CodeQL library for Python
codeql/python-all 0.12.1 (changelog, source)

Member predicate RegExp::char_set_delimiter

Helper predicate for chars that could be character-set delimiters. Holds if the (non-escaped) char at pos in the string, is the (one-based) index occurrence of a bracket ([ or ]) in the string. Result if true is the char is [, and false if the char is ].

boolean char_set_delimiter(int index, int pos)