Add shell completion definitions for Bash, Fish and Zsh

Paths of completion definitions in this repo are inconsequential, and I
don't know a convention for that, so I just modelled it on git.git
https://github.com/git/git/tree/master/contrib/completion. What's
different here is that instead of using a uniform naming scheme for each
file (you-get-completion.<shellname>), I'm using the conventional name
for each shell, which means _you-get for Zsh, for instance. Users of
each shell should be able to pick out the completion definition for
their shell based on the filenames; in the worst case, they can still
tell from the comment at the top of each file.

Note that I'm no expert on Bash or Fish completion, so
you-get-completion.bash and you-get.fish may not be written in the
idiomatic way. (you-get-completion.bash is most certainly not idiomatic,
if there's an idiom at all.)

Closes #1178.

README.md

@@ -93,6 +93,10 @@ $ git clone git://github.com/soimort/you-get.git
 
 Then put the cloned directory into your `PATH`, or run `./setup.py install` to install `you-get` to a permanent path.
 
+### Shell completion
+
+Completion definitions for Bash, Fish and Zsh can be found in [`contrib/completion`](contrib/completion). Please consult your shell's manual for how to take advantage of them.
+
 ## Upgrading
 
 Based on which option you chose to install `you-get`, you may upgrade it via:

contrib/completion/_you-get

@@ -0,0 +1,29 @@
+#compdef you-get
+
+# Zsh completion definition for soimort/you-get.
+
+setopt localoptions noshwordsplit noksharrays
+local -a args
+
+args=(
+    '(- : *)'{-V,--version}'[print version and exit]'
+    '(- : *)'{-h,--help}'[print help and exit]'
+    '(-i --info)'{-i,--info}'[print extracted information]'
+    '(-u --url)'{-u,--url}'[print extracted information with URLs]'
+    '(--json)--json[print extracted URLs in JSON format]'
+    '(-n --no-merge)'{-n,--no-merge}'[do not merge video parts]'
+    '(--no-caption)--no-caption[do not download captions]'
+    '(-f --force)'{-f,--force}'[force overwrite existing files]'
+    '(-F --format)'{-F,--format}'[set video format to the specified stream id]:stream id'
+    '(-O --output-filename)'{-O,--output-filename}'[set output filename]:filename:_files'
+    '(-o --output-dir)'{-o,--output-dir}'[set output directory]:directory:_files -/'
+    '(-p --player)'{-p,--player}'[stream extracted URL to the specified player]:player and options'
+    '(-c --cookies)'{-c,--cookies}'[load cookies.txt or cookies.sqlite]:cookies file:_files'
+    '(-x --http-proxy)'{-x,--http-proxy}'[use the specified HTTP proxy for downloading]:host\:port:'
+    '(-y --extractor-proxy)'{-y,--extractor-proxy}'[use the specified HTTP proxy for extraction only]:host\:port'
+    '(--no-proxy)--no-proxy[do not use a proxy]'
+    '(-t --timeout)'{-t,--timeout}'[set socket timeout]:seconds'
+    '(-d --debug)'{-d,--debug}'[show traceback and other debug info]'
+    '*: :_guard "^-*" url'
+)
+_arguments -S -s $args

contrib/completion/you-get-completion.bash

@@ -0,0 +1,31 @@
+# Bash completion definition for you-get.
+
+_you-get () {
+    COMPREPLY=()
+    local IFS=$' \n'
+    local cur=$2 prev=$3
+    local -a opts_without_arg opts_with_arg
+    opts_without_arg=(
+        -V --version -h --help -i --info -u --url --json -n --no-merge
+        --no-caption -f --force --no-proxy -d --debug
+    )
+    opts_with_arg=(
+        -F --format -O --output-filename -o --output-dir -p --player
+        -c --cookies -x --http-proxy -y --extractor-proxy -t --timeout
+    )
+
+    # Do not complete non option names
+    [[ $cur == -* ]] || return 1
+
+    # Do not complete when the previous arg is an option expecting an argument
+    for opt in "${opts_with_arg[@]}"; do
+        [[ $opt == $prev ]] && return 1
+    done
+
+    # Complete option names
+    COMPREPLY=( $(compgen -W "${opts_without_arg[*]} ${opts_with_arg[*]}" \
+                          -- "$cur") )
+    return 0
+}
+
+complete -F _you-get you-get

contrib/completion/you-get.fish

@@ -0,0 +1,23 @@
+# Fish completion definition for you-get.
+
+complete -c you-get -s V -l version -d 'print version and exit'
+complete -c you-get -s h -l help -d 'print help and exit'
+complete -c you-get -s i -l info -d 'print extracted information'
+complete -c you-get -s u -l url -d 'print extracted information'
+complete -c you-get -l json -d 'print extracted URLs in JSON format'
+complete -c you-get -s n -l no-merge -d 'do not merge video parts'
+complete -c you-get -l no-caption -d 'do not download captions'
+complete -c you-get -s f -l force -d 'force overwrite existing files'
+complete -c you-get -s F -l format -x -d 'set video format to the specified stream id'
+complete -c you-get -s O -l output-filename -d 'set output filename' \
+         -x -a '(__fish_complete_path (commandline -ct) "output filename")'
+complete -c you-get -s o -l output-dir  -d 'set output directory' \
+         -x -a '(__fish_complete_directories (commandline -ct) "output directory")'
+complete -c you-get -s p -l player -x -d 'stream extracted URL to the specified player'
+complete -c you-get -s c -l cookies -d 'load cookies.txt or cookies.sqlite' \
+         -x -a '(__fish_complete_path (commandline -ct) "cookies.txt or cookies.sqlite")'
+complete -c you-get -s x -l http-proxy -x -d 'use the specified HTTP proxy for downloading'
+complete -c you-get -s y -l extractor-proxy -x -d 'use the specified HTTP proxy for extraction only'
+complete -c you-get -l no-proxy -d 'do not use a proxy'
+complete -c you-get -s t -l timeout -x -d 'set socket timeout'
+complete -c you-get -s d -l debug -d 'show traceback and other debug info'