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List:       antlr-interest
Subject:    [antlr-interest] node construction proposed upgrade
From:       Terence Parr <parrt () cs ! usfca ! edu>
Date:       2011-02-26 21:45:54
Message-ID: 3905B53A-0C9D-4CEC-ACAD-14C8EBA24281 () cs ! usfca ! edu
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At moment you can set hetero node type with token option:

type : ID<TypeNode> ;

var : ID<VarNode> ;

Sometimes you want to set token type / text of node.  can use -> now

type : ID -> TYPENAME[$ID] ; // sets new token type for ID; copies text, line, col

a : lc='{' ... '}' -> BLOCK[$lc, "BLOCK"] ; // sets new token type and text

Inline i'm proposing two new token option names: text, ttype to join current options node and assoc.

type : ID<ttype=TYPENAME> ;

a : '{'<ttype=BLOCK, text="BLOCK"> ... '}' ;

My motivation is this

    |   e '?'^ e ':' e

following is gross but would work:

    |   e '?'<type=TERNARY, text="?:">^ e ':' e

we could also mimic rewrite stuff by allowing args on tokens in parser rules:

    |   e '?'[TERNARY, "?:"]^ e ':' e

what say ye? 2nd option is appealing but slightly diff fom how rewrite element args work.

Ter

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