[antlr-interest] Explicit whitespace handling in W3C grammars
antlr at mirality.co.nz
Tue Oct 23 04:25:28 PDT 2007
At 02:32 23/10/2007, Andreas Ravnestad wrote:
>Consider this example:
>A : B C;
>With explicit whitespace handling, there can NOT be whitespace
>between B and C in this production.
>How can this be implemented with Antlr?
Write it as a lexer rule. Since whitespace is typically converted
into a hidden token (or discarded outright) as another (lower
priority) lexer rule, all other lexer rules that support internal
whitespace must explicitly state where it is allowed to occur.
(The same would be true of parser rules as well, if whitespace
wasn't skipped or hidden during lexing.)
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