R/utf8_format.R

In utf8: Unicode Text Processing

#  Copyright 2017 Patrick O. Perry.
#
#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
#  You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
#  Unless required by applicable law or agreed to in writing, software
#  distributed under the License is distributed on an "AS IS" BASIS,
#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#  See the License for the specific language governing permissions and
#  limitations under the License.

utf8_format <- function(x, trim = FALSE, chars = NULL, justify = "left",
                        width = NULL, na.encode = TRUE, quote = FALSE,
                        na.print = NULL, print.gap = NULL, utf8 = NULL, ...) {
  if (is.null(x)) {
    return(NULL)
  }

  if (!is.character(x)) {
    stop("argument is not a character object")
  }

  with_rethrow({
    trim <- as_option("trim", trim)
    chars <- as_chars("chars", chars)
    justify <- as_justify("justify", justify)
    width <- as_integer_scalar("width", width)
    na.encode <- as_option("na.encode", na.encode)
    quote <- as_option("quote", quote)
    na.print <- as_na_print("na.print", na.print)
    print.gap <- as_print_gap("print_gap", print.gap)
    utf8 <- as_output_utf8("utf8", utf8)
  })

  ellipsis <- "\u2026"
  iellipsis <- iconv(ellipsis, "UTF-8", "")
  if (is.na(iellipsis) || identical(iellipsis, "...")) {
    ellipsis <- "..."
    wellipsis <- 3L
  } else {
    wellipsis <- 1L
  }

  if (is.null(chars) && length(x) > 0) {
    linewidth <- getOption("width")
    quotes <- if (quote) 2 else 0
    gap <- if (is.null(print.gap)) 1 else NULL

    dim <- dim(x)
    dimnames <- dimnames(x)
    names <- if (is.null(dimnames)) names(x) else dimnames[[1]]

    if (is.null(names)) {
      comma <- length(dim) > 1
      namewidth <- floor(log10(length(x)) + 1) + 2 + comma
    } else if (length(dim) > 1) {
      namewidth <- max(0, utf8_width(names, utf8 = utf8))
    } else {
      namewidth <- 0
    }

    chars <- (linewidth - wellipsis - quotes - gap - namewidth)
    chars <- max(chars, 12)
  }

  .Call(
    rutf8_utf8_format, x, trim, chars, justify, width, na.encode,
    quote, na.print, ellipsis, wellipsis, utf8
  )
}