privs
: (MULT|IDENTIFIER) (DOT^ privelement)*
;
privelement
: MULT
| IDENTIFIER
| -> MISSING
;
In your tree walker, count the elements to verify them and issue an error
for the MISSING node.
privs
@init {
int count = 0;
}
: privelement { count++; }
| ^(DOT privs privs)
;
privelement
: MULT
| IDENTIFIER
| MISSING { error(“Cannot….etc”); }
;
*From:* antlr-dev-boun...@antlr.org [mailto:antlr-dev-boun...@antlr.org] *On
Behalf Of *Mike Lischke
*Sent:* Friday, April 20, 2012 12:49 AM
*To:* ANTLR Mailing Mailing List
*Subject:* Re: [antlr-dev] Bug in C target generation
Hey Jim,
It is a problem with the code generation templates for all the targets
(well, Java and C at least), someone did post a fix for it on the list, but
it has not been issued as any formal patch yet.
Definitely not for C# because this code was taken from a grammar that works
well with C#.
privilege_level
: privs -> ^(PRIVILEGE_LEVEL $privs)
;
privs
: (MULT|IDENTIFIER) (DOT^ (MULT|IDENTIFIER))?
;
Though in fact I would avoid the PRIVILEGE_LEVEL node altogether unless its
absence causes ambiguity issues in the tree grammar.
Hmm, in fact, what I want to achieve actually is a bit different. But I
have some difficulties to formulate the grammar properly. These are the
cases I want to handle:
id
id. (error: missing id or star)
id.*
id.id
id.id. (error: missing id or star)
id.id.*
id.id.id
I would be thankful for a hint to get my brain into the right
direction. The best I could come up with is that I get a tree with an
invalid node. Tho actually I would like the special node with the missing
value (to ease their handling, e.g. for code completion). My current
grammar is:
primary:
parExpression
| literal
| number
| { LA(2) != DOT }? identifier (INC | DEC)?
| identifier DOT qualified_field
;
number:
NUM
| HEX_NUM
| DIGITS
| DECIMAL_NUM
;
qualified_field:
MULT
| { LA(2) != DOT }? identifier
| identifier DOT qualified_field2
;
qualified_field2:
MULT
| { LA(2) != DOT }? identifier
;
Without the lookaheads the matching process stops for cases like "id."
returning only the id without error.
Mike
--
www.soft-gems.net
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