completion: match ctags symbol names in grep patterns

A common thing to grep for is the name of a symbol. This
patch teaches the completion for "git grep" to look in
a 'tags' file, if present, to complete a pattern. For
example, in git.git:

  $ make tags
  $ git grep get_sha1<Tab><Tab>
  get_sha1                 get_sha1_oneline
  get_sha1_1               get_sha1_with_context
  get_sha1_basic           get_sha1_with_context_1
  get_sha1_hex             get_sha1_with_mode
  get_sha1_hex_segment     get_sha1_with_mode_1
  get_sha1_mb

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 888e8e10ccd932df3aa8f30a3d83441d5485fc30..af283cb73b0b71490948f755c82339b688b77095 100755 (executable)
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -1429,6 +1429,10 @@ _git_gitk ()
        _gitk
 }
 
+__git_match_ctag() {
+       awk "/^${1////\\/}/ { print \$1 }" "$2"
+}
+
 _git_grep ()
 {
        __git_has_doubledash && return
@@ -1451,6 +1455,15 @@ _git_grep ()
                ;;
        esac
 
+       case "$cword,$prev" in
+       2,*|*,-*)
+               if test -r tags; then
+                       __gitcomp "$(__git_match_ctag "$cur" tags)"
+                       return
+               fi
+               ;;
+       esac
+
        __gitcomp "$(__git_refs)"
 }