Log message:
(math/R-xfun) Updated 0.25 to 0.26

# CHANGES IN xfun VERSION 0.26

- The `windows_only` argument of `native_encode()` has been
  removed. Now `native_encode()` only tries the conversion to native
  encoding on platforms where `l10n_info()[['UTF-8']]` does not return
  `TRUE`.

- Added a `solaris` argument to `upload_win_builder()`.

Log message:
(devel/R-xfun) Update TEST_DEPENDS+, fix typo

Log message:
(devel/R-xfun) Update TEST_DEPENDS+, but still failing

Log message:
(devel/R-xfun) Updated 0.2.0 to 0.23

# CHANGES IN xfun VERSION 0.23

## NEW FEATURES

- Added a `tinify()` function to compress PNG/JPEG images via [the Tinify \ 
API](https://tinypng.com/developers).

- Added a `news2md()` function to convert package news to the Markdown format. \ 
This is mainly for converting the plain-text `NEWS` file and the `NEWS.Rd` file \ 
to `NEWS.md`.

- Added a `format_bytes()` function to format numbers of bytes using a specified \ 
unit, e.g., `1024` can be formatted as `1 Kb`.

- When using `pkg_load2()` in an **renv** project, it will use `renv::install()` \ 
to install missing packages by default to take advantage of **renv**'s caching \ 
feature (thanks, @chunyunma @cderv, #52).

- `upload_win_builder()` no longer requires the system command `curl` to be \ 
available; if `curl` is not available, the R package **curl** will be used \ 
instead, which means this R package must be installed. In addition to uploading \ 
to the `ftp` server of win-builder, it's also possible to upload to \ 
<https://win-builder.r-project.org/upload.aspx>: call \ 
`upload_win_builder(..., server = 'https')`. This change was made so that it \ 
would be possible to continue to upload to win-builder in case it should stop \ 
supporting `ftp` (CRAN has discouraged package authors from using `ftp://`).

## BUG FIXES

- Backticks are added to math environments by mistake when `\begin{}` and \ 
`\end{}` do not match (thanks, @oliviergimenez, #51).

## MINOR CHANGES

- The argument `src` was renamed to `pkg` in `install_dir()`.

- The argument `file` of `upload_win_builder()` defaults to `pkg_build()` now, \ 
i.e., by default, it will build a source package and upload it, so you do not \ 
need to build the package separately.

# CHANGES IN xfun VERSION 0.22

## NEW FEATURES

- `relative_path()` is vectorized now.

- Added a new function `retry()` to retry calling a function for a number of \ 
times in case of errors.

- Added a new function `sort_file()`, which is a shorthand for `process_file(fun \ 
= sort)` to sort the lines in a text file.

## MAJOR CHANGES

- The argument `FUN` was renamed to `fun` in `process_file()`.

## MINOR CHANGES

- Inside `download_file()`, the `timeout` option in `options()` is set to 3600 \ 
seconds when it takes the default value of 60 seconds, which may not be enough \ 
for downloading large files (thanks, @matthewgson, yihui/tinytex#286).

# CHANGES IN xfun VERSION 0.21

## NEW FEATURES

- Added a new function `pkg_available()` to test if a package with a minimal \ 
version is available (thanks, @cderv, #45).

- Added a new function `set_envvar()` to set environment variables and return \ 
their old values, so they could be restored later.

- Added a new function `exit_call()` to call a function when a parent function exits.

- Exported the internal function `read_bin()`.

- Added an argument `verbose` to `bg_process()`.

- `Rscript_call()` gains an `options` argument to pass command-line options to \ 
`Rscript` (thanks, @cderv, #48).

Log message:
(devel/R-xfun) Updated 0.19 to 0.20

# CHANGES IN xfun VERSION 0.20

## NEW FEATURES

- Added a function `msg_cat()` to generate a message with `cat()`. See
  the help page `?xfun::msg_cat` for more information.

- Added a function `mark_dirs()` to mark directories with a trailing
  slash in a vector of paths to differentiate them from normal
  filenames (#44).

## BUG FIXES

- `xfun::proc_kill()` failed to work on *nix.

- `xfun::del_empty_dir()` failed to delete empty dirs.

- `xfun::file_string()` preserves emptiness (thanks, @MichaelChirico,
  #38).

- `xfun::raw_string()` preserves the class(es) of the input now
  (thanks, @MichaelChirico, #40).

## MINOR CHANGES

- Exported the function `dir_create()`.

Log message:
(devel/R-xfun) Updated 0.18 to 0.19

# CHANGES IN xfun VERSION 0.19

## NEW FEATURES

- Added functions `bg_process()` to run a command in a background
  process, and `proc_kill()` to kill a process.

- Added a function `del_empty_dir()` to delete a directory if it is
  empty.

- Added functions `is_abs_path()` and `is_rel_path()` to check if
  paths are absolute or relative.

- Added a function `is_sub_path()` to test if a path is under a
  directory.

- Added a function `is_web_path()` to test if a path is a web path
  that starts with `http://` or `https://` or `ftp://` or `ftps://`.

- Documented and exported the previously internal functions
  `dir_exists()` and `file_exists()` (thanks, @cderv, #36).

- Added a function `dir_create()` to create a directory recursively by
  default when it does not exist.

- Added an argument `fail` to `Rscript_call()` to allow users to
  customize the error message when an error occurred in calling the
  function in a new R session.

## MINOR CHANGES

- `file_ext()`, `sans_ext()`, and `with_ext()` no longer use
  `tools::file_ext()` or `tools::file_path_sans_ext()`, but provide a
  slightly different implementation. They treat `tar.(gz|bz2|xz)` and
  `nb.html` as file extensions, and also allow extensions to contain a
  trailing `~` or `#`.

Log message:
(devel/R-xfun)  Updated 0.17 to 0.18

# CHANGES IN xfun VERSION 0.18

## NEW FEATURES

- Added a function `grep_sub()` to perform replacement with `gsub()` on elements
  matched from `grep()`.

- Added a function `github_releases()` to obtain the tags from the Github
  releases of a repo.

- Added a function `bump_version()` to increase the last digit of version
  numbers by one.

- Moved a function `process_file()` from the **blogdown** package to this
  package, and documented it.

- Added a function `valid_syntax()` to check if an R code fragment is
 syntactically valid. This function was moved from the **highr** package.

- Added a function `url_filename()` to extract filenames from URLs.
  This function is used by `download_file()` to determine the default
  output filename.

- Added a function `do_once()` to perform a task once in an R session.

- Added a function `proj_root()` to find the root directory of a project.
  Currently it only supports R package projects and RStudio projects by default.

- Added a function `relative_path()` to calculate the relative path of a path
  relative to a directory.

- Added a function `from_root()`, which is similar to `here::here()` but
  returns a relative path instead of an absolute path.

- Added a function `magic_path()` that, given an incomplete input path,
  tries to find the actual path recursively under subdirectories of a root
  directory. For example, users may only provide a base filename, and
  `magic_path()` will look for this file under subdirectories and return
  the actual path if it is found.

## MINOR CHANGES

- Now `download_file()` tries the download method `winnet` first (previously
  it was `libcurl`) on Windows (thanks, @cderv, #33).

Log message:
(devel/R-xfun) Updated 0.8 to 0.17

# CHANGES IN xfun VERSION 0.17

## NEW FEATURES

- Supports `xfun::pkg_attach(packages, install = "pak")`, i.e., use \ 
`pak::pkg_install()` to install a package when it is not installed (thanks, \ 
@GitHunter0, #32).

- Added a new function `xfun::split_source()` to split lines of R source code \ 
into minimal complete expressions.

# CHANGES IN xfun VERSION 0.16

- Added a new function `base64_decode()` to decode data from the base64 encoding \ 
(thanks, @wush978, #31).

# CHANGES IN xfun VERSION 0.15

## NEW FEATURES

- Added a new function `tree()`, which is based on `str()` in base R, but \ 
changes the output of `str()` into a tree diagram to make it easier to \ 
understand nested data structures.

- Added a new function `base64_encode()` to encode data into the base64 encoding \ 
(thanks, @wush978, #27).

- Added a new function `base64_uri()` to generate the Data URI (or Data URL) for \ 
a file.

## BUG FIXES

- Fenced code blocks commented out in `<!-- -->` are not longer recognized \ 
as code blocks but prose (thanks, @jarauh, #25).

# CHANGES IN xfun VERSION 0.14

## NEW FEATURES

- The `cache_rds()` function can invalidate the cache automatically when the \ 
code passed to its `expr` argument has changed. Two new arguments, `hash` and \ 
`clean` were added to this function to make it more useful and powerful. See the \ 
help page `?xfun::cache_rds()` for more information.

# CHANGES IN xfun VERSION 0.13

## NEW FEATURES

- Added a new function `cache_rds()` to cache an R expression to a `*.rds` file.

- Added a new function `Rscript_call()` to call a function (with arguments) in a \ 
new R session via the command `Rscript`.

- The `recheck` argument of `rev_check()` can take a vector of package names, \ 
and only these packages will be checked. See `?xfun::rev_check` for more \ 
details.

# CHANGES IN xfun VERSION 0.12

## NEW FEATURES

- Added a new function `split_lines()`.

# CHANGES IN xfun VERSION 0.11

## BUG FIXES

- `read_utf8()` will read the file with `options(encoding = 'native.enc')` and \ 
ignore user's setting such as `options(encoding = 'UTF-8')` (#21).

# CHANGES IN xfun VERSION 0.10

## NEW FEATURES

- Added the function `as_strict_list()` to convert an existing object to a \ 
strict list without wrapping it in another list if the object already is of type \ 
list (in contrast to how `strict_list()` behaves) (thanks, @salim-b, #20).

# CHANGES IN xfun VERSION 0.9

## NEW FEATURES

- Added a function `rename_seq()` to rename files to add an incremental numeric \ 
prefix to the filenames, e.g., rename `a.txt`, `b.txt`, `c.txt` to `1-a.txt`, \ 
`2-b.txt`, `3-c.txt`.

Log message:
Update all R packages to canonical form.

The canonical form [1] of an R package Makefile includes the
following:

- The first stanza includes R_PKGNAME, R_PKGVER, PKGREVISION (as
  needed), and CATEGORIES.

- HOMEPAGE is not present but defined in math/R/Makefile.extension to
  refer to the CRAN web page describing the package.  Other relevant
  web pages are often linked from there via the URL field.

This updates all current R packages to this form, which will make
regular updates _much_ easier, especially using pkgtools/R2pkg.

[1] http://mail-index.netbsd.org/tech-pkg/2019/08/02/msg021711.html