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# Generate checksums for a vector of file paths.
# @keywords internal
md5 <- function(paths) {
unlist(lapply(paths, tools::md5sum))
}
make_cache <- function() {
.file_cache <- character()
make <- function(paths) {
paths <- path.expand(paths)
new_hash <- md5(paths)
old_hash <- .file_cache[paths]
changed <- is.na(old_hash) | new_hash != old_hash
.file_cache[paths[changed]] <<- new_hash[changed]
paths[changed]
}
clear <- function() {
.file_cache <<- character()
}
list(make = make, clear = clear)
}
.cache <- make_cache()
# Given vector of paths, return only those paths that have changed since the
# last invocation.
# @keywords internal
changed_files <- .cache$make
# Clear file cache.
# @keywords internal
clear_cache <- .cache$clear
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