add example/form.lua

lua/u/renderer.lua

@@ -5,7 +5,7 @@ local H = {}
 
 --- @alias u.renderer.TagEventHandler fun(tag: u.renderer.Tag, mode: string, lhs: string): string
 
---- @alias u.renderer.TagAttributes { [string]?: unknown; imap?: table<string, u.renderer.TagEventHandler>; nmap?: table<string, u.renderer.TagEventHandler>; vmap?: table<string, u.renderer.TagEventHandler>; xmap?: table<string, u.renderer.TagEventHandler>; omap?: table<string, u.renderer.TagEventHandler> }
+--- @alias u.renderer.TagAttributes { [string]?: unknown; imap?: table<string, u.renderer.TagEventHandler>; nmap?: table<string, u.renderer.TagEventHandler>; vmap?: table<string, u.renderer.TagEventHandler>; xmap?: table<string, u.renderer.TagEventHandler>; omap?: table<string, u.renderer.TagEventHandler>, on_change?: fun(text: string): unknown }
 
 --- @class u.renderer.Tag
 --- @field kind 'tag'
@@ -296,10 +296,15 @@ function Renderer:_reconcile() -- {{{
 
   --
   -- Step 2: reconcile extmarks:
+  -- You may be tempted to try to keep track of which extmarks are needed, and
+  -- only delete those that are not needed. However, each time a tree is
+  -- rendered, brand new extmarks are created. For simplicity, it is better to
+  -- just delete all extmarks, and recreate them.
   --
 
   -- Clear current extmarks:
   vim.api.nvim_buf_clear_namespace(self.bufnr, self.ns, 0, -1)
+
   -- Set current extmarks:
   for _, extmark in ipairs(self.curr.extmarks) do
     extmark.id = vim.api.nvim_buf_set_extmark(
@@ -361,10 +366,9 @@ function Renderer:_on_text_changed()
   for _, pos_info in ipairs(pos_infos) do
     local extmark_inf = pos_info.extmark
     local tag = pos_info.tag
-    if tag.attributes.signal and getmetatable(tag.attributes.signal) == Signal then
-      --- @type u.Signal
-      local signal = tag.attributes.signal
 
+    local on_change = tag.attributes.on_change
+    if on_change and type(on_change) == 'function' then
       local extmark =
         vim.api.nvim_buf_get_extmark_by_id(self.bufnr, self.ns, extmark_inf.id, { details = true })
 
@@ -381,7 +385,7 @@ function Renderer:_on_text_changed()
           { type = 'v' }
         )
         local text = table.concat(lines, '\n')
-        if text ~= signal:get() then signal:schedule_set(text) end
+        on_change(text)
       end
     end
   end