[antlr-interest] Re: #( root children ) syntax change proposal?
Terence Parr
parrt at cs.usfca.edu
Tue Nov 18 13:56:08 PST 2003
On Tuesday, November 18, 2003, at 01:40 PM, lgcraymer wrote:
> Ter--
>
> There would not be any ambiguity between ^ as a suffix and ^( as a
> tree notation--"^(" can be interpreted as a token by the lexer.
> However, the current semantics of ^ is "root", not tree or AST
> node--that's #. I can see the ^( as a construction syntax, but would
> prefer to keep # as a tree matching prefix. In fact, I'd be willing
> to change my tree construction syntax from "#{" to "^{" and "#(" to
> "^("
> to emphasize the construct versus match differential.
Interesting. Verrrrry interesting. So to add an imaginary node you'd
say:
a : A^ ^{IMAG} B ;
To make a tree like this
A
|
IMAG -- B
?? Looks a bit weird, the ^{...} constructor. Is this what you were
thinking?
I do like this for the matching:
expr : ^(PLUS expr expr) | INT ;
rather than
expr : #(PLUS expr expr) | INT ;
Ter
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