WIP: Initial infrastructure for editions

DESCRIPTION

@@ -33,11 +33,13 @@ Depends:
     R (>= 4.0)
 Imports: 
     cli,
+    desc,
     grDevices,
     grid,
     gtable (>= 0.1.1),
     isoband,
     lifecycle (> 1.0.1),
+    pkgload,
     rlang (>= 1.1.0),
     scales (>= 1.3.0),
     stats,
@@ -122,6 +124,7 @@ Collate:
     'coord-transform.R'
     'data.R'
     'docs_layer.R'
+    'edition.R'
     'facet-.R'
     'facet-grid-.R'
     'facet-null.R'

R/edition.R

@@ -0,0 +1,72 @@
+
+ggplot_edition <- new.env(parent = emptyenv())
+
+local_edition <- function(edition, .env = parent.frame()) {
+  stopifnot(is_zap(edition) || (is.numeric(edition) && length(edition) == 1))
+  pkg <- get_pkg_name(.env)
+  local_bindings(!!pkg := edition, .env = ggplot_edition, .frame = .env)
+}
+
+edition_get <- function(.env = parent.frame(), default = 2024L) {
+  pkg <- get_pkg_name(.env)
+
+  # Try to query edition from cache
+  edition <- env_get(ggplot_edition, nm = pkg, default = NULL)
+  if (!is.null(edition)) {
+    return(edition)
+  }
+
+  # Try to query package description
+  desc <- find_description(path = ".", package = pkg)
+  if (is.null(desc)) {
+    return(default)
+  }
+
+  # Look up edition from the description
+  field_name <- "Config/ggplot2/edition"
+  edition <- as.integer(desc$get_field(field_name, default = default))
+
+  # Cache result
+  env_bind(ggplot_edition, !!pkg := edition)
+  return(edition)
+}
+
+edition_deprecate <- function(edition, ..., .env = parent.frame()) {
+  check_number_whole(edition)
+  if (edition_get(.env) < edition) {
+    return(invisible(NULL))
+  }
+
+  edition <- I(paste0("edition ", edition))
+  lifecycle::deprecate_stop(edition, ...)
+}
+
+edition_require <- function(edition, what, .env = parent.frame()) {
+  check_number_whole(edition)
+  current <- edition_get(.env)
+  if (current >= edition) {
+    return(invisible(NULL))
+  }
+  msg <- paste0(what, " requires the ", edition, " edition of {.pkg ggplot2}.")
+  cli::cli_abort(msg)
+}
+
+find_description <- function(path, package = NULL) {
+  if (!is.null(package)) {
+    return(desc::desc(package = package))
+  } else {
+    try_fetch(
+      pkgload::pkg_desc(path),
+      error = function(e) NULL
+    )
+  }
+}
+
+get_pkg_name <- function(env = parent.frame()) {
+  env  <- topenv(env)
+  name <- environmentName(env)
+  if (!isNamespace(env) && name != "R_GlobalEnv") {
+    return(NULL)
+  }
+  name
+}