refactor: introduce nvim_on internally #39883

Problem:
`nvim_create_autocmd` is too verbose and its `callback` requires extra
"nesting".

Solution:
Introduce `nvim_on`. Start using it internally. Then we can get a feel
for how it should look before making it public.

1 files changed, 90 insertions, 123 deletions

diff --git a/runtime/lua/vim/treesitter/dev.lua b/runtime/lua/vim/treesitter/dev.lua
index a1dd988497..64d9a1352e 100644
--- a/runtime/lua/vim/treesitter/dev.lua
+++ b/runtime/lua/vim/treesitter/dev.lua
@@ -1,4 +1,5 @@
 local api = vim.api
+local nvim_on = require('vim._core.util').nvim_on
 
 local Range = require('vim.treesitter._range')
 
@@ -469,107 +470,83 @@ function M.inspect_tree(opts)
 
   local group = api.nvim_create_augroup('nvim.treesitter.dev', {})
 
-  api.nvim_create_autocmd('CursorMoved', {
-    group = group,
-    buf = b,
-    callback = function()
-      if not api.nvim_buf_is_loaded(buf) then
-        return true
-      end
+  nvim_on('CursorMoved', group, { buf = b }, function()
+    if not api.nvim_buf_is_loaded(buf) then
+      return true
+    end
 
-      w = api.nvim_get_current_win()
-      api.nvim_buf_clear_namespace(buf, treeview.ns, 0, -1)
-      local row = api.nvim_win_get_cursor(w)[1]
-      local lnum, col, end_lnum, end_col = treeview:get(row).node:range()
-      api.nvim_buf_set_extmark(buf, treeview.ns, lnum, col, {
-        end_row = end_lnum,
-        end_col = math.max(0, end_col),
-        hl_group = 'Visual',
-      })
+    w = api.nvim_get_current_win()
+    api.nvim_buf_clear_namespace(buf, treeview.ns, 0, -1)
+    local row = api.nvim_win_get_cursor(w)[1]
+    local lnum, col, end_lnum, end_col = treeview:get(row).node:range()
+    api.nvim_buf_set_extmark(buf, treeview.ns, lnum, col, {
+      end_row = end_lnum,
+      end_col = math.max(0, end_col),
+      hl_group = 'Visual',
+    })
 
-      -- update source window if original was closed
-      if not api.nvim_win_is_valid(win) then
-        win = assert(vim.fn.win_findbuf(buf)[1])
-      end
+    -- update source window if original was closed
+    if not api.nvim_win_is_valid(win) then
+      win = assert(vim.fn.win_findbuf(buf)[1])
+    end
 
-      local topline, botline = vim.fn.line('w0', win), vim.fn.line('w$', win)
+    local topline, botline = vim.fn.line('w0', win), vim.fn.line('w$', win)
 
-      -- Move the cursor if highlighted range is completely out of view
-      if lnum < topline and end_lnum < topline then
-        api.nvim_win_set_cursor(win, { end_lnum + 1, 0 })
-      elseif lnum > botline and end_lnum > botline then
-        api.nvim_win_set_cursor(win, { lnum + 1, 0 })
-      end
-    end,
-  })
+    -- Move the cursor if highlighted range is completely out of view
+    if lnum < topline and end_lnum < topline then
+      api.nvim_win_set_cursor(win, { end_lnum + 1, 0 })
+    elseif lnum > botline and end_lnum > botline then
+      api.nvim_win_set_cursor(win, { lnum + 1, 0 })
+    end
+  end)
 
-  api.nvim_create_autocmd('CursorMoved', {
-    group = group,
-    buf = buf,
-    callback = function()
-      if not api.nvim_buf_is_loaded(b) then
-        return true
-      end
+  nvim_on('CursorMoved', group, { buf = buf }, function()
+    if not api.nvim_buf_is_loaded(b) then
+      return true
+    end
 
-      set_inspector_cursor(treeview, opts.lang, buf, b, w)
-    end,
-  })
+    set_inspector_cursor(treeview, opts.lang, buf, b, w)
+  end)
 
-  api.nvim_create_autocmd({ 'TextChanged', 'InsertLeave' }, {
-    group = group,
-    buf = buf,
-    callback = function()
-      if not api.nvim_buf_is_loaded(b) then
-        return true
-      end
+  nvim_on({ 'TextChanged', 'InsertLeave' }, group, { buf = buf }, function()
+    if not api.nvim_buf_is_loaded(b) then
+      return true
+    end
 
-      local treeview_opts = treeview.opts
-      treeview = assert(TSTreeView:new(buf, opts.lang))
-      treeview.opts = treeview_opts
-      treeview:draw(b)
-    end,
-  })
+    local treeview_opts = treeview.opts
+    treeview = assert(TSTreeView:new(buf, opts.lang))
+    treeview.opts = treeview_opts
+    treeview:draw(b)
+  end)
 
-  api.nvim_create_autocmd('BufLeave', {
-    group = group,
-    buf = b,
-    callback = function()
-      if not api.nvim_buf_is_loaded(buf) then
-        return true
-      end
-      api.nvim_buf_clear_namespace(buf, treeview.ns, 0, -1)
-    end,
-  })
+  nvim_on('BufLeave', group, { buf = b }, function()
+    if not api.nvim_buf_is_loaded(buf) then
+      return true
+    end
+    api.nvim_buf_clear_namespace(buf, treeview.ns, 0, -1)
+  end)
 
-  api.nvim_create_autocmd('BufLeave', {
-    group = group,
-    buf = buf,
-    callback = function()
-      if not api.nvim_buf_is_loaded(b) then
-        return true
-      end
-      api.nvim_buf_clear_namespace(b, treeview.ns, 0, -1)
-    end,
-  })
+  nvim_on('BufLeave', group, { buf = buf }, function()
+    if not api.nvim_buf_is_loaded(b) then
+      return true
+    end
+    api.nvim_buf_clear_namespace(b, treeview.ns, 0, -1)
+  end)
 
-  api.nvim_create_autocmd({ 'BufHidden', 'BufUnload', 'QuitPre' }, {
-    group = group,
-    buf = buf,
-    callback = function()
-      -- don't close inpector window if source buffer
-      -- has more than one open window
-      if #vim.fn.win_findbuf(buf) > 1 then
-        return
-      end
+  nvim_on({ 'BufHidden', 'BufUnload', 'QuitPre' }, group, { buf = buf }, function()
+    -- don't close inpector window if source buffer
+    -- has more than one open window
+    if #vim.fn.win_findbuf(buf) > 1 then
+      return
+    end
 
-      -- close all tree windows
-      for _, window in pairs(vim.fn.win_findbuf(b)) do
-        close_win(window)
-      end
+    -- close all tree windows
+    for _, window in pairs(vim.fn.win_findbuf(b)) do
+      close_win(window)
+    end
 
-      return true
-    end,
-  })
+    return true
+  end)
 end
 
 local edit_ns = api.nvim_create_namespace('nvim.treesitter.dev_edit')
@@ -671,53 +648,43 @@ function M.edit_query(lang)
   api.nvim_buf_set_name(query_buf, string.format('%s/query_editor.scm', lang))
 
   local group = api.nvim_create_augroup('nvim.treesitter.dev_edit', {})
-  api.nvim_create_autocmd({ 'TextChanged', 'InsertLeave' }, {
-    group = group,
+  nvim_on({ 'TextChanged', 'InsertLeave' }, group, {
     buf = query_buf,
     desc = 'Update query editor diagnostics when the query changes',
-    callback = function()
-      vim.treesitter.query.lint(query_buf, { langs = lang, clear = false })
-    end,
-  })
-  api.nvim_create_autocmd({ 'TextChanged', 'InsertLeave', 'CursorMoved', 'BufEnter' }, {
-    group = group,
+  }, function()
+    vim.treesitter.query.lint(query_buf, { langs = lang, clear = false })
+  end)
+  nvim_on({ 'TextChanged', 'InsertLeave', 'CursorMoved', 'BufEnter' }, group, {
     buf = query_buf,
     desc = 'Update query editor highlights when the cursor moves',
-    callback = function()
-      if api.nvim_win_is_valid(win) then
-        update_editor_highlights(query_win, win, lang)
-      end
-    end,
-  })
-  api.nvim_create_autocmd('BufLeave', {
-    group = group,
+  }, function()
+    if api.nvim_win_is_valid(win) then
+      update_editor_highlights(query_win, win, lang)
+    end
+  end)
+  nvim_on('BufLeave', group, {
     buf = query_buf,
     desc = 'Clear highlights when leaving the query editor',
-    callback = function()
-      api.nvim_buf_clear_namespace(buf, edit_ns, 0, -1)
-    end,
-  })
-  api.nvim_create_autocmd('BufLeave', {
-    group = group,
+  }, function()
+    api.nvim_buf_clear_namespace(buf, edit_ns, 0, -1)
+  end)
+  nvim_on('BufLeave', group, {
     buf = buf,
     desc = 'Clear the query editor highlights when leaving the source buffer',
-    callback = function()
-      if not api.nvim_buf_is_loaded(query_buf) then
-        return true
-      end
+  }, function()
+    if not api.nvim_buf_is_loaded(query_buf) then
+      return true
+    end
 
-      api.nvim_buf_clear_namespace(query_buf, edit_ns, 0, -1)
-    end,
-  })
-  api.nvim_create_autocmd({ 'BufHidden', 'BufUnload' }, {
-    group = group,
+    api.nvim_buf_clear_namespace(query_buf, edit_ns, 0, -1)
+  end)
+  nvim_on({ 'BufHidden', 'BufUnload' }, group, {
     buf = buf,
     desc = 'Close the editor window when the source buffer is hidden or unloaded',
     once = true,
-    callback = function()
-      close_win(query_win)
-    end,
-  })
+  }, function()
+    close_win(query_win)
+  end)
 
   api.nvim_buf_set_lines(query_buf, 0, -1, false, {
     ';; Write queries here (see $VIMRUNTIME/queries/ for examples).',