feat: add option to show the context with the **folded** current buffer

README.md

@@ -207,6 +207,12 @@ require'treesitter-context'.setup{
   multiline_threshold = 20, -- Maximum number of lines to show for a single context
   trim_scope = 'outer', -- Which context lines to discard if `max_lines` is exceeded. Choices: 'inner', 'outer'
   mode = 'cursor',  -- Line used to calculate context. Choices: 'cursor', 'topline'
+  -- Summarizer can be 'set_lines' or 'fold'. The latter recommends nvim >= 0.10.
+  summarizer = 'set_lines',
+  -- The 'foldtext' option for the context window when `summarizer = 'fold'`.
+  -- If `nil` (default), tries `"v:lua.vim.treesitter.foldtext()"` and fallbacks to
+  -- "getline(v:foldstart)"
+  foldtext = nil,
   -- Separator between context and content. Should be a single character string, like '-'.
   -- When separator is set, the context will only show up when there are at least 2 lines above cursorline.
   separator = nil,

lua/treesitter-context/config.lua

@@ -8,6 +8,8 @@
 --- @field trim_scope 'outer'|'inner'
 --- @field zindex integer
 --- @field mode 'cursor'|'topline'
+--- @field summarizer 'set_lines' | 'fold'
+--- @field foldtext? string
 --- @field separator? string
 --- @field on_attach? fun(buf: integer): boolean
 
@@ -52,6 +54,7 @@ local default_config = {
   trim_scope = 'outer',
   zindex = 20,
   mode = 'cursor',
+  summarizer = 'set_lines',
 }
 
 local config = vim.deepcopy(default_config)

lua/treesitter-context/render.lua

@@ -62,8 +62,23 @@ local function display_window(bufnr, winid, width, height, col, ty, hl)
     })
     vim.w[winid][ty] = true
     vim.wo[winid].wrap = false
-    vim.wo[winid].foldenable = false
+    vim.wo[winid].signcolumn = 'no'
     vim.wo[winid].winhl = 'NormalFloat:' .. hl
+
+    local fold = config.summarizer == 'fold'
+    vim.wo[winid].foldenable = fold
+    if fold then
+      api.nvim_set_hl(ns, "Folded", { link = "TreesitterContext" })
+      api.nvim_win_set_hl_ns(winid, ns)
+      vim.wo[winid].foldmethod = "manual"
+      if config.foldtext then
+        vim.wo[winid].foldtext = config.foldtext
+      elseif vim.treesitter.foldtext then
+        vim.wo[winid].foldtext = "v:lua.vim.treesitter.foldtext()"
+      else
+        vim.wo[winid].foldtext = "getline(v:foldstart)"
+      end
+    end
   else
     api.nvim_win_set_config(winid, {
       win = api.nvim_get_current_win(),
@@ -348,8 +363,10 @@ function M.open(bufnr, winid, ctx_ranges, ctx_lines)
     win_close(gutter_winid)
   end
 
+  local fold = config.summarizer == "fold"
+
   context_winid = display_window(
-    ctx_bufnr,
+    fold and bufnr or ctx_bufnr,
     context_winid,
     win_width,
     win_height,
@@ -358,6 +375,22 @@ function M.open(bufnr, winid, ctx_ranges, ctx_lines)
     'TreesitterContext'
   )
 
+  if fold then
+    vim.api.nvim_win_call(context_winid, function()
+      vim.api.nvim_win_set_cursor(context_winid, {ctx_ranges[1][1] + 1, 1})
+      vim.cmd([[normal! ztzE]])
+
+      for i, range in ipairs(ctx_ranges) do
+        if ctx_ranges[i + 1] then
+          local srow = range[1] + 1
+          local erow = ctx_ranges[i + 1][1]
+          vim.cmd(srow .. "," .. erow .. "fold")
+        end
+      end
+    end)
+    return
+  end
+
   if not set_lines(ctx_bufnr, ctx_lines) then
     -- Context didn't change, can return here
     return