Calculate folds for buffers with inline diffs.

lua/diffview/init.lua

@@ -5,6 +5,7 @@ end
 local hl = require("diffview.hl")
 local lazy = require("diffview.lazy")
 
+local StandardView = lazy.access("diffview.scene.views.standard.standard_view", "StandardView") ---@type StandardView|LazyModule
 local arg_parser = lazy.require("diffview.arg_parser") ---@module "diffview.arg_parser"
 local config = lazy.require("diffview.config") ---@module "diffview.config"
 local lib = lazy.require("diffview.lib") ---@module "diffview.lib"
@@ -75,6 +76,18 @@ function M.init()
       M.emit("refresh_files")
     end,
   })
+  au("User", {
+    group = M.augroup,
+    pattern = "GitSignsUpdate",
+    callback = function()
+      local view = lib.get_current_view()
+
+      if view and view:instanceof(StandardView.__get()) then
+        ---@cast view StandardView
+        view.cur_layout:gs_update_folds()
+      end
+    end,
+  })
 
   -- Set up user autocommand emitters
   DiffviewGlobal.emitter:on("view_opened", function(_)

lua/diffview/scene/layout.lua

@@ -323,5 +323,7 @@ function Layout:sync_scroll()
   end
 end
 
+function Layout:gs_update_folds() end
+
 M.Layout = Layout
 return M

lua/diffview/scene/layouts/diff_1_inline.lua

@@ -2,6 +2,8 @@ local Diff1 = require("diffview.scene.layouts.diff_1").Diff1
 local lazy = require("diffview.lazy")
 local oop = require("diffview.oop")
 
+local GitAdapter = lazy.access("diffview.vcs.adapters.git", "GitAdapter") ---@type GitAdapter|LazyModule
+
 local M = {}
 
 ---@class Diff1Inline : Diff1
@@ -12,5 +14,14 @@ function Diff1Inline:init(opt)
   Diff1Inline:super().init(self, opt)
 end
 
+function Diff1Inline:gs_update_folds()
+  if self.b:is_file_open()
+    and self.b.file.adapter:instanceof(GitAdapter.__get())
+    and self.b.file.kind ~= "conflicting"
+  then
+    self.b:gs_update_folds()
+  end
+end
+
 M.Diff1Inline = Diff1Inline
 return M

lua/diffview/scene/window.lua

@@ -7,6 +7,7 @@ local FileHistoryView = lazy.access("diffview.scene.views.file_history.file_hist
 local GitAdapter = lazy.access("diffview.vcs.adapters.git", "GitAdapter") ---@type GitAdapter|LazyModule
 local RevType = lazy.access("diffview.vcs.rev", "RevType") ---@type RevType|LazyModule
 local config = lazy.require("diffview.config") ---@module "diffview.config"
+local gs_actions = lazy.require("gitsigns.actions") ---@module "gitsigns.actions"
 local lib = lazy.require("diffview.lib") ---@module "diffview.lib"
 local utils = lazy.require("diffview.utils") ---@module "diffview.utils"
 
@@ -227,8 +228,8 @@ function Window:apply_file_winopts(overrides)
     if overrides then
       utils.set_local(self.id, vim.tbl_extend("force", self.file.winopts, overrides))
     else
-    utils.set_local(self.id, self.file.winopts)
-  end
+      utils.set_local(self.id, self.file.winopts)
+    end
   end
 end
 
@@ -246,5 +247,47 @@ function Window:set_file(file)
   self.file = file
 end
 
+function Window:gs_update_folds()
+  if self:is_file_open() and vim.wo[self.id].foldenable then
+    api.nvim_win_call(self.id, function()
+      pcall(vim.cmd, "norm! zE") -- Delete all folds in window
+      local hunks = gs_actions.get_hunks(self.file.bufnr) or {}
+      local context
+
+      for _, v in ipairs(vim.opt.diffopt:get()) do
+        context = tonumber(v:match("^context:(%d+)"))
+        if context then break end
+      end
+
+      context = math.max(1, context or 6)
+
+      local prev_last = -context + 1
+      local lcount = api.nvim_buf_line_count(self.file.bufnr)
+
+      for i = 1, #hunks + 1 do
+        local hunk = hunks[i]
+        local first, last
+
+        if hunk then
+          first = hunk.added.start
+          last = first + hunk.added.count - 1
+        else
+          first = lcount + context
+          last = first
+        end
+
+        -- print(prev_last, first, last, hunk and "hunk" or "nil")
+
+        if first - prev_last > context * 2 + 1 then
+          -- print("FOLD:", prev_last + context, first - context)
+          vim.cmd(("%d,%dfold"):format(prev_last + context, first - context))
+        end
+
+        prev_last = last
+      end
+    end)
+  end
+end
+
 M.Window = Window
 return M