Function builtin_grep 

fn builtin_grep(
    args: &[RValue],
    named: &[(String, RValue)],
) -> Result<RValue, RError>

Search for pattern matches in a character vector.

@param pattern character scalar: regular expression or fixed string @param x character vector to search @param value logical: if TRUE, return matching elements instead of indices @param fixed logical: if TRUE, pattern is a literal string @param ignore.case logical: if TRUE, matching is case-insensitive @return integer vector of indices (default) or character vector of matching elements