watch text-changes with signals

examples/counter.lua

@@ -22,29 +22,10 @@ tracker.create_effect(function()
   -- constructed with `h(...)` calls). To help organize the markup, text and
   -- tags can be nested in tables at any depth. Line breaks must be specified
   -- manually, with '\n'.
-  local text_ref = ui_buf.renderer:create_ref()
   ui_buf:render {
     'Reactive Counter Example\n',
     '========================\n\n',
 
-    {
-      'Text field: ',
-      h('text', { hl = 'DiffAdd', ref = text_ref }, { '[]' }),
-      '\n',
-      h('text', {
-        hl = 'DiffAdd',
-        nmap = {
-          ['<CR>'] = function()
-            vim.notify(text_ref:text())
-            return ''
-          end,
-        },
-      }, ' Submit '),
-    },
-
-    '\n',
-    '\n',
-
     { 'Counter: ', tostring(count), '\n' },
 
     '\n',

lua/u/renderer.lua

@@ -1,3 +1,5 @@
+local Signal = require('u.tracker').Signal
+
 local M = {}
 local H = {}
 
@@ -33,52 +35,6 @@ M.h = setmetatable({}, {
   end,
 })
 
--- TagRef {{{
---- @class u.renderer.TagRef
---- @field tag? u.renderer.Tag
---- @field renderer u.renderer.Renderer
-local TagRef = {}
-TagRef.__index = TagRef
-
-function TagRef:extmark()
-  if not self.tag then return {} end
-
-  --- @type u.renderer.RendererExtmark?
-  local extmark_inf = vim
-    .iter(self.renderer.curr.extmarks)
-    --- @param x u.renderer.RendererExtmark
-    :find(function(x) return x.tag == self.tag end)
-  if not extmark_inf then return {} end
-
-  local extmark = vim.api.nvim_buf_get_extmark_by_id(
-    self.renderer.bufnr,
-    self.renderer.ns,
-    extmark_inf.id,
-    { details = true }
-  )
-  return extmark
-end
-
-function TagRef:range()
-  local extmark = self:extmark()
-  if not extmark then return nil end
-  local Range = require 'u.range'
-  return Range.from_extmark(self.renderer.bufnr, extmark)
-end
-
-function TagRef:lines()
-  local range = self:range()
-  if not range then return {} end
-  return range:lines()
-end
-
-function TagRef:text()
-  local range = self:range()
-  if not range then return '' end
-  return range:text()
-end
--- }}}
-
 -- Renderer {{{
 --- @class u.renderer.RendererExtmark
 --- @field id? number
@@ -124,11 +80,15 @@ function Renderer.new(bufnr) -- {{{
     old = { lines = {}, extmarks = {} },
     curr = { lines = {}, extmarks = {} },
   }, Renderer)
+
+  vim.api.nvim_create_autocmd({ 'TextChanged', 'TextChangedI', 'TextChangedP' }, {
+    buffer = bufnr,
+    callback = function() self:_on_text_changed() end,
+  })
+
   return self
 end -- }}}
 
-function Renderer:create_ref() return setmetatable({ renderer = self }, TagRef) end
-
 --- @param opts {
 ---   tree: u.renderer.Tree;
 ---   on_tag?: fun(tag: u.renderer.Tag, start0: [number, number], stop0: [number, number]): any;
@@ -276,14 +236,13 @@ function Renderer:render(tree) -- {{{
           tag.attributes.extmark.hl_group = tag.attributes.extmark.hl_group or hl
         end
 
-        local extmark_opts = tag.attributes.extmark
+        local extmark_opts = tag.attributes.extmark or {}
 
         -- Set any necessary keymaps:
         for _, mode in ipairs { 'i', 'n', 'v', 'x', 'o' } do
           for lhs, _ in pairs(tag.attributes[mode .. 'map'] or {}) do
             -- Force creating an extmark if there are key handlers. To accurately
             -- sense the bounds of the text, we need an extmark:
-            extmark_opts = extmark_opts or {}
             vim.keymap.set(
               mode,
               lhs,
@@ -293,15 +252,6 @@ function Renderer:render(tree) -- {{{
           end
         end
 
-        -- Check for refs:
-        if tag.attributes.ref and getmetatable(tag.attributes.ref) == TagRef then
-          --- @type u.renderer.TagRef
-          local ref = tag.attributes.ref
-          ref.tag = tag
-          extmark_opts = extmark_opts or {}
-        end
-
-        if extmark_opts then
         table.insert(extmarks, {
           start = start0,
           stop = stop0,
@@ -309,7 +259,6 @@ function Renderer:render(tree) -- {{{
           tag = tag,
         })
       end
-      end
     end, -- }}}
   }
 
@@ -404,6 +353,40 @@ function Renderer:_expr_map_callback(mode, lhs) -- {{{
   return cancel and '' or lhs
 end -- }}}
 
+function Renderer:_on_text_changed()
+  --- @type integer, integer
+  local l, c = unpack(vim.api.nvim_win_get_cursor(0))
+  l = l - 1 -- make it actually 0-based
+  local pos_infos = self:get_pos_infos { l, c }
+  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 extmark =
+        vim.api.nvim_buf_get_extmark_by_id(self.bufnr, self.ns, extmark_inf.id, { details = true })
+
+      --- @type integer, integer, vim.api.keyset.extmark_details
+      local start_row0, start_col0, details = unpack(extmark)
+      local end_row0, end_col0 = details.end_row, details.end_col
+
+      if start_row0 == end_row0 and start_col0 == end_col0 then
+        -- Invalid extmark
+      else
+        local lines = vim.fn.getregion(
+          { self.bufnr, start_row0 + 1, start_col0 + 1 },
+          { self.bufnr, end_row0 + 1, end_col0 },
+          { type = 'v' }
+        )
+        local text = table.concat(lines, '\n')
+        if text ~= signal:get() then signal:schedule_set(text) end
+      end
+    end
+  end
+end
+
 --- Returns pairs of extmarks and tags associate with said extmarks. The
 --- returned tags/extmarks are sorted smallest (innermost) to largest
 --- (outermost).