ECMAScript.g4

[Jason Hullinger]

Hi, I'm getting the following errors with ECMAScript.g4 when running Antlr4:

error(156): ECMAScript.g4:1460:4: invalid escape sequence

error(156): ECMAScript.g4:1470:4: invalid escape sequence

Upon inspecting the lines, it looks like there is an invalid escape sequence on the following lines (https://github.com/antlr/grammars-v4/blob/master/ecmascript/ECMAScript.g4#L1460 and https://github.com/antlr/grammars-v4/blob/master/ecmascript/ECMAScript.g4#L1470):

: ~[\r\n\u2028\u2029*\\/\[]

I believe it should be the following because "\[" is not a valid escape character:

: ~[\r\n\u2028\u2029*\\/[]

Can anyone please confirm?

Thanks,

Jason

[Vassili Bykov]

I think you are right, because I made the same change when I borrowed regex literal-related stuff from that grammar for my needs.

There is also a performance gotcha in the way RegularExpressionLiteral puts the isRegexPossible() predicate at the start of the rule:

RegularExpressionLiteral

: {isRegexPossible()}? '/' RegularExpressionBody '/' RegularExpressionFlags

;

I moved the predicate after the '/' and got a 30x performance improvement.

[Jason Hullinger]

Great, thanks much for the input and gotcha!

Jason