[PATCH 2/2] git-gui: support for diff3 conflict style

[Bert Wesarg <bert.wesarg@xxxxxxxxxxxxxx>]

This adds highlight support for the diff3 conflict style.

The common pre-image will be reversed to --, because it has been removed
and either replaced with ours or theirs side.

Signed-off-by: Bert Wesarg <bert.wesarg@xxxxxxxxxxxxxx>
---
 git-gui.sh   |  3 +++
 lib/diff.tcl | 22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/git-gui.sh b/git-gui.sh
index fd476b6..6d80f82 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -3581,6 +3581,9 @@ $ui_diff tag conf d_s- \
 $ui_diff tag conf d< \
 	-foreground orange \
 	-font font_diffbold
+$ui_diff tag conf d| \
+	-foreground orange \
+	-font font_diffbold
 $ui_diff tag conf d= \
 	-foreground orange \
 	-font font_diffbold
diff --git a/lib/diff.tcl b/lib/diff.tcl
index 0fd4600..6caf4e7 100644
--- a/lib/diff.tcl
+++ b/lib/diff.tcl
@@ -347,6 +347,7 @@ proc start_show_diff {cont_info {add_opts {}}} {
 	}
 
 	set ::current_diff_inheader 1
+	set ::conflict_state {CONTEXT}
 	fconfigure $fd \
 		-blocking 0 \
 		-encoding [get_path_encoding $path] \
@@ -450,10 +451,28 @@ proc read_diff {fd conflict_size cont_info} {
 			{++} {
 				set regexp [string map [list %conflict_size $conflict_size]\
 								{^\+\+([<>=]){%conflict_size}(?: |$)}]
+				set regexp_pre_image [string map [list %conflict_size $conflict_size]\
+								{^\+\+\|{%conflict_size}(?: |$)}]
 				if {[regexp $regexp $line _g op]} {
 					set is_conflict_diff 1
 					set line [string replace $line 0 1 {  }]
+					set markup {}
 					set tags d$op
+					switch -exact -- $op {
+					< { set ::conflict_state {OURS} }
+					= { set ::conflict_state {THEIRS} }
+					> { set ::conflict_state {CONTEXT} }
+					}
+				} elseif {[regexp $regexp_pre_image $line]} {
+					set is_conflict_diff 1
+					set line [string replace $line 0 1 {  }]
+					set markup {}
+					set tags d|
+					set ::conflict_state {BASE}
+				} elseif {$::conflict_state eq {BASE}} {
+					set line [string replace $line 0 1 {--}]
+					set markup {}
+					set tags d_--
 				} else {
 					set tags d_++
 				}
@@ -505,6 +524,9 @@ proc read_diff {fd conflict_size cont_info} {
 			}
 		}
 		set mark [$ui_diff index "end - 1 line linestart"]
+		if {[llength $markup] > 0} {
+			set tags {}
+		}
 		$ui_diff insert end $line $tags
 		if {[string index $line end] eq "\r"} {
 			$ui_diff tag add d_cr {end - 2c}
-- 
2.21.0.789.ga095d9d866