Add completion for fishshell (#440)

Closes #436 

Thank you @ccoVeille !

completions/README.md

@@ -0,0 +1,11 @@
+# Shell completion scripts
+
+By default, rmw completions are copied to the rmw documentation dir when rmw
+is installed. If they aren't present on your system, you can install a shell
+completion manually by getting the completion from the source package or git
+repository. See the links below for specific installation instructions for
+each completion.
+
+## Fish
+
+[Where to put completions](https://fishshell.com/docs/current/completions.html#where-to-put-completions)

completions/fish/rmw.fish

@@ -0,0 +1,31 @@
+# This file contains the fish completion for rmw
+#
+# rmw is a trashcan/recycle bin utility for the command line
+#
+# More information about this tool on https://github.com/theimpossibleastronaut/rmw
+#
+# This file is intended to be released with rmw with various packaging managers
+
+complete rmw -s h -l help -d 'show help for command line options' -f
+complete rmw -s c -l config -d 'use an alternate configuration' -r
+complete rmw -s l -l list -d 'list waste directories' -f
+complete rmw -s g -l purge -d 'purge expired files'
+complete rmw -s o -l orphaned -d 'check for orphaned files (maintenance)'  -f
+complete rmw -s f -l force -d 'allow purging of expired files' -f
+complete rmw -l empty -d 'completely empty (purge) all waste directories'  -f
+complete rmw -l top-level-bypass -d 'bypass protection of top-level files'
+
+complete rmw -s v -l verbose -d 'increase output messages' -f
+complete rmw -l warranty -d 'display warranty' -f
+complete rmw -l version -d 'display version and license information' -f
+
+complete rmw -s z -l restore -d 'restore FILE(s) (see man page example)'
+complete rmw -s s -l select -d 'select files from list to restore' -f
+complete rmw -s u -l undo-last -d 'undo last move' -f
+complete rmw -s m -l most-recent-list -d "list most recently rmw'ed files" -f
+
+# Options kept for compatibility purpose that do not need to be completed
+# they are listed here to avoid people wondering why they are missing
+# complete rmw -s R -s r -l recursive -d 'kept for compatibility purpose with rm (recursive operation is enabled by default)'
+# complete rmw -s i -l interactive -d 'Prompt for removal (not implemented)'
+

meson.build

@@ -87,3 +87,10 @@ install_data(
     ),
   install_dir : get_option('docdir')
   )
+
+# Copy completions to docdir
+install_subdir(
+  'completions',
+  install_dir : join_paths(get_option('docdir')),
+  strip_directory : false
+  )

meson_options.txt

@@ -9,3 +9,7 @@ option('docdir', type : 'string', value : 'share/doc/rmw',
 
 option('without-curses', type : 'boolean', value : 'false',
        description : 'build without curses/menu support')
+
+option('install_shell_completions', type: 'boolean', value: true,
+       description: 'Install shell completions')
+