organize and document completion scripts

README.md

@@ -109,6 +109,14 @@ You should place this command in your `.bash_profile` or other startup script:
 eval "$(hub alias -s)"
 ~~~
 
+### Shell tab-completion
+
+hub repository contains tab-completion scripts for bash and zsh. These scripts
+complement existing completion scripts that ship with git.
+
+* [hub bash completion](https://github.com/defunkt/hub/blob/master/etc/hub.bash_completion.sh)
+* [hub zsh completion](https://github.com/defunkt/hub/blob/master/etc/hub.zsh_completion)
+
 
 Commands
 --------

tab_completion/bash → etc/hub.bash_completion.sh

@@ -1,9 +1,5 @@
-#
-# Source this file from your ~/.bashrc
-#
-# bash completion support for hub.
-#   Adds hub commands to __git_list_all_commands function.
-# -------------------------------------------------------------
+# hub tab-completion script for bash.
+# This script complements the completion script that ships with git.
 
 # Check that git tab completion is available
 if declare -F _git > /dev/null; then
@@ -14,6 +10,7 @@ if declare -F _git > /dev/null; then
   # Wrap the 'list_all_commands' function with extra hub commands
   __git_list_all_commands() {
     cat <<-EOF
+alias
 pull-request
 fork
 create

etc/hub.zsh_completion

@@ -0,0 +1,22 @@
+# hub tab-completion script for zsh.
+# This script complements the completion script that ships with git.
+#
+# vim: ft=zsh sw=2 ts=2 et
+
+# Autoload _git completion functions
+if declare -f _git > /dev/null; then
+  _git
+fi
+
+if declare -f _git_commands > /dev/null; then
+  _hub_commands=(
+    'alias:show shell instructions for wrapping git'
+    'pull-request:open a pull request on GitHub'
+    'fork:fork origin repo on GitHub'
+    'create:create new repo on GitHub for the current project'
+    'browse:browse the project on GitHub'
+    'compare:open GitHub compare view'
+  )
+  # Extend the '_git_commands' function with hub commands
+  eval "$(declare -f _git_commands | sed -e 's/base_commands=(/base_commands=(${_hub_commands} /')"
+fi