[antlr-interest] Would somebody help me clarify the difference between AST, Tree Grammars, and Parse Trees?

[ANTLR Mailing List]

I need a good example/explanation between the difference between tree
grammars, ASTs and Parse Trees.

I see that grammars don't have to be tree grammars to output ASTs.

This is very confusing to me...


For a simple grammar to test:

// Begin Grammar
grammar TestGrammar;


options {
    output = AST;
    k = 10;
}

tokens {
    STAT;
    SEMI = ';';
}

program    :    statement *;

statement
    :    expression SEMI;

expression
    :    INT;

INT    :    ( '0'..'9' ) +;
// End Grammar

When removing "output = AST", I see no difference in the output generated by
ANTLRWorks.

When putting "tree " in front of "grammar TestGrammar", it fails and
generates a NullPointerException.

Anybody have an explanation?
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.antlr.org/pipermail/antlr-interest/attachments/20071014/c9f2e50a/attachment.html