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# A registry of caches for different directories
.caches <- new.env(parent = emptyenv())
#' Get and set the cache object registered for a specific directory
#'
#' @details
#'
#' If `sass_cache_get_dir()` is called for a given directory, before
#' `sass_cache_set_dir()` has been called for that directory, then it will
#' return `NULL`.
#'
#' After `sass_cache_set_dir()` is called for a directory, any future calls to
#' `sass_cache_get_dir()` with that directory will return that specific cache
#' object. This can be useful if you customize parameters for the cache object,
#' like maximum size or age.
#'
#'
#' @param dir A directory. An error will be thrown if the directory does not
#' exist.
#' @param cache A [sass_file_cache()] object, or `NULL` if you don't want to
#' unset the cache for a directory.
#' @param create If `TRUE`, then if the cache directory doesn't exist, or if
#' there is not a registered cache object for the directory, create them as
#' needed.
#'
#' @seealso [sass_cache_get()], [sass_file_cache()], [sass()]
#'
#' @keywords internal
#' @export
sass_cache_get_dir <- function(dir, create = FALSE) {
if (create) {
# Create dir if needed
if (!dir.exists(dir)) {
dir.create2(dir)
}
dir <- normalizePath(dir, mustWork = TRUE)
# Create cache object if needed
if (is.null(.caches[[dir]])) {
sass_cache_set_dir(dir, sass_file_cache(dir))
}
} else {
if (!dir.exists(dir)) {
stop("`dir` does not exist.")
}
}
dir <- normalizePath(dir, mustWork = TRUE)
.caches[[dir]]
}
#' @rdname sass_cache_get_dir
#' @export
sass_cache_set_dir <- function(dir, cache) {
if (!is.null(cache) && !inherits(cache, "FileCache")) {
stop("`cache` must be a FileCache object or NULL.")
}
if (!dir.exists(dir)) {
stop("`dir` does not exist.")
}
dir <- normalizePath(dir, mustWork = TRUE)
if (is.null(cache)) {
# Unset the cache registered for a directory
if (exists(dir, envir = .caches, inherits = FALSE)) {
rm(list = dir, envir = .caches)
}
return(invisible(NULL))
}
if (!identical(dir, normalizePath(cache$dir()))) {
stop("`dir` and the cache object's directory do not match.")
}
.caches[[dir]] <- cache
invisible(cache)
}
#' Get default sass cache object for the current context
#'
#' @description
#'
#' Get the default sass cache object, for the current context. The context
#' depends on factors described below.
#'
#' `sass_cache_get()` first checks the `sass.cache` option. If it is set to
#' `NULL` or `FALSE`, then this function returns `NULL`. If it has been set to a string,
#' it is treated as a directory name, and this function returns a
#' `sass_file_cache()` object using that directory. If the option has been set
#' to a `sass_file_cache()` object, then it will return that object.
#'
#' In most cases, this function uses the user's cache directory, by calling
#' `tools::R_user_dir("sass", which = "cache")` (for R 4.0 and above) or
#' `rappdirs::user_cache_dir("R-sass")` (for older versions of R).
#'
#' If this function is called from a Shiny application, it will also look for a
#' subdirectory named `app_cache/`. If it exists, it will use a directory named
#' `app_cache/sass/` to store the cache.
#'
#' When running a Shiny application in a typical R session, it will not create
#' the `app_cache/` subdirectory, but it will use it if present. This scopes the
#' cache to the application.
#'
#' With Shiny applications hosted on Shiny Server and Connect, it _will_ create
#' a `app_cache/sass/` subdirectory, so that the cache is scoped to the
#' application and will not interfere with another application's cache.
#'
#' @section Shiny Developer Mode:
#'
# TODO change shiny devmode link to a roxygen link once shiny is released
# Would need a shiny version >= 1.5.0.9006
#' If Shiny Developer Mode is enabled (by setting `options(shiny.devmode = TRUE)` or calling `shiny::devmode(TRUE)`,
#' the default global option value for `sass.cache` is updated to `FALSE` instead
#' of `TRUE`, similar to `getOption("sass.cache", FALSE)`. This setting allows
#' developers to make sure what is being returned from [sass()] is not an incorrect
#' cache result.
#'
#' @seealso [sass_cache_get_dir()], [sass()]
#'
#' @export
sass_cache_get <- function() {
cache_option <-
get_shiny_devmode_option(
"sass.cache",
default = TRUE,
devmode_default = FALSE,
devmode_message = "Turning off caching of Sass -> CSS compilation. To turn caching on, call `options(sass.cache = TRUE)`"
)
if (is.null(cache_option) || identical(cache_option, FALSE)) {
return(NULL)
}
if (inherits(cache_option, "FileCache")) {
return(cache_option)
}
cache_dir <- NULL
if (is.character(cache_option)) {
cache_dir <- cache_option
}
# Default case
if (is.null(cache_dir)) {
cache_dir <- sass_cache_context_dir()
}
sass_cache_get_dir(cache_dir, create = TRUE)
}
#' Return the cache directory for the current context.
#'
#' @keywords internal
#' @export
sass_cache_context_dir <- function() {
tryCatch(
{
# The usual place we'll look. This may be superseded below.
cache_dir <- find_cache_dir("sass")
if (is_shiny_app()) {
# We might use ./cache/sass, if it's a hosted app, or if the directory
# already exists. (We won't automatically create the directory on
# locally-running apps.)
app_dir <- shiny::getShinyOption("appDir")
app_cache_dir <- file.path(app_dir, "app_cache", "sass")
if (is_hosted_app()) {
# On hosted platforms, always create a ./cache/sass subdir for caching
# sass stuff.
cache_dir <- app_cache_dir
} else {
# When running an app in a normal R session...
if (dir.exists(app_cache_dir) || dir.exists(dirname(app_cache_dir))) {
# If ./cache/sass or ./cache already exists, use it.
cache_dir <- app_cache_dir
}
}
}
if (!dir.exists(cache_dir)) {
res <- dir.create(cache_dir, recursive = TRUE)
if (!res) {
stop("Error creating cache directory")
}
}
},
error = function(e) {
# If all of the attempts to find/create a dir failed, just use a temp dir.
warning("Error using cache directory at '", cache_dir,
"'. Using temp dir instead.")
cache_dir <<- tempfile("sass-")
dir.create(cache_dir)
}
)
normalizePath(cache_dir)
}
#' Returns a hash of the object, including sass_file mtimes
#'
#' This function returns a hash of the object `x`, intended for use in caching.
#' It recurses into lists, and any [sass_file()] objects will have the file's
#' mtime attached as an attribute. This is useful for detecting if the file has
#' been modified.
#'
#' @param x A list with sass objects.
#' @noRd
sass_hash <- function(x) {
digest::digest(
add_sass_file_mtime(list(x, utils::packageVersion("sass"))),
algo = "xxhash64"
)
}
# Given an object, return an object that can be \code{digest::digest}-ed into a
# hash key. This traverses the object and adds file mtimes for files imported
# via `sass_file` directives (but not files that are imported by those files).
add_sass_file_mtime <- function(x) {
if (inherits(x, "sass_file")) {
# Add the file's mtime to the cache key. This will cause mtime changes to
# bust the cache.
input_path <- attr(x, "sass_file_path", exact = TRUE)
attr(x, "sass_timestamp") <- file.mtime(input_path)
x
} else if (inherits(x, "list")) {
lapply(x, add_sass_file_mtime)
} else {
x
}
}
find_cache_dir <- function(pkg) {
# In R 4.0 and above, CRAN wants us to use the new tools::R_user_dir().
# If not present, fall back to rappdirs::user_cache_dir().
R_user_dir <- getNamespace('tools')$R_user_dir
if (!is.null(R_user_dir)) {
R_user_dir(pkg, which = "cache")
} else {
rappdirs::user_cache_dir(paste0("R-", pkg))
}
}
#' Caching Options for Sass (defunct)
#'
#' This function is no longer used. Please see [sass_cache_get()].
#' @param cache No longer used.
#' @param cache_dir No longer used.
#' @export
#' @keywords internal
sass_cache_options <- function(cache, cache_dir) {
message(
"The function `sass_cache_options` is no longer used. ",
"Please see ?sass_cache_set and ?sass_file_cache"
)
}
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