Move semicolon hack into lexer#18931
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nik9000 merged 1 commit intoelastic:masterfrom Jun 17, 2016
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Nit: please drop the semicolon down a line to conform to the style of the other multi-line rules.
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Couple of minor comments, otherwise +1. |
Perviously we used token level lookbehind in the parser. That worked,
but only if the parser didn't have any ambiguity *at all*. Since the
parser has ambiguity it didn't work everywhere. In particular it failed
when parsing blocks in lambdas like `a -> {int b = a + 2; b * b}`.
This moves the hack from the parser into the lexer. There we can use
token lookbehind (same trick) to *insert* semicolons into the token
stream. This works much better for antlr because antlr's prediction
code can work with real tokens.
Also, the lexer is simpler than the parser, so if there is a place
to introduce a hack, that is a better place.
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Thanks for reviewing @jdconrad ! I renamed the class, fixed the style and merged. We can rename the class again if anyone comes up with a better name. |
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Perviously we used token level lookbehind in the parser. That worked,
but only if the parser didn't have any ambiguity at all. Since the
parser has ambiguity it didn't work everywhere. In particular it failed
when parsing blocks in lambdas like
a -> {int b = a + 2; b * b}.This moves the hack from the parser into the lexer. There we can use
token lookbehind (same trick) to insert semicolons into the token
stream. This works much better for antlr because antlr's prediction
code can work with real tokens.
Also, the lexer is simpler than the parser, so if there is a place
to introduce a hack, that is a better place.