git-gui: Always indicate the file in the diff viewer.

When we did a rescan to update the file lists we lost the tag which
indicated which file was currently in the diff viewer.  This occurs
because we delete every line from the two file list boxes (thus
removing the tag) and then redisplay the diff in the diff viewer
but then fail to restore the tag in the file list.

Now we restore that tag by searching for the file in the file lists
and adding the tag back when the diff viewer displays something.

We also no longer obtain the file path directly from the file list
text box.  Instead we now keep two Tcl lists, one for each file list,
holding the file names in sorted order.  These lists can be searched
with the native [lsearch -sorted] operation (which should be faster
than our crude bsearch) or can be quickly accessed by index to return
the file path.  This should help make things safer should we ever be
given a file name which contains an LF within it (as that would span
two lines in the file list, not one).

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

git-gui

@@ -150,7 +150,7 @@ proc repository_state {hdvar ctvar} {
 proc update_status {{final Ready.}} {
 	global HEAD PARENT commit_type
 	global ui_index ui_other ui_status_value ui_comm
-	global status_active file_states
+	global status_active file_states file_lists
 	global cfg_trust_mtime
 
 	if {$status_active || ![lock_index read]} return
@@ -166,6 +166,7 @@ proc update_status {{final Ready.}} {
 	}
 
 	array unset file_states
+	array unset file_lists
 	foreach w [list $ui_index $ui_other] {
 		$w conf -state normal
 		$w delete 0.0 end
@@ -196,7 +197,7 @@ proc update_status {{final Ready.}} {
 proc update_status_stage2 {fd final} {
 	global gitdir PARENT commit_type
 	global ui_index ui_other ui_status_value ui_comm
-	global status_active file_states
+	global status_active
 	global buf_rdi buf_rdf buf_rlo
 
 	if {$fd != {}} {
@@ -346,22 +347,40 @@ proc status_eof {fd buf final} {
 ## diff
 
 proc clear_diff {} {
-	global ui_diff ui_fname_value ui_fstatus_value
+	global ui_diff ui_fname_value ui_fstatus_value ui_index ui_other
 
 	$ui_diff conf -state normal
 	$ui_diff delete 0.0 end
 	$ui_diff conf -state disabled
+
 	set ui_fname_value {}
 	set ui_fstatus_value {}
+
+	$ui_index tag remove in_diff 0.0 end
+	$ui_other tag remove in_diff 0.0 end
 }
 
-proc show_diff {path} {
-	global file_states PARENT diff_3way diff_active
+proc show_diff {path {w {}} {lno {}}} {
+	global file_states file_lists
+	global PARENT diff_3way diff_active
 	global ui_diff ui_fname_value ui_fstatus_value ui_status_value
 
 	if {$diff_active || ![lock_index read]} return
 
 	clear_diff
+	if {$w == {} || $lno == {}} {
+		foreach w [array names file_lists] {
+			set lno [lsearch -sorted $file_lists($w) $path]
+			if {$lno >= 0} {
+				incr lno
+				break
+			}
+		}
+	}
+	if {$w != {} && $lno >= 1} {
+		$w tag add in_diff $lno.0 [expr $lno + 1].0
+	}
+
 	set s $file_states($path)
 	set m [lindex $s 0]
 	set diff_3way 0
@@ -823,27 +842,6 @@ proc mapdesc {state path} {
 	return $r
 }
 
-proc bsearch {w path} {
-	set hi [expr [lindex [split [$w index end] .] 0] - 2]
-	if {$hi == 0} {
-		return -1
-	}
-	set lo 0
-	while {$lo < $hi} {
-		set mi [expr [expr $lo + $hi] / 2]
-		set ti [expr $mi + 1]
-		set cmp [string compare [$w get $ti.1 $ti.end] $path]
-		if {$cmp < 0} {
-			set lo $ti
-		} elseif {$cmp == 0} {
-			return $mi
-		} else {
-			set hi $mi
-		}
-	}
-	return -[expr $lo + 1]
-}
-
 set next_icon_id 0
 
 proc merge_state {path new_state} {
@@ -877,7 +875,8 @@ proc merge_state {path new_state} {
 }
 
 proc display_file {path state} {
-	global ui_index ui_other file_states status_active
+	global ui_index ui_other
+	global file_states file_lists status_active
 
 	set old_m [merge_state $path $state]
 	if {$status_active} return
@@ -889,7 +888,7 @@ proc display_file {path state} {
 	set new_icon [mapicon $new_m $path]
 
 	if {$new_w != $old_w} {
-		set lno [bsearch $old_w $path]
+		set lno [lsearch -sorted $file_lists($old_w) $path]
 		if {$lno >= 0} {
 			incr lno
 			$old_w conf -state normal
@@ -897,7 +896,10 @@ proc display_file {path state} {
 			$old_w conf -state disabled
 		}
 
-		set lno [expr abs([bsearch $new_w $path] + 1) + 1]
+		lappend file_lists($new_w) $path
+		set file_lists($new_w) [lsort $file_lists($new_w)]
+		set lno [lsearch -sorted $file_lists($new_w) $path]
+		incr lno
 		$new_w conf -state normal
 		$new_w image create $lno.0 \
 			-align center -padx 5 -pady 1 \
@@ -913,7 +915,7 @@ proc display_file {path state} {
 }
 
 proc display_all_files {} {
-	global ui_index ui_other file_states
+	global ui_index ui_other file_states file_lists
 
 	$ui_index conf -state normal
 	$ui_other conf -state normal
@@ -922,6 +924,7 @@ proc display_all_files {} {
 		set s $file_states($path)
 		set m [lindex $s 0]
 		set w [mapcol $m $path]
+		lappend file_lists($w) $path
 		$w image create end \
 			-align center -padx 5 -pady 1 \
 			-name [lindex $s 1] \
@@ -1484,19 +1487,16 @@ proc do_commit {} {
 # shift == 1: left click
 #          3: right click  
 proc click {w x y shift wx wy} {
-	global ui_index ui_other
+	global ui_index ui_other file_lists
 
 	set pos [split [$w index @$x,$y] .]
 	set lno [lindex $pos 0]
 	set col [lindex $pos 1]
-	set path [$w get $lno.1 $lno.end]
+	set path [lindex $file_lists($w) [expr $lno - 1]]
 	if {$path == {}} return
 
 	if {$col > 0 && $shift == 1} {
-		$ui_index tag remove in_diff 0.0 end
-		$ui_other tag remove in_diff 0.0 end
-		$w tag add in_diff $lno.0 [expr $lno + 1].0
-		show_diff $path
+		show_diff $path $w $lno
 	}
 }