[antlr-interest] Navigate the C target AST

[Jim Idle]

Use the super pointer in the ANTLR3_BASE_TREE and cast it to
pANTLR3_COMMON_TREE. The getToken returns the BASE_TOKEN, which  has a
super, which is casy to COMMON_TOKEN.

Check: makeDot in basetreeadaptor for some examples.

You can only get tokens for nodes that have them of course.

Jim

> -----Original Message-----
> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
> bounces at antlr.org] On Behalf Of Richard Connon
> Sent: Tuesday, December 07, 2010 2:51 PM
> To: antlr-interest at antlr.org
> Subject: [antlr-interest] Navigate the C target AST
> 
> Hi. I'm trying to navigate the AST built using the ANTLR3 C target.
> 
> I'm wondering how the token information is stored in the tree nodes. It
> seems there are two types of tree nodes. ANTLR3_BASE_TREE and
> ANTLR3_COMMON_TREE and I can set my grammar to produce the AST with
> either one.
> 
> The documentation suggests that an ANTLR3_BASE_TREE has no token
> information yet it contains a pointer to the getToken(ANTLR3_BASE_TREE)
> function. Can anyone clarify this?
> 
> I've been trying out each type to try and work it out.
> 
> getToken(ANTLR3_BASE_TREE) on the ANTLR3_BASE_TREE seems to return 0x0
> which would support what the docs say about it having no token
> "payload"
> but then why does this function exist.
> 
> When using ANTLR3_COMMON_TREE instead since I assumed this to be the
> solution, the token member of the struct is also 0x0 Finally doing
> commonTree->baseTree.getToken(&commonTree->basetree) as a last resort
> caused the program to segfault in dupTree()
> 
> All in all I'm a bit confused about where the "content" of the AST
> actually lies.
> 
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