git-gui/lib/diff.tcl

   1 # git-gui diff viewer
   2 # Copyright (C) 2006, 2007 Shawn Pearce
   3
   4 proc apply_tab_size {{firsttab {}}} {
   5         global have_tk85 repo_config ui_diff
   6
   7         set w [font measure font_diff "0"]
   8         if {$have_tk85 && $firsttab != 0} {
   9                 $ui_diff configure -tabs [list [expr {$firsttab * $w}] [expr {($firsttab + $repo_config(gui.tabsize)) * $w}]]
  10         } elseif {$have_tk85 || $repo_config(gui.tabsize) != 8} {
  11                 $ui_diff configure -tabs [expr {$repo_config(gui.tabsize) * $w}]
  12         } else {
  13                 $ui_diff configure -tabs {}
  14         }
  15 }
  16
  17 proc clear_diff {} {
  18         global ui_diff current_diff_path current_diff_header
  19         global ui_index ui_workdir
  20
  21         $ui_diff conf -state normal
  22         $ui_diff delete 0.0 end
  23         $ui_diff conf -state disabled
  24
  25         set current_diff_path {}
  26         set current_diff_header {}
  27
  28         $ui_index tag remove in_diff 0.0 end
  29         $ui_workdir tag remove in_diff 0.0 end
  30 }
  31
  32 proc reshow_diff {{after {}}} {
  33         global file_states file_lists
  34         global current_diff_path current_diff_side
  35         global ui_diff
  36
  37         set p $current_diff_path
  38         if {$p eq {}} {
  39                 # No diff is being shown.
  40         } elseif {$current_diff_side eq {}} {
  41                 clear_diff
  42         } elseif {[catch {set s $file_states($p)}]
  43                 || [lsearch -sorted -exact $file_lists($current_diff_side) $p] == -1} {
  44
  45                 if {[find_next_diff $current_diff_side $p {} {[^O]}]} {
  46                         next_diff $after
  47                 } else {
  48                         clear_diff
  49                 }
  50         } else {
  51                 set save_pos [lindex [$ui_diff yview] 0]
  52                 show_diff $p $current_diff_side {} $save_pos $after
  53         }
  54 }
  55
  56 proc force_diff_encoding {enc} {
  57         global current_diff_path
  58
  59         if {$current_diff_path ne {}} {
  60                 force_path_encoding $current_diff_path $enc
  61                 reshow_diff
  62         }
  63 }
  64
  65 proc handle_empty_diff {} {
  66         global current_diff_path file_states file_lists
  67         global diff_empty_count
  68
  69         set path $current_diff_path
  70         set s $file_states($path)
  71         if {[lindex $s 0] ne {_M} || [has_textconv $path]} return
  72
  73         # Prevent infinite rescan loops
  74         incr diff_empty_count
  75         if {$diff_empty_count > 1} return
  76
  77         info_popup [mc "No differences detected.
  78
  79 %s has no changes.
  80
  81 The modification date of this file was updated by another application, but the content within the file was not changed.
  82
  83 A rescan will be automatically started to find other files which may have the same state." [short_path $path]]
  84
  85         clear_diff
  86         display_file $path __
  87         rescan ui_ready 0
  88 }
  89
  90 proc show_diff {path w {lno {}} {scroll_pos {}} {callback {}}} {
  91         global file_states file_lists
  92         global is_3way_diff is_conflict_diff diff_active repo_config
  93         global ui_diff ui_index ui_workdir
  94         global current_diff_path current_diff_side current_diff_header
  95         global current_diff_queue
  96
  97         if {$diff_active || ![lock_index read]} return
  98
  99         clear_diff
 100         if {$lno == {}} {
 101                 set lno [lsearch -sorted -exact $file_lists($w) $path]
 102                 if {$lno >= 0} {
 103                         incr lno
 104                 }
 105         }
 106         if {$lno >= 1} {
 107                 $w tag add in_diff $lno.0 [expr {$lno + 1}].0
 108                 $w see $lno.0
 109         }
 110
 111         set s $file_states($path)
 112         set m [lindex $s 0]
 113         set is_conflict_diff 0
 114         set current_diff_path $path
 115         set current_diff_side $w
 116         set current_diff_queue {}
 117         ui_status [mc "Loading diff of %s..." [escape_path $path]]
 118
 119         set cont_info [list $scroll_pos $callback]
 120
 121         apply_tab_size 0
 122
 123         if {[string first {U} $m] >= 0} {
 124                 merge_load_stages $path [list show_unmerged_diff $cont_info]
 125         } elseif {$m eq {_O}} {
 126                 show_other_diff $path $w $m $cont_info
 127         } else {
 128                 start_show_diff $cont_info
 129         }
 130
 131         global current_diff_path selected_paths
 132         set selected_paths($current_diff_path) 1
 133 }
 134
 135 proc show_unmerged_diff {cont_info} {
 136         global current_diff_path current_diff_side
 137         global merge_stages ui_diff is_conflict_diff
 138         global current_diff_queue
 139
 140         if {$merge_stages(2) eq {}} {
 141                 set is_conflict_diff 1
 142                 lappend current_diff_queue \
 143                         [list [mc "LOCAL: deleted\nREMOTE:\n"] d= \
 144                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 145         } elseif {$merge_stages(3) eq {}} {
 146                 set is_conflict_diff 1
 147                 lappend current_diff_queue \
 148                         [list [mc "REMOTE: deleted\nLOCAL:\n"] d= \
 149                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 150         } elseif {[lindex $merge_stages(1) 0] eq {120000}
 151                 || [lindex $merge_stages(2) 0] eq {120000}
 152                 || [lindex $merge_stages(3) 0] eq {120000}} {
 153                 set is_conflict_diff 1
 154                 lappend current_diff_queue \
 155                         [list [mc "LOCAL:\n"] d= \
 156                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 157                 lappend current_diff_queue \
 158                         [list [mc "REMOTE:\n"] d= \
 159                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 160         } else {
 161                 start_show_diff $cont_info
 162                 return
 163         }
 164
 165         advance_diff_queue $cont_info
 166 }
 167
 168 proc advance_diff_queue {cont_info} {
 169         global current_diff_queue ui_diff
 170
 171         set item [lindex $current_diff_queue 0]
 172         set current_diff_queue [lrange $current_diff_queue 1 end]
 173
 174         $ui_diff conf -state normal
 175         $ui_diff insert end [lindex $item 0] [lindex $item 1]
 176         $ui_diff conf -state disabled
 177
 178         start_show_diff $cont_info [lindex $item 2]
 179 }
 180
 181 proc show_other_diff {path w m cont_info} {
 182         global file_states file_lists
 183         global is_3way_diff diff_active repo_config
 184         global ui_diff ui_index ui_workdir
 185         global current_diff_path current_diff_side current_diff_header
 186
 187         # - Git won't give us the diff, there's nothing to compare to!
 188         #
 189         if {$m eq {_O}} {
 190                 set max_sz 100000
 191                 set type unknown
 192                 if {[catch {
 193                                 set type [file type $path]
 194                                 switch -- $type {
 195                                 directory {
 196                                         set type submodule
 197                                         set content {}
 198                                         set sz 0
 199                                 }
 200                                 link {
 201                                         set content [file readlink $path]
 202                                         set sz [string length $content]
 203                                 }
 204                                 file {
 205                                         set fd [open $path r]
 206                                         fconfigure $fd \
 207                                                 -eofchar {} \
 208                                                 -encoding [get_path_encoding $path]
 209                                         set content [read $fd $max_sz]
 210                                         close $fd
 211                                         set sz [file size $path]
 212                                 }
 213                                 default {
 214                                         error "'$type' not supported"
 215                                 }
 216                                 }
 217                         } err ]} {
 218                         set diff_active 0
 219                         unlock_index
 220                         ui_status [mc "Unable to display %s" [escape_path $path]]
 221                         error_popup [strcat [mc "Error loading file:"] "\n\n$err"]
 222                         return
 223                 }
 224                 $ui_diff conf -state normal
 225                 if {$type eq {submodule}} {
 226                         $ui_diff insert end \
 227                                 "* [mc "Git Repository (subproject)"]\n" \
 228                                 d_info
 229                 } elseif {![catch {set type [exec file $path]}]} {
 230                         set n [string length $path]
 231                         if {[string equal -length $n $path $type]} {
 232                                 set type [string range $type $n end]
 233                                 regsub {^:?\s*} $type {} type
 234                         }
 235                         $ui_diff insert end "* $type\n" d_info
 236                 }
 237                 if {[string first "\0" $content] != -1} {
 238                         $ui_diff insert end \
 239                                 [mc "* Binary file (not showing content)."] \
 240                                 d_info
 241                 } else {
 242                         if {$sz > $max_sz} {
 243                                 $ui_diff insert end [mc \
 244 "* Untracked file is %d bytes.
 245 * Showing only first %d bytes.
 246 " $sz $max_sz] d_info
 247                         }
 248                         $ui_diff insert end $content
 249                         if {$sz > $max_sz} {
 250                                 $ui_diff insert end [mc "
 251 * Untracked file clipped here by %s.
 252 * To see the entire file, use an external editor.
 253 " [appname]] d_info
 254                         }
 255                 }
 256                 $ui_diff conf -state disabled
 257                 set diff_active 0
 258                 unlock_index
 259                 set scroll_pos [lindex $cont_info 0]
 260                 if {$scroll_pos ne {}} {
 261                         update
 262                         $ui_diff yview moveto $scroll_pos
 263                 }
 264                 ui_ready
 265                 set callback [lindex $cont_info 1]
 266                 if {$callback ne {}} {
 267                         eval $callback
 268                 }
 269                 return
 270         }
 271 }
 272
 273 proc start_show_diff {cont_info {add_opts {}}} {
 274         global file_states file_lists
 275         global is_3way_diff is_submodule_diff diff_active repo_config
 276         global ui_diff ui_index ui_workdir
 277         global current_diff_path current_diff_side current_diff_header
 278
 279         set path $current_diff_path
 280         set w $current_diff_side
 281
 282         set s $file_states($path)
 283         set m [lindex $s 0]
 284         set is_3way_diff 0
 285         set is_submodule_diff 0
 286         set diff_active 1
 287         set current_diff_header {}
 288         set conflict_size [gitattr $path conflict-marker-size 7]
 289
 290         set cmd [list]
 291         if {$w eq $ui_index} {
 292                 lappend cmd diff-index
 293                 lappend cmd --cached
 294                 if {[git-version >= "1.7.2"]} {
 295                         lappend cmd --ignore-submodules=dirty
 296                 }
 297         } elseif {$w eq $ui_workdir} {
 298                 if {[string first {U} $m] >= 0} {
 299                         lappend cmd diff
 300                 } else {
 301                         lappend cmd diff-files
 302                 }
 303         }
 304         if {![is_config_false gui.textconv] && [git-version >= 1.6.1]} {
 305                 lappend cmd --textconv
 306         }
 307
 308         if {[string match {160000 *} [lindex $s 2]]
 309          || [string match {160000 *} [lindex $s 3]]} {
 310                 set is_submodule_diff 1
 311
 312                 if {[git-version >= "1.6.6"]} {
 313                         lappend cmd --submodule
 314                 }
 315         }
 316
 317         lappend cmd -p
 318         lappend cmd --color
 319         set cmd [concat $cmd $repo_config(gui.diffopts)]
 320         if {$repo_config(gui.diffcontext) >= 1} {
 321                 lappend cmd "-U$repo_config(gui.diffcontext)"
 322         }
 323         if {$w eq $ui_index} {
 324                 lappend cmd [PARENT]
 325         }
 326         if {$add_opts ne {}} {
 327                 eval lappend cmd $add_opts
 328         } else {
 329                 lappend cmd --
 330                 lappend cmd $path
 331         }
 332
 333         if {$is_submodule_diff && [git-version < "1.6.6"]} {
 334                 if {$w eq $ui_index} {
 335                         set cmd [list submodule summary --cached -- $path]
 336                 } else {
 337                         set cmd [list submodule summary --files -- $path]
 338                 }
 339         }
 340
 341         if {[catch {set fd [eval git_read --nice $cmd]} err]} {
 342                 set diff_active 0
 343                 unlock_index
 344                 ui_status [mc "Unable to display %s" [escape_path $path]]
 345                 error_popup [strcat [mc "Error loading diff:"] "\n\n$err"]
 346                 return
 347         }
 348
 349         set ::current_diff_inheader 1
 350         # Detect pre-image lines of the diff3 conflict-style. They are just
 351         # '++' lines which is not bijective. Thus, we need to maintain a state
 352         # across lines.
 353         set ::conflict_in_pre_image 0
 354         fconfigure $fd \
 355                 -blocking 0 \
 356                 -encoding [get_path_encoding $path] \
 357                 -translation lf
 358         fileevent $fd readable [list read_diff $fd $conflict_size $cont_info]
 359 }
 360
 361 proc parse_color_line {line} {
 362         set start 0
 363         set result ""
 364         set markup [list]
 365         set regexp {\033\[((?:\d+;)*\d+)?m}
 366         set need_reset 0
 367         while {[regexp -indices -start $start $regexp $line match code]} {
 368                 foreach {begin end} $match break
 369                 append result [string range $line $start [expr {$begin - 1}]]
 370                 set pos [string length $result]
 371                 set col [eval [linsert $code 0 string range $line]]
 372                 set start [incr end]
 373                 if {$col eq "0" || $col eq ""} {
 374                         if {!$need_reset} continue
 375                         set need_reset 0
 376                 } else {
 377                         set need_reset 1
 378                 }
 379                 lappend markup $pos $col
 380         }
 381         append result [string range $line $start end]
 382         if {[llength $markup] < 4} {set markup {}}
 383         return [list $result $markup]
 384 }
 385
 386 proc read_diff {fd conflict_size cont_info} {
 387         global ui_diff diff_active is_submodule_diff
 388         global is_3way_diff is_conflict_diff current_diff_header
 389         global current_diff_queue
 390         global diff_empty_count
 391
 392         $ui_diff conf -state normal
 393         while {[gets $fd line] >= 0} {
 394                 foreach {line markup} [parse_color_line $line] break
 395                 set line [string map {\033 ^} $line]
 396
 397                 set tags {}
 398
 399                 # -- Check for start of diff header.
 400                 if {   [string match {diff --git *}      $line]
 401                     || [string match {diff --cc *}       $line]
 402                     || [string match {diff --combined *} $line]} {
 403                         set ::current_diff_inheader 1
 404                 }
 405
 406                 # -- Check for end of diff header (any hunk line will do this).
 407                 #
 408                 if {[regexp {^@@+ } $line]} {set ::current_diff_inheader 0}
 409
 410                 # -- Automatically detect if this is a 3 way diff.
 411                 #
 412                 if {[string match {@@@ *} $line]} {
 413                         set is_3way_diff 1
 414                         apply_tab_size 1
 415                 }
 416
 417                 if {$::current_diff_inheader} {
 418
 419                         # -- These two lines stop a diff header and shouldn't be in there
 420                         if {   [string match {Binary files * and * differ} $line]
 421                             || [regexp {^\* Unmerged path }                $line]} {
 422                                 set ::current_diff_inheader 0
 423                         } else {
 424                                 append current_diff_header $line "\n"
 425                         }
 426
 427                         # -- Cleanup uninteresting diff header lines.
 428                         #
 429                         if {   [string match {diff --git *}      $line]
 430                             || [string match {diff --cc *}       $line]
 431                             || [string match {diff --combined *} $line]
 432                             || [string match {--- *}             $line]
 433                             || [string match {+++ *}             $line]
 434                             || [string match {index *}           $line]} {
 435                                 continue
 436                         }
 437
 438                         # -- Name it symlink, not 120000
 439                         #    Note, that the original line is in $current_diff_header
 440                         regsub {^(deleted|new) file mode 120000} $line {\1 symlink} line
 441
 442                 } elseif {   $line eq {\ No newline at end of file}} {
 443                         # -- Handle some special lines
 444                 } elseif {$is_3way_diff} {
 445                         set op [string range $line 0 1]
 446                         switch -- $op {
 447                         {  } {set tags {}}
 448                         {@@} {set tags d_@}
 449                         { +} {set tags d_s+}
 450                         { -} {set tags d_s-}
 451                         {+ } {set tags d_+s}
 452                         {- } {set tags d_-s}
 453                         {--} {set tags d_--}
 454                         {++} {
 455                                 set regexp [string map [list %conflict_size $conflict_size]\
 456                                                                 {^\+\+([<>=|]){%conflict_size}(?: |$)}]
 457                                 if {[regexp $regexp $line _g op]} {
 458                                         set is_conflict_diff 1
 459                                         set line [string replace $line 0 1 {  }]
 460                                         set tags d$op
 461
 462                                         # The ||| conflict-marker marks the start of the pre-image.
 463                                         # All those lines are also prefixed with '++'. Thus we need
 464                                         # to maintain this state.
 465                                         set ::conflict_in_pre_image [expr {$op eq {|}}]
 466                                 } elseif {$::conflict_in_pre_image} {
 467                                         # This is a pre-image line. It is the one which both sides
 468                                         # are based on. As it has also the '++' line start, it is
 469                                         # normally shown as 'added'. Invert this to '--' to make
 470                                         # it a 'removed' line.
 471                                         set line [string replace $line 0 1 {--}]
 472                                         set tags d_--
 473                                 } else {
 474                                         set tags d_++
 475                                 }
 476                         }
 477                         default {
 478                                 puts "error: Unhandled 3 way diff marker: {$op}"
 479                                 set tags {}
 480                         }
 481                         }
 482                 } elseif {$is_submodule_diff} {
 483                         if {$line == ""} continue
 484                         if {[regexp {^Submodule } $line]} {
 485                                 set tags d_info
 486                         } elseif {[regexp {^\* } $line]} {
 487                                 set line [string replace $line 0 1 {Submodule }]
 488                                 set tags d_info
 489                         } else {
 490                                 set op [string range $line 0 2]
 491                                 switch -- $op {
 492                                 {  <} {set tags d_-}
 493                                 {  >} {set tags d_+}
 494                                 {  W} {set tags {}}
 495                                 default {
 496                                         puts "error: Unhandled submodule diff marker: {$op}"
 497                                         set tags {}
 498                                 }
 499                                 }
 500                         }
 501                 } else {
 502                         set op [string index $line 0]
 503                         switch -- $op {
 504                         { } {set tags {}}
 505                         {@} {set tags d_@}
 506                         {-} {set tags d_-}
 507                         {+} {
 508                                 set regexp [string map [list %conflict_size $conflict_size]\
 509                                                                 {^\+([<>=]){%conflict_size}(?: |$)}]
 510                                 if {[regexp $regexp $line _g op]} {
 511                                         set is_conflict_diff 1
 512                                         set tags d$op
 513                                 } else {
 514                                         set tags d_+
 515                                 }
 516                         }
 517                         default {
 518                                 puts "error: Unhandled 2 way diff marker: {$op}"
 519                                 set tags {}
 520                         }
 521                         }
 522                 }
 523                 set mark [$ui_diff index "end - 1 line linestart"]
 524                 $ui_diff insert end $line $tags
 525                 if {[string index $line end] eq "\r"} {
 526                         $ui_diff tag add d_cr {end - 2c}
 527                 }
 528                 $ui_diff insert end "\n" $tags
 529
 530                 foreach {posbegin colbegin posend colend} $markup {
 531                         set prefix clr
 532                         foreach style [lsort -integer [split $colbegin ";"]] {
 533                                 if {$style eq "7"} {append prefix i; continue}
 534                                 if {$style != 4 && ($style < 30 || $style > 47)} {continue}
 535                                 set a "$mark linestart + $posbegin chars"
 536                                 set b "$mark linestart + $posend chars"
 537                                 catch {$ui_diff tag add $prefix$style $a $b}
 538                         }
 539                 }
 540         }
 541         $ui_diff conf -state disabled
 542
 543         if {[eof $fd]} {
 544                 close $fd
 545
 546                 if {$current_diff_queue ne {}} {
 547                         advance_diff_queue $cont_info
 548                         return
 549                 }
 550
 551                 set diff_active 0
 552                 unlock_index
 553                 set scroll_pos [lindex $cont_info 0]
 554                 if {$scroll_pos ne {}} {
 555                         update
 556                         $ui_diff yview moveto $scroll_pos
 557                 }
 558                 ui_ready
 559
 560                 if {[$ui_diff index end] eq {2.0}} {
 561                         handle_empty_diff
 562                 } else {
 563                         set diff_empty_count 0
 564                 }
 565
 566                 set callback [lindex $cont_info 1]
 567                 if {$callback ne {}} {
 568                         eval $callback
 569                 }
 570         }
 571 }
 572
 573 proc apply_or_revert_hunk {x y revert} {
 574         global current_diff_path current_diff_header current_diff_side
 575         global ui_diff ui_index file_states last_revert last_revert_enc
 576
 577         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 578         if {![lock_index apply_hunk]} return
 579
 580         set apply_cmd {apply --whitespace=nowarn}
 581         set mi [lindex $file_states($current_diff_path) 0]
 582         if {$current_diff_side eq $ui_index} {
 583                 set failed_msg [mc "Failed to unstage selected hunk."]
 584                 lappend apply_cmd --reverse --cached
 585                 if {[string index $mi 0] ne {M}} {
 586                         unlock_index
 587                         return
 588                 }
 589         } else {
 590                 if {$revert} {
 591                         set failed_msg [mc "Failed to revert selected hunk."]
 592                         lappend apply_cmd --reverse
 593                 } else {
 594                         set failed_msg [mc "Failed to stage selected hunk."]
 595                         lappend apply_cmd --cached
 596                 }
 597
 598                 if {[string index $mi 1] ne {M}} {
 599                         unlock_index
 600                         return
 601                 }
 602         }
 603
 604         set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
 605         set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
 606         if {$s_lno eq {}} {
 607                 unlock_index
 608                 return
 609         }
 610
 611         set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
 612         if {$e_lno eq {}} {
 613                 set e_lno end
 614         }
 615
 616         set wholepatch "$current_diff_header[$ui_diff get $s_lno $e_lno]"
 617
 618         if {[catch {
 619                 set enc [get_path_encoding $current_diff_path]
 620                 set p [eval git_write $apply_cmd]
 621                 fconfigure $p -translation binary -encoding $enc
 622                 puts -nonewline $p $wholepatch
 623                 close $p} err]} {
 624                 error_popup "$failed_msg\n\n$err"
 625                 unlock_index
 626                 return
 627         }
 628
 629         if {$revert} {
 630                 # Save a copy of this patch for undoing reverts.
 631                 set last_revert $wholepatch
 632                 set last_revert_enc $enc
 633         }
 634
 635         $ui_diff conf -state normal
 636         $ui_diff delete $s_lno $e_lno
 637         $ui_diff conf -state disabled
 638
 639         # Check if the hunk was the last one in the file.
 640         if {[$ui_diff get 1.0 end] eq "\n"} {
 641                 set o _
 642         } else {
 643                 set o ?
 644         }
 645
 646         # Update the status flags.
 647         if {$revert} {
 648                 set mi [string index $mi 0]$o
 649         } elseif {$current_diff_side eq $ui_index} {
 650                 set mi ${o}M
 651         } elseif {[string index $mi 0] eq {_}} {
 652                 set mi M$o
 653         } else {
 654                 set mi ?$o
 655         }
 656         unlock_index
 657         display_file $current_diff_path $mi
 658         # This should trigger shift to the next changed file
 659         if {$o eq {_}} {
 660                 reshow_diff
 661         }
 662 }
 663
 664 proc apply_or_revert_range_or_line {x y revert} {
 665         global current_diff_path current_diff_header current_diff_side
 666         global ui_diff ui_index file_states last_revert
 667
 668         set selected [$ui_diff tag nextrange sel 0.0]
 669
 670         if {$selected == {}} {
 671                 set first [$ui_diff index "@$x,$y"]
 672                 set last $first
 673         } else {
 674                 set first [lindex $selected 0]
 675                 set last [lindex $selected 1]
 676         }
 677
 678         set first_l [$ui_diff index "$first linestart"]
 679         set last_l [$ui_diff index "$last lineend"]
 680
 681         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 682         if {![lock_index apply_hunk]} return
 683
 684         set apply_cmd {apply --whitespace=nowarn}
 685         set mi [lindex $file_states($current_diff_path) 0]
 686         if {$current_diff_side eq $ui_index} {
 687                 set failed_msg [mc "Failed to unstage selected line."]
 688                 set to_context {+}
 689                 lappend apply_cmd --reverse --cached
 690                 if {[string index $mi 0] ne {M}} {
 691                         unlock_index
 692                         return
 693                 }
 694         } else {
 695                 if {$revert} {
 696                         set failed_msg [mc "Failed to revert selected line."]
 697                         set to_context {+}
 698                         lappend apply_cmd --reverse
 699                 } else {
 700                         set failed_msg [mc "Failed to stage selected line."]
 701                         set to_context {-}
 702                         lappend apply_cmd --cached
 703                 }
 704
 705                 if {[string index $mi 1] ne {M}} {
 706                         unlock_index
 707                         return
 708                 }
 709         }
 710
 711         set wholepatch {}
 712
 713         while {$first_l < $last_l} {
 714                 set i_l [$ui_diff search -backwards -regexp ^@@ $first_l 0.0]
 715                 if {$i_l eq {}} {
 716                         # If there's not a @@ above, then the selected range
 717                         # must have come before the first_l @@
 718                         set i_l [$ui_diff search -regexp ^@@ $first_l $last_l]
 719                 }
 720                 if {$i_l eq {}} {
 721                         unlock_index
 722                         return
 723                 }
 724                 # $i_l is now at the beginning of a line
 725
 726                 # pick start line number from hunk header
 727                 set hh [$ui_diff get $i_l "$i_l + 1 lines"]
 728                 set hh [lindex [split $hh ,] 0]
 729                 set hln [lindex [split $hh -] 1]
 730                 set hln [lindex [split $hln " "] 0]
 731
 732                 # There is a special situation to take care of. Consider this
 733                 # hunk:
 734                 #
 735                 #    @@ -10,4 +10,4 @@
 736                 #     context before
 737                 #    -old 1
 738                 #    -old 2
 739                 #    +new 1
 740                 #    +new 2
 741                 #     context after
 742                 #
 743                 # We used to keep the context lines in the order they appear in
 744                 # the hunk. But then it is not possible to correctly stage only
 745                 # "-old 1" and "+new 1" - it would result in this staged text:
 746                 #
 747                 #    context before
 748                 #    old 2
 749                 #    new 1
 750                 #    context after
 751                 #
 752                 # (By symmetry it is not possible to *un*stage "old 2" and "new
 753                 # 2".)
 754                 #
 755                 # We resolve the problem by introducing an asymmetry, namely,
 756                 # when a "+" line is *staged*, it is moved in front of the
 757                 # context lines that are generated from the "-" lines that are
 758                 # immediately before the "+" block. That is, we construct this
 759                 # patch:
 760                 #
 761                 #    @@ -10,4 +10,5 @@
 762                 #     context before
 763                 #    +new 1
 764                 #     old 1
 765                 #     old 2
 766                 #     context after
 767                 #
 768                 # But we do *not* treat "-" lines that are *un*staged in a
 769                 # special way.
 770                 #
 771                 # With this asymmetry it is possible to stage the change "old
 772                 # 1" -> "new 1" directly, and to stage the change "old 2" ->
 773                 # "new 2" by first staging the entire hunk and then unstaging
 774                 # the change "old 1" -> "new 1".
 775                 #
 776                 # Applying multiple lines adds complexity to the special
 777                 # situation.  The pre_context must be moved after the entire
 778                 # first block of consecutive staged "+" lines, so that
 779                 # staging both additions gives the following patch:
 780                 #
 781                 #    @@ -10,4 +10,6 @@
 782                 #     context before
 783                 #    +new 1
 784                 #    +new 2
 785                 #     old 1
 786                 #     old 2
 787                 #     context after
 788
 789                 # This is non-empty if and only if we are _staging_ changes;
 790                 # then it accumulates the consecutive "-" lines (after
 791                 # converting them to context lines) in order to be moved after
 792                 # "+" change lines.
 793                 set pre_context {}
 794
 795                 set n 0
 796                 set m 0
 797                 set i_l [$ui_diff index "$i_l + 1 lines"]
 798                 set patch {}
 799                 while {[$ui_diff compare $i_l < "end - 1 chars"] &&
 800                        [$ui_diff get $i_l "$i_l + 2 chars"] ne {@@}} {
 801                         set next_l [$ui_diff index "$i_l + 1 lines"]
 802                         set c1 [$ui_diff get $i_l]
 803                         if {[$ui_diff compare $first_l <= $i_l] &&
 804                             [$ui_diff compare $i_l < $last_l] &&
 805                             ($c1 eq {-} || $c1 eq {+})} {
 806                                 # a line to stage/unstage
 807                                 set ln [$ui_diff get $i_l $next_l]
 808                                 if {$c1 eq {-}} {
 809                                         set n [expr $n+1]
 810                                         set patch "$patch$pre_context$ln"
 811                                         set pre_context {}
 812                                 } else {
 813                                         set m [expr $m+1]
 814                                         set patch "$patch$ln"
 815                                 }
 816                         } elseif {$c1 ne {-} && $c1 ne {+}} {
 817                                 # context line
 818                                 set ln [$ui_diff get $i_l $next_l]
 819                                 set patch "$patch$pre_context$ln"
 820                                 # Skip the "\ No newline at end of
 821                                 # file". Depending on the locale setting
 822                                 # we don't know what this line looks
 823                                 # like exactly. The only thing we do
 824                                 # know is that it starts with "\ "
 825                                 if {![string match {\\ *} $ln]} {
 826                                         set n [expr $n+1]
 827                                         set m [expr $m+1]
 828                                 }
 829                                 set pre_context {}
 830                         } elseif {$c1 eq $to_context} {
 831                                 # turn change line into context line
 832                                 set ln [$ui_diff get "$i_l + 1 chars" $next_l]
 833                                 if {$c1 eq {-}} {
 834                                         set pre_context "$pre_context $ln"
 835                                 } else {
 836                                         set patch "$patch $ln"
 837                                 }
 838                                 set n [expr $n+1]
 839                                 set m [expr $m+1]
 840                         } else {
 841                                 # a change in the opposite direction of
 842                                 # to_context which is outside the range of
 843                                 # lines to apply.
 844                                 set patch "$patch$pre_context"
 845                                 set pre_context {}
 846                         }
 847                         set i_l $next_l
 848                 }
 849                 set patch "$patch$pre_context"
 850                 set wholepatch "$wholepatch@@ -$hln,$n +$hln,$m @@\n$patch"
 851                 set first_l [$ui_diff index "$next_l + 1 lines"]
 852         }
 853
 854         if {[catch {
 855                 set enc [get_path_encoding $current_diff_path]
 856                 set p [eval git_write $apply_cmd]
 857                 fconfigure $p -translation binary -encoding $enc
 858                 puts -nonewline $p $current_diff_header
 859                 puts -nonewline $p $wholepatch
 860                 close $p} err]} {
 861                 error_popup "$failed_msg\n\n$err"
 862                 unlock_index
 863                 return
 864         }
 865
 866         if {$revert} {
 867                 # Save a copy of this patch for undoing reverts.
 868                 set last_revert $current_diff_header$wholepatch
 869                 set last_revert_enc $enc
 870         }
 871
 872         unlock_index
 873 }
 874
 875 # Undo the last line/hunk reverted. When hunks and lines are reverted, a copy
 876 # of the diff applied is saved. Re-apply that diff to undo the revert.
 877 #
 878 # Right now, we only use a single variable to hold the copy, and not a
 879 # stack/deque for simplicity, so multiple undos are not possible. Maybe this
 880 # can be added if the need for something like this is felt in the future.
 881 proc undo_last_revert {} {
 882         global last_revert current_diff_path current_diff_header
 883         global last_revert_enc
 884
 885         if {$last_revert eq {}} return
 886         if {![lock_index apply_hunk]} return
 887
 888         set apply_cmd {apply --whitespace=nowarn}
 889         set failed_msg [mc "Failed to undo last revert."]
 890
 891         if {[catch {
 892                 set enc $last_revert_enc
 893                 set p [eval git_write $apply_cmd]
 894                 fconfigure $p -translation binary -encoding $enc
 895                 puts -nonewline $p $last_revert
 896                 close $p} err]} {
 897                 error_popup "$failed_msg\n\n$err"
 898                 unlock_index
 899                 return
 900         }
 901
 902         set last_revert {}
 903
 904         unlock_index
 905 }