# ==================================================
# extractor.r
# --------------------------------------------------
#
# List extractor function creator function.
#
# --------------------------------------------------
# Author: RlonRyan
# Date : 5/3/2018
# ==================================================
#'
#' Create an Extractor Function
#'
#' Creates an extractor function for the given data input.
#'
#' @param x the list to create the extractor for.
#' @param default the default value to return in the case that an applied index turns out to be invalid.
#'
#' @return an extractor function for the list x.
#'
#' @export
#'
extractor <- function(x, default=NA) {
# Create basic extractor function.
extractor <- function(...) {
# Attempt to extract.
result <- tryCatch(
x[...],
error = function(e) { return(NA); }
);
# Remove NULL and NAs.
if(is.null(result) || is.na(result)) {
result <- default;
}
# Return the result.
return(result);
}
# Return the wrapped extractor.
return(extractor);
}
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