---
title: "Installation"
author: 
  - "Mark Padgham"
date: "`r Sys.Date()`"
vignette: >
  %\VignetteIndexEntry{Installation}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

```{r setup, include=FALSE}
knitr::opts_chunk$set (
    collapse = TRUE,
    warning = TRUE,
    message = TRUE,
    width = 120,
    comment = "#>",
    fig.retina = 2,
    fig.path = "README-"
)
options (repos = c (
    ropenscireviewtools = "https://ropensci-review-tools.r-universe.dev",
    CRAN = "https://cloud.r-project.org"
))
```

The `pkgstats` package [is on
CRAN](https://cran.r-project.org/package=pkgstats), so can be installed
directly with,

```{r install, eval = FALSE}
install.packages ("pkgstats")
```

The latest development version can be installed [via the associated
`r-universe`](https://ropensci-review-tools.r-universe.dev/pkgstats). As
shown there, simply enable the universe with

```{r options, eval = FALSE}
options (repos = c (
    ropenscireviewtools = "https://ropensci-review-tools.r-universe.dev",
    CRAN = "https://cloud.r-project.org"
))
```

And then call `install.packages()` the same way. Alternatively, the development
version of the package can be installed by running one of the following lines:


```{r remotes, eval = FALSE}
remotes::install_github ("ropensci-review-tools/pkgstats")
pak::pkg_install ("ropensci-review-tools/pkgstats")
```

The package can then loaded for use with:

```{r library, eval = TRUE}
library (pkgstats)
```

## Installation on Linux systems

This package requires the [system libraries
`ctags-universal`](https://ctags.io) and [GNU
`global`](https://www.gnu.org/software/global/), both of which are
automatically installed along with the package on both Windows and MacOS
systems. Most Linux distributions do not include a sufficiently up-to-date
version of [`ctags-universal`](https://ctags.io), and so it must be compiled
from source. This can be done by running a single function, `ctags_install()`,
which will install both [`ctags-universal`](https://ctags.io) and [GNU
`global`](https://www.gnu.org/software/global/).

The `pkgstats` package includes a function to ensure your local installations
of `universal-ctags` and `global` work correctly. Please ensure you see the
following prior to proceeding:

```{r ctags-check, eval = FALSE}
ctags_test ()
#> [1] TRUE
```

Note that GNU `global` can be linked at installation to the Universal Ctags
plug-in parser to expand the [default 5 languages to
30](https://www.gnu.org/software/global/). This makes no difference to
`pkgstats` results, as `gtags` output is only used to trace function call
networks, which is only possible for compiled languages able to dynamically
share pointers to the same objects. This is possible with the default parser
regardless. The wealth of extra information obtained from linking `global` to
the Universal Ctags parser is ultimately discarded anyway, yet parsing may take
considerably longer. If this is the case, "default" behaviour may be recovered
by first running the following command:

```{r unsetenv, eval = FALSE}
Sys.unsetenv (c ("GTAGSCONF", "GTAGSLABEL"))
```

# Installation on macOS systems

On macOS, [GNU `global` and `universal-ctags`](https://formulae.brew.sh/formula/global) can be easily installed with Homebrew. First follow the instructions at [https://brew.sh/](https://brew.sh/) to install Homebrew if you don't have it already. Then run the following command in your terminal:

```bash
brew install global
```

This will install both `global` and a compatible version of `universal-ctags`.

::: callout-note
Do not install `ctags` via Homebrew with `brew install ctags` as the installed version will conflict with `global`'s required `universal-ctags` dependency. If you have `ctags` already installed for another purpose, see Homebrew's messages in the console on how to proceed after attempting to intall `global`, it will usually involve unlinking the existing `ctags` with `brew unlink ctags` or removing it completely with `brew rm ctags`.
:::
