[PATCH] git-gui: support core.whitespace rules in diff view

@@ -806,6 +806,7 @@ proc apply_config {} {
 }
 
 set default_config(branch.autosetupmerge) true
+set default_config(core.whitespace) ""
 set default_config(merge.tool) {}
 set default_config(mergetool.keepbackup) true
 set default_config(merge.diffstat) true

@@ -836,6 +837,13 @@ set font_descs {
 	{fontdiff font_diff {mc "Diff/Console Font"}}
 }
 
+set whitespace_config(blank-at-eol) 1
+set whitespace_config(space-before-tab) 1
+set whitespace_config(indent-with-non-tab) 0
+set whitespace_config(tab-in-indent) 0
+set whitespace_config(blank-at-eof) 1
+set whitespace_config(cr-at-eol) 0
+
 ######################################################################
 ##
 ## find git

@@ -1060,6 +1068,7 @@ git-version proc _parse_config {arr_name args} {
 
 proc load_config {include_global} {
 	global repo_config global_config system_config default_config
+	global whitespace_config
 
 	if {$include_global} {
 		_parse_config system_config --system

@@ -1080,6 +1089,23 @@ proc load_config {include_global} {
 			set repo_config($name) $system_config($name)
 		}
 	}
+	set whitespace ""
+	foreach cf {default_config system_config global_config repo_config} {
+		upvar #0 $cf config
+		if {[info exists config(core.whitespace)]} {
+			set whitespace $config(core.whitespace)
+		}
+	}
+	foreach var [split $whitespace ,] {
+		set state [expr {![string match -* $var]}]
+		set var [string trimleft $var -]
+		if {[string match "trailing-space" $var]} {
+			set whitespace_config(blank-at-eol) $state
+			set whitespace_config(blank-at-eof) $state
+		} else {
+			set whitespace_config($var) $state
+		}
+	}
 }
 
 ######################################################################

@@ -3323,6 +3349,7 @@ pack .vpane.lower.diff.header -side top -fill x
 pack .vpane.lower.diff.body -side bottom -fill both -expand 1
 
 $ui_diff tag conf d_cr -elide true
+$ui_diff tag conf ws -background red
 $ui_diff tag conf d_@ -foreground blue -font font_diffbold
 $ui_diff tag conf d_+ -foreground {#00a000}
 $ui_diff tag conf d_- -foreground red

@@ -332,11 +332,17 @@ proc start_show_diff {cont_info {add_opts {}}} {
 	fileevent $fd readable [list read_diff $fd $cont_info]
 }
 
+proc add_tag {w tag pos ndx} {
+	set begin "$pos + [lindex $ndx 0] chars"
+	set end "$pos + [expr {[lindex $ndx 1] + 1}] chars"
+	$w tag add $tag $begin $end
+}
+
 proc read_diff {fd cont_info} {
 	global ui_diff diff_active is_submodule_diff
 	global is_3way_diff is_conflict_diff current_diff_header
 	global current_diff_queue
-	global diff_empty_count
+	global diff_empty_count whitespace_config
 
 	$ui_diff conf -state normal
 	while {[gets $fd line] >= 0} {

@@ -434,7 +440,38 @@ proc read_diff {fd cont_info} {
 			}
 			}
 		}
-		$ui_diff insert end $line $tags
+		set insertion [list $line $tags]
+		if {$whitespace_config(blank-at-eol)} {
+			if {[regexp -indices {^[+-](?:.*\S)?(\s+)$} $line -> ndx]} {
+				set ndx [expr {[lindex $ndx 0] - 1}]
+				set insertion [list [string range $line 0 $ndx] $tags\
+								   [string range $line [incr ndx] end]\
+								   [concat $tags ws]]
+			}
+		}
+		set pos [$ui_diff index "end - 1 line linestart"]
+		eval [linsert $insertion 0 $ui_diff insert end]
+		if {[regexp {^[+-](\s*)\S} [lindex $insertion 0] -> initial]} {
+			if {$whitespace_config(indent-with-non-tab)} {
+				if {[regexp -indices {^x( {8,})} x$initial -> ndx]} {
+					add_tag $ui_diff ws $pos $ndx
+				}
+			}
+			if {$whitespace_config(space-before-tab)} {
+				set start 0
+				while {[regexp -indices -start $start {( +)\t} x$initial -> ndx]} {
+					add_tag $ui_diff ws $pos $ndx
+					set start [expr {[lindex $ndx 1] + 1}]
+				}
+			}
+			if {$whitespace_config(tab-in-indent)} {
+				set start 0
+				while {[regexp -indices -start $start {\t} x$initial ndx]} {
+					add_tag $ui_diff ws $pos $ndx
+					set start [expr {[lindex $ndx 1] + 1}]
+				}
+			}
+		}
 		if {[string index $line end] eq "\r"} {
 			$ui_diff tag add d_cr {end - 2c}
 		}

@@ -450,6 +487,16 @@ proc read_diff {fd cont_info} {
 			return
 		}
 
+		if {$whitespace_config(blank-at-eof)} {
+			set n 2
+			$ui_diff configure -state normal
+			while {[regexp {^[+-]$} [$ui_diff get "end - $n line linestart" "end - $n line lineend"]]} {
+				$ui_diff tag add ws "end - $n line linestart" "end - $n line lineend"
+				incr n
+			}
+			$ui_diff configure -state disabled
+		}
+
 		set diff_active 0
 		unlock_index
 		set scroll_pos [lindex $cont_info 0]

@@ -731,3 +778,10 @@ proc apply_range_or_line {x y} {
 
 	unlock_index
 }
+
+# Local variables:
+# mode: tcl
+# indent-tabs-mode: t
+# tcl-indent-level: 4
+# tab-width: 4
+# End: