tree - ANTLR syntax error unexpected token: + -

-

hi have small problem in antlr tree grammar. using antlrworks 1.4. in parser grammar have rule this:

declaration :       'variable' identifier ( ',' identifier)* ':' type ';' ->    ^('variable' identifier type)+

so wanted 1 tree per each identifier.

and in tree grammar left rewrite rules:

declaration :     ^('variable' identifier type)+

but when check grammar got syntax error unexpected token +. , + sign @ end of declaration rule in tree grammar. doing wrong?

parser grammar works fine , builds ast tree expected. generated lexer , parser c# , test input.

when parsing source:

variable a, b, c : int;

you're trying construct ast looks like:

variable variable variable     /        |        \            b         c   /          |          \ int         int         int

but since 'variable' , type same token, see no need create duplicate nodes. why not do:

declaration   :  'variable' identifier ( ',' identifier)* ':' type ';'       -> ^('variable' type identifier+)   ;

which create ast like:

 variable   / | | \ int b  c

?


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