hgmerge: add and use more tool variables

This patch adds even more customisable variables with tool paths.
Also moves $FILEMERGE where it belongs.

hgmerge

@@ -1,143 +1,154 b''
 #!/bin/sh
 #
 # hgmerge - default merge helper for Mercurial
 #
 # This tries to find a way to do three-way merge on the current system.
 # The result ought to end up in $1.
 
 set -e # bail out quickly on failure
 
 LOCAL="$1"
 BASE="$2"
 OTHER="$3"
 
 if [ -z "$EDITOR" ]; then
     EDITOR="vi"
 fi
 
 # find decent versions of our utilities, insisting on the GNU versions where we
 # need to
+MERGE=merge
 DIFF3=gdiff3
 DIFF=gdiff
 PATCH=gpatch
 
+type $MERGE >/dev/null 2>&1 || MERGE=
 type $DIFF3 >/dev/null 2>&1 || DIFF3=diff3
 type $DIFF  >/dev/null 2>&1 || DIFF=diff
-type $PATCH  >/dev/null 2>&1 || PATCH=patch
+type $PATCH >/dev/null 2>&1 || PATCH=patch
 $DIFF3 --version >/dev/null 2>&1 || DIFF3=
 
+# find optional visual utilities
+FILEMERGE='/Developer/Applications/Utilities/FileMerge.app/Contents/MacOS/FileMerge'
+KDIFF3=kdiff3
+TKDIFF=tkdiff
+
+type $FILEMERGE >/dev/null 2>&1 || FILEMERGE=
+type $KDIFF3    >/dev/null 2>&1 || KDIFF3=
+type $TKDIFF    >/dev/null 2>&1 || TKDIFF=
+
 # Back up our file
 cp "$LOCAL" "$LOCAL.orig"
 
 # Attempt to do a non-interactive merge
-if type merge > /dev/null 2>&1; then
-    merge "$LOCAL" "$BASE" "$OTHER" 2> /dev/null && exit 0
+if [ -n "$MERGE" ]; then
+    $MERGE "$LOCAL" "$BASE" "$OTHER" 2> /dev/null && exit 0
     cp "$LOCAL.orig" "$LOCAL"
 elif [ -n "$DIFF3" ]; then
     echo $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER"
     $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER" > "$LOCAL" && exit 0
     if [ $? -eq 2 ]; then
         echo "$DIFF3 failed! Exiting." 1>&2
         cp "$LOCAL.orig" "$LOCAL"
         exit 1
     fi
     cp "$LOCAL.orig" "$LOCAL"
 fi
 
 # on MacOS X try FileMerge.app, shipped with Apple's developer tools
 # TODO: make proper temp files. foo.orig and foo.link are dangerous
-FILEMERGE='/Developer/Applications/Utilities/FileMerge.app/Contents/MacOS/FileMerge'
-if type "$FILEMERGE" > /dev/null 2>&1; then
+
+if [ -n "$FILEMERGE" ]; then
     cp "$LOCAL.orig" "$LOCAL"
     ln "$LOCAL" "$LOCAL.link"
     # filemerge prefers the right by default
     if ! "$FILEMERGE" -left "$OTHER" -right "$LOCAL" -ancestor "$BASE" -merge "$LOCAL"
     then
         echo "FileMerge failed to launch"
         exit 1
     fi
     if ! test "$LOCAL" -ef "$LOCAL.link"
     then
         rm "$LOCAL.orig" "$LOCAL.link"
         exit 0
     else
         rm "$LOCAL.link"
         echo "$LOCAL is unchanged. Was the merge successful?"
         select answer in yes no
         do
             if test "$answer" == "yes"
             then
                 rm "$LOCAL.orig"
                 exit 0
             else
                 exit 1
             fi
         done
         exit 1
     fi
 fi
 
 if [ -n "$DISPLAY" ]; then
     # try using kdiff3, which is fairly nice
-    if type kdiff3 > /dev/null 2>&1; then
-	kdiff3 --auto "$BASE" "$LOCAL" "$OTHER" -o "$LOCAL" || exit 1
+    if [ -n "$KDIFF3" ]; then
+	$KDIFF3 --auto "$BASE" "$LOCAL" "$OTHER" -o "$LOCAL" || exit 1
 	exit 0
     fi
 
     # try using tkdiff, which is a bit less sophisticated
-    if type tkdiff > /dev/null 2>&1; then
-	tkdiff "$LOCAL" "$OTHER" -a "$BASE" -o "$LOCAL" || exit 1
+    if [ -n "$TKDIFF" ]; then
+	$TKDIFF "$LOCAL" "$OTHER" -a "$BASE" -o "$LOCAL" || exit 1
 	exit 0
     fi
 fi
 
 # Attempt to do a merge with $EDITOR
-if type merge > /dev/null 2>&1; then
+if [ -n "$MERGE" ]; then
     echo "conflicts detected in $LOCAL"
-    merge "$LOCAL" "$BASE" "$OTHER" 2>/dev/null || $EDITOR "$LOCAL"
+    $MERGE "$LOCAL" "$BASE" "$OTHER" 2>/dev/null || $EDITOR "$LOCAL"
     exit 0
 fi
 
 if [ -n "$DIFF3" ]; then
     echo "conflicts detected in $LOCAL"
     $DIFF3 -m "$LOCAL.orig" "$BASE" "$OTHER" > "$LOCAL" || {
         case $? in
             1)
                 $EDITOR "$LOCAL" ;;
             2)  echo "$DIFF3 failed! Exiting." 1>&2
                 cp "$LOCAL.orig" "$LOCAL"
                 exit 1 ;;
         esac
         exit 0
     }
 fi
 
 HGTMP=""
 cleanup_exit() {
     rm -rf "$HGTMP"
 }
 
 # attempt to manually merge with diff and patch
 if [ -n "$DIFF" -a -n "$PATCH" ]; then
     # Remove temporary files even if we get interrupted
     trap "cleanup_exit" 0 # normal exit
     trap "exit 1" 1 2 3 6 15 # HUP INT QUIT ABRT TERM
 
     HGTMP="${TMPDIR-/tmp}/hgmerge.$RANDOM.$RANDOM.$RANDOM.$$"
     (umask 077 && mkdir "$HGTMP") || {
 	echo "Could not create temporary directory! Exiting." 1>&2
 	exit 1
     }
 
     $DIFF -u "$BASE" "$OTHER" > "$HGTMP/diff" || :
     if $PATCH "$LOCAL" < "$HGTMP/diff"; then
 	exit 0
     else
 	# If rejects are empty after using the editor, merge was ok
 	$EDITOR "$LOCAL" "$LOCAL.rej" && test -s "$LOCAL.rej" || exit 0
     fi
     exit 1
 fi
 
 echo "hgmerge: unable to find merge, tkdiff, kdiff3, or diff+patch!"
 exit 1