[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.

The original vimdiff/gvimdiff configuration is now available by using
'vimdiff2' or 'gvimdiff2' as the preferred merge tool.

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

This should address the comments I got once I pestered people. The new behavior
is the default, but it at least becomes possible to use the previous behavior
without much hassle (just set your mergetool appropriately).

-Dan

 git-mergetool--lib.sh |   23 ++++++++++++++++++++---
 1 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index f9a51ba..77d4aee 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -10,10 +10,10 @@ merge_mode() {
 
 translate_merge_tool_path () {
 	case "$1" in
-	vimdiff)
+	vimdiff|vimdiff2)
 		echo vim
 		;;
-	gvimdiff)
+	gvimdiff|gvimdiff2)
 		echo gvim
 		;;
 	emerge)
@@ -47,7 +47,8 @@ check_unchanged () {
 valid_tool () {
 	case "$1" in
 	kdiff3 | tkdiff | xxdiff | meld | opendiff | \
-	emerge | vimdiff | gvimdiff | ecmerge | diffuse | araxis | p4merge)
+	vimdiff | gvimdiff | vimdiff2 | gvimdiff2 | \
+	emerge | ecmerge | diffuse | araxis | p4merge)
 		;; # happy
 	tortoisemerge)
 		if ! merge_mode; then
@@ -172,6 +173,22 @@ run_merge_tool () {
 	vimdiff|gvimdiff)
 		if merge_mode; then
 			touch "$BACKUP"
+			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
+			"$merge_tool_path" -f -d -c "wincmd l" \
+				"$LOCAL" "$REMOTE"
+		fi
+		;;
+	vimdiff2|gvimdiff2)
+		if merge_mode; then
+			touch "$BACKUP"
 			"$merge_tool_path" -f -d -c "wincmd l" \
 				"$LOCAL" "$MERGED" "$REMOTE"
 			check_unchanged
-- 
1.7.3