feat(): show old version of hunks via virtual lines

Use virtual lines to show the old version of hunks inline in the buffer.

- Added config.show_deleted
- Added toggle_deleted()

doc/gitsigns.txt

@@ -388,6 +388,9 @@ stage_hunk({range})                                    *gitsigns.stage_hunk()*
                     {range} table|nil List-like table of two integers making
                     up the line range from which you want to stage the hunks.
 
+toggle_deleted()                                   *gitsigns.toggle_deleted()*
+                Toggle |gitsigns-config-show_deleted|
+
 toggle_current_line_blame()             *gitsigns.toggle_current_line_blame()*
                 Toggle |gitsigns-config-current_line_blame|
 
@@ -558,6 +561,13 @@ linehl                                                *gitsigns-config-linehl*
       the highlight group does not exist, then it is automatically defined
       and linked to the corresponding highlight group in `signs.*.hl`.
 
+show_deleted                                    *gitsigns-config-show_deleted*
+      Type: `boolean`, Default: `false`
+
+      Show the old version of hunks inline in the buffer (via virtual lines).
+
+      Note: Virtual lines currently use the highlight `GitSignsDeleteLn`.
+
 diff_opts                                          *gitsigns-config-diff_opts*
       Type: `table[extended]`, Default: derived from 'diffopt'
 

lua/gitsigns/actions.lua

@@ -69,6 +69,7 @@ local M = {QFListOpts = {}, }
 
 
 
+
 
 
 M.toggle_signs = function()
@@ -100,6 +101,12 @@ M.toggle_current_line_blame = function()
    M.refresh()
 end
 
+
+M.toggle_deleted = function()
+   config.show_deleted = not config.show_deleted
+   M.refresh()
+end
+
 local function get_cursor_hunk(bufnr, hunks)
    bufnr = bufnr or current_buf()
    hunks = hunks or cache[bufnr].hunks

lua/gitsigns/config.lua

@@ -103,6 +103,7 @@ local M = {Config = {DiffOpts = {}, SignsConfig = {}, watch_gitdir = {}, current
 
 
 
+
 
 
 M.config = {}
@@ -272,6 +273,16 @@ M.schema = {
     ]],
    },
 
+   show_deleted = {
+      type = 'boolean',
+      default = false,
+      description = [[
+      Show the old version of hunks inline in the buffer (via virtual lines).
+
+      Note: Virtual lines currently use the highlight `GitSignsDeleteLn`.
+    ]],
+   },
+
    diff_opts = {
       type = 'table',
       deep_extend = true,

lua/gitsigns/manager.lua

@@ -212,6 +212,67 @@ M.apply_word_diff = function(bufnr, row)
    end
 end
 
+local ns_rm = api.nvim_create_namespace('gitsigns_removed')
+
+local VIRT_LINE_LEN = 300
+
+local function clear_deleted(bufnr)
+   local marks = api.nvim_buf_get_extmarks(bufnr, ns_rm, 0, -1, {})
+   for _, mark in ipairs(marks) do
+      api.nvim_buf_del_extmark(bufnr, ns_rm, mark[1])
+   end
+end
+
+local function show_deleted(bufnr)
+   local bcache = cache[bufnr]
+
+   clear_deleted(bufnr)
+
+   if not config.show_deleted then
+      return
+   end
+
+   for _, hunk in ipairs(bcache.hunks) do
+      local virt_lines = {}
+      local do_word_diff = config.word_diff and #hunk.removed.lines == #hunk.added.lines
+
+      for i, line in ipairs(hunk.removed.lines) do
+         local vline = {}
+         local last_ecol = 1
+
+         if do_word_diff then
+            local regions = require('gitsigns.diff_int').run_word_diff(
+            { hunk.removed.lines[i] }, { hunk.added.lines[i] })
+
+            for _, region in ipairs(regions) do
+               local rline, scol, ecol = region[1], region[3], region[4]
+               if rline > 1 then
+                  break
+               end
+               vline[#vline + 1] = { line:sub(last_ecol, scol - 1), config.signs.delete.linehl }
+               vline[#vline + 1] = { line:sub(scol, ecol - 1), 'TermCursor' }
+               last_ecol = ecol
+            end
+         end
+
+         if #line > 0 then
+            vline[#vline + 1] = { line:sub(last_ecol, -1), config.signs.delete.linehl }
+         end
+
+
+         local padding = string.rep(' ', VIRT_LINE_LEN - #line)
+         vline[#vline + 1] = { padding, config.signs.delete.linehl }
+
+         virt_lines[i] = vline
+      end
+
+      api.nvim_buf_set_extmark(bufnr, ns_rm, hunk.start - 1, -1, {
+         virt_lines = virt_lines,
+         virt_lines_above = hunk.type ~= 'delete',
+      })
+   end
+end
+
 local update_cnt = 0
 
 local update0 = function(bufnr, bcache)
@@ -251,6 +312,8 @@ local update0 = function(bufnr, bcache)
 
 
       M.apply_win_signs(bufnr, bcache.pending_signs)
+
+      show_deleted(bufnr)
    end
    local summary = gs_hunks.get_summary(bcache.hunks)
    summary.head = git_obj.repo.abbrev_head

teal/gitsigns/actions.tl

@@ -68,6 +68,7 @@ local record M
   toggle_linehl      : function()
   toggle_word_diff   : function()
   toggle_current_line_blame : function()
+  toggle_deleted     : function()
 end
 
 --- Toggle |gitsigns-config-signcolumn|
@@ -100,6 +101,12 @@ M.toggle_current_line_blame = function()
   M.refresh()
 end
 
+--- Toggle |gitsigns-config-show_deleted|
+M.toggle_deleted = function()
+  config.show_deleted = not config.show_deleted
+  M.refresh()
+end
+
 local function get_cursor_hunk(bufnr: integer, hunks: {Hunk}): Hunk, integer
   bufnr = bufnr or current_buf()
   hunks = hunks or cache[bufnr].hunks

teal/gitsigns/config.tl

@@ -50,6 +50,7 @@ local record M
     signcolumn: boolean
     numhl: boolean
     linehl: boolean
+    show_deleted: boolean
     sign_priority: integer
     keymaps: {string:any}
     on_attach: function(bufnr: integer)
@@ -272,6 +273,16 @@ M.schema = {
     ]]
   },
 
+  show_deleted = {
+    type = 'boolean',
+    default = false,
+    description = [[
+      Show the old version of hunks inline in the buffer (via virtual lines).
+
+      Note: Virtual lines currently use the highlight `GitSignsDeleteLn`.
+    ]]
+  },
+
   diff_opts = {
     type = 'table',
     deep_extend = true,

teal/gitsigns/manager.tl

@@ -212,6 +212,67 @@ M.apply_word_diff = function(bufnr: integer, row: integer)
   end
 end
 
+local ns_rm = api.nvim_create_namespace('gitsigns_removed')
+
+local VIRT_LINE_LEN = 300
+
+local function clear_deleted(bufnr: integer)
+  local marks = api.nvim_buf_get_extmarks(bufnr, ns_rm, 0, -1, {})
+  for _, mark in ipairs(marks as {{integer, integer, integer}}) do
+    api.nvim_buf_del_extmark(bufnr, ns_rm, mark[1])
+  end
+end
+
+local function show_deleted(bufnr: integer)
+  local bcache = cache[bufnr]
+
+   clear_deleted(bufnr)
+
+   if not config.show_deleted then
+     return
+   end
+
+  for _, hunk in ipairs(bcache.hunks) do
+    local virt_lines = {}
+    local do_word_diff = config.word_diff and #hunk.removed.lines == #hunk.added.lines
+
+    for i, line in ipairs(hunk.removed.lines) do
+      local vline = {}
+      local last_ecol = 1
+
+      if do_word_diff then
+        local regions = require('gitsigns.diff_int').run_word_diff(
+          {hunk.removed.lines[i]}, {hunk.added.lines[i]})
+
+        for _, region in ipairs(regions) do
+          local rline, scol, ecol = region[1], region[3], region[4]
+          if rline > 1 then
+            break
+          end
+          vline[#vline+1] = { line:sub(last_ecol, scol-1), config.signs.delete.linehl }
+          vline[#vline+1] = { line:sub(scol, ecol-1), 'TermCursor'}
+          last_ecol = ecol
+        end
+      end
+
+      if #line > 0 then
+        vline[#vline+1] = { line:sub(last_ecol, -1), config.signs.delete.linehl }
+      end
+
+      -- Add extra padding so the entire line is highlighted
+      local padding = string.rep(' ', VIRT_LINE_LEN-#line)
+      vline[#vline+1] = { padding, config.signs.delete.linehl }
+
+      virt_lines[i] = vline
+    end
+
+    api.nvim_buf_set_extmark(bufnr, ns_rm, hunk.start-1, -1, {
+      virt_lines       = virt_lines,
+      virt_lines_above = hunk.type ~= 'delete',
+    })
+  end
+end
+
 local update_cnt = 0
 
 local update0 = function(bufnr: integer, bcache: CacheEntry)
@@ -251,6 +312,8 @@ local update0 = function(bufnr: integer, bcache: CacheEntry)
     -- Apply signs to the window. Other signs will be added by the decoration
     -- provider as they are drawn.
     M.apply_win_signs(bufnr, bcache.pending_signs)
+
+    show_deleted(bufnr)
   end
   local summary = gs_hunks.get_summary(bcache.hunks)
   summary.head = git_obj.repo.abbrev_head