[PATCH 2/2] mergetool-lib: add a three-way diff view for vim/gvim

[Dan McGee <dpmcgee@gmail.com>]

When the base version is available, use a three-way, four panel view by
default. This shows the (local, base, remote) revisions up top and the
merged result by itself in the lower pane. All revisions will still scroll
together by default, and the cursor still defaults to the merged result edit
pane.

Signed-off-by: Dan McGee <dpmcgee@gmail.com>
---

Vim was one of the few diff commands to not support a three-way merge showing
the base revision, so this is a stab at resolving that shortfall. The biggest
objection I can see to this is making the interface a bit more cumbersome and
bloated.

An example screenshot of what this produces:
http://www.toofishes.net/media/extra/vim_three_way.png

-Dan

 git-mergetool--lib.sh |    9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index f9a51ba..b84ac58 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -172,8 +172,13 @@ run_merge_tool () {
 	vimdiff|gvimdiff)
 		if merge_mode; then
 			touch "$BACKUP"
-			"$merge_tool_path" -f -d -c "wincmd l" \
-				"$LOCAL" "$MERGED" "$REMOTE"
+			if $base_present; then
+				"$merge_tool_path" -f -d -c "wincmd J" \
+					"$MERGED" "$LOCAL" "$BASE" "$REMOTE"
+			else
+				"$merge_tool_path" -f -d -c "wincmd l" \
+					"$LOCAL" "$MERGED" "$REMOTE"
+			fi
 			check_unchanged
 		else
 			"$merge_tool_path" -f -d -c "wincmd l" \
-- 
1.7.2.3