From fdd7aa17f805b376f49a1bf031bf1b88eec89ddf Mon Sep 17 00:00:00 2001
From: David Aguilar <davvid@gmail.com>
Date: Thu, 18 Aug 2011 00:23:44 -0700
Subject: [PATCH 1/4] difftool--helper: Make style consistent with git

Use the predominant conditional style where "then" appears
alone on the line after the test expression.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git-difftool--helper.sh | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/git-difftool--helper.sh b/git-difftool--helper.sh
index 0594bf7ca5..8452890be9 100755
--- a/git-difftool--helper.sh
+++ b/git-difftool--helper.sh
@@ -13,7 +13,8 @@ TOOL_MODE=diff
 should_prompt () {
 	prompt_merge=$(git config --bool mergetool.prompt || echo true)
 	prompt=$(git config --bool difftool.prompt || echo $prompt_merge)
-	if test "$prompt" = true; then
+	if test "$prompt" = true
+	then
 		test -z "$GIT_DIFFTOOL_NO_PROMPT"
 	else
 		test -n "$GIT_DIFFTOOL_PROMPT"
@@ -37,9 +38,11 @@ launch_merge_tool () {
 
 	# $LOCAL and $REMOTE are temporary files so prompt
 	# the user with the real $MERGED name before launching $merge_tool.
-	if should_prompt; then
+	if should_prompt
+	then
 		printf "\nViewing: '$MERGED'\n"
-		if use_ext_cmd; then
+		if use_ext_cmd
+		then
 			printf "Hit return to launch '%s': " \
 				"$GIT_DIFFTOOL_EXTCMD"
 		else
@@ -48,7 +51,8 @@ launch_merge_tool () {
 		read ans
 	fi
 
-	if use_ext_cmd; then
+	if use_ext_cmd
+	then
 		export BASE
 		eval $GIT_DIFFTOOL_EXTCMD '"$LOCAL"' '"$REMOTE"'
 	else
@@ -56,8 +60,10 @@ launch_merge_tool () {
 	fi
 }
 
-if ! use_ext_cmd; then
-	if test -n "$GIT_DIFF_TOOL"; then
+if ! use_ext_cmd
+then
+	if test -n "$GIT_DIFF_TOOL"
+	then
 		merge_tool="$GIT_DIFF_TOOL"
 	else
 		merge_tool="$(get_merge_tool)" || exit

From 240dc3e8edb3ae4ee968febc006fa761811c60e6 Mon Sep 17 00:00:00 2001
From: David Aguilar <davvid@gmail.com>
Date: Thu, 18 Aug 2011 00:23:45 -0700
Subject: [PATCH 2/4] mergetool--lib: Make style consistent with git

Use the predominant conditional style where "then" appears
alone on the line after the test expression.
Remove spaces after ">" output redirections.
Remove unnecessary parentheses around the kdiff3 commands.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 git-mergetool--lib.sh | 153 +++++++++++++++++++++++++++---------------
 1 file changed, 100 insertions(+), 53 deletions(-)

diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 9a89e8f319..5820a6354a 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -32,10 +32,12 @@ translate_merge_tool_path () {
 }
 
 check_unchanged () {
-	if test "$MERGED" -nt "$BACKUP"; then
+	if test "$MERGED" -nt "$BACKUP"
+	then
 		status=0
 	else
-		while true; do
+		while true
+		do
 			echo "$MERGED seems unchanged."
 			printf "Was the merge successful? [y/n] "
 			read answer
@@ -53,17 +55,20 @@ valid_tool () {
 	kdiff3 | meld | opendiff | p4merge | tkdiff | vimdiff | vimdiff2 | xxdiff)
 		;; # happy
 	kompare)
-		if ! diff_mode; then
+		if ! diff_mode
+		then
 			return 1
 		fi
 		;;
 	tortoisemerge)
-		if ! merge_mode; then
+		if ! merge_mode
+		then
 			return 1
 		fi
 		;;
 	*)
-		if test -z "$(get_merge_tool_cmd "$1")"; then
+		if test -z "$(get_merge_tool_cmd "$1")"
+		then
 			return 1
 		fi
 		;;
@@ -72,12 +77,14 @@ valid_tool () {
 
 get_merge_tool_cmd () {
 	# Prints the custom command for a merge tool
-	if test -n "$1"; then
+	if test -n "$1"
+	then
 		merge_tool="$1"
 	else
 		merge_tool="$(get_merge_tool)"
 	fi
-	if diff_mode; then
+	if diff_mode
+	then
 		echo "$(git config difftool.$merge_tool.cmd ||
 			git config mergetool.$merge_tool.cmd)"
 	else
@@ -97,9 +104,11 @@ run_merge_tool () {
 
 	case "$1" in
 	araxis)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" -wait -merge -3 -a1 \
 					"$BASE" "$LOCAL" "$REMOTE" "$MERGED" \
 					>/dev/null 2>&1
@@ -115,9 +124,11 @@ run_merge_tool () {
 		fi
 		;;
 	bc3)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" "$LOCAL" "$REMOTE" "$BASE" \
 					-mergeoutput="$MERGED"
 			else
@@ -130,9 +141,11 @@ run_merge_tool () {
 		fi
 		;;
 	diffuse)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" \
 					"$LOCAL" "$MERGED" "$REMOTE" \
 					"$BASE" | cat
@@ -146,9 +159,11 @@ run_merge_tool () {
 		fi
 		;;
 	ecmerge)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" \
 					--default --mode=merge3 --to="$MERGED"
 			else
@@ -162,8 +177,10 @@ run_merge_tool () {
 		fi
 		;;
 	emerge)
-		if merge_mode; then
-			if $base_present; then
+		if merge_mode
+		then
+			if $base_present
+			then
 				"$merge_tool_path" \
 					-f emerge-files-with-ancestor-command \
 					"$LOCAL" "$REMOTE" "$BASE" \
@@ -181,9 +198,11 @@ run_merge_tool () {
 		fi
 		;;
 	gvimdiff|vimdiff)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" -f -d -c "wincmd J" \
 					"$MERGED" "$LOCAL" "$BASE" "$REMOTE"
 			else
@@ -198,7 +217,8 @@ run_merge_tool () {
 		fi
 		;;
 	gvimdiff2|vimdiff2)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
 			"$merge_tool_path" -f -d -c "wincmd l" \
 				"$LOCAL" "$MERGED" "$REMOTE"
@@ -210,36 +230,39 @@ run_merge_tool () {
 		fi
 		;;
 	kdiff3)
-		if merge_mode; then
-			if $base_present; then
-				("$merge_tool_path" --auto \
+		if merge_mode
+		then
+			if $base_present
+			then
+				"$merge_tool_path" --auto \
 					--L1 "$MERGED (Base)" \
 					--L2 "$MERGED (Local)" \
 					--L3 "$MERGED (Remote)" \
 					-o "$MERGED" \
 					"$BASE" "$LOCAL" "$REMOTE" \
-				> /dev/null 2>&1)
+				>/dev/null 2>&1
 			else
-				("$merge_tool_path" --auto \
+				"$merge_tool_path" --auto \
 					--L1 "$MERGED (Local)" \
 					--L2 "$MERGED (Remote)" \
 					-o "$MERGED" \
 					"$LOCAL" "$REMOTE" \
-				> /dev/null 2>&1)
+				>/dev/null 2>&1
 			fi
 			status=$?
 		else
-			("$merge_tool_path" --auto \
+			"$merge_tool_path" --auto \
 				--L1 "$MERGED (A)" \
 				--L2 "$MERGED (B)" "$LOCAL" "$REMOTE" \
-			> /dev/null 2>&1)
+			>/dev/null 2>&1
 		fi
 		;;
 	kompare)
 		"$merge_tool_path" "$LOCAL" "$REMOTE"
 		;;
 	meld)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
 			"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
 			check_unchanged
@@ -248,9 +271,11 @@ run_merge_tool () {
 		fi
 		;;
 	opendiff)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" "$LOCAL" "$REMOTE" \
 					-ancestor "$BASE" \
 					-merge "$MERGED" | cat
@@ -264,7 +289,8 @@ run_merge_tool () {
 		fi
 		;;
 	p4merge)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
 			$base_present || >"$BASE"
 			"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
@@ -274,8 +300,10 @@ run_merge_tool () {
 		fi
 		;;
 	tkdiff)
-		if merge_mode; then
-			if $base_present; then
+		if merge_mode
+		then
+			if $base_present
+			then
 				"$merge_tool_path" -a "$BASE" \
 					-o "$MERGED" "$LOCAL" "$REMOTE"
 			else
@@ -288,7 +316,8 @@ run_merge_tool () {
 		fi
 		;;
 	tortoisemerge)
-		if $base_present; then
+		if $base_present
+		then
 			touch "$BACKUP"
 			"$merge_tool_path" \
 				-base:"$BASE" -mine:"$LOCAL" \
@@ -300,9 +329,11 @@ run_merge_tool () {
 		fi
 		;;
 	xxdiff)
-		if merge_mode; then
+		if merge_mode
+		then
 			touch "$BACKUP"
-			if $base_present; then
+			if $base_present
+			then
 				"$merge_tool_path" -X --show-merged-pane \
 					-R 'Accel.SaveAsMerged: "Ctrl-S"' \
 					-R 'Accel.Search: "Ctrl+F"' \
@@ -327,16 +358,20 @@ run_merge_tool () {
 		;;
 	*)
 		merge_tool_cmd="$(get_merge_tool_cmd "$1")"
-		if test -z "$merge_tool_cmd"; then
-			if merge_mode; then
+		if test -z "$merge_tool_cmd"
+		then
+			if merge_mode
+			then
 				status=1
 			fi
 			break
 		fi
-		if merge_mode; then
+		if merge_mode
+		then
 			trust_exit_code="$(git config --bool \
 				mergetool."$1".trustExitCode || echo false)"
-			if test "$trust_exit_code" = "false"; then
+			if test "$trust_exit_code" = "false"
+			then
 				touch "$BACKUP"
 				( eval $merge_tool_cmd )
 				check_unchanged
@@ -353,13 +388,16 @@ run_merge_tool () {
 }
 
 guess_merge_tool () {
-	if merge_mode; then
+	if merge_mode
+	then
 		tools="tortoisemerge"
 	else
 		tools="kompare"
 	fi
-	if test -n "$DISPLAY"; then
-		if test -n "$GNOME_DESKTOP_SESSION_ID" ; then
+	if test -n "$DISPLAY"
+	then
+		if test -n "$GNOME_DESKTOP_SESSION_ID"
+		then
 			tools="meld opendiff kdiff3 tkdiff xxdiff $tools"
 		else
 			tools="opendiff kdiff3 tkdiff xxdiff meld $tools"
@@ -380,7 +418,8 @@ guess_merge_tool () {
 	for i in $tools
 	do
 		merge_tool_path="$(translate_merge_tool_path "$i")"
-		if type "$merge_tool_path" > /dev/null 2>&1; then
+		if type "$merge_tool_path" >/dev/null 2>&1
+		then
 			echo "$i"
 			return 0
 		fi
@@ -393,12 +432,14 @@ guess_merge_tool () {
 get_configured_merge_tool () {
 	# Diff mode first tries diff.tool and falls back to merge.tool.
 	# Merge mode only checks merge.tool
-	if diff_mode; then
+	if diff_mode
+	then
 		merge_tool=$(git config diff.tool || git config merge.tool)
 	else
 		merge_tool=$(git config merge.tool)
 	fi
-	if test -n "$merge_tool" && ! valid_tool "$merge_tool"; then
+	if test -n "$merge_tool" && ! valid_tool "$merge_tool"
+	then
 		echo >&2 "git config option $TOOL_MODE.tool set to unknown tool: $merge_tool"
 		echo >&2 "Resetting to default..."
 		return 1
@@ -408,26 +449,31 @@ get_configured_merge_tool () {
 
 get_merge_tool_path () {
 	# A merge tool has been set, so verify that it's valid.
-	if test -n "$1"; then
+	if test -n "$1"
+	then
 		merge_tool="$1"
 	else
 		merge_tool="$(get_merge_tool)"
 	fi
-	if ! valid_tool "$merge_tool"; then
+	if ! valid_tool "$merge_tool"
+	then
 		echo >&2 "Unknown merge tool $merge_tool"
 		exit 1
 	fi
-	if diff_mode; then
+	if diff_mode
+	then
 		merge_tool_path=$(git config difftool."$merge_tool".path ||
 				  git config mergetool."$merge_tool".path)
 	else
 		merge_tool_path=$(git config mergetool."$merge_tool".path)
 	fi
-	if test -z "$merge_tool_path"; then
+	if test -z "$merge_tool_path"
+	then
 		merge_tool_path="$(translate_merge_tool_path "$merge_tool")"
 	fi
 	if test -z "$(get_merge_tool_cmd "$merge_tool")" &&
-	! type "$merge_tool_path" > /dev/null 2>&1; then
+		! type "$merge_tool_path" >/dev/null 2>&1
+	then
 		echo >&2 "The $TOOL_MODE tool $merge_tool is not available as"\
 			 "'$merge_tool_path'"
 		exit 1
@@ -439,7 +485,8 @@ get_merge_tool () {
 	# Check if a merge tool has been configured
 	merge_tool=$(get_configured_merge_tool)
 	# Try to guess an appropriate merge tool if no tool has been set.
-	if test -z "$merge_tool"; then
+	if test -z "$merge_tool"
+	then
 		merge_tool="$(guess_merge_tool)" || exit
 	fi
 	echo "$merge_tool"

From bc7a96a8965d4ce0651689301e1702a942dfb9f0 Mon Sep 17 00:00:00 2001
From: David Aguilar <davvid@gmail.com>
Date: Thu, 18 Aug 2011 00:23:46 -0700
Subject: [PATCH 3/4] mergetool--lib: Refactor tools into separate files

Individual merge tools are now defined in a mergetools/$tool
file which is sourced at runtime.

The individual files are installed into $(git --exec-path)/mergetools/.
New tools can be added by creating a new file instead of editing the
git-mergetool--lib.sh scriptlet.

http://thread.gmane.org/gmane.comp.version-control.git/134906/focus=135006

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Makefile                 |  11 ++
 git-mergetool--lib.sh    | 385 ++++++---------------------------------
 mergetools/araxis        |  20 ++
 mergetools/bc3           |  20 ++
 mergetools/defaults      |  46 +++++
 mergetools/diffuse       |  17 ++
 mergetools/ecmerge       |  16 ++
 mergetools/emerge        |  23 +++
 mergetools/kdiff3        |  24 +++
 mergetools/kompare       |   7 +
 mergetools/meld          |   9 +
 mergetools/opendiff      |  16 ++
 mergetools/p4merge       |  10 +
 mergetools/tkdiff        |  12 ++
 mergetools/tortoisemerge |  17 ++
 mergetools/vim           |  44 +++++
 mergetools/xxdiff        |  25 +++
 17 files changed, 369 insertions(+), 333 deletions(-)
 create mode 100644 mergetools/araxis
 create mode 100644 mergetools/bc3
 create mode 100644 mergetools/defaults
 create mode 100644 mergetools/diffuse
 create mode 100644 mergetools/ecmerge
 create mode 100644 mergetools/emerge
 create mode 100644 mergetools/kdiff3
 create mode 100644 mergetools/kompare
 create mode 100644 mergetools/meld
 create mode 100644 mergetools/opendiff
 create mode 100644 mergetools/p4merge
 create mode 100644 mergetools/tkdiff
 create mode 100644 mergetools/tortoisemerge
 create mode 100644 mergetools/vim
 create mode 100644 mergetools/xxdiff

diff --git a/Makefile b/Makefile
index 89cc6245a7..1e91b19c4d 100644
--- a/Makefile
+++ b/Makefile
@@ -302,6 +302,7 @@ bindir = $(prefix)/$(bindir_relative)
 mandir = share/man
 infodir = share/info
 gitexecdir = libexec/git-core
+mergetoolsdir = $(gitexecdir)/mergetools
 sharedir = $(prefix)/share
 gitwebdir = $(sharedir)/gitweb
 template_dir = share/git-core/templates
@@ -2257,6 +2258,13 @@ endif
 gitexec_instdir_SQ = $(subst ','\'',$(gitexec_instdir))
 export gitexec_instdir
 
+ifneq ($(filter /%,$(firstword $(mergetoolsdir))),)
+mergetools_instdir = $(mergetoolsdir)
+else
+mergetools_instdir = $(prefix)/$(mergetoolsdir)
+endif
+mergetools_instdir_SQ = $(subst ','\'',$(mergetools_instdir))
+
 install_bindir_programs := $(patsubst %,%$X,$(BINDIR_PROGRAMS_NEED_X)) $(BINDIR_PROGRAMS_NO_X)
 
 install: all
@@ -2266,6 +2274,9 @@ install: all
 	$(INSTALL) -m 644 $(SCRIPT_LIB) '$(DESTDIR_SQ)$(gitexec_instdir_SQ)'
 	$(INSTALL) $(install_bindir_programs) '$(DESTDIR_SQ)$(bindir_SQ)'
 	$(MAKE) -C templates DESTDIR='$(DESTDIR_SQ)' install
+	$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$(mergetools_instdir_SQ)'
+	(cd mergetools && $(TAR) cf - .) | \
+	(cd '$(DESTDIR_SQ)$(mergetools_instdir_SQ)' && umask 022 && $(TAR) xof -)
 ifndef NO_PERL
 	$(MAKE) -C perl prefix='$(prefix_SQ)' DESTDIR='$(DESTDIR_SQ)' install
 	$(MAKE) -C gitweb install
diff --git a/git-mergetool--lib.sh b/git-mergetool--lib.sh
index 5820a6354a..8fc65d0400 100644
--- a/git-mergetool--lib.sh
+++ b/git-mergetool--lib.sh
@@ -9,26 +9,7 @@ merge_mode() {
 }
 
 translate_merge_tool_path () {
-	case "$1" in
-	araxis)
-		echo compare
-		;;
-	bc3)
-		echo bcompare
-		;;
-	emerge)
-		echo emacs
-		;;
-	gvimdiff|gvimdiff2)
-		echo gvim
-		;;
-	vimdiff|vimdiff2)
-		echo vim
-		;;
-	*)
-		echo "$1"
-		;;
-	esac
+	echo "$1"
 }
 
 check_unchanged () {
@@ -49,40 +30,55 @@ check_unchanged () {
 	fi
 }
 
+valid_tool_config () {
+	if test -n "$(get_merge_tool_cmd "$1")"
+	then
+		return 0
+	else
+		return 1
+	fi
+}
+
 valid_tool () {
+	setup_tool "$1" || valid_tool_config "$1"
+}
+
+setup_tool () {
 	case "$1" in
-	araxis | bc3 | diffuse | ecmerge | emerge | gvimdiff | gvimdiff2 | \
-	kdiff3 | meld | opendiff | p4merge | tkdiff | vimdiff | vimdiff2 | xxdiff)
-		;; # happy
-	kompare)
-		if ! diff_mode
-		then
-			return 1
-		fi
-		;;
-	tortoisemerge)
-		if ! merge_mode
-		then
-			return 1
-		fi
+	vim*|gvim*)
+		tool=vim
 		;;
 	*)
-		if test -z "$(get_merge_tool_cmd "$1")"
-		then
-			return 1
-		fi
+		tool="$1"
 		;;
 	esac
+	mergetools="$(git --exec-path)/mergetools"
+
+	# Load the default definitions
+	. "$mergetools/defaults"
+	if ! test -f "$mergetools/$tool"
+	then
+		return 1
+	fi
+
+	# Load the redefined functions
+	. "$mergetools/$tool"
+
+	if merge_mode && ! can_merge
+	then
+		echo "error: '$tool' can not be used to resolve merges" >&2
+		exit 1
+	elif diff_mode && ! can_diff
+	then
+		echo "error: '$tool' can only be used to resolve merges" >&2
+		exit 1
+	fi
+	return 0
 }
 
 get_merge_tool_cmd () {
 	# Prints the custom command for a merge tool
-	if test -n "$1"
-	then
-		merge_tool="$1"
-	else
-		merge_tool="$(get_merge_tool)"
-	fi
+	merge_tool="$1"
 	if diff_mode
 	then
 		echo "$(git config difftool.$merge_tool.cmd ||
@@ -92,6 +88,7 @@ get_merge_tool_cmd () {
 	fi
 }
 
+# Entry point for running tools
 run_merge_tool () {
 	# If GIT_PREFIX is empty then we cannot use it in tools
 	# that expect to be able to chdir() to its value.
@@ -102,288 +99,15 @@ run_merge_tool () {
 	base_present="$2"
 	status=0
 
-	case "$1" in
-	araxis)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" -wait -merge -3 -a1 \
-					"$BASE" "$LOCAL" "$REMOTE" "$MERGED" \
-					>/dev/null 2>&1
-			else
-				"$merge_tool_path" -wait -2 \
-					"$LOCAL" "$REMOTE" "$MERGED" \
-					>/dev/null 2>&1
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" -wait -2 "$LOCAL" "$REMOTE" \
-				>/dev/null 2>&1
-		fi
-		;;
-	bc3)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" "$LOCAL" "$REMOTE" "$BASE" \
-					-mergeoutput="$MERGED"
-			else
-				"$merge_tool_path" "$LOCAL" "$REMOTE" \
-					-mergeoutput="$MERGED"
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE"
-		fi
-		;;
-	diffuse)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" \
-					"$LOCAL" "$MERGED" "$REMOTE" \
-					"$BASE" | cat
-			else
-				"$merge_tool_path" \
-					"$LOCAL" "$MERGED" "$REMOTE" | cat
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
-		fi
-		;;
-	ecmerge)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" \
-					--default --mode=merge3 --to="$MERGED"
-			else
-				"$merge_tool_path" "$LOCAL" "$REMOTE" \
-					--default --mode=merge2 --to="$MERGED"
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" --default --mode=diff2 \
-				"$LOCAL" "$REMOTE"
-		fi
-		;;
-	emerge)
-		if merge_mode
-		then
-			if $base_present
-			then
-				"$merge_tool_path" \
-					-f emerge-files-with-ancestor-command \
-					"$LOCAL" "$REMOTE" "$BASE" \
-					"$(basename "$MERGED")"
-			else
-				"$merge_tool_path" \
-					-f emerge-files-command \
-					"$LOCAL" "$REMOTE" \
-					"$(basename "$MERGED")"
-			fi
-			status=$?
-		else
-			"$merge_tool_path" -f emerge-files-command \
-				"$LOCAL" "$REMOTE"
-		fi
-		;;
-	gvimdiff|vimdiff)
-		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" -R -f -d -c "wincmd l" \
-				-c 'cd $GIT_PREFIX' \
-				"$LOCAL" "$REMOTE"
-		fi
-		;;
-	gvimdiff2|vimdiff2)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			"$merge_tool_path" -f -d -c "wincmd l" \
-				"$LOCAL" "$MERGED" "$REMOTE"
-			check_unchanged
-		else
-			"$merge_tool_path" -R -f -d -c "wincmd l" \
-				-c 'cd $GIT_PREFIX' \
-				"$LOCAL" "$REMOTE"
-		fi
-		;;
-	kdiff3)
-		if merge_mode
-		then
-			if $base_present
-			then
-				"$merge_tool_path" --auto \
-					--L1 "$MERGED (Base)" \
-					--L2 "$MERGED (Local)" \
-					--L3 "$MERGED (Remote)" \
-					-o "$MERGED" \
-					"$BASE" "$LOCAL" "$REMOTE" \
-				>/dev/null 2>&1
-			else
-				"$merge_tool_path" --auto \
-					--L1 "$MERGED (Local)" \
-					--L2 "$MERGED (Remote)" \
-					-o "$MERGED" \
-					"$LOCAL" "$REMOTE" \
-				>/dev/null 2>&1
-			fi
-			status=$?
-		else
-			"$merge_tool_path" --auto \
-				--L1 "$MERGED (A)" \
-				--L2 "$MERGED (B)" "$LOCAL" "$REMOTE" \
-			>/dev/null 2>&1
-		fi
-		;;
-	kompare)
-		"$merge_tool_path" "$LOCAL" "$REMOTE"
-		;;
-	meld)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
-			check_unchanged
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE"
-		fi
-		;;
-	opendiff)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" "$LOCAL" "$REMOTE" \
-					-ancestor "$BASE" \
-					-merge "$MERGED" | cat
-			else
-				"$merge_tool_path" "$LOCAL" "$REMOTE" \
-					-merge "$MERGED" | cat
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
-		fi
-		;;
-	p4merge)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			$base_present || >"$BASE"
-			"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
-			check_unchanged
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE"
-		fi
-		;;
-	tkdiff)
-		if merge_mode
-		then
-			if $base_present
-			then
-				"$merge_tool_path" -a "$BASE" \
-					-o "$MERGED" "$LOCAL" "$REMOTE"
-			else
-				"$merge_tool_path" \
-					-o "$MERGED" "$LOCAL" "$REMOTE"
-			fi
-			status=$?
-		else
-			"$merge_tool_path" "$LOCAL" "$REMOTE"
-		fi
-		;;
-	tortoisemerge)
-		if $base_present
-		then
-			touch "$BACKUP"
-			"$merge_tool_path" \
-				-base:"$BASE" -mine:"$LOCAL" \
-				-theirs:"$REMOTE" -merged:"$MERGED"
-			check_unchanged
-		else
-			echo "TortoiseMerge cannot be used without a base" 1>&2
-			status=1
-		fi
-		;;
-	xxdiff)
-		if merge_mode
-		then
-			touch "$BACKUP"
-			if $base_present
-			then
-				"$merge_tool_path" -X --show-merged-pane \
-					-R 'Accel.SaveAsMerged: "Ctrl-S"' \
-					-R 'Accel.Search: "Ctrl+F"' \
-					-R 'Accel.SearchForward: "Ctrl-G"' \
-					--merged-file "$MERGED" \
-					"$LOCAL" "$BASE" "$REMOTE"
-			else
-				"$merge_tool_path" -X $extra \
-					-R 'Accel.SaveAsMerged: "Ctrl-S"' \
-					-R 'Accel.Search: "Ctrl+F"' \
-					-R 'Accel.SearchForward: "Ctrl-G"' \
-					--merged-file "$MERGED" \
-					"$LOCAL" "$REMOTE"
-			fi
-			check_unchanged
-		else
-			"$merge_tool_path" \
-				-R 'Accel.Search: "Ctrl+F"' \
-				-R 'Accel.SearchForward: "Ctrl-G"' \
-				"$LOCAL" "$REMOTE"
-		fi
-		;;
-	*)
-		merge_tool_cmd="$(get_merge_tool_cmd "$1")"
-		if test -z "$merge_tool_cmd"
-		then
-			if merge_mode
-			then
-				status=1
-			fi
-			break
-		fi
-		if merge_mode
-		then
-			trust_exit_code="$(git config --bool \
-				mergetool."$1".trustExitCode || echo false)"
-			if test "$trust_exit_code" = "false"
-			then
-				touch "$BACKUP"
-				( eval $merge_tool_cmd )
-				check_unchanged
-			else
-				( eval $merge_tool_cmd )
-				status=$?
-			fi
-		else
-			( eval $merge_tool_cmd )
-		fi
-		;;
-	esac
+	# Bring tool-specific functions into scope
+	setup_tool "$1"
+
+	if merge_mode
+	then
+		merge_cmd "$1"
+	else
+		diff_cmd "$1"
+	fi
 	return $status
 }
 
@@ -449,12 +173,7 @@ get_configured_merge_tool () {
 
 get_merge_tool_path () {
 	# A merge tool has been set, so verify that it's valid.
-	if test -n "$1"
-	then
-		merge_tool="$1"
-	else
-		merge_tool="$(get_merge_tool)"
-	fi
+	merge_tool="$1"
 	if ! valid_tool "$merge_tool"
 	then
 		echo >&2 "Unknown merge tool $merge_tool"
@@ -483,7 +202,7 @@ get_merge_tool_path () {
 
 get_merge_tool () {
 	# Check if a merge tool has been configured
-	merge_tool=$(get_configured_merge_tool)
+	merge_tool="$(get_configured_merge_tool)"
 	# Try to guess an appropriate merge tool if no tool has been set.
 	if test -z "$merge_tool"
 	then
diff --git a/mergetools/araxis b/mergetools/araxis
new file mode 100644
index 0000000000..64f97c5e97
--- /dev/null
+++ b/mergetools/araxis
@@ -0,0 +1,20 @@
+diff_cmd () {
+	"$merge_tool_path" -wait -2 "$LOCAL" "$REMOTE" >/dev/null 2>&1
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" -wait -merge -3 -a1 \
+			"$BASE" "$LOCAL" "$REMOTE" "$MERGED" >/dev/null 2>&1
+	else
+		"$merge_tool_path" -wait -2 \
+			"$LOCAL" "$REMOTE" "$MERGED" >/dev/null 2>&1
+	fi
+	check_unchanged
+}
+
+translate_merge_tool_path() {
+	echo compare
+}
diff --git a/mergetools/bc3 b/mergetools/bc3
new file mode 100644
index 0000000000..27b3dd48b8
--- /dev/null
+++ b/mergetools/bc3
@@ -0,0 +1,20 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" "$LOCAL" "$REMOTE" "$BASE" \
+			-mergeoutput="$MERGED"
+	else
+		"$merge_tool_path" "$LOCAL" "$REMOTE" \
+			-mergeoutput="$MERGED"
+	fi
+	check_unchanged
+}
+
+translate_merge_tool_path() {
+	echo bcompare
+}
diff --git a/mergetools/defaults b/mergetools/defaults
new file mode 100644
index 0000000000..1d8f2a3dd3
--- /dev/null
+++ b/mergetools/defaults
@@ -0,0 +1,46 @@
+# Redefined by builtin tools
+can_merge () {
+	return 0
+}
+
+can_diff () {
+	return 0
+}
+
+diff_cmd () {
+	merge_tool_cmd="$(get_merge_tool_cmd "$1")"
+	if test -z "$merge_tool_cmd"
+	then
+		status=1
+		break
+	fi
+	( eval $merge_tool_cmd )
+	status=$?
+	return $status
+}
+
+merge_cmd () {
+	merge_tool_cmd="$(get_merge_tool_cmd "$1")"
+	if test -z "$merge_tool_cmd"
+	then
+		status=1
+		break
+	fi
+	trust_exit_code="$(git config --bool \
+		mergetool."$1".trustExitCode || echo false)"
+	if test "$trust_exit_code" = "false"
+	then
+		touch "$BACKUP"
+		( eval $merge_tool_cmd )
+		status=$?
+		check_unchanged
+	else
+		( eval $merge_tool_cmd )
+		status=$?
+	fi
+	return $status
+}
+
+translate_merge_tool_path () {
+	echo "$1"
+}
diff --git a/mergetools/diffuse b/mergetools/diffuse
new file mode 100644
index 0000000000..02e0843f47
--- /dev/null
+++ b/mergetools/diffuse
@@ -0,0 +1,17 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" \
+			"$LOCAL" "$MERGED" "$REMOTE" \
+			"$BASE" | cat
+	else
+		"$merge_tool_path" \
+			"$LOCAL" "$MERGED" "$REMOTE" | cat
+	fi
+	check_unchanged
+}
diff --git a/mergetools/ecmerge b/mergetools/ecmerge
new file mode 100644
index 0000000000..13c2e439de
--- /dev/null
+++ b/mergetools/ecmerge
@@ -0,0 +1,16 @@
+diff_cmd () {
+	"$merge_tool_path" --default --mode=diff2 "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" \
+			--default --mode=merge3 --to="$MERGED"
+	else
+		"$merge_tool_path" "$LOCAL" "$REMOTE" \
+			--default --mode=merge2 --to="$MERGED"
+	fi
+	check_unchanged
+}
diff --git a/mergetools/emerge b/mergetools/emerge
new file mode 100644
index 0000000000..f96d9e550a
--- /dev/null
+++ b/mergetools/emerge
@@ -0,0 +1,23 @@
+diff_cmd () {
+	"$merge_tool_path" -f emerge-files-command "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	if $base_present
+	then
+		"$merge_tool_path" \
+			-f emerge-files-with-ancestor-command \
+			"$LOCAL" "$REMOTE" "$BASE" \
+			"$(basename "$MERGED")"
+	else
+		"$merge_tool_path" \
+			-f emerge-files-command \
+			"$LOCAL" "$REMOTE" \
+			"$(basename "$MERGED")"
+	fi
+	status=$?
+}
+
+translate_merge_tool_path() {
+	echo emacs
+}
diff --git a/mergetools/kdiff3 b/mergetools/kdiff3
new file mode 100644
index 0000000000..28fead428b
--- /dev/null
+++ b/mergetools/kdiff3
@@ -0,0 +1,24 @@
+diff_cmd () {
+	"$merge_tool_path" --auto \
+		--L1 "$MERGED (A)" --L2 "$MERGED (B)" \
+		"$LOCAL" "$REMOTE" >/dev/null 2>&1
+}
+
+merge_cmd () {
+	if $base_present
+	then
+		"$merge_tool_path" --auto \
+			--L1 "$MERGED (Base)" \
+			--L2 "$MERGED (Local)" \
+			--L3 "$MERGED (Remote)" \
+			-o "$MERGED" "$BASE" "$LOCAL" "$REMOTE" \
+		>/dev/null 2>&1
+	else
+		"$merge_tool_path" --auto \
+			--L1 "$MERGED (Local)" \
+			--L2 "$MERGED (Remote)" \
+			-o "$MERGED" "$LOCAL" "$REMOTE" \
+		>/dev/null 2>&1
+	fi
+	status=$?
+}
diff --git a/mergetools/kompare b/mergetools/kompare
new file mode 100644
index 0000000000..433686c12a
--- /dev/null
+++ b/mergetools/kompare
@@ -0,0 +1,7 @@
+can_merge () {
+	return 1
+}
+
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
diff --git a/mergetools/meld b/mergetools/meld
new file mode 100644
index 0000000000..73d70ae28a
--- /dev/null
+++ b/mergetools/meld
@@ -0,0 +1,9 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
+	check_unchanged
+}
diff --git a/mergetools/opendiff b/mergetools/opendiff
new file mode 100644
index 0000000000..0942b2a733
--- /dev/null
+++ b/mergetools/opendiff
@@ -0,0 +1,16 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE" | cat
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" "$LOCAL" "$REMOTE" \
+			-ancestor "$BASE" -merge "$MERGED" | cat
+	else
+		"$merge_tool_path" "$LOCAL" "$REMOTE" \
+			-merge "$MERGED" | cat
+	fi
+	check_unchanged
+}
diff --git a/mergetools/p4merge b/mergetools/p4merge
new file mode 100644
index 0000000000..1a45c1b0c5
--- /dev/null
+++ b/mergetools/p4merge
@@ -0,0 +1,10 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	$base_present || >"$BASE"
+	"$merge_tool_path" "$BASE" "$LOCAL" "$REMOTE" "$MERGED"
+	check_unchanged
+}
diff --git a/mergetools/tkdiff b/mergetools/tkdiff
new file mode 100644
index 0000000000..618c438e87
--- /dev/null
+++ b/mergetools/tkdiff
@@ -0,0 +1,12 @@
+diff_cmd () {
+	"$merge_tool_path" "$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	if $base_present
+	then
+		"$merge_tool_path" -a "$BASE" -o "$MERGED" "$LOCAL" "$REMOTE"
+	else
+		"$merge_tool_path" -o "$MERGED" "$LOCAL" "$REMOTE"
+	fi
+}
diff --git a/mergetools/tortoisemerge b/mergetools/tortoisemerge
new file mode 100644
index 0000000000..ed7db495ed
--- /dev/null
+++ b/mergetools/tortoisemerge
@@ -0,0 +1,17 @@
+can_diff () {
+	return 1
+}
+
+merge_cmd () {
+	if $base_present
+	then
+		touch "$BACKUP"
+		"$merge_tool_path" \
+			-base:"$BASE" -mine:"$LOCAL" \
+			-theirs:"$REMOTE" -merged:"$MERGED"
+		check_unchanged
+	else
+		echo "TortoiseMerge cannot be used without a base" 1>&2
+		return 1
+	fi
+}
diff --git a/mergetools/vim b/mergetools/vim
new file mode 100644
index 0000000000..619594ae4b
--- /dev/null
+++ b/mergetools/vim
@@ -0,0 +1,44 @@
+diff_cmd () {
+	case "$1" in
+	gvimdiff|vimdiff)
+		"$merge_tool_path" -R -f -d \
+			-c 'wincmd l' -c 'cd $GIT_PREFIX' "$LOCAL" "$REMOTE"
+		;;
+	gvimdiff2|vimdiff2)
+		"$merge_tool_path" -R -f -d \
+			-c 'wincmd l' -c 'cd $GIT_PREFIX' "$LOCAL" "$REMOTE"
+		;;
+	esac
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	case "$1" in
+	gvimdiff|vimdiff)
+		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
+		;;
+	gvimdiff2|vimdiff2)
+		"$merge_tool_path" -f -d -c 'wincmd l' \
+			"$LOCAL" "$MERGED" "$REMOTE"
+		;;
+	esac
+	check_unchanged
+}
+
+translate_merge_tool_path() {
+	case "$1" in
+	gvimdiff|gvimdiff2)
+		echo gvim
+		;;
+	vimdiff|vimdiff2)
+		echo vim
+		;;
+	esac
+}
diff --git a/mergetools/xxdiff b/mergetools/xxdiff
new file mode 100644
index 0000000000..05b443394b
--- /dev/null
+++ b/mergetools/xxdiff
@@ -0,0 +1,25 @@
+diff_cmd () {
+	"$merge_tool_path" \
+		-R 'Accel.Search: "Ctrl+F"' \
+		-R 'Accel.SearchForward: "Ctrl-G"' \
+		"$LOCAL" "$REMOTE"
+}
+
+merge_cmd () {
+	touch "$BACKUP"
+	if $base_present
+	then
+		"$merge_tool_path" -X --show-merged-pane \
+			-R 'Accel.SaveAsMerged: "Ctrl-S"' \
+			-R 'Accel.Search: "Ctrl+F"' \
+			-R 'Accel.SearchForward: "Ctrl-G"' \
+			--merged-file "$MERGED" "$LOCAL" "$BASE" "$REMOTE"
+	else
+		"$merge_tool_path" -X $extra \
+			-R 'Accel.SaveAsMerged: "Ctrl-S"' \
+			-R 'Accel.Search: "Ctrl+F"' \
+			-R 'Accel.SearchForward: "Ctrl-G"' \
+			--merged-file "$MERGED" "$LOCAL" "$REMOTE"
+	fi
+	check_unchanged
+}

From f61bd9c68a4ed81afcc1fbbf5b956e781d88b434 Mon Sep 17 00:00:00 2001
From: David Aguilar <davvid@gmail.com>
Date: Fri, 19 Aug 2011 02:14:45 -0700
Subject: [PATCH 4/4] mergetools/meld: Use '--output' when available

meld 1.5.0 and newer allow the output file to be specified
when merging multiple files.  Check whether the meld command
supports '--output' and use it when available.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 mergetools/meld | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/mergetools/meld b/mergetools/meld
index 73d70ae28a..eaa115ccb7 100644
--- a/mergetools/meld
+++ b/mergetools/meld
@@ -3,7 +3,30 @@ diff_cmd () {
 }
 
 merge_cmd () {
+	if test -z "${meld_has_output_option:+set}"
+	then
+		check_meld_for_output_version
+	fi
 	touch "$BACKUP"
-	"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
+	if test "$meld_has_output_option" = true
+	then
+		"$merge_tool_path" --output "$MERGED" \
+			"$LOCAL" "$BASE" "$REMOTE"
+	else
+		"$merge_tool_path" "$LOCAL" "$MERGED" "$REMOTE"
+	fi
 	check_unchanged
 }
+
+# Check whether 'meld --output <file>' is supported
+check_meld_for_output_version () {
+	meld_path="$(git config mergetool.meld.path)"
+	meld_path="${meld_path:-meld}"
+
+	if "$meld_path" --output /dev/null --help >/dev/null 2>&1
+	then
+		meld_has_output_option=true
+	else
+		meld_has_output_option=false
+	fi
+}