Added basic completion (the commands) for gclient.

To try it out, do 
. $DEPOT_TOOLS/gclient_completion.sh

Review URL: https://codereview.chromium.org/100463007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@245134 0039d316-1c4b-4281-b951-d872f2087c98

gclient_completion.sh

@@ -0,0 +1,76 @@
+# gclient_completion.sh
+#
+# This adds completion to bash shells for gclient commands. It is
+# meant for developers and not needed for inclusion by any automated
+# processes that will, of course, specify the full command, not rely
+# on or benefit from tab-completion.
+#
+# Requires:
+#   bash-completion package for _get_comp_words_by_ref.
+#   newer versions of sed for the improved regular expression handling.
+#
+# On Mac, this is accomplished by installing fink (www.finkproject.org)
+# then doing sudo apt-get update ; sudo apt-get install sed
+#
+# Usage:
+#   Put something like the following in your .bashrc:
+#   . $PATH_TO_DEPOT_TOOLS/gclient_completion.sh
+#
+
+
+# Parses commands from gclient -h.
+__gclient_commands () {
+  gclient -h 2> /dev/null | sed -n 's/^\s*\x1b\[32m\(.*\)\x1b\[39m.*$/\1/p'
+}
+
+# Caches variables in __gclient_all_commands.
+# Adds "update" command, which is not listed.
+__gclient_compute_all_commands () {
+  test -n "$__gclient_all_commands" ||
+  __gclient_all_commands="$(__gclient_commands) update"
+}
+
+# Since gclient fetch is a passthrough to git, let the completions
+# come from git's completion if it's defined.
+if [[ -n _git_fetch ]]; then
+    _gclient_fetch=_git_fetch
+fi
+
+# Completion callback for gclient cmdlines.
+_gclient () {
+  local cur prev words cword
+  _get_comp_words_by_ref -n =: cur prev words cword
+
+  # Find the command by ignoring flags.
+  local i c=1 cword_adjust=0 command 
+  while [ $c -lt $cword ]; do
+    i="${words[$c]}"
+    case "$i" in
+      -*)
+        ((cword_adjust++))
+        : ignore options ;;
+      *) command="$i"; break ;;
+    esac
+    ((c++))
+  done
+
+  # If there is a completion function for the command, use it and
+  # return.
+  local completion_func="_gclient_${command//-/_}"
+  local -f $completion_func >/dev/null && $completion_func && return
+
+  # If the command or hasn't been given, provide completions for all
+  # commands. Also provide all commands as completion for the help
+  # command.
+  # echo "command=$command" >> /tmp/comp.log
+  case "$command" in
+    ""|help)
+      if [[ "$command" != help || $((cword - cword_adjust)) -le 2 ]]; then
+        __gclient_compute_all_commands
+        COMPREPLY=($(compgen -W "$__gclient_all_commands" $cur))
+      fi
+      ;;
+    *) : just use the default ;;
+  esac
+} &&
+complete -F _gclient -o default gclient