shell completion of official taps added to 'brew tap'

Closes Homebrew/homebrew#42421.

Signed-off-by: Baptiste Fontaine <batifon@yahoo.fr>

Library/Contributions/brew_bash_completion.sh

@@ -140,6 +140,7 @@ _brew_complete_tap ()
         return
         ;;
     esac
+    __brewcomp "$(brew tap --list-official)"
 }
 
 _brew_bottle ()

Library/Contributions/brew_zsh_completion.zsh

@@ -18,6 +18,10 @@ _brew_installed_taps() {
   installed_taps=(`brew tap`)
 }
 
+_brew_official_taps() {
+  official_taps=(`brew tap --list-official`)
+}
+
 _brew_outdated_formulae() {
   outdated_formulae=(`brew outdated`)
 }
@@ -58,7 +62,7 @@ _1st_arguments=(
 )
 
 local expl
-local -a formulae installed_formulae installed_taps outdated_formulae
+local -a formulae installed_formulae installed_taps official_taps outdated_formulae
 
 _arguments \
   '(-v)-v[verbose]' \
@@ -100,6 +104,9 @@ case "$words[1]" in
   untap|tap-info)
     _brew_installed_taps
     _wanted installed_taps expl 'installed taps' compadd -a installed_taps ;;
+  tap)
+    _brew_official_taps
+    _wanted official_taps expl 'official taps' compadd -a official_taps ;;
   upgrade)
     _brew_outdated_formulae
     _wanted outdated_formulae expl 'outdated formulae' compadd -a outdated_formulae ;;

Library/Homebrew/cmd/tap.rb

@@ -6,6 +6,9 @@ module Homebrew
       puts Tap.names
     elsif ARGV.first == "--repair"
       migrate_taps :force => true
+    elsif ARGV.first == "--list-official"
+      require "official_taps"
+      puts OFFICIAL_TAPS.map { |t| "homebrew/#{t}" } * "\n"
     else
       user, repo = tap_args
       clone_target = ARGV.named[1]