util/X86LINUX64/share/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 $cont_info
 129         }
 130 }
 131
 132 proc show_unmerged_diff {cont_info} {
 133         global current_diff_path current_diff_side
 134         global merge_stages ui_diff is_conflict_diff
 135         global current_diff_queue
 136
 137         if {$merge_stages(2) eq {}} {
 138                 set is_conflict_diff 1
 139                 lappend current_diff_queue \
 140                         [list [mc "LOCAL: deleted\nREMOTE:\n"] d= \
 141                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 142         } elseif {$merge_stages(3) eq {}} {
 143                 set is_conflict_diff 1
 144                 lappend current_diff_queue \
 145                         [list [mc "REMOTE: deleted\nLOCAL:\n"] d= \
 146                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 147         } elseif {[lindex $merge_stages(1) 0] eq {120000}
 148                 || [lindex $merge_stages(2) 0] eq {120000}
 149                 || [lindex $merge_stages(3) 0] eq {120000}} {
 150                 set is_conflict_diff 1
 151                 lappend current_diff_queue \
 152                         [list [mc "LOCAL:\n"] d= \
 153                             [list ":1:$current_diff_path" ":2:$current_diff_path"]]
 154                 lappend current_diff_queue \
 155                         [list [mc "REMOTE:\n"] d= \
 156                             [list ":1:$current_diff_path" ":3:$current_diff_path"]]
 157         } else {
 158                 start_show_diff $cont_info
 159                 return
 160         }
 161
 162         advance_diff_queue $cont_info
 163 }
 164
 165 proc advance_diff_queue {cont_info} {
 166         global current_diff_queue ui_diff
 167
 168         set item [lindex $current_diff_queue 0]
 169         set current_diff_queue [lrange $current_diff_queue 1 end]
 170
 171         $ui_diff conf -state normal
 172         $ui_diff insert end [lindex $item 0] [lindex $item 1]
 173         $ui_diff conf -state disabled
 174
 175         start_show_diff $cont_info [lindex $item 2]
 176 }
 177
 178 proc show_other_diff {path w m cont_info} {
 179         global file_states file_lists
 180         global is_3way_diff diff_active repo_config
 181         global ui_diff ui_index ui_workdir
 182         global current_diff_path current_diff_side current_diff_header
 183
 184         # - Git won't give us the diff, there's nothing to compare to!
 185         #
 186         if {$m eq {_O}} {
 187                 set max_sz 100000
 188                 set type unknown
 189                 if {[catch {
 190                                 set type [file type $path]
 191                                 switch -- $type {
 192                                 directory {
 193                                         set type submodule
 194                                         set content {}
 195                                         set sz 0
 196                                 }
 197                                 link {
 198                                         set content [file readlink $path]
 199                                         set sz [string length $content]
 200                                 }
 201                                 file {
 202                                         set fd [open $path r]
 203                                         fconfigure $fd \
 204                                                 -eofchar {} \
 205                                                 -encoding [get_path_encoding $path]
 206                                         set content [read $fd $max_sz]
 207                                         close $fd
 208                                         set sz [file size $path]
 209                                 }
 210                                 default {
 211                                         error "'$type' not supported"
 212                                 }
 213                                 }
 214                         } err ]} {
 215                         set diff_active 0
 216                         unlock_index
 217                         ui_status [mc "Unable to display %s" [escape_path $path]]
 218                         error_popup [strcat [mc "Error loading file:"] "\n\n$err"]
 219                         return
 220                 }
 221                 $ui_diff conf -state normal
 222                 if {$type eq {submodule}} {
 223                         $ui_diff insert end [append \
 224                                 "* " \
 225                                 [mc "Git Repository (subproject)"] \
 226                                 "\n"] d_info
 227                 } elseif {![catch {set type [exec file $path]}]} {
 228                         set n [string length $path]
 229                         if {[string equal -length $n $path $type]} {
 230                                 set type [string range $type $n end]
 231                                 regsub {^:?\s*} $type {} type
 232                         }
 233                         $ui_diff insert end "* $type\n" d_info
 234                 }
 235                 if {[string first "\0" $content] != -1} {
 236                         $ui_diff insert end \
 237                                 [mc "* Binary file (not showing content)."] \
 238                                 d_info
 239                 } else {
 240                         if {$sz > $max_sz} {
 241                                 $ui_diff insert end [mc \
 242 "* Untracked file is %d bytes.
 243 * Showing only first %d bytes.
 244 " $sz $max_sz] d_info
 245                         }
 246                         $ui_diff insert end $content
 247                         if {$sz > $max_sz} {
 248                                 $ui_diff insert end [mc "
 249 * Untracked file clipped here by %s.
 250 * To see the entire file, use an external editor.
 251 " [appname]] d_info
 252                         }
 253                 }
 254                 $ui_diff conf -state disabled
 255                 set diff_active 0
 256                 unlock_index
 257                 set scroll_pos [lindex $cont_info 0]
 258                 if {$scroll_pos ne {}} {
 259                         update
 260                         $ui_diff yview moveto $scroll_pos
 261                 }
 262                 ui_ready
 263                 set callback [lindex $cont_info 1]
 264                 if {$callback ne {}} {
 265                         eval $callback
 266                 }
 267                 return
 268         }
 269 }
 270
 271 proc get_conflict_marker_size {path} {
 272         set size 7
 273         catch {
 274                 set fd_rc [eval [list git_read check-attr "conflict-marker-size" -- $path]]
 275                 set ret [gets $fd_rc line]
 276                 close $fd_rc
 277                 if {$ret > 0} {
 278                         regexp {.*: conflict-marker-size: (\d+)$} $line line size
 279                 }
 280         }
 281         return $size
 282 }
 283
 284 proc start_show_diff {cont_info {add_opts {}}} {
 285         global file_states file_lists
 286         global is_3way_diff is_submodule_diff diff_active repo_config
 287         global ui_diff ui_index ui_workdir
 288         global current_diff_path current_diff_side current_diff_header
 289
 290         set path $current_diff_path
 291         set w $current_diff_side
 292
 293         set s $file_states($path)
 294         set m [lindex $s 0]
 295         set is_3way_diff 0
 296         set is_submodule_diff 0
 297         set diff_active 1
 298         set current_diff_header {}
 299         set conflict_size [get_conflict_marker_size $path]
 300
 301         set cmd [list]
 302         if {$w eq $ui_index} {
 303                 lappend cmd diff-index
 304                 lappend cmd --cached
 305                 if {[git-version >= "1.7.2"]} {
 306                         lappend cmd --ignore-submodules=dirty
 307                 }
 308         } elseif {$w eq $ui_workdir} {
 309                 if {[string first {U} $m] >= 0} {
 310                         lappend cmd diff
 311                 } else {
 312                         lappend cmd diff-files
 313                 }
 314         }
 315         if {![is_config_false gui.textconv] && [git-version >= 1.6.1]} {
 316                 lappend cmd --textconv
 317         }
 318
 319         if {[string match {160000 *} [lindex $s 2]]
 320          || [string match {160000 *} [lindex $s 3]]} {
 321                 set is_submodule_diff 1
 322
 323                 if {[git-version >= "1.6.6"]} {
 324                         lappend cmd --submodule
 325                 }
 326         }
 327
 328         lappend cmd -p
 329         lappend cmd --color
 330         set cmd [concat $cmd $repo_config(gui.diffopts)]
 331         if {$repo_config(gui.diffcontext) >= 1} {
 332                 lappend cmd "-U$repo_config(gui.diffcontext)"
 333         }
 334         if {$w eq $ui_index} {
 335                 lappend cmd [PARENT]
 336         }
 337         if {$add_opts ne {}} {
 338                 eval lappend cmd $add_opts
 339         } else {
 340                 lappend cmd --
 341                 lappend cmd $path
 342         }
 343
 344         if {$is_submodule_diff && [git-version < "1.6.6"]} {
 345                 if {$w eq $ui_index} {
 346                         set cmd [list submodule summary --cached -- $path]
 347                 } else {
 348                         set cmd [list submodule summary --files -- $path]
 349                 }
 350         }
 351
 352         if {[catch {set fd [eval git_read --nice $cmd]} err]} {
 353                 set diff_active 0
 354                 unlock_index
 355                 ui_status [mc "Unable to display %s" [escape_path $path]]
 356                 error_popup [strcat [mc "Error loading diff:"] "\n\n$err"]
 357                 return
 358         }
 359
 360         set ::current_diff_inheader 1
 361         fconfigure $fd \
 362                 -blocking 0 \
 363                 -encoding [get_path_encoding $path] \
 364                 -translation lf
 365         fileevent $fd readable [list read_diff $fd $conflict_size $cont_info]
 366 }
 367
 368 proc parse_color_line {line} {
 369         set start 0
 370         set result ""
 371         set markup [list]
 372         set regexp {\033\[((?:\d+;)*\d+)?m}
 373         set need_reset 0
 374         while {[regexp -indices -start $start $regexp $line match code]} {
 375                 foreach {begin end} $match break
 376                 append result [string range $line $start [expr {$begin - 1}]]
 377                 set pos [string length $result]
 378                 set col [eval [linsert $code 0 string range $line]]
 379                 set start [incr end]
 380                 if {$col eq "0" || $col eq ""} {
 381                         if {!$need_reset} continue
 382                         set need_reset 0
 383                 } else {
 384                         set need_reset 1
 385                 }
 386                 lappend markup $pos $col
 387         }
 388         append result [string range $line $start end]
 389         if {[llength $markup] < 4} {set markup {}}
 390         return [list $result $markup]
 391 }
 392
 393 proc read_diff {fd conflict_size cont_info} {
 394         global ui_diff diff_active is_submodule_diff
 395         global is_3way_diff is_conflict_diff current_diff_header
 396         global current_diff_queue
 397         global diff_empty_count
 398
 399         $ui_diff conf -state normal
 400         while {[gets $fd line] >= 0} {
 401                 foreach {line markup} [parse_color_line $line] break
 402                 set line [string map {\033 ^} $line]
 403
 404                 set tags {}
 405
 406                 # -- Check for start of diff header.
 407                 if {   [string match {diff --git *}      $line]
 408                     || [string match {diff --cc *}       $line]
 409                     || [string match {diff --combined *} $line]} {
 410                         set ::current_diff_inheader 1
 411                 }
 412
 413                 # -- Check for end of diff header (any hunk line will do this).
 414                 #
 415                 if {[regexp {^@@+ } $line]} {set ::current_diff_inheader 0}
 416
 417                 # -- Automatically detect if this is a 3 way diff.
 418                 #
 419                 if {[string match {@@@ *} $line]} {
 420                         set is_3way_diff 1
 421                         apply_tab_size 1
 422                 }
 423
 424                 if {$::current_diff_inheader} {
 425
 426                         # -- These two lines stop a diff header and shouldn't be in there
 427                         if {   [string match {Binary files * and * differ} $line]
 428                             || [regexp {^\* Unmerged path }                $line]} {
 429                                 set ::current_diff_inheader 0
 430                         } else {
 431                                 append current_diff_header $line "\n"
 432                         }
 433
 434                         # -- Cleanup uninteresting diff header lines.
 435                         #
 436                         if {   [string match {diff --git *}      $line]
 437                             || [string match {diff --cc *}       $line]
 438                             || [string match {diff --combined *} $line]
 439                             || [string match {--- *}             $line]
 440                             || [string match {+++ *}             $line]
 441                             || [string match {index *}           $line]} {
 442                                 continue
 443                         }
 444
 445                         # -- Name it symlink, not 120000
 446                         #    Note, that the original line is in $current_diff_header
 447                         regsub {^(deleted|new) file mode 120000} $line {\1 symlink} line
 448
 449                 } elseif {   $line eq {\ No newline at end of file}} {
 450                         # -- Handle some special lines
 451                 } elseif {$is_3way_diff} {
 452                         set op [string range $line 0 1]
 453                         switch -- $op {
 454                         {  } {set tags {}}
 455                         {@@} {set tags d_@}
 456                         { +} {set tags d_s+}
 457                         { -} {set tags d_s-}
 458                         {+ } {set tags d_+s}
 459                         {- } {set tags d_-s}
 460                         {--} {set tags d_--}
 461                         {++} {
 462                                 set regexp [string map [list %conflict_size $conflict_size]\
 463                                                                 {^\+\+([<>=]){%conflict_size}(?: |$)}]
 464                                 if {[regexp $regexp $line _g op]} {
 465                                         set is_conflict_diff 1
 466                                         set line [string replace $line 0 1 {  }]
 467                                         set tags d$op
 468                                 } else {
 469                                         set tags d_++
 470                                 }
 471                         }
 472                         default {
 473                                 puts "error: Unhandled 3 way diff marker: {$op}"
 474                                 set tags {}
 475                         }
 476                         }
 477                 } elseif {$is_submodule_diff} {
 478                         if {$line == ""} continue
 479                         if {[regexp {^Submodule } $line]} {
 480                                 set tags d_info
 481                         } elseif {[regexp {^\* } $line]} {
 482                                 set line [string replace $line 0 1 {Submodule }]
 483                                 set tags d_info
 484                         } else {
 485                                 set op [string range $line 0 2]
 486                                 switch -- $op {
 487                                 {  <} {set tags d_-}
 488                                 {  >} {set tags d_+}
 489                                 {  W} {set tags {}}
 490                                 default {
 491                                         puts "error: Unhandled submodule diff marker: {$op}"
 492                                         set tags {}
 493                                 }
 494                                 }
 495                         }
 496                 } else {
 497                         set op [string index $line 0]
 498                         switch -- $op {
 499                         { } {set tags {}}
 500                         {@} {set tags d_@}
 501                         {-} {set tags d_-}
 502                         {+} {
 503                                 set regexp [string map [list %conflict_size $conflict_size]\
 504                                                                 {^\+([<>=]){%conflict_size}(?: |$)}]
 505                                 if {[regexp $regexp $line _g op]} {
 506                                         set is_conflict_diff 1
 507                                         set tags d$op
 508                                 } else {
 509                                         set tags d_+
 510                                 }
 511                         }
 512                         default {
 513                                 puts "error: Unhandled 2 way diff marker: {$op}"
 514                                 set tags {}
 515                         }
 516                         }
 517                 }
 518                 set mark [$ui_diff index "end - 1 line linestart"]
 519                 $ui_diff insert end $line $tags
 520                 if {[string index $line end] eq "\r"} {
 521                         $ui_diff tag add d_cr {end - 2c}
 522                 }
 523                 $ui_diff insert end "\n" $tags
 524
 525                 foreach {posbegin colbegin posend colend} $markup {
 526                         set prefix clr
 527                         foreach style [lsort -integer [split $colbegin ";"]] {
 528                                 if {$style eq "7"} {append prefix i; continue}
 529                                 if {$style != 4 && ($style < 30 || $style > 47)} {continue}
 530                                 set a "$mark linestart + $posbegin chars"
 531                                 set b "$mark linestart + $posend chars"
 532                                 catch {$ui_diff tag add $prefix$style $a $b}
 533                         }
 534                 }
 535         }
 536         $ui_diff conf -state disabled
 537
 538         if {[eof $fd]} {
 539                 close $fd
 540
 541                 if {$current_diff_queue ne {}} {
 542                         advance_diff_queue $cont_info
 543                         return
 544                 }
 545
 546                 set diff_active 0
 547                 unlock_index
 548                 set scroll_pos [lindex $cont_info 0]
 549                 if {$scroll_pos ne {}} {
 550                         update
 551                         $ui_diff yview moveto $scroll_pos
 552                 }
 553                 ui_ready
 554
 555                 if {[$ui_diff index end] eq {2.0}} {
 556                         handle_empty_diff
 557                 } else {
 558                         set diff_empty_count 0
 559                 }
 560
 561                 set callback [lindex $cont_info 1]
 562                 if {$callback ne {}} {
 563                         eval $callback
 564                 }
 565         }
 566 }
 567
 568 proc apply_hunk {x y} {
 569         global current_diff_path current_diff_header current_diff_side
 570         global ui_diff ui_index file_states
 571
 572         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 573         if {![lock_index apply_hunk]} return
 574
 575         set apply_cmd {apply --cached --whitespace=nowarn}
 576         set mi [lindex $file_states($current_diff_path) 0]
 577         if {$current_diff_side eq $ui_index} {
 578                 set failed_msg [mc "Failed to unstage selected hunk."]
 579                 lappend apply_cmd --reverse
 580                 if {[string index $mi 0] ne {M}} {
 581                         unlock_index
 582                         return
 583                 }
 584         } else {
 585                 set failed_msg [mc "Failed to stage selected hunk."]
 586                 if {[string index $mi 1] ne {M}} {
 587                         unlock_index
 588                         return
 589                 }
 590         }
 591
 592         set s_lno [lindex [split [$ui_diff index @$x,$y] .] 0]
 593         set s_lno [$ui_diff search -backwards -regexp ^@@ $s_lno.0 0.0]
 594         if {$s_lno eq {}} {
 595                 unlock_index
 596                 return
 597         }
 598
 599         set e_lno [$ui_diff search -forwards -regexp ^@@ "$s_lno + 1 lines" end]
 600         if {$e_lno eq {}} {
 601                 set e_lno end
 602         }
 603
 604         if {[catch {
 605                 set enc [get_path_encoding $current_diff_path]
 606                 set p [eval git_write $apply_cmd]
 607                 fconfigure $p -translation binary -encoding $enc
 608                 puts -nonewline $p $current_diff_header
 609                 puts -nonewline $p [$ui_diff get $s_lno $e_lno]
 610                 close $p} err]} {
 611                 error_popup [append $failed_msg "\n\n$err"]
 612                 unlock_index
 613                 return
 614         }
 615
 616         $ui_diff conf -state normal
 617         $ui_diff delete $s_lno $e_lno
 618         $ui_diff conf -state disabled
 619
 620         if {[$ui_diff get 1.0 end] eq "\n"} {
 621                 set o _
 622         } else {
 623                 set o ?
 624         }
 625
 626         if {$current_diff_side eq $ui_index} {
 627                 set mi ${o}M
 628         } elseif {[string index $mi 0] eq {_}} {
 629                 set mi M$o
 630         } else {
 631                 set mi ?$o
 632         }
 633         unlock_index
 634         display_file $current_diff_path $mi
 635         # This should trigger shift to the next changed file
 636         if {$o eq {_}} {
 637                 reshow_diff
 638         }
 639 }
 640
 641 proc apply_range_or_line {x y} {
 642         global current_diff_path current_diff_header current_diff_side
 643         global ui_diff ui_index file_states
 644
 645         set selected [$ui_diff tag nextrange sel 0.0]
 646
 647         if {$selected == {}} {
 648                 set first [$ui_diff index "@$x,$y"]
 649                 set last $first
 650         } else {
 651                 set first [lindex $selected 0]
 652                 set last [lindex $selected 1]
 653         }
 654
 655         set first_l [$ui_diff index "$first linestart"]
 656         set last_l [$ui_diff index "$last lineend"]
 657
 658         if {$current_diff_path eq {} || $current_diff_header eq {}} return
 659         if {![lock_index apply_hunk]} return
 660
 661         set apply_cmd {apply --cached --whitespace=nowarn}
 662         set mi [lindex $file_states($current_diff_path) 0]
 663         if {$current_diff_side eq $ui_index} {
 664                 set failed_msg [mc "Failed to unstage selected line."]
 665                 set to_context {+}
 666                 lappend apply_cmd --reverse
 667                 if {[string index $mi 0] ne {M}} {
 668                         unlock_index
 669                         return
 670                 }
 671         } else {
 672                 set failed_msg [mc "Failed to stage selected line."]
 673                 set to_context {-}
 674                 if {[string index $mi 1] ne {M}} {
 675                         unlock_index
 676                         return
 677                 }
 678         }
 679
 680         set wholepatch {}
 681
 682         while {$first_l < $last_l} {
 683                 set i_l [$ui_diff search -backwards -regexp ^@@ $first_l 0.0]
 684                 if {$i_l eq {}} {
 685                         # If there's not a @@ above, then the selected range
 686                         # must have come before the first_l @@
 687                         set i_l [$ui_diff search -regexp ^@@ $first_l $last_l]
 688                 }
 689                 if {$i_l eq {}} {
 690                         unlock_index
 691                         return
 692                 }
 693                 # $i_l is now at the beginning of a line
 694
 695                 # pick start line number from hunk header
 696                 set hh [$ui_diff get $i_l "$i_l + 1 lines"]
 697                 set hh [lindex [split $hh ,] 0]
 698                 set hln [lindex [split $hh -] 1]
 699
 700                 # There is a special situation to take care of. Consider this
 701                 # hunk:
 702                 #
 703                 #    @@ -10,4 +10,4 @@
 704                 #     context before
 705                 #    -old 1
 706                 #    -old 2
 707                 #    +new 1
 708                 #    +new 2
 709                 #     context after
 710                 #
 711                 # We used to keep the context lines in the order they appear in
 712                 # the hunk. But then it is not possible to correctly stage only
 713                 # "-old 1" and "+new 1" - it would result in this staged text:
 714                 #
 715                 #    context before
 716                 #    old 2
 717                 #    new 1
 718                 #    context after
 719                 #
 720                 # (By symmetry it is not possible to *un*stage "old 2" and "new
 721                 # 2".)
 722                 #
 723                 # We resolve the problem by introducing an asymmetry, namely,
 724                 # when a "+" line is *staged*, it is moved in front of the
 725                 # context lines that are generated from the "-" lines that are
 726                 # immediately before the "+" block. That is, we construct this
 727                 # patch:
 728                 #
 729                 #    @@ -10,4 +10,5 @@
 730                 #     context before
 731                 #    +new 1
 732                 #     old 1
 733                 #     old 2
 734                 #     context after
 735                 #
 736                 # But we do *not* treat "-" lines that are *un*staged in a
 737                 # special way.
 738                 #
 739                 # With this asymmetry it is possible to stage the change "old
 740                 # 1" -> "new 1" directly, and to stage the change "old 2" ->
 741                 # "new 2" by first staging the entire hunk and then unstaging
 742                 # the change "old 1" -> "new 1".
 743                 #
 744                 # Applying multiple lines adds complexity to the special
 745                 # situation.  The pre_context must be moved after the entire
 746                 # first block of consecutive staged "+" lines, so that
 747                 # staging both additions gives the following patch:
 748                 #
 749                 #    @@ -10,4 +10,6 @@
 750                 #     context before
 751                 #    +new 1
 752                 #    +new 2
 753                 #     old 1
 754                 #     old 2
 755                 #     context after
 756
 757                 # This is non-empty if and only if we are _staging_ changes;
 758                 # then it accumulates the consecutive "-" lines (after
 759                 # converting them to context lines) in order to be moved after
 760                 # "+" change lines.
 761                 set pre_context {}
 762
 763                 set n 0
 764                 set m 0
 765                 set i_l [$ui_diff index "$i_l + 1 lines"]
 766                 set patch {}
 767                 while {[$ui_diff compare $i_l < "end - 1 chars"] &&
 768                        [$ui_diff get $i_l "$i_l + 2 chars"] ne {@@}} {
 769                         set next_l [$ui_diff index "$i_l + 1 lines"]
 770                         set c1 [$ui_diff get $i_l]
 771                         if {[$ui_diff compare $first_l <= $i_l] &&
 772                             [$ui_diff compare $i_l < $last_l] &&
 773                             ($c1 eq {-} || $c1 eq {+})} {
 774                                 # a line to stage/unstage
 775                                 set ln [$ui_diff get $i_l $next_l]
 776                                 if {$c1 eq {-}} {
 777                                         set n [expr $n+1]
 778                                         set patch "$patch$pre_context$ln"
 779                                         set pre_context {}
 780                                 } else {
 781                                         set m [expr $m+1]
 782                                         set patch "$patch$ln"
 783                                 }
 784                         } elseif {$c1 ne {-} && $c1 ne {+}} {
 785                                 # context line
 786                                 set ln [$ui_diff get $i_l $next_l]
 787                                 set patch "$patch$pre_context$ln"
 788                                 # Skip the "\ No newline at end of
 789                                 # file". Depending on the locale setting
 790                                 # we don't know what this line looks
 791                                 # like exactly. The only thing we do
 792                                 # know is that it starts with "\ "
 793                                 if {![string match {\\ *} $ln]} {
 794                                         set n [expr $n+1]
 795                                         set m [expr $m+1]
 796                                 }
 797                                 set pre_context {}
 798                         } elseif {$c1 eq $to_context} {
 799                                 # turn change line into context line
 800                                 set ln [$ui_diff get "$i_l + 1 chars" $next_l]
 801                                 if {$c1 eq {-}} {
 802                                         set pre_context "$pre_context $ln"
 803                                 } else {
 804                                         set patch "$patch $ln"
 805                                 }
 806                                 set n [expr $n+1]
 807                                 set m [expr $m+1]
 808                         } else {
 809                                 # a change in the opposite direction of
 810                                 # to_context which is outside the range of
 811                                 # lines to apply.
 812                                 set patch "$patch$pre_context"
 813                                 set pre_context {}
 814                         }
 815                         set i_l $next_l
 816                 }
 817                 set patch "$patch$pre_context"
 818                 set wholepatch "$wholepatch@@ -$hln,$n +$hln,$m @@\n$patch"
 819                 set first_l [$ui_diff index "$next_l + 1 lines"]
 820         }
 821
 822         if {[catch {
 823                 set enc [get_path_encoding $current_diff_path]
 824                 set p [eval git_write $apply_cmd]
 825                 fconfigure $p -translation binary -encoding $enc
 826                 puts -nonewline $p $current_diff_header
 827                 puts -nonewline $p $wholepatch
 828                 close $p} err]} {
 829                 error_popup [append $failed_msg "\n\n$err"]
 830         }
 831
 832         unlock_index
 833 }