[antlr-interest] Lexer rule with alternatives (Newbie question)
Gavin Lambert
antlr at mirality.co.nz
Sat Nov 22 15:57:55 PST 2008
At 05:26 23/11/2008, Johannes Luber wrote:
>but there can be problems as '+' used in to different rules will
>create two distinct token types which will cause a
>MismatchedTokenTypeException later.
Actually normally it won't create separate token types, if you're
just using '+' on its own only in parser rules. But it's easy to
accidentally introduce additional types (if you forget to import
the lexer tokens; if you combine it with additional characters; if
you refer to it in other lexer rules as well; etc).
This is one of the reasons why I prefer to never use literal
characters in parser rules at all, and make explicit lexer rules
for them.
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