How should one interpret the rule
fragment LETTER_UPPERCASE : [\p{Lu}] ;
at
https://github.com/okellogg/ada_antlr_grammar/blob/master/antlr4/ada.g4#L200
Is \p an ANTLR-specific escape sequence?
Meaning of [\p{Lu}] in ANTLR grammar
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1 Answers
\p{Lu} or \p{Uppercase_Letter} is a unicode category. It matches an uppercase letter that has a lowercase variant. By wrapping [ and ] around it, it is made into a character set.
See:
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