Add information about updating in tools/

.Rbuildignore

@@ -1,3 +1,4 @@
 ^civil\.Rproj$
 ^\.Rproj\.user$
 ^LICENSE\.md$
+^tools$

tools/update

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+--------------------------------------------------------------------------------
+Updating `civil` dependencies
+
+1. Update the version in `update-database.R`.
+
+2. Run `update-database.R` to update `inst/tzdata/` and
+   `inst/tzdata/windowsZones.xml`.
+
+3. Run `update-date-library.R` to update the headers and `tz.cpp` in `src/`.
+
+4. Go back through `tz.cpp` and comment out all uses to `std::cerr()`, which
+   R CMD Check doesn't like.

tools/update-database.R

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+library(here)
+library(fs)
+
+# Notes about this updater:
+#
+# Don't forget to update the version below.
+#
+# This updater will download all the required information and will place it
+# in the right place. The next few paragraphs describe what it downloads in
+# case you have to do it manually for some reason.
+#
+# The time zone database is downloaded from: https://www.iana.org/time-zones.
+# If you are going to do it manually for some reason, choose the latest
+# version, and grab the one with JUST the data, in the format like
+# `tzdata2019c.tar.gz`. Uncompress it, and then take the contents of the
+# folder and move them into `inst/tzdata/`.
+#
+# On Windows, we also need a `windowsZone.xml` mapping file.
+# It can be found here if you need to download it manually:
+# https://raw.githubusercontent.com/unicode-org/cldr/master/common/supplemental/windowsZones.xml.
+# Download this file and place it in `inst/tzdata` as `windowsZones.xml`.
+
+# Update the version!
+version <- "2020d"
+
+# ------------------------------------------------------------------------------
+# Download the time zone database
+
+file <- paste0("tzdata", version, ".tar.gz")
+
+path_base <- "https://data.iana.org/time-zones/releases/"
+path_version <- path(path_base, file)
+
+dir_temp <- tempdir()
+path_temp <- tempfile(fileext = ".tar.gz", tmpdir = dir_temp)
+
+download.file(path_version, path_temp)
+
+untar(path_temp, exdir = here("inst", "tzdata"))
+
+unlink(path_temp)
+unlink(dir_temp, recursive = TRUE, force = TRUE)
+
+# ------------------------------------------------------------------------------
+# Download the Windows mapping file
+
+windows_mapping_url <- "https://raw.githubusercontent.com/unicode-org/cldr/master/common/supplemental/windowsZones.xml"
+path_dest_windows_mapping <- here("inst/tzdata/windowsZones.xml")
+
+download.file(windows_mapping_url, path_dest_windows_mapping)

tools/update-date-library.R

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+library(here)
+library(fs)
+library(glue)
+
+# Notes about this updater:
+#
+# The `tz.cpp` file that is downloaded into `src/tz.cpp` will need to be updated
+# to pass R CMD Check. All calls to `std::cerr` will have to be commented out.
+
+# ------------------------------------------------------------------------------
+# cd into temp dir
+# git clone the repo
+
+dir_temp <- tempdir()
+dir_dest <- dir_create(path(dir_temp, "dest/"))
+
+url_repo <- "https://github.com/HowardHinnant/date"
+
+cmd_cd <- glue(shQuote("cd"), " ", dir_dest)
+cmd_clone <- glue(shQuote("git"), " clone ", url_repo)
+cmd <- glue(cmd_cd, "; ", cmd_clone)
+
+# cd into temp dir
+# git clone the repo
+system(cmd)
+
+dir_date <- path(dir_dest, "date")
+
+# ------------------------------------------------------------------------------
+# Update headers and tz.cpp
+# Will overwrite src/tz.cpp (which will need to be tweaked)
+
+dir_src <- here("src")
+
+dir_date_include_date <- path(dir_date, "include", "date")
+dir_copy(dir_date_include_date, dir_src, overwrite = TRUE)
+
+file_date_src_tz <- path(dir_date, "src", "tz.cpp")
+file_pkg_src_tz <- path(dir_src, "tz.cpp")
+
+file_copy(file_date_src_tz, file_pkg_src_tz, overwrite = TRUE)
+
+# ------------------------------------------------------------------------------
+
+unlink(dir_temp, recursive = TRUE, force = TRUE)