R/escapeRegex_(from_Hmisc).R

In Matherion/userfriendlyscience: Quantitative Analysis Made Accessible

### Taken directly from Hmisc (to avoid importing the package for just this function)


#' Escapes any characters that would have special meaning in a reqular
#' expression.
#' 
#' Escapes any characters that would have special meaning in a reqular
#' expression.
#' 
#' \code{escapeRegex} will escape any characters that would have special
#' meaning in a reqular expression. For any string
#' \code{grep(regexpEscape(string), string)} will always be true.
#' 
#' @aliases escapeRegex escapeBS
#' @param string string being operated on.
#' @return The value of the string with any characters that would have special
#' meaning in a reqular expression escaped.
#' @note Note that this function was copied literally from the \code{Hmisc}
#' package (to prevent importing the entire package for one line of code).
#' @author Charles Dupont\cr Department of Biostatistics\cr Vanderbilt
#' University
#' 
#' Maintainer: Gjalt-Jorn Peters <gjalt-jorn@@userfriendlyscience.com>
#' @seealso \code{\link[base]{grep}}, \code{Hmisc},
#' \url{http://biostat.mc.vanderbilt.edu/wiki/Main/Hmisc},
#' \url{https://github.com/harrelfe/Hmisc}
#' @keywords manip character programming
#' @examples
#' 
#' string <- "this\\(system) {is} [full]."
#' escapeRegex(string)
#' \dontshow{
#' if(!any(grep(escapeRegex(string), string))) {
#'   stop("function escapeRegex failed test")
#' }
#' }
#' 
#' @export escapeRegex
escapeRegex <- function (string)
{
  gsub("([.|()\\^{}+$*?]|\\[|\\])", "\\\\\\1", string)
}