git.oblomov.eu Git - git/blob - git-gui/lib/diff.tcl

   1 # git-gui diff viewer
   2 # Copyright (C) 2006, 2007 Shawn Pearce
   3
   4 proc clear_diff {} {
   5         global ui_diff current_diff_path current_diff_header
   6         global ui_index ui_workdir
   7
   8         $ui_diff conf -state normal
   9         $ui_diff delete 0.0 end
  10         $ui_diff conf -state disabled
  11
  12         set current_diff_path {}
  13         set current_diff_header {}
  14
  15         $ui_index tag remove in_diff 0.0 end
  16         $ui_workdir tag remove in_diff 0.0 end
  17 }
  18
  19 proc reshow_diff {{after {}}} {
  20         global file_states file_lists
  21         global current_diff_path current_diff_side
  22         global ui_diff
  23
  24         set p $current_diff_path
  25         if {$p eq {}} {
  26                 # No diff is being shown.
  27         } elseif {$current_diff_side eq {}} {
  28                 clear_diff
  29         } elseif {[catch {set s $file_states($p)}]
  30                 || [lsearch -sorted -exact $file_lists($current_diff_side) $p] == -1} {
  31
  32                 if {[find_next_diff $current_diff_side $p {} {[^O]}]} {
  33                         next_diff $after
  34                 } else {
  35                         clear_diff
  36                 }
  37         } else {
  38                 set save_pos [lindex [$ui_diff yview] 0]
  39                 show_diff $p $current_diff_side {} $save_pos $after
  40         }
  41 }
  42
  43 proc force_diff_encoding {enc} {
  44         global current_diff_path
  45
  46         if {$current_diff_path ne {}} {
  47                 force_path_encoding $current_diff_path $enc
  48                 reshow_diff
  49         }
  50 }
  51
  52 proc handle_empty_diff {} {
  53         global current_diff_path file_states file_lists
  54         global diff_empty_count
  55
  56         set path $current_diff_path
  57         set s $file_states($path)
  58         if {[lindex $s 0] ne {_M} || [has_textconv $path]} return
  59
  60         # Prevent infinite rescan loops
  61         incr diff_empty_count
  62         if {$diff_empty_count > 1} return
  63
  64         info_popup [mc "No differences detected.
  65
  66 %s has no changes.
  67
  68 The modification date of this file was updated by another application, but the content within the file was not changed.
  69
  70 A rescan will be automatically started to find other files which may have the same state." [short_path $path]]
  71
  72         clear_diff
  73         display_file $path __
  74         rescan ui_ready 0
  75 }
  76
  77 proc show_diff {path w {lno {}} {scroll_pos {}} {callback {}}} {
  78         global file_states file_lists
  79         global is_3way_diff is_conflict_diff diff_active repo_config
  80         global ui_diff ui_index ui_workdir
  81         global current_diff_path current_diff_side current_diff_header
  82         global current_diff_queue
  83
  84         if {$diff_active || ![lock_index read]} return
  85
  86         clear_diff
  87         if {$lno == {}} {
  88                 set lno [lsearch -sorted -exact $file_lists($w) $path]
  89                 if {$lno >= 0} {
  90                         incr lno
  91                 }
  92         }
  93         if {$lno >= 1} {
  94                 $w tag add in_diff $lno.0 [expr {$lno + 1}].0
  95                 $w see $lno.0
  96         }
  97
  98         set s $file_states($path)
  99         set m [lindex $s 0]
 100         set is_conflict_diff 0
 101         set current_diff_path $path
 102         set current_diff_side $w
 103         set current_diff_queue {}
 104         ui_status [mc "Loading diff of %s..." [escape_path $path]]
 105
 106         set cont_info [list $scroll_pos $callback]
 107
 108         if {[string first {U} $m] >= 0} {
 109                 merge_load_stages $path [list show_unmerged_diff $cont_info]
 110         } elseif {$m eq {_O}} {
 111                 show_other_diff $path $w $m $cont_info
 112         } else {
 113                 start_show_diff $cont_info
 114         }
 115 }
 116
 117 proc show_unmerged_diff {cont_info} {
 118         global current_diff_path current_diff_side
 119         global merge_stages ui_diff is_conflict_diff
 120         global current_diff_queue
 121
 122         if {$merge_stages(2) eq {}} {
 123                 set is_conflict_diff 1
 124                 lappend current_diff_queue \
 125                         [list [mc "LOCAL: deleted\nREMOTE:\n"] d= \
 126                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 127         } elseif {$merge_stages(3) eq {}} {
 128                 set is_conflict_diff 1
 129                 lappend current_diff_queue \
 130                         [list [mc "REMOTE: deleted\nLOCAL:\n"] d= \
 131                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 132         } elseif {[lindex $merge_stages(1) 0] eq {120000}
 133                 || [lindex $merge_stages(2) 0] eq {120000}
 134                 || [lindex $merge_stages(3) 0] eq {120000}} {
 135                 set is_conflict_diff 1
 136                 lappend current_diff_queue \
 137                         [list [mc "LOCAL:\n"] d= \
 138                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 139                 lappend current_diff_queue \
 140                         [list [mc "REMOTE:\n"] d= \
 141                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 142         } else {
 143                 start_show_diff $cont_info
 144                 return
 145         }
 146
 147         advance_diff_queue $cont_info
 148 }
 149
 150 proc advance_diff_queue {cont_info} {
 151         global current_diff_queue ui_diff
 152
 153         set item [lindex $current_diff_queue 0]
 154         set current_diff_queue [lrange $current_diff_queue 1 end]
 155
 156         $ui_diff conf -state normal
 157         $ui_diff insert end [lindex $item 0] [lindex $item 1]
 158         $ui_diff conf -state disabled
 159
 160         start_show_diff $cont_info [lindex $item 2]
 161 }
 162
 163 proc show_other_diff {path w m cont_info} {
 164         global file_states file_lists
 165         global is_3way_diff diff_active repo_config
 166         global ui_diff ui_index ui_workdir
 167         global current_diff_path current_diff_side current_diff_header
 168
 169         # - Git won't give us the diff, there's nothing to compare to!
 170         #
 171         if {$m eq {_O}} {
 172                 set max_sz 100000
 173                 set type unknown
 174                 if {[catch {
 175                                 set type [file type $path]
 176                                 switch -- $type {
 177                                 directory {
 178                                         set type submodule
 179                                         set content {}
 180                                         set sz 0
 181                                 }
 182                                 link {
 183                                         set content [file readlink $path]
 184                                         set sz [string length $content]
 185                                 }
 186                                 file {
 187                                         set fd [open $path r]
 188                                         fconfigure $fd \
 189                                                 -eofchar {} \
 190                                                 -encoding [get_path_encoding $path]
 191                                         set content [read $fd $max_sz]
 192                                         close $fd
 193                                         set sz [file size $path]
 194                                 }
 195                                 default {
 196                                         error "'$type' not supported"
 197                                 }
 198                                 }
 199                         } err ]} {
 200                         set diff_active 0
 201                         unlock_index
 202                         ui_status [mc "Unable to display %s" [escape_path $path]]
 203                         error_popup [strcat [mc "Error loading file:"] "\n\n$err"]
 204                         return
 205                 }
 206                 $ui_diff conf -state normal
 207                 if {$type eq {submodule}} {
 208                         $ui_diff insert end [append \
 209                                 "* " \
 210                                 [mc "Git Repository (subproject)"] \
 211                                 "\n"] d_info
 212                 } elseif {![catch {set type [exec file $path]}]} {
 213                         set n [string length $path]
 214                         if {[string equal -length $n $path $type]} {
 215                                 set type [string range $type $n end]
 216                                 regsub {^:?\s*} $type {} type
 217                         }
 218                         $ui_diff insert end "* $type\n" d_info
 219                 }
 220                 if {[string first "\0" $content] != -1} {
 221                         $ui_diff insert end \
 222                                 [mc "* Binary file (not showing content)."] \
 223                                 d_info
 224                 } else {
 225                         if {$sz > $max_sz} {
 226                                 $ui_diff insert end [mc \
 227 "* Untracked file is %d bytes.
 228 * Showing only first %d bytes.
 229 " $sz $max_sz] d_info
 230                         }
 231                         $ui_diff insert end $content
 232                         if {$sz > $max_sz} {
 233                                 $ui_diff insert end [mc "
 234 * Untracked file clipped here by %s.
 235 * To see the entire file, use an external editor.
 236 " [appname]] d_info
 237                         }
 238                 }
 239                 $ui_diff conf -state disabled
 240                 set diff_active 0
 241                 unlock_index
 242                 set scroll_pos [lindex $cont_info 0]
 243                 if {$scroll_pos ne {}} {
 244                         update
 245                         $ui_diff yview moveto $scroll_pos
 246                 }
 247                 ui_ready
 248                 set callback [lindex $cont_info 1]
 249                 if {$callback ne {}} {
 250                         eval $callback
 251                 }
 252                 return
 253         }
 254 }
 255
 256 proc get_conflict_marker_size {path} {
 257         set size 7
 258         catch {
 259                 set fd_rc [eval [list git_read check-attr "conflict-marker-size" -- $path]]
 260                 set ret [gets $fd_rc line]
 261                 close $fd_rc
 262                 if {$ret > 0} {
 263                         regexp {.*: conflict-marker-size: (\d+)$} $line line size
 264                 }
 265         }
 266         return $size
 267 }
 268
 269 proc start_show_diff {cont_info {add_opts {}}} {
 270         global file_states file_lists
 271         global is_3way_diff is_submodule_diff diff_active repo_config
 272         global ui_diff ui_index ui_workdir
 273         global current_diff_path current_diff_side current_diff_header
 274
 275         set path $current_diff_path
 276         set w $current_diff_side
 277
 278         set s $file_states($path)
 279         set m [lindex $s 0]
 280         set is_3way_diff 0
 281         set is_submodule_diff 0
 282         set diff_active 1
 283         set current_diff_header {}
 284         set conflict_size [get_conflict_marker_size $path]
 285
 286         set cmd [list]
 287         if {$w eq $ui_index} {
 288                 lappend cmd diff-index
 289                 lappend cmd --cached
 290                 if {[git-version >= "1.7.2"]} {
 291                         lappend cmd --ignore-submodules=dirty
 292                 }
 293         } elseif {$w eq $ui_workdir} {
 294                 if {[string first {U} $m] >= 0} {
 295                         lappend cmd diff
 296                 } else {
 297                         lappend cmd diff-files
 298                 }
 299         }
 300         if {![is_config_false gui.textconv] && [git-version >= 1.6.1]} {
 301                 lappend cmd --textconv
 302         }
 303
 304         if {[string match {160000 *} [lindex $s 2]]
 305          || [string match {160000 *} [lindex $s 3]]} {
 306                 set is_submodule_diff 1
 307
 308                 if {[git-version >= "1.6.6"]} {
 309                         lappend cmd --submodule
 310                 }
 311         }
 312
 313         lappend cmd -p
 314         lappend cmd --color
 315         set cmd [concat $cmd $repo_config(gui.diffopts)]
 316         if {$repo_config(gui.diffcontext) >= 1} {
 317                 lappend cmd "-U$repo_config(gui.diffcontext)"
 318         }
 319         if {$w eq $ui_index} {
 320                 lappend cmd [PARENT]
 321         }
 322         if {$add_opts ne {}} {
 323                 eval lappend cmd $add_opts
 324         } else {
 325                 lappend cmd --
 326                 lappend cmd $path
 327         }
 328
 329         if {$is_submodule_diff && [git-version < "1.6.6"]} {
 330                 if {$w eq $ui_index} {
 331                         set cmd [list submodule summary --cached -- $path]
 332                 } else {
 333                         set cmd [list submodule summary --files -- $path]
 334                 }
 335         }
 336
 337         if {[catch {set fd [eval git_read --nice $cmd]} err]} {
 338                 set diff_active 0
 339                 unlock_index
 340                 ui_status [mc "Unable to display %s" [escape_path $path]]
 341                 error_popup [strcat [mc "Error loading diff:"] "\n\n$err"]
 342                 return
 343         }
 344
 345         set ::current_diff_inheader 1
 346         fconfigure $fd \
 347                 -blocking 0 \
 348                 -encoding [get_path_encoding $path] \
 349                 -translation lf
 350         fileevent $fd readable [list read_diff $fd $conflict_size $cont_info]
 351 }
 352
 353 proc parse_color_line {line} {
 354         set start 0
 355         set result ""
 356         set markup [list]
 357         set regexp {\033\[((?:\d+;)*\d+)?m}
 358         set need_reset 0
 359         while {[regexp -indices -start $start $regexp $line match code]} {
 360                 foreach {begin end} $match break
 361                 append result [string range $line $start [expr {$begin - 1}]]
 362                 set pos [string length $result]
 363                 set col [eval [linsert $code 0 string range $line]]
 364                 set start [incr end]
 365                 if {$col eq "0" || $col eq ""} {
 366                         if {!$need_reset} continue
 367                         set need_reset 0
 368                 } else {
 369                         set need_reset 1
 370                 }
 371                 lappend markup $pos $col
 372         }
 373         append result [string range $line $start end]
 374         if {[llength $markup] < 4} {set markup {}}
 375         return [list $result $markup]
 376 }
 377
 378 proc read_diff {fd conflict_size cont_info} {
 379         global ui_diff diff_active is_submodule_diff
 380         global is_3way_diff is_conflict_diff current_diff_header
 381         global current_diff_queue
 382         global diff_empty_count
 383
 384         $ui_diff conf -state normal
 385         while {[gets $fd line] >= 0} {
 386                 foreach {line markup} [parse_color_line $line] break
 387                 set line [string map {\033 ^} $line]
 388
 389                 set tags {}
 390
 391                 # -- Check for start of diff header.
 392                 if {   [string match {diff --git *}      $line]
 393                     || [string match {diff --cc *}       $line]
 394                     || [string match {diff --combined *} $line]} {
 395                         set ::current_diff_inheader 1
 396                 }
 397
 398                 # -- Check for end of diff header (any hunk line will do this).
 399                 #
 400                 if {[regexp {^@@+ } $line]} {set ::current_diff_inheader 0}
 401
 402                 # -- Automatically detect if this is a 3 way diff.
 403                 #
 404                 if {[string match {@@@ *} $line]} {set is_3way_diff 1}
 405
 406                 if {$::current_diff_inheader} {
 407
 408                         # -- These two lines stop a diff header and shouldn't be in there
 409                         if {   [string match {Binary files * and * differ} $line]
 410                             || [regexp {^\* Unmerged path }                $line]} {
 411                                 set ::current_diff_inheader 0
 412                         } else {
 413                                 append current_diff_header $line "\n"
 414                         }
 415
 416                         # -- Cleanup uninteresting diff header lines.
 417                         #
 418                         if {   [string match {diff --git *}      $line]
 419                             || [string match {diff --cc *}       $line]
 420                             || [string match {diff --combined *} $line]
 421                             || [string match {--- *}             $line]
 422                             || [string match {+++ *}             $line]
 423                             || [string match {index *}           $line]} {
 424                                 continue
 425                         }
 426
 427                         # -- Name it symlink, not 120000
 428                         #    Note, that the original line is in $current_diff_header
 429                         regsub {^(deleted|new) file mode 120000} $line {\1 symlink} line
 430
 431                 } elseif {   $line eq {\ No newline at end of file}} {
 432                         # -- Handle some special lines
 433                 } elseif {$is_3way_diff} {
 434                         set op [string range $line 0 1]
 435                         switch -- $op {
 436                         {  } {set tags {}}
 437                         {@@} {set tags d_@}
 438                         { +} {set tags d_s+}
 439                         { -} {set tags d_s-}
 440                         {+ } {set tags d_+s}
 441                         {- } {set tags d_-s}
 442                         {--} {set tags d_--}
 443                         {++} {
 444                                 set regexp [string map [list %conflict_size $conflict_size]\
 445                                                                 {^\+\+([<>=]){%conflict_size}(?: |$)}]
 446                                 if {[regexp $regexp $line _g op]} {
 447                                         set is_conflict_diff 1
 448                                         set line [string replace $line 0 1 {  }]
 449                                         set tags d$op
 450                                 } else {
 451                                         set tags d_++
 452                                 }
 453                         }
 454                         default {
 455                                 puts "error: Unhandled 3 way diff marker: {$op}"
 456                                 set tags {}
 457                         }
 458                         }
 459                 } elseif {$is_submodule_diff} {
 460                         if {$line == ""} continue
 461                         if {[regexp {^Submodule } $line]} {
 462                                 set tags d_info
 463                         } elseif {[regexp {^\* } $line]} {
 464                                 set line [string replace $line 0 1 {Submodule }]
 465                                 set tags d_info
 466                         } else {
 467                                 set op [string range $line 0 2]
 468                                 switch -- $op {
 469                                 {  <} {set tags d_-}
 470                                 {  >} {set tags d_+}
 471                                 {  W} {set tags {}}
 472                                 default {
 473                                         puts "error: Unhandled submodule diff marker: {$op}"
 474                                         set tags {}
 475                                 }
 476                                 }
 477                         }
 478                 } else {
 479                         set op [string index $line 0]
 480                         switch -- $op {
 481                         { } {set tags {}}
 482                         {@} {set tags d_@}
 483                         {-} {set tags d_-}
 484                         {+} {
 485                                 set regexp [string map [list %conflict_size $conflict_size]\
 486                                                                 {^\+([<>=]){%conflict_size}(?: |$)}]
 487                                 if {[regexp $regexp $line _g op]} {
 488                                         set is_conflict_diff 1
 489                                         set tags d$op
 490                                 } else {
 491                                         set tags d_+
 492                                 }
 493                         }
 494                         default {
 495                                 puts "error: Unhandled 2 way diff marker: {$op}"
 496                                 set tags {}
 497                         }
 498                         }
 499                 }
 500                 set mark [$ui_diff index "end - 1 line linestart"]
 501                 $ui_diff insert end $line $tags
 502                 if {[string index $line end] eq "\r"} {
 503                         $ui_diff tag add d_cr {end - 2c}
 504                 }
 505                 $ui_diff insert end "\n" $tags
 506
 507                 foreach {posbegin colbegin posend colend} $markup {
 508                         set prefix clr
 509                         foreach style [lsort -integer [split $colbegin ";"]] {
 510                                 if {$style eq "7"} {append prefix i; continue}
 511                                 if {$style != 4 && ($style < 30 || $style > 47)} {continue}
 512                                 set a "$mark linestart + $posbegin chars"
 513                                 set b "$mark linestart + $posend chars"
 514                                 catch {$ui_diff tag add $prefix$style $a $b}
 515                         }
 516                 }
 517         }
 518         $ui_diff conf -state disabled
 519
 520         if {[eof $fd]} {
 521                 close $fd
 522
 523                 if {$current_diff_queue ne {}} {
 524                         advance_diff_queue $cont_info
 525                         return
 526                 }
 527
 528                 set diff_active 0
 529                 unlock_index
 530                 set scroll_pos [lindex $cont_info 0]
 531                 if {$scroll_pos ne {}} {
 532                         update
 533                         $ui_diff yview moveto $scroll_pos
 534                 }
 535                 ui_ready
 536
 537                 if {[$ui_diff index end] eq {2.0}} {
 538                         handle_empty_diff
 539                 } else {
 540                         set diff_empty_count 0
 541                 }
 542
 543                 set callback [lindex $cont_info 1]
 544                 if {$callback ne {}} {
 545                         eval $callback
 546                 }
 547         }
 548 }
 549
 550 proc apply_hunk {x y} {
 551         global current_diff_path current_diff_header current_diff_side
 552         global ui_diff ui_index file_states
 553
 554         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 555         if {![lock_index apply_hunk]} return
 556
 557         set apply_cmd {apply --cached --whitespace=nowarn}
 558         set mi [lindex $file_states($current_diff_path) 0]
 559         if {$current_diff_side eq $ui_index} {
 560                 set failed_msg [mc "Failed to unstage selected hunk."]
 561                 lappend apply_cmd --reverse
 562                 if {[string index $mi 0] ne {M}} {
 563                         unlock_index
 564                         return
 565                 }
 566         } else {
 567                 set failed_msg [mc "Failed to stage selected hunk."]
 568                 if {[string index $mi 1] ne {M}} {
 569                         unlock_index
 570                         return
 571                 }
 572         }
 573
 574         set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
 575         set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
 576         if {$s_lno eq {}} {
 577                 unlock_index
 578                 return
 579         }
 580
 581         set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
 582         if {$e_lno eq {}} {
 583                 set e_lno end
 584         }
 585
 586         if {[catch {
 587                 set enc [get_path_encoding $current_diff_path]
 588                 set p [eval git_write $apply_cmd]
 589                 fconfigure $p -translation binary -encoding $enc
 590                 puts -nonewline $p $current_diff_header
 591                 puts -nonewline $p [$ui_diff get $s_lno $e_lno]
 592                 close $p} err]} {
 593                 error_popup [append $failed_msg "\n\n$err"]
 594                 unlock_index
 595                 return
 596         }
 597
 598         $ui_diff conf -state normal
 599         $ui_diff delete $s_lno $e_lno
 600         $ui_diff conf -state disabled
 601
 602         if {[$ui_diff get 1.0 end] eq "\n"} {
 603                 set o _
 604         } else {
 605                 set o ?
 606         }
 607
 608         if {$current_diff_side eq $ui_index} {
 609                 set mi ${o}M
 610         } elseif {[string index $mi 0] eq {_}} {
 611                 set mi M$o
 612         } else {
 613                 set mi ?$o
 614         }
 615         unlock_index
 616         display_file $current_diff_path $mi
 617         # This should trigger shift to the next changed file
 618         if {$o eq {_}} {
 619                 reshow_diff
 620         }
 621 }
 622
 623 proc apply_range_or_line {x y} {
 624         global current_diff_path current_diff_header current_diff_side
 625         global ui_diff ui_index file_states
 626
 627         set selected [$ui_diff tag nextrange sel 0.0]
 628
 629         if {$selected == {}} {
 630                 set first [$ui_diff index "@$x,$y"]
 631                 set last $first
 632         } else {
 633                 set first [lindex $selected 0]
 634                 set last [lindex $selected 1]
 635         }
 636
 637         set first_l [$ui_diff index "$first linestart"]
 638         set last_l [$ui_diff index "$last lineend"]
 639
 640         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 641         if {![lock_index apply_hunk]} return
 642
 643         set apply_cmd {apply --cached --whitespace=nowarn}
 644         set mi [lindex $file_states($current_diff_path) 0]
 645         if {$current_diff_side eq $ui_index} {
 646                 set failed_msg [mc "Failed to unstage selected line."]
 647                 set to_context {+}
 648                 lappend apply_cmd --reverse
 649                 if {[string index $mi 0] ne {M}} {
 650                         unlock_index
 651                         return
 652                 }
 653         } else {
 654                 set failed_msg [mc "Failed to stage selected line."]
 655                 set to_context {-}
 656                 if {[string index $mi 1] ne {M}} {
 657                         unlock_index
 658                         return
 659                 }
 660         }
 661
 662         set wholepatch {}
 663
 664         while {$first_l < $last_l} {
 665                 set i_l [$ui_diff search -backwards -regexp ^@@ $first_l 0.0]
 666                 if {$i_l eq {}} {
 667                         # If there's not a @@ above, then the selected range
 668                         # must have come before the first_l @@
 669                         set i_l [$ui_diff search -regexp ^@@ $first_l $last_l]
 670                 }
 671                 if {$i_l eq {}} {
 672                         unlock_index
 673                         return
 674                 }
 675                 # $i_l is now at the beginning of a line
 676
 677                 # pick start line number from hunk header
 678                 set hh [$ui_diff get $i_l "$i_l + 1 lines"]
 679                 set hh [lindex [split $hh ,] 0]
 680                 set hln [lindex [split $hh -] 1]
 681
 682                 # There is a special situation to take care of. Consider this
 683                 # hunk:
 684                 #
 685                 #    @@ -10,4 +10,4 @@
 686                 #     context before
 687                 #    -old 1
 688                 #    -old 2
 689                 #    +new 1
 690                 #    +new 2
 691                 #     context after
 692                 #
 693                 # We used to keep the context lines in the order they appear in
 694                 # the hunk. But then it is not possible to correctly stage only
 695                 # "-old 1" and "+new 1" - it would result in this staged text:
 696                 #
 697                 #    context before
 698                 #    old 2
 699                 #    new 1
 700                 #    context after
 701                 #
 702                 # (By symmetry it is not possible to *un*stage "old 2" and "new
 703                 # 2".)
 704                 #
 705                 # We resolve the problem by introducing an asymmetry, namely,
 706                 # when a "+" line is *staged*, it is moved in front of the
 707                 # context lines that are generated from the "-" lines that are
 708                 # immediately before the "+" block. That is, we construct this
 709                 # patch:
 710                 #
 711                 #    @@ -10,4 +10,5 @@
 712                 #     context before
 713                 #    +new 1
 714                 #     old 1
 715                 #     old 2
 716                 #     context after
 717                 #
 718                 # But we do *not* treat "-" lines that are *un*staged in a
 719                 # special way.
 720                 #
 721                 # With this asymmetry it is possible to stage the change "old
 722                 # 1" -> "new 1" directly, and to stage the change "old 2" ->
 723                 # "new 2" by first staging the entire hunk and then unstaging
 724                 # the change "old 1" -> "new 1".
 725                 #
 726                 # Applying multiple lines adds complexity to the special
 727                 # situation.  The pre_context must be moved after the entire
 728                 # first block of consecutive staged "+" lines, so that
 729                 # staging both additions gives the following patch:
 730                 #
 731                 #    @@ -10,4 +10,6 @@
 732                 #     context before
 733                 #    +new 1
 734                 #    +new 2
 735                 #     old 1
 736                 #     old 2
 737                 #     context after
 738
 739                 # This is non-empty if and only if we are _staging_ changes;
 740                 # then it accumulates the consecutive "-" lines (after
 741                 # converting them to context lines) in order to be moved after
 742                 # "+" change lines.
 743                 set pre_context {}
 744
 745                 set n 0
 746                 set m 0
 747                 set i_l [$ui_diff index "$i_l + 1 lines"]
 748                 set patch {}
 749                 while {[$ui_diff compare $i_l < "end - 1 chars"] &&
 750                        [$ui_diff get $i_l "$i_l + 2 chars"] ne {@@}} {
 751                         set next_l [$ui_diff index "$i_l + 1 lines"]
 752                         set c1 [$ui_diff get $i_l]
 753                         if {[$ui_diff compare $first_l <= $i_l] &&
 754                             [$ui_diff compare $i_l < $last_l] &&
 755                             ($c1 eq {-} || $c1 eq {+})} {
 756                                 # a line to stage/unstage
 757                                 set ln [$ui_diff get $i_l $next_l]
 758                                 if {$c1 eq {-}} {
 759                                         set n [expr $n+1]
 760                                         set patch "$patch$pre_context$ln"
 761                                         set pre_context {}
 762                                 } else {
 763                                         set m [expr $m+1]
 764                                         set patch "$patch$ln"
 765                                 }
 766                         } elseif {$c1 ne {-} && $c1 ne {+}} {
 767                                 # context line
 768                                 set ln [$ui_diff get $i_l $next_l]
 769                                 set patch "$patch$pre_context$ln"
 770                                 # Skip the "\ No newline at end of
 771                                 # file". Depending on the locale setting
 772                                 # we don't know what this line looks
 773                                 # like exactly. The only thing we do
 774                                 # know is that it starts with "\ "
 775                                 if {![string match {\\ *} $ln]} {
 776                                         set n [expr $n+1]
 777                                         set m [expr $m+1]
 778                                 }
 779                                 set pre_context {}
 780                         } elseif {$c1 eq $to_context} {
 781                                 # turn change line into context line
 782                                 set ln [$ui_diff get "$i_l + 1 chars" $next_l]
 783                                 if {$c1 eq {-}} {
 784                                         set pre_context "$pre_context $ln"
 785                                 } else {
 786                                         set patch "$patch $ln"
 787                                 }
 788                                 set n [expr $n+1]
 789                                 set m [expr $m+1]
 790                         } else {
 791                                 # a change in the opposite direction of
 792                                 # to_context which is outside the range of
 793                                 # lines to apply.
 794                                 set patch "$patch$pre_context"
 795                                 set pre_context {}
 796                         }
 797                         set i_l $next_l
 798                 }
 799                 set patch "$patch$pre_context"
 800                 set wholepatch "$wholepatch@@ -$hln,$n +$hln,$m @@\n$patch"
 801                 set first_l [$ui_diff index "$next_l + 1 lines"]
 802         }
 803
 804         if {[catch {
 805                 set enc [get_path_encoding $current_diff_path]
 806                 set p [eval git_write $apply_cmd]
 807                 fconfigure $p -translation binary -encoding $enc
 808                 puts -nonewline $p $current_diff_header
 809                 puts -nonewline $p $wholepatch
 810                 close $p} err]} {
 811                 error_popup [append $failed_msg "\n\n$err"]
 812         }
 813
 814         unlock_index
 815 }