gregexpr.extract_subpattern.R

gregexpr.extract_subpattern <- function(pattern, text, pattern.name) {
  r <- gregexpr(pattern, text, perl=TRUE)
  sapply(seq_along(r), function(i) {
    if (r[[i]] == -1) return("")
    a <- attributes(r[[i]])
    stopifnot(isTRUE(all.equal(pattern.name, a$capture.names)))
    substring(text[i], a$capture.start, a$capture.start + a$capture.length - 1)
  })
}