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#' @title
#' Trim Characters from the Left and/or Right Side of a String
#'
#' @description
#' These functions may be used e.g. to get rid of unnecessary
#' whitespaces from strings. Trimming ends at the first or
#' starts at the last \code{pattern} match.
#'
#' @details
#' Vectorized over \code{str} and \code{pattern}.
#'
#' \code{stri_trim} is a wrapper, which calls \code{stri_trim_left}
#' or \code{stri_trim_right} as appropriate. It's slightly slower than trim_left or
#' trim_right, and so shouldn't be used except for convenience.
#'
#' Contrary to many other string processing libraries,
#' our trimming functions are quite general. A character class,
#' given by \code{pattern},
#' may be adjusted to suit your needs (most often you will use the default
#' value). On the other hand, for replacing pattern matches with
#' arbitrary replacement string, see \code{\link{stri_replace}}.
#'
#' Interestingly, with these functions you may sometimes extract data, which
#' in some cases require using regular expressions. E.g. you may get
#' \code{"23.5"} out of \code{"total of 23.5 bitcoins"}.
#'
#' For trimming whitespaces, please note the difference
#' between Unicode binary property `\code{\\p\{Wspace\}}` (more general)
#' and general character category `\code{\\p\{Z\}}`,
#' see \link{stringi-search-charclass}.
#'
#' @param str a character vector of strings to be trimmed
#' @param pattern a single pattern, specifying character
#' classes that should be preserved (see \link{stringi-search-charclass}). Defaults to
#' `\code{\\P\{Wspace\}}.
#' @param side character [\code{stri_trim} only]; defaults to \code{"both"}
#'
#' @return All these functions return a character vector.
#'
#' @examples
#' stri_trim_left("               aaa")
#' stri_trim_right("rexamine.com/", "\\p{P}")
#' stri_trim_both(" Total of 23.5 bitcoins. ", "\\p{N}")
#' stri_trim_both(" Total of 23.5 bitcoins. ", "\\p{L}")
#'
#' @aliases stri_trim
#' @family search_replace
#' @family search_charclass
#' @rdname stri_trim
#' @export
stri_trim_both <- function(str, pattern="\\P{Wspace}") {
   .Call(C_stri_trim_both, str, pattern)
}


#' @rdname stri_trim
#' @export
stri_trim_left <- function(str, pattern="\\P{Wspace}") {
  .Call(C_stri_trim_left, str, pattern)
}


#' @rdname stri_trim
#' @export
stri_trim_right <- function(str, pattern="\\P{Wspace}") {
  .Call(C_stri_trim_right, str, pattern)
}


#' @rdname stri_trim
#' @export
stri_trim <- function(str, side=c("both", "left", "right"), pattern="\\P{Wspace}") {
   # `both` is default for compatibility with stringr
   side <- match.arg(side) # this is slow

   switch(side,
          both  =stri_trim_both(str, pattern),
          left  =stri_trim_left(str, pattern),
          right =stri_trim_right(str, pattern)
   )
}