To get to the question if I look at for instance ParseTreeDebugParser:

Some of the constructors would be ported to:

public:
ParseTreeDebugParser( int k ) 
: LLkParser(k)
{
}
public:
ParseTreeDebugParser( TokenBuffer& tokenBuf, int k ) 
: LLkParser(tokenBuf,k)
{
}
public:
ParseTreeDebugParser( TokenStream& lexer, int k )
: LLkParser(lexer,k)
{
}

It's basically chaining the constructors to the superclass.

Add the necessary ugly ANTLR_USE_NAMESPACE(antlr) macro's for the antlr
classes btw.

The super.match( .. ) things would translate to LLkParser::match( .. ) 

Cheers,

Ric
--
-----+++++*****************************************************+++++++++-------
    ---- Ric Klaren ----- j.klaren at utwente.nl ----- +31 53 4893755  ----
-----+++++*****************************************************+++++++++-------
  Chaos often breeds life, when order breeds habit.
  --- Henry B. Adams, The Education of Henry Adams


 
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