Re: [PATCH v3 4/4] git-gui: allow undoing last revert

>
> Accidental clicks on the revert hunk/lines buttons can cause loss of
> work, and can be frustrating. So, allow undoing the last revert.
>
> Right now, a stack or deque are not being used for the sake of
> simplicity, so only one undo is possible. Any reverts before the
> previous one are lost.
>
> Signed-off-by: Pratyush Yadav <me@yadavpratyush.com>
> ---
>  git-gui.sh   | 18 +++++++++++++++++-
>  lib/diff.tcl | 53 ++++++++++++++++++++++++++++++++++++++++++++++++----
>  2 files changed, 66 insertions(+), 5 deletions(-)
>
> diff --git a/git-gui.sh b/git-gui.sh
> index 1592544..e03a2d2 100755
> --- a/git-gui.sh
> +++ b/git-gui.sh
> @@ -1350,6 +1350,8 @@ set is_submodule_diff 0
>  set is_conflict_diff 0
>  set selected_commit_type new
>  set diff_empty_count 0
> +set last_revert {}
> +set last_revert_enc {}
>
>  set nullid "0000000000000000000000000000000000000000"
>  set nullid2 "0000000000000000000000000000000000000001"
> @@ -3601,6 +3603,11 @@ $ctxm add command \
>         -command {apply_or_revert_range_or_line $cursorX $cursorY 1; do_rescan}
>  set ui_diff_revertline [$ctxm index last]
>  lappend diff_actions [list $ctxm entryconf $ui_diff_revertline -state]
> +$ctxm add command \
> +       -label [mc "Undo Last Revert"] \
> +       -command {undo_last_revert; do_rescan}
> +set ui_diff_undorevert [$ctxm index last]
> +lappend diff_actions [list $ctxm entryconf $ui_diff_undorevert -state]
>  $ctxm add separator
>  $ctxm add command \
>         -label [mc "Show Less Context"] \
> @@ -3680,7 +3687,7 @@ proc has_textconv {path} {
>  }
>
>  proc popup_diff_menu {ctxm ctxmmg ctxmsm x y X Y} {
> -       global current_diff_path file_states
> +       global current_diff_path file_states last_revert
>         set ::cursorX $x
>         set ::cursorY $y
>         if {[info exists file_states($current_diff_path)]} {
> @@ -3694,6 +3701,7 @@ proc popup_diff_menu {ctxm ctxmmg ctxmsm x y X Y} {
>                 tk_popup $ctxmsm $X $Y
>         } else {
>                 set has_range [expr {[$::ui_diff tag nextrange sel 0.0] != {}}]
> +               set u [mc "Undo Last Revert"]
>                 if {$::ui_index eq $::current_diff_side} {
>                         set l [mc "Unstage Hunk From Commit"]
>                         set h [mc "Revert Hunk"]
> @@ -3739,12 +3747,20 @@ proc popup_diff_menu {ctxm ctxmmg ctxmsm x y X Y} {
>                         }
>                 }
>
> +               if {$last_revert eq {}} {
> +                       set undo_state disabled
> +               } else {
> +                       set undo_state normal
> +               }
> +
>                 $ctxm entryconf $::ui_diff_applyhunk -state $s -label $l
>                 $ctxm entryconf $::ui_diff_applyline -state $s -label $t
>                 $ctxm entryconf $::ui_diff_revertline -state $revert_state \
>                         -label $r
>                 $ctxm entryconf $::ui_diff_reverthunk -state $revert_state \
>                         -label $h
> +               $ctxm entryconf $::ui_diff_undorevert -state $undo_state \
> +                       -label $u
>
>                 tk_popup $ctxm $X $Y
>         }
> diff --git a/lib/diff.tcl b/lib/diff.tcl
> index 0659029..96288fc 100644
> --- a/lib/diff.tcl
> +++ b/lib/diff.tcl
> @@ -569,7 +569,7 @@ proc read_diff {fd conflict_size cont_info} {
>
>  proc apply_or_revert_hunk {x y revert} {
>         global current_diff_path current_diff_header current_diff_side
> -       global ui_diff ui_index file_states
> +       global ui_diff ui_index file_states last_revert last_revert_enc
>
>         if {$current_diff_path eq {} || $current_diff_header eq {}} return
>         if {![lock_index apply_hunk]} return
> @@ -610,18 +610,25 @@ proc apply_or_revert_hunk {x y revert} {
>                 set e_lno end
>         }
>
> +       set wholepatch "$current_diff_header[$ui_diff get $s_lno $e_lno]"
> +
>         if {[catch {
>                 set enc [get_path_encoding $current_diff_path]
>                 set p [eval git_write $apply_cmd]
>                 fconfigure $p -translation binary -encoding $enc
> -               puts -nonewline $p $current_diff_header
> -               puts -nonewline $p [$ui_diff get $s_lno $e_lno]
> +               puts -nonewline $p $wholepatch
>                 close $p} err]} {
>                 error_popup "$failed_msg\n\n$err"
>                 unlock_index
>                 return
>         }
>
> +       if {$revert} {
> +               # Save a copy of this patch for undoing reverts.
> +               set last_revert $wholepatch
> +               set last_revert_enc $enc
> +       }
> +
>         $ui_diff conf -state normal
>         $ui_diff delete $s_lno $e_lno
>         $ui_diff conf -state disabled
> @@ -653,7 +660,7 @@ proc apply_or_revert_hunk {x y revert} {
>
>  proc apply_or_revert_range_or_line {x y revert} {
>         global current_diff_path current_diff_header current_diff_side
> -       global ui_diff ui_index file_states
> +       global ui_diff ui_index file_states last_revert
>
>         set selected [$ui_diff tag nextrange sel 0.0]
>
> @@ -852,5 +859,43 @@ proc apply_or_revert_range_or_line {x y revert} {
>                 return
>         }
>
> +       if {$revert} {
> +               # Save a copy of this patch for undoing reverts.
> +               set last_revert $current_diff_header$wholepatch
> +               set last_revert_enc $enc
> +       }
> +
> +       unlock_index
> +}
> +
> +# Undo the last line/hunk reverted. When hunks and lines are reverted, a copy
> +# of the diff applied is saved. Re-apply that diff to undo the revert.
> +#
> +# Right now, we only use a single variable to hold the copy, and not a
> +# stack/deque for simplicity, so multiple undos are not possible. Maybe this
> +# can be added if the need for something like this is felt in the future.
> +proc undo_last_revert {} {
> +       global last_revert current_diff_path current_diff_header
> +       global last_revert_enc
> +
> +       if {$last_revert eq {}} return
> +       if {![lock_index apply_hunk]} return
> +
> +       set apply_cmd {apply --whitespace=nowarn}
> +       set failed_msg [mc "Failed to undo last revert."]
> +
> +       if {[catch {
> +               set enc $last_revert_enc
> +               set p [eval git_write $apply_cmd]
> +               fconfigure $p -translation binary -encoding $enc
> +               puts -nonewline $p $last_revert
> +               close $p} err]} {
> +               error_popup "$failed_msg\n\n$err"
> +               unlock_index
> +               return
> +       }
> +
> +       set last_revert {}
> +
>         unlock_index
>  }
> --
> 2.21.0
>