git-gui/lib/diff.tcl - jrn/git - Git at Google

 # git-gui diff viewer
 # Copyright (C) 2006, 2007 Shawn Pearce

 proc clear_diff {} {
 	global ui_diff current_diff_path current_diff_header
 	global ui_index ui_workdir

 	$ui_diff conf -state normal
 	$ui_diff delete 0.0 end
 	$ui_diff conf -state disabled

 	set current_diff_path {}
 	set current_diff_header {}

 	$ui_index tag remove in_diff 0.0 end
 	$ui_workdir tag remove in_diff 0.0 end
 }

 proc reshow_diff {{after {}}} {
 	global file_states file_lists
 	global current_diff_path current_diff_side
 	global ui_diff

 	set p $current_diff_path
 	if {$p eq {}} {
 		# No diff is being shown.
 	} elseif {$current_diff_side eq {}} {
 		clear_diff
 	} elseif {[catch {set s $file_states($p)}]
 		|| [lsearch -sorted -exact $file_lists($current_diff_side) $p] == -1} {

 		if {[find_next_diff $current_diff_side $p {} {[^O]}]} {
 			next_diff $after
 		} else {
 			clear_diff
 		}
 	} else {
 		set save_pos [lindex [$ui_diff yview] 0]
 		show_diff $p $current_diff_side {} $save_pos $after
 	}
 }

 proc force_diff_encoding {enc} {
 	global current_diff_path

 	if {$current_diff_path ne {}} {
 		force_path_encoding $current_diff_path $enc
 		reshow_diff
 	}
 }

 proc handle_empty_diff {} {
 	global current_diff_path file_states file_lists
 	global diff_empty_count

 	set path $current_diff_path
 	set s $file_states($path)
 	if {[lindex $s 0] ne {_M}} return

 	# Prevent infinite rescan loops
 	incr diff_empty_count
 	if {$diff_empty_count > 1} return

 	info_popup [mc "No differences detected.

 %s has no changes.

 The modification date of this file was updated by another application, but the content within the file was not changed.

 A rescan will be automatically started to find other files which may have the same state." [short_path $path]]

 	clear_diff
 	display_file $path __
 	rescan ui_ready 0
 }

 proc show_diff {path w {lno {}} {scroll_pos {}} {callback {}}} {
 	global file_states file_lists
 	global is_3way_diff is_conflict_diff diff_active repo_config
 	global ui_diff ui_index ui_workdir
 	global current_diff_path current_diff_side current_diff_header
 	global current_diff_queue

 	if {$diff_active || ![lock_index read]} return

 	clear_diff
 	if {$lno == {}} {
 		set lno [lsearch -sorted -exact $file_lists($w) $path]
 		if {$lno >= 0} {
 			incr lno
 		}
 	}
 	if {$lno >= 1} {
 		$w tag add in_diff $lno.0 [expr {$lno + 1}].0
 		$w see $lno.0
 	}

 	set s $file_states($path)
 	set m [lindex $s 0]
 	set is_conflict_diff 0
 	set current_diff_path $path
 	set current_diff_side $w
 	set current_diff_queue {}
 	ui_status [mc "Loading diff of %s..." [escape_path $path]]

 	set cont_info [list $scroll_pos $callback]

 	if {[string first {U} $m] >= 0} {
 		merge_load_stages $path [list show_unmerged_diff $cont_info]
 	} elseif {$m eq {_O}} {
 		show_other_diff $path $w $m $cont_info
 	} else {
 		start_show_diff $cont_info
 	}
 }

 proc show_unmerged_diff {cont_info} {
 	global current_diff_path current_diff_side
 	global merge_stages ui_diff is_conflict_diff
 	global current_diff_queue

 	if {$merge_stages(2) eq {}} {
 		set is_conflict_diff 1
 		lappend current_diff_queue \
 			[list [mc "LOCAL: deleted\nREMOTE:\n"] d======= \
 			    [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 	} elseif {$merge_stages(3) eq {}} {
 		set is_conflict_diff 1
 		lappend current_diff_queue \
 			[list [mc "REMOTE: deleted\nLOCAL:\n"] d======= \
 			    [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 	} elseif {[lindex $merge_stages(1) 0] eq {120000}
 		|| [lindex $merge_stages(2) 0] eq {120000}
 		|| [lindex $merge_stages(3) 0] eq {120000}} {
 		set is_conflict_diff 1
 		lappend current_diff_queue \
 			[list [mc "LOCAL:\n"] d======= \
 			    [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 		lappend current_diff_queue \
 			[list [mc "REMOTE:\n"] d======= \
 			    [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 	} else {
 		start_show_diff $cont_info
 		return
 	}

 	advance_diff_queue $cont_info
 }

 proc advance_diff_queue {cont_info} {
 	global current_diff_queue ui_diff

 	set item [lindex $current_diff_queue 0]
 	set current_diff_queue [lrange $current_diff_queue 1 end]

 	$ui_diff conf -state normal
 	$ui_diff insert end [lindex $item 0] [lindex $item 1]
 	$ui_diff conf -state disabled

 	start_show_diff $cont_info [lindex $item 2]
 }

 proc show_other_diff {path w m cont_info} {
 	global file_states file_lists
 	global is_3way_diff diff_active repo_config
 	global ui_diff ui_index ui_workdir
 	global current_diff_path current_diff_side current_diff_header

 	# - Git won't give us the diff, there's nothing to compare to!
 	#
 	if {$m eq {_O}} {
 		set max_sz 100000
 		set type unknown
 		if {[catch {
 				set type [file type $path]
 				switch -- $type {
 				directory {
 					set type submodule
 					set content {}
 					set sz 0
 				}
 				link {
 					set content [file readlink $path]
 					set sz [string length $content]
 				}
 				file {
 					set fd [open $path r]
 					fconfigure $fd \
 						-eofchar {} \
 						-encoding [get_path_encoding $path]
 					set content [read $fd $max_sz]
 					close $fd
 					set sz [file size $path]
 				}
 				default {
 					error "'$type' not supported"
 				}
 				}
 			} err ]} {
 			set diff_active 0
 			unlock_index
 			ui_status [mc "Unable to display %s" [escape_path $path]]
 			error_popup [strcat [mc "Error loading file:"] "\n\n$err"]
 			return
 		}
 		$ui_diff conf -state normal
 		if {$type eq {submodule}} {
 			$ui_diff insert end [append \
 				"* " \
 				[mc "Git Repository (subproject)"] \
 				"\n"] d_@
 		} elseif {![catch {set type [exec file $path]}]} {
 			set n [string length $path]
 			if {[string equal -length $n $path $type]} {
 				set type [string range $type $n end]
 				regsub {^:?\s*} $type {} type
 			}
 			$ui_diff insert end "* $type\n" d_@
 		}
 		if {[string first "\0" $content] != -1} {
 			$ui_diff insert end \
 				[mc "* Binary file (not showing content)."] \
 				d_@
 		} else {
 			if {$sz > $max_sz} {
 				$ui_diff insert end [mc \
 "* Untracked file is %d bytes.
 * Showing only first %d bytes.
 " $sz $max_sz] d_@
 			}
 			$ui_diff insert end $content
 			if {$sz > $max_sz} {
 				$ui_diff insert end [mc "
 * Untracked file clipped here by %s.
 * To see the entire file, use an external editor.
 " [appname]] d_@
 			}
 		}
 		$ui_diff conf -state disabled
 		set diff_active 0
 		unlock_index
 		set scroll_pos [lindex $cont_info 0]
 		if {$scroll_pos ne {}} {
 			update
 			$ui_diff yview moveto $scroll_pos
 		}
 		ui_ready
 		set callback [lindex $cont_info 1]
 		if {$callback ne {}} {
 			eval $callback
 		}
 		return
 	}
 }

 proc start_show_diff {cont_info {add_opts {}}} {
 	global file_states file_lists
 	global is_3way_diff is_submodule_diff diff_active repo_config
 	global ui_diff ui_index ui_workdir
 	global current_diff_path current_diff_side current_diff_header

 	set path $current_diff_path
 	set w $current_diff_side

 	set s $file_states($path)
 	set m [lindex $s 0]
 	set is_3way_diff 0
 	set is_submodule_diff 0
 	set diff_active 1
 	set current_diff_header {}

 	set cmd [list]
 	if {$w eq $ui_index} {
 		lappend cmd diff-index
 		lappend cmd --cached
 	} elseif {$w eq $ui_workdir} {
 		if {[string first {U} $m] >= 0} {
 			lappend cmd diff
 		} else {
 			lappend cmd diff-files
 		}
 	}

 	if {[string match {160000 *} [lindex $s 2]]
 	 || [string match {160000 *} [lindex $s 3]]} {
 		set is_submodule_diff 1

 		if {[git-version >= "1.6.6"]} {
 			lappend cmd --submodule
 		}
 	}

 	lappend cmd -p
 	lappend cmd --no-color
 	if {$repo_config(gui.diffcontext) >= 1} {
 		lappend cmd "-U$repo_config(gui.diffcontext)"
 	}
 	if {$w eq $ui_index} {
 		lappend cmd [PARENT]
 	}
 	if {$add_opts ne {}} {
 		eval lappend cmd $add_opts
 	} else {
 		lappend cmd --
 		lappend cmd $path
 	}

 	if {$is_submodule_diff && [git-version < "1.6.6"]} {
 		if {$w eq $ui_index} {
 			set cmd [list submodule summary --cached -- $path]
 		} else {
 			set cmd [list submodule summary --files -- $path]
 		}
 	}

 	if {[catch {set fd [eval git_read --nice $cmd]} err]} {
 		set diff_active 0
 		unlock_index
 		ui_status [mc "Unable to display %s" [escape_path $path]]
 		error_popup [strcat [mc "Error loading diff:"] "\n\n$err"]
 		return
 	}

 	set ::current_diff_inheader 1
 	fconfigure $fd \
 		-blocking 0 \
 		-encoding [get_path_encoding $path] \
 		-translation lf
 	fileevent $fd readable [list read_diff $fd $cont_info]
 }

 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

 	$ui_diff conf -state normal
 	while {[gets $fd line] >= 0} {
 		# -- Cleanup uninteresting diff header lines.
 		#
 		if {$::current_diff_inheader} {
 			if {   [string match {diff --git *}      $line]
 			    || [string match {diff --cc *}       $line]
 			    || [string match {diff --combined *} $line]
 			    || [string match {--- *}             $line]
 			    || [string match {+++ *}             $line]} {
 				append current_diff_header $line "\n"
 				continue
 			}
 		}
 		if {[string match {index *} $line]} continue
 		if {$line eq {deleted file mode 120000}} {
 			set line "deleted symlink"
 		}
 		set ::current_diff_inheader 0

 		# -- Automatically detect if this is a 3 way diff.
 		#
 		if {[string match {@@@ *} $line]} {set is_3way_diff 1}

 		if {[string match {mode *} $line]
 			|| [string match {new file *} $line]
 			|| [regexp {^(old|new) mode *} $line]
 			|| [string match {deleted file *} $line]
 			|| [string match {deleted symlink} $line]
 			|| [string match {Binary files * and * differ} $line]
 			|| $line eq {\ No newline at end of file}
 			|| [regexp {^\* Unmerged path } $line]} {
 			set tags {}
 		} elseif {$is_3way_diff} {
 			set op [string range $line 0 1]
 			switch -- $op {
 			{  } {set tags {}}
 			{@@} {set tags d_@}
 			{ +} {set tags d_s+}
 			{ -} {set tags d_s-}
 			{+ } {set tags d_+s}
 			{- } {set tags d_-s}
 			{--} {set tags d_--}
 			{++} {
 				if {[regexp {^\+\+([<>]{7} |={7})} $line _g op]} {
 					set is_conflict_diff 1
 					set line [string replace $line 0 1 {  }]
 					set tags d$op
 				} else {
 					set tags d_++
 				}
 			}
 			default {
 				puts "error: Unhandled 3 way diff marker: {$op}"
 				set tags {}
 			}
 			}
 		} elseif {$is_submodule_diff} {
 			if {$line == ""} continue
 			if {[regexp {^Submodule } $line]} {
 				set tags d_@
 			} elseif {[regexp {^\* } $line]} {
 				set line [string replace $line 0 1 {Submodule }]
 				set tags d_@
 			} else {
 				set op [string range $line 0 2]
 				switch -- $op {
 				{  <} {set tags d_-}
 				{  >} {set tags d_+}
 				{  W} {set tags {}}
 				default {
 					puts "error: Unhandled submodule diff marker: {$op}"
 					set tags {}
 				}
 				}
 			}
 		} else {
 			set op [string index $line 0]
 			switch -- $op {
 			{ } {set tags {}}
 			{@} {set tags d_@}
 			{-} {set tags d_-}
 			{+} {
 				if {[regexp {^\+([<>]{7} |={7})} $line _g op]} {
 					set is_conflict_diff 1
 					set tags d$op
 				} else {
 					set tags d_+
 				}
 			}
 			default {
 				puts "error: Unhandled 2 way diff marker: {$op}"
 				set tags {}
 			}
 			}
 		}
 		$ui_diff insert end $line $tags
 		if {[string index $line end] eq "\r"} {
 			$ui_diff tag add d_cr {end - 2c}
 		}
 		$ui_diff insert end "\n" $tags
 	}
 	$ui_diff conf -state disabled

 	if {[eof $fd]} {
 		close $fd

 		if {$current_diff_queue ne {}} {
 			advance_diff_queue $cont_info
 			return
 		}

 		set diff_active 0
 		unlock_index
 		set scroll_pos [lindex $cont_info 0]
 		if {$scroll_pos ne {}} {
 			update
 			$ui_diff yview moveto $scroll_pos
 		}
 		ui_ready

 		if {[$ui_diff index end] eq {2.0}} {
 			handle_empty_diff
 		} else {
 			set diff_empty_count 0
 		}

 		set callback [lindex $cont_info 1]
 		if {$callback ne {}} {
 			eval $callback
 		}
 	}
 }

 proc apply_hunk {x y} {
 	global current_diff_path current_diff_header current_diff_side
 	global ui_diff ui_index file_states

 	if {$current_diff_path eq {} || $current_diff_header eq {}} return
 	if {![lock_index apply_hunk]} return

 	set apply_cmd {apply --cached --whitespace=nowarn}
 	set mi [lindex $file_states($current_diff_path) 0]
 	if {$current_diff_side eq $ui_index} {
 		set failed_msg [mc "Failed to unstage selected hunk."]
 		lappend apply_cmd --reverse
 		if {[string index $mi 0] ne {M}} {
 			unlock_index
 			return
 		}
 	} else {
 		set failed_msg [mc "Failed to stage selected hunk."]
 		if {[string index $mi 1] ne {M}} {
 			unlock_index
 			return
 		}
 	}

 	set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
 	set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
 	if {$s_lno eq {}} {
 		unlock_index
 		return
 	}

 	set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
 	if {$e_lno eq {}} {
 		set e_lno end
 	}

 	if {[catch {
 		set enc [get_path_encoding $current_diff_path]
 		set p [eval git_write $apply_cmd]
 		fconfigure $p -translation binary -encoding $enc
 		puts -nonewline $p $current_diff_header
 		puts -nonewline $p [$ui_diff get $s_lno $e_lno]
 		close $p} err]} {
 		error_popup [append $failed_msg "\n\n$err"]
 		unlock_index
 		return
 	}

 	$ui_diff conf -state normal
 	$ui_diff delete $s_lno $e_lno
 	$ui_diff conf -state disabled

 	if {[$ui_diff get 1.0 end] eq "\n"} {
 		set o _
 	} else {
 		set o ?
 	}

 	if {$current_diff_side eq $ui_index} {
 		set mi ${o}M
 	} elseif {[string index $mi 0] eq {_}} {
 		set mi M$o
 	} else {
 		set mi ?$o
 	}
 	unlock_index
 	display_file $current_diff_path $mi
 	# This should trigger shift to the next changed file
 	if {$o eq {_}} {
 		reshow_diff
 	}
 }

 proc apply_range_or_line {x y} {
 	global current_diff_path current_diff_header current_diff_side
 	global ui_diff ui_index file_states

 	set selected [$ui_diff tag nextrange sel 0.0]

 	if {$selected == {}} {
 		set first [$ui_diff index "@$x,$y"]
 		set last $first
 	} else {
 		set first [lindex $selected 0]
 		set last [lindex $selected 1]
 	}

 	set first_l [$ui_diff index "$first linestart"]
 	set last_l [$ui_diff index "$last lineend"]

 	if {$current_diff_path eq {} || $current_diff_header eq {}} return
 	if {![lock_index apply_hunk]} return

 	set apply_cmd {apply --cached --whitespace=nowarn}
 	set mi [lindex $file_states($current_diff_path) 0]
 	if {$current_diff_side eq $ui_index} {
 		set failed_msg [mc "Failed to unstage selected line."]
 		set to_context {+}
 		lappend apply_cmd --reverse
 		if {[string index $mi 0] ne {M}} {
 			unlock_index
 			return
 		}
 	} else {
 		set failed_msg [mc "Failed to stage selected line."]
 		set to_context {-}
 		if {[string index $mi 1] ne {M}} {
 			unlock_index
 			return
 		}
 	}

 	set wholepatch {}

 	while {$first_l < $last_l} {
 		set i_l [$ui_diff search -backwards -regexp ^@@ $first_l 0.0]
 		if {$i_l eq {}} {
 			# If there's not a @@ above, then the selected range
 			# must have come before the first_l @@
 			set i_l [$ui_diff search -regexp ^@@ $first_l $last_l]
 		}
 		if {$i_l eq {}} {
 			unlock_index
 			return
 		}
 		# $i_l is now at the beginning of a line

 		# pick start line number from hunk header
 		set hh [$ui_diff get $i_l "$i_l + 1 lines"]
 		set hh [lindex [split $hh ,] 0]
 		set hln [lindex [split $hh -] 1]

 		# There is a special situation to take care of. Consider this
 		# hunk:
 		#
 		#    @@ -10,4 +10,4 @@
 		#     context before
 		#    -old 1
 		#    -old 2
 		#    +new 1
 		#    +new 2
 		#     context after
 		#
 		# We used to keep the context lines in the order they appear in
 		# the hunk. But then it is not possible to correctly stage only
 		# "-old 1" and "+new 1" - it would result in this staged text:
 		#
 		#    context before
 		#    old 2
 		#    new 1
 		#    context after
 		#
 		# (By symmetry it is not possible to *un*stage "old 2" and "new
 		# 2".)
 		#
 		# We resolve the problem by introducing an asymmetry, namely,
 		# when a "+" line is *staged*, it is moved in front of the
 		# context lines that are generated from the "-" lines that are
 		# immediately before the "+" block. That is, we construct this
 		# patch:
 		#
 		#    @@ -10,4 +10,5 @@
 		#     context before
 		#    +new 1
 		#     old 1
 		#     old 2
 		#     context after
 		#
 		# But we do *not* treat "-" lines that are *un*staged in a
 		# special way.
 		#
 		# With this asymmetry it is possible to stage the change "old
 		# 1" -> "new 1" directly, and to stage the change "old 2" ->
 		# "new 2" by first staging the entire hunk and then unstaging
 		# the change "old 1" -> "new 1".
 		#
 		# Applying multiple lines adds complexity to the special
 		# situation.  The pre_context must be moved after the entire
 		# first block of consecutive staged "+" lines, so that
 		# staging both additions gives the following patch:
 		#
 		#    @@ -10,4 +10,6 @@
 		#     context before
 		#    +new 1
 		#    +new 2
 		#     old 1
 		#     old 2
 		#     context after

 		# This is non-empty if and only if we are _staging_ changes;
 		# then it accumulates the consecutive "-" lines (after
 		# converting them to context lines) in order to be moved after
 		# "+" change lines.
 		set pre_context {}

 		set n 0
 		set m 0
 		set i_l [$ui_diff index "$i_l + 1 lines"]
 		set patch {}
 		while {[$ui_diff compare $i_l < "end - 1 chars"] &&
 		       [$ui_diff get $i_l "$i_l + 2 chars"] ne {@@}} {
 			set next_l [$ui_diff index "$i_l + 1 lines"]
 			set c1 [$ui_diff get $i_l]
 			if {[$ui_diff compare $first_l <= $i_l] &&
 			    [$ui_diff compare $i_l < $last_l] &&
 			    ($c1 eq {-} || $c1 eq {+})} {
 				# a line to stage/unstage
 				set ln [$ui_diff get $i_l $next_l]
 				if {$c1 eq {-}} {
 					set n [expr $n+1]
 					set patch "$patch$pre_context$ln"
 					set pre_context {}
 				} else {
 					set m [expr $m+1]
 					set patch "$patch$ln"
 				}
 			} elseif {$c1 ne {-} && $c1 ne {+}} {
 				# context line
 				set ln [$ui_diff get $i_l $next_l]
 				set patch "$patch$pre_context$ln"
 				set n [expr $n+1]
 				set m [expr $m+1]
 				set pre_context {}
 			} elseif {$c1 eq $to_context} {
 				# turn change line into context line
 				set ln [$ui_diff get "$i_l + 1 chars" $next_l]
 				if {$c1 eq {-}} {
 					set pre_context "$pre_context $ln"
 				} else {
 					set patch "$patch $ln"
 				}
 				set n [expr $n+1]
 				set m [expr $m+1]
 			} else {
 				# a change in the opposite direction of
 				# to_context which is outside the range of
 				# lines to apply.
 				set patch "$patch$pre_context"
 				set pre_context {}
 			}
 			set i_l $next_l
 		}
 		set patch "$patch$pre_context"
 		set wholepatch "$wholepatch@@ -$hln,$n +$hln,$m @@\n$patch"
 		set first_l [$ui_diff index "$next_l + 1 lines"]
 	}

 	if {[catch {
 		set enc [get_path_encoding $current_diff_path]
 		set p [eval git_write $apply_cmd]
 		fconfigure $p -translation binary -encoding $enc
 		puts -nonewline $p $current_diff_header
 		puts -nonewline $p $wholepatch
 		close $p} err]} {
 		error_popup [append $failed_msg "\n\n$err"]
 	}

 	unlock_index
 }
	# git-gui diff viewer
	# Copyright (C) 2006, 2007 Shawn Pearce

	proc clear_diff {} {
	global ui_diff current_diff_path current_diff_header
	global ui_index ui_workdir

	$ui_diff conf -state normal
	$ui_diff delete 0.0 end
	$ui_diff conf -state disabled

	set current_diff_path {}
	set current_diff_header {}

	$ui_index tag remove in_diff 0.0 end
	$ui_workdir tag remove in_diff 0.0 end
	}

	proc reshow_diff {{after {}}} {
	global file_states file_lists
	global current_diff_path current_diff_side
	global ui_diff

	set p $current_diff_path
	if {$p eq {}} {
	# No diff is being shown.
	} elseif {$current_diff_side eq {}} {
	clear_diff
	} elseif {[catch {set s $file_states($p)}]
	\|\| [lsearch -sorted -exact $file_lists($current_diff_side) $p] == -1} {

	if {[find_next_diff $current_diff_side $p {} {[^O]}]} {
	next_diff $after
	} else {
	clear_diff
	}
	} else {
	set save_pos [lindex [$ui_diff yview] 0]
	show_diff $p $current_diff_side {} $save_pos $after
	}
	}

	proc force_diff_encoding {enc} {
	global current_diff_path

	if {$current_diff_path ne {}} {
	force_path_encoding $current_diff_path $enc
	reshow_diff
	}
	}

	proc handle_empty_diff {} {
	global current_diff_path file_states file_lists
	global diff_empty_count

	set path $current_diff_path
	set s $file_states($path)
	if {[lindex $s 0] ne {_M}} return

	# Prevent infinite rescan loops
	incr diff_empty_count
	if {$diff_empty_count > 1} return

	info_popup [mc "No differences detected.

	%s has no changes.

	The modification date of this file was updated by another application, but the content within the file was not changed.

	A rescan will be automatically started to find other files which may have the same state." [short_path $path]]

	clear_diff
	display_file $path __
	rescan ui_ready 0
	}

	proc show_diff {path w {lno {}} {scroll_pos {}} {callback {}}} {
	global file_states file_lists
	global is_3way_diff is_conflict_diff diff_active repo_config
	global ui_diff ui_index ui_workdir
	global current_diff_path current_diff_side current_diff_header
	global current_diff_queue

	if {$diff_active \|\| ![lock_index read]} return

	clear_diff
	if {$lno == {}} {
	set lno [lsearch -sorted -exact $file_lists($w) $path]
	if {$lno >= 0} {
	incr lno
	}
	}
	if {$lno >= 1} {
	$w tag add in_diff $lno.0 [expr {$lno + 1}].0
	$w see $lno.0
	}

	set s $file_states($path)
	set m [lindex $s 0]
	set is_conflict_diff 0
	set current_diff_path $path
	set current_diff_side $w
	set current_diff_queue {}
	ui_status [mc "Loading diff of %s..." [escape_path $path]]

	set cont_info [list $scroll_pos $callback]

	if {[string first {U} $m] >= 0} {
	merge_load_stages $path [list show_unmerged_diff $cont_info]
	} elseif {$m eq {_O}} {
	show_other_diff $path $w $m $cont_info
	} else {
	start_show_diff $cont_info
	}
	}

	proc show_unmerged_diff {cont_info} {
	global current_diff_path current_diff_side
	global merge_stages ui_diff is_conflict_diff
	global current_diff_queue

	if {$merge_stages(2) eq {}} {
	set is_conflict_diff 1
	lappend current_diff_queue \
	[list [mc "LOCAL: deleted\nREMOTE:\n"] d======= \
	[list ":1:$current_diff_path" ":3:$current_diff_path"]]
	} elseif {$merge_stages(3) eq {}} {
	set is_conflict_diff 1
	lappend current_diff_queue \
	[list [mc "REMOTE: deleted\nLOCAL:\n"] d======= \
	[list ":1:$current_diff_path" ":2:$current_diff_path"]]
	} elseif {[lindex $merge_stages(1) 0] eq {120000}
	\|\| [lindex $merge_stages(2) 0] eq {120000}
	\|\| [lindex $merge_stages(3) 0] eq {120000}} {
	set is_conflict_diff 1
	lappend current_diff_queue \
	[list [mc "LOCAL:\n"] d======= \
	[list ":1:$current_diff_path" ":2:$current_diff_path"]]
	lappend current_diff_queue \
	[list [mc "REMOTE:\n"] d======= \
	[list ":1:$current_diff_path" ":3:$current_diff_path"]]
	} else {
	start_show_diff $cont_info
	return
	}

	advance_diff_queue $cont_info
	}

	proc advance_diff_queue {cont_info} {
	global current_diff_queue ui_diff

	set item [lindex $current_diff_queue 0]
	set current_diff_queue [lrange $current_diff_queue 1 end]

	$ui_diff conf -state normal
	$ui_diff insert end [lindex $item 0] [lindex $item 1]
	$ui_diff conf -state disabled

	start_show_diff $cont_info [lindex $item 2]
	}

	proc show_other_diff {path w m cont_info} {
	global file_states file_lists
	global is_3way_diff diff_active repo_config
	global ui_diff ui_index ui_workdir
	global current_diff_path current_diff_side current_diff_header

	# - Git won't give us the diff, there's nothing to compare to!
	#
	if {$m eq {_O}} {
	set max_sz 100000
	set type unknown
	if {[catch {
	set type [file type $path]
	switch -- $type {
	directory {
	set type submodule
	set content {}
	set sz 0
	}
	link {
	set content [file readlink $path]
	set sz [string length $content]
	}
	file {
	set fd [open $path r]
	fconfigure $fd \
	-eofchar {} \
	-encoding [get_path_encoding $path]
	set content [read $fd $max_sz]
	close $fd
	set sz [file size $path]
	}
	default {
	error "'$type' not supported"
	}
	}
	} err ]} {
	set diff_active 0
	unlock_index
	ui_status [mc "Unable to display %s" [escape_path $path]]
	error_popup [strcat [mc "Error loading file:"] "\n\n$err"]
	return
	}
	$ui_diff conf -state normal
	if {$type eq {submodule}} {
	$ui_diff insert end [append \
	"* " \
	[mc "Git Repository (subproject)"] \
	"\n"] d_@
	} elseif {![catch {set type [exec file $path]}]} {
	set n [string length $path]
	if {[string equal -length $n $path $type]} {
	set type [string range $type $n end]
	regsub {^:?\s*} $type {} type
	}
	$ui_diff insert end "* $type\n" d_@
	}
	if {[string first "\0" $content] != -1} {
	$ui_diff insert end \
	[mc "* Binary file (not showing content)."] \
	d_@
	} else {
	if {$sz > $max_sz} {
	$ui_diff insert end [mc \
	"* Untracked file is %d bytes.
	* Showing only first %d bytes.
	" $sz $max_sz] d_@
	}
	$ui_diff insert end $content
	if {$sz > $max_sz} {
	$ui_diff insert end [mc "
	* Untracked file clipped here by %s.
	* To see the entire file, use an external editor.
	" [appname]] d_@
	}
	}
	$ui_diff conf -state disabled
	set diff_active 0
	unlock_index
	set scroll_pos [lindex $cont_info 0]
	if {$scroll_pos ne {}} {
	update
	$ui_diff yview moveto $scroll_pos
	}
	ui_ready
	set callback [lindex $cont_info 1]
	if {$callback ne {}} {
	eval $callback
	}
	return
	}
	}

	proc start_show_diff {cont_info {add_opts {}}} {
	global file_states file_lists
	global is_3way_diff is_submodule_diff diff_active repo_config
	global ui_diff ui_index ui_workdir
	global current_diff_path current_diff_side current_diff_header

	set path $current_diff_path
	set w $current_diff_side

	set s $file_states($path)
	set m [lindex $s 0]
	set is_3way_diff 0
	set is_submodule_diff 0
	set diff_active 1
	set current_diff_header {}

	set cmd [list]
	if {$w eq $ui_index} {
	lappend cmd diff-index
	lappend cmd --cached
	} elseif {$w eq $ui_workdir} {
	if {[string first {U} $m] >= 0} {
	lappend cmd diff
	} else {
	lappend cmd diff-files
	}
	}

	if {[string match {160000 *} [lindex $s 2]]
	\|\| [string match {160000 *} [lindex $s 3]]} {
	set is_submodule_diff 1

	if {[git-version >= "1.6.6"]} {
	lappend cmd --submodule
	}
	}

	lappend cmd -p
	lappend cmd --no-color
	if {$repo_config(gui.diffcontext) >= 1} {
	lappend cmd "-U$repo_config(gui.diffcontext)"
	}
	if {$w eq $ui_index} {
	lappend cmd [PARENT]
	}
	if {$add_opts ne {}} {
	eval lappend cmd $add_opts
	} else {
	lappend cmd --
	lappend cmd $path
	}

	if {$is_submodule_diff && [git-version < "1.6.6"]} {
	if {$w eq $ui_index} {
	set cmd [list submodule summary --cached -- $path]
	} else {
	set cmd [list submodule summary --files -- $path]
	}
	}

	if {[catch {set fd [eval git_read --nice $cmd]} err]} {
	set diff_active 0
	unlock_index
	ui_status [mc "Unable to display %s" [escape_path $path]]
	error_popup [strcat [mc "Error loading diff:"] "\n\n$err"]
	return
	}

	set ::current_diff_inheader 1
	fconfigure $fd \
	-blocking 0 \
	-encoding [get_path_encoding $path] \
	-translation lf
	fileevent $fd readable [list read_diff $fd $cont_info]
	}

	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

	$ui_diff conf -state normal
	while {[gets $fd line] >= 0} {
	# -- Cleanup uninteresting diff header lines.
	#
	if {$::current_diff_inheader} {
	if { [string match {diff --git *} $line]
	\|\| [string match {diff --cc *} $line]
	\|\| [string match {diff --combined *} $line]
	\|\| [string match {--- *} $line]
	\|\| [string match {+++ *} $line]} {
	append current_diff_header $line "\n"
	continue
	}
	}
	if {[string match {index *} $line]} continue
	if {$line eq {deleted file mode 120000}} {
	set line "deleted symlink"
	}
	set ::current_diff_inheader 0

	# -- Automatically detect if this is a 3 way diff.
	#
	if {[string match {@@@ *} $line]} {set is_3way_diff 1}

	if {[string match {mode *} $line]
	\|\| [string match {new file *} $line]
	\|\| [regexp {^(old\|new) mode *} $line]
	\|\| [string match {deleted file *} $line]
	\|\| [string match {deleted symlink} $line]
	\|\| [string match {Binary files * and * differ} $line]
	\|\| $line eq {\ No newline at end of file}
	\|\| [regexp {^\* Unmerged path } $line]} {
	set tags {}
	} elseif {$is_3way_diff} {
	set op [string range $line 0 1]
	switch -- $op {
	{ } {set tags {}}
	{@@} {set tags d_@}
	{ +} {set tags d_s+}
	{ -} {set tags d_s-}
	{+ } {set tags d_+s}
	{- } {set tags d_-s}
	{--} {set tags d_--}
	{++} {
	if {[regexp {^\+\+([<>]{7} \|={7})} $line _g op]} {
	set is_conflict_diff 1
	set line [string replace $line 0 1 { }]
	set tags d$op
	} else {
	set tags d_++
	}
	}
	default {
	puts "error: Unhandled 3 way diff marker: {$op}"
	set tags {}
	}
	}
	} elseif {$is_submodule_diff} {
	if {$line == ""} continue
	if {[regexp {^Submodule } $line]} {
	set tags d_@
	} elseif {[regexp {^\* } $line]} {
	set line [string replace $line 0 1 {Submodule }]
	set tags d_@
	} else {
	set op [string range $line 0 2]
	switch -- $op {
	{ <} {set tags d_-}
	{ >} {set tags d_+}
	{ W} {set tags {}}
	default {
	puts "error: Unhandled submodule diff marker: {$op}"
	set tags {}
	}
	}
	}
	} else {
	set op [string index $line 0]
	switch -- $op {
	{ } {set tags {}}
	{@} {set tags d_@}
	{-} {set tags d_-}
	{+} {
	if {[regexp {^\+([<>]{7} \|={7})} $line _g op]} {
	set is_conflict_diff 1
	set tags d$op
	} else {
	set tags d_+
	}
	}
	default {
	puts "error: Unhandled 2 way diff marker: {$op}"
	set tags {}
	}
	}
	}
	$ui_diff insert end $line $tags
	if {[string index $line end] eq "\r"} {
	$ui_diff tag add d_cr {end - 2c}
	}
	$ui_diff insert end "\n" $tags
	}
	$ui_diff conf -state disabled

	if {[eof $fd]} {
	close $fd

	if {$current_diff_queue ne {}} {
	advance_diff_queue $cont_info
	return
	}

	set diff_active 0
	unlock_index
	set scroll_pos [lindex $cont_info 0]
	if {$scroll_pos ne {}} {
	update
	$ui_diff yview moveto $scroll_pos
	}
	ui_ready

	if {[$ui_diff index end] eq {2.0}} {
	handle_empty_diff
	} else {
	set diff_empty_count 0
	}

	set callback [lindex $cont_info 1]
	if {$callback ne {}} {
	eval $callback
	}
	}
	}

	proc apply_hunk {x y} {
	global current_diff_path current_diff_header current_diff_side
	global ui_diff ui_index file_states

	if {$current_diff_path eq {} \|\| $current_diff_header eq {}} return
	if {![lock_index apply_hunk]} return

	set apply_cmd {apply --cached --whitespace=nowarn}
	set mi [lindex $file_states($current_diff_path) 0]
	if {$current_diff_side eq $ui_index} {
	set failed_msg [mc "Failed to unstage selected hunk."]
	lappend apply_cmd --reverse
	if {[string index $mi 0] ne {M}} {
	unlock_index
	return
	}
	} else {
	set failed_msg [mc "Failed to stage selected hunk."]
	if {[string index $mi 1] ne {M}} {
	unlock_index
	return
	}
	}

	set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
	set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
	if {$s_lno eq {}} {
	unlock_index
	return
	}

	set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
	if {$e_lno eq {}} {
	set e_lno end
	}

	if {[catch {
	set enc [get_path_encoding $current_diff_path]
	set p [eval git_write $apply_cmd]
	fconfigure $p -translation binary -encoding $enc
	puts -nonewline $p $current_diff_header
	puts -nonewline $p [$ui_diff get $s_lno $e_lno]
	close $p} err]} {
	error_popup [append $failed_msg "\n\n$err"]
	unlock_index
	return
	}

	$ui_diff conf -state normal
	$ui_diff delete $s_lno $e_lno
	$ui_diff conf -state disabled

	if {[$ui_diff get 1.0 end] eq "\n"} {
	set o _
	} else {
	set o ?
	}

	if {$current_diff_side eq $ui_index} {
	set mi ${o}M
	} elseif {[string index $mi 0] eq {_}} {
	set mi M$o
	} else {
	set mi ?$o
	}
	unlock_index
	display_file $current_diff_path $mi
	# This should trigger shift to the next changed file
	if {$o eq {_}} {
	reshow_diff
	}
	}

	proc apply_range_or_line {x y} {
	global current_diff_path current_diff_header current_diff_side
	global ui_diff ui_index file_states

	set selected [$ui_diff tag nextrange sel 0.0]

	if {$selected == {}} {
	set first [$ui_diff index "@$x,$y"]
	set last $first
	} else {
	set first [lindex $selected 0]
	set last [lindex $selected 1]
	}

	set first_l [$ui_diff index "$first linestart"]
	set last_l [$ui_diff index "$last lineend"]

	if {$current_diff_path eq {} \|\| $current_diff_header eq {}} return
	if {![lock_index apply_hunk]} return

	set apply_cmd {apply --cached --whitespace=nowarn}
	set mi [lindex $file_states($current_diff_path) 0]
	if {$current_diff_side eq $ui_index} {
	set failed_msg [mc "Failed to unstage selected line."]
	set to_context {+}
	lappend apply_cmd --reverse
	if {[string index $mi 0] ne {M}} {
	unlock_index
	return
	}
	} else {
	set failed_msg [mc "Failed to stage selected line."]
	set to_context {-}
	if {[string index $mi 1] ne {M}} {
	unlock_index
	return
	}
	}

	set wholepatch {}

	while {$first_l < $last_l} {
	set i_l [$ui_diff search -backwards -regexp ^@@ $first_l 0.0]
	if {$i_l eq {}} {
	# If there's not a @@ above, then the selected range
	# must have come before the first_l @@
	set i_l [$ui_diff search -regexp ^@@ $first_l $last_l]
	}
	if {$i_l eq {}} {
	unlock_index
	return
	}
	# $i_l is now at the beginning of a line

	# pick start line number from hunk header
	set hh [$ui_diff get $i_l "$i_l + 1 lines"]
	set hh [lindex [split $hh ,] 0]
	set hln [lindex [split $hh -] 1]

	# There is a special situation to take care of. Consider this
	# hunk:
	#
	# @@ -10,4 +10,4 @@
	# context before
	# -old 1
	# -old 2
	# +new 1
	# +new 2
	# context after
	#
	# We used to keep the context lines in the order they appear in
	# the hunk. But then it is not possible to correctly stage only
	# "-old 1" and "+new 1" - it would result in this staged text:
	#
	# context before
	# old 2
	# new 1
	# context after
	#
	# (By symmetry it is not possible to unstage "old 2" and "new
	# 2".)
	#
	# We resolve the problem by introducing an asymmetry, namely,
	# when a "+" line is staged, it is moved in front of the
	# context lines that are generated from the "-" lines that are
	# immediately before the "+" block. That is, we construct this
	# patch:
	#
	# @@ -10,4 +10,5 @@
	# context before
	# +new 1
	# old 1
	# old 2
	# context after
	#
	# But we do not treat "-" lines that are unstaged in a
	# special way.
	#
	# With this asymmetry it is possible to stage the change "old
	# 1" -> "new 1" directly, and to stage the change "old 2" ->
	# "new 2" by first staging the entire hunk and then unstaging
	# the change "old 1" -> "new 1".
	#
	# Applying multiple lines adds complexity to the special
	# situation. The pre_context must be moved after the entire
	# first block of consecutive staged "+" lines, so that
	# staging both additions gives the following patch:
	#
	# @@ -10,4 +10,6 @@
	# context before
	# +new 1
	# +new 2
	# old 1
	# old 2
	# context after

	# This is non-empty if and only if we are _staging_ changes;
	# then it accumulates the consecutive "-" lines (after
	# converting them to context lines) in order to be moved after
	# "+" change lines.
	set pre_context {}

	set n 0
	set m 0
	set i_l [$ui_diff index "$i_l + 1 lines"]
	set patch {}
	while {[$ui_diff compare $i_l < "end - 1 chars"] &&
	[$ui_diff get $i_l "$i_l + 2 chars"] ne {@@}} {
	set next_l [$ui_diff index "$i_l + 1 lines"]
	set c1 [$ui_diff get $i_l]
	if {[$ui_diff compare $first_l <= $i_l] &&
	[$ui_diff compare $i_l < $last_l] &&
	($c1 eq {-} \|\| $c1 eq {+})} {
	# a line to stage/unstage
	set ln [$ui_diff get $i_l $next_l]
	if {$c1 eq {-}} {
	set n [expr $n+1]
	set patch "$patch$pre_context$ln"
	set pre_context {}
	} else {
	set m [expr $m+1]
	set patch "$patch$ln"
	}
	} elseif {$c1 ne {-} && $c1 ne {+}} {
	# context line
	set ln [$ui_diff get $i_l $next_l]
	set patch "$patch$pre_context$ln"
	set n [expr $n+1]
	set m [expr $m+1]
	set pre_context {}
	} elseif {$c1 eq $to_context} {
	# turn change line into context line
	set ln [$ui_diff get "$i_l + 1 chars" $next_l]
	if {$c1 eq {-}} {
	set pre_context "$pre_context $ln"
	} else {
	set patch "$patch $ln"
	}
	set n [expr $n+1]
	set m [expr $m+1]
	} else {
	# a change in the opposite direction of
	# to_context which is outside the range of
	# lines to apply.
	set patch "$patch$pre_context"
	set pre_context {}
	}
	set i_l $next_l
	}
	set patch "$patch$pre_context"
	set wholepatch "$wholepatch@@ -$hln,$n +$hln,$m @@\n$patch"
	set first_l [$ui_diff index "$next_l + 1 lines"]
	}

	if {[catch {
	set enc [get_path_encoding $current_diff_path]
	set p [eval git_write $apply_cmd]
	fconfigure $p -translation binary -encoding $enc
	puts -nonewline $p $current_diff_header
	puts -nonewline $p $wholepatch
	close $p} err]} {
	error_popup [append $failed_msg "\n\n$err"]
	}

	unlock_index
	}