R/rematch2.R

In r-hub/pkgsearch: Search and Query CRAN R Packages

re_match <- function(text, pattern, perl = TRUE, ...) {

  assert_that(is_string(pattern))
  text <- as.character(text)

  match <- regexpr(pattern, text, perl = perl, ...)

  start  <- as.vector(match)
  length <- attr(match, "match.length")
  end    <- start + length - 1L

  matchstr <- substring(text, start, end)
  matchstr[ start == -1 ] <- NA_character_

  res <- data_frame(.text = text, .match = matchstr)

  if (!is.null(attr(match, "capture.start"))) {

    gstart  <- attr(match, "capture.start")
    glength <- attr(match, "capture.length")
    gend    <- gstart + glength - 1L

    groupstr <- substring(text, gstart, gend)
    groupstr[ gstart == -1 ] <- NA_character_
    dim(groupstr) <- dim(gstart)

    res <- cbind(groupstr, res, stringsAsFactors = FALSE)
  }
  names(res) <- c(attr(match, "capture.names"), ".text", ".match")
  class(res) <- c("tbl", class(res))
  res
}