R/add_gg.R

In jtlandis/ggside: Side Grammar Graphics

### INCLUDE BEGIN
#' @include side-coord-cartesian.R
#' @include ggplot_add.R
#' @include side-facet_.R
#' @include z-depricated.R
NULL
### INCLUDE END



#' @keywords internal
validate_ggside <- function(e2, plot) UseMethod('validate_ggside')
#' @keywords internal
validate_ggside.default <- function(e2, plot) plot
#' @keywords internal
validate_ggside.Facet <- function(e2, plot){
  plot[['facet']] <- ggside_facet(plot[['facet']], plot[['ggside']])
  plot
}
#' @keywords internal
validate_ggside.Coord <- function(e2, plot) {
  plot[["coordinates"]] <- ggside_coord(plot[["coordinates"]])
  plot
}

plot_clone <- function(plot) {
  p <- plot
  p$scales <- plot$scales$clone()

  p
}

#' @export
`+.gg` <- function(e1, e2) {
  if (missing(e2)) {
    abort("Cannot use `+.gg()` with a single argument. Did you accidentally put + on a new line?")
  }
  e2name <- deparse(substitute(e2))
  add_gg(e1 = e1, e2 = e2, e2name = e2name)
}

#' @keywords internal
add_gg <- function(e1, e2, e2name) {
  UseMethod("add_gg")
}

#' @keywords internal
add_gg.default <- function(e1, e2, e2name) {
  abort(glue("No method defined for class {paste(class(e1),collapse = ', ')}."))
}

#' @keywords internal
add_gg.ggplot <- function(e1, e2, e2name){
  if (is.null(e2)) return(e1)

  p <- plot_clone(e1)
  p <- ggplot_add(object = e2, plot = p, object_name = e2name)
  set_last_plot(p)
  p
}

#' @importFrom ggplot2 merge_element
#' @keywords internal
add_gg.theme <- function(e1, e2, e2name) {
  if (!is.list(e2)) { # in various places in the code base, simple lists are used as themes
    abort(glue("Can't add `{e2name}` to a theme object."))
  }

  # If e2 is a complete theme or e1 is NULL, just return e2
  if (is_theme_complete(e2) || is.null(e1))
    return(e2)

  # Iterate over the elements that are to be updated
  for (item in names(e2)) {
    x <- merge_element(e2[[item]], e1[[item]])

    # Assign it back to e1
    # This is like doing e1[[item]] <- x, except that it preserves NULLs.
    # The other form will simply drop NULL values
    e1[item] <- list(x)
  }

  # make sure the "complete" attribute is set; this can be missing
  # when e1 is an empty list
  attr(e1, "complete") <- is_theme_complete(e1)

  # Only validate if both themes should be validated
  attr(e1, "validate") <-
    is_theme_validate(e1) && is_theme_validate(e2)

  e1
}

#' @keywords internal
add_gg.ggproto <- function(e1, e2, e2name) {
  abort("Cannot add ggproto objects together. Did you forget to add this object to a ggplot object?")
}

#' @keywords internal
add_gg.ggside <- function(e1, e2, e2name) {
  p <- NextMethod("add_gg")
  p <- clone_ggside_plot(p)
  validate_ggside(e2, plot = p)
}

is_theme_complete <- function(x) isTRUE(attr(x, "complete", exact = TRUE))

is_theme_validate <- function(x) {
  validate <- attr(x, "validate", exact = TRUE)
  if (is.null(validate))
    TRUE # we validate by default
  else
    isTRUE(validate)
}




# # @export
# merge_element.default <- function(new, old) {
#   if (is.null(old) || inherits(old, "element_blank")) {
#     return(new)
#   }
#   else if (is.null(new) || is.character(new) || is.numeric(new) ||
#            is.unit(new) || is.logical(new)) {
#     return(new)
#   }
#   cli::cli_abort("No method for merging {.cls {class(new)[1]}} into {.cls {class(old)[1]}}.")
# }
#
# merge_element.element <- function(new, old) {
#   if (is.null(old) || inherits(old, "element_blank")) {
#     return(new)
#   }
#   if (!inherits(new, class(old)[1])) {
#     cli::cli_abort("Only elements of the same class can be merged.")
#   }
#   idx <- vapply(new, is.null, logical(1))
#   idx <- names(idx[idx])
#   new[idx] <- old[idx]
#   new
# }
#
# merge_element.element_blank <- function(new, old) {
#   # If new is element_blank, just return it
#   new
# }