R/generate_po_from_pot.R

In RL10N/poio: Input/Output Functionality for "PO" and "POT" Message Translation Files

#' Generate a PO object from a POT object
#'
#' Generates a PO object from a POT object.
#' @param x An object of class \code{po}, as read by \code{\link{read_po}} from
#' a POT file.
#' @param lang A language code, possibly with a country code attached. See
#' \code{\link{language_codes}} for possible values.
#' @param ... Currently unused.
#' @return An object of class \code{po}, ready to be written to a PO file by
#' \code{\link{write_po}}.
#' @details The \code{file_type} element is changed from "pot" to "po", and
#' "Language" and "Plural-Forms" values are added to the metadata element.
#' @note If the plural form is unknown for the specified language, the plural
#' form is set to \code{NA}.  See \code{\link{plural_forms}} for supported
#' languages.
#' @examples
#' pot_file <- system.file("extdata/R-summerof69.pot", package = "poio")
#' pot <- read_po(pot_file)
#' # It's a good idea to fix the metadata before you generate the PO files
#' pot_fixed <- fix_metadata(pot, system.file(package = "poio"))
#'
#' # Call generate_po_from_pot for each language that you want to translate to
#' two_pos <- lapply(
#'   c(German = "de", Qatari_Arabic = "ar_QA"),
#'   generate_po_from_pot,
#'   x = pot_fixed
#' )
#'
#' # Notice the Language and Plural-forms elements in the metadata
#' two_pos$German$metadata
#' # Also notice that the countable msgstr elements for Arabic now
#' # have length 6, since Arabic has 6 plural forms
#' two_pos$Qatari_Arabic$countable$msgstr
#' @export
generate_po_from_pot <- function(x, lang, ...)
{
  UseMethod("generate_po_from_pot")
}

#' @importFrom dplyr bind_rows
#' @importFrom magrittr %>%
#' @importFrom tibble tibble
#' @rdname generate_po_from_pot
#' @export
generate_po_from_pot.po <- function(x, lang, ...)
{
  check_language(lang)
  x <- x$clone()
  x$file_type <- "po"
  # Add or fix the Language and Plural-Forms elements of the metadata
  plural_forms <- lookup_plural_forms_for_language(lang)
  if("Language" %in% x$metadata$name)
  {
    # Don't bother with dplyr here. The code isn't clearer.
    # x$metadata <- x$metadata %>%
    #   mutate(value = ~ ifelse(name == "Language", lang, value))
    x$metadata$value[x$metadata$name == "Language"] <- lang
  } else
  {
    x$metadata <- x$metadata %>%
      bind_rows(tibble(name = "Language", value = lang))
  }
  if("Plural-Forms" %in% x$metadata$name)
  {
    x$metadata$value[x$metadata$name == "Plural-Forms"] <- plural_forms
  } else
  {
    x$metadata <- x$metadata %>%
      bind_rows(tibble(name = "Plural-Forms", value = plural_forms))
  }

  # For countable messages, change the number of plural forms for the
  # translations
  # Can't just do lapply(`length<-`) since that appends NAs not ""
  n_plural_forms <- get_n_plural_forms(x$metadata)
  x$countable$msgstr <- x$countable$msgstr %>%
    lapply(
      function(x)
      {
        lenx <- length(x)
        if(n_plural_forms <= lenx)
        {
          return(x[seq_len(n_plural_forms)])
        } else # n_plural_forms > lenx
        {
          return(c(x, character(n_plural_forms - lenx)))
        }
      }
    )
  x
}