[antlr-interest] Why cant += be used without an "output=" option (and other Q's)
Gavin Lambert
antlr at mirality.co.nz
Mon Feb 18 11:09:47 PST 2008
At 07:19 19/02/2008, Benjamin Shropshire wrote:
>What I'm having trouble with it using the += operator. If I set
>output=AST then ANTLR adds the sub rules return to some sort of
>list, however it also seems to expect me to generate an AST node
>in the sub rule for it to return. If I don't, I get a list of
>nulls (and end up with seg-v's) I still haven't figured out how
>to have a sub rule generate and return a specific type rather
>than the default antlr type.
If you're using code fragments to construct your own data
structures (and thus aren't generating an AST), there's no need to
use += at all.
If you are generating an AST, then every rule needs to generate an
AST, although you can also return additional information.
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