Renderer.mount: add tests

It seems that closures are not interacting well with the global nature
of operatorfunc's. That is just a hunch, and this feels like a hack, but
it fixes the issue.

.busted

@@ -0,0 +1,13 @@
+return {
+  _all = {
+    coverage = false,
+    lpath = "lua/?.lua;lua/?/init.lua",
+    lua = "nvim -u NONE -i NONE -l",
+  },
+  default = {
+    verbose = true
+  },
+  tests = {
+    verbose = true
+  },
+}

.emmyrc.json

@@ -0,0 +1,12 @@
+{
+  "$schema": "https://raw.githubusercontent.com/EmmyLuaLs/emmylua-analyzer-rust/refs/heads/main/crates/emmylua_code_analysis/resources/schema.json",
+  "runtime": {
+    "version": "LuaJIT"
+  },
+  "workspace": {
+    "library": [
+      "$VIMRUNTIME",
+      "library/busted"
+    ]
+  }
+}

.github/workflows/ci.yaml

@@ -2,15 +2,28 @@
 name: NeoVim tests
 on: [push]
 jobs:
-  plenary-tests:
+  code-quality:
     runs-on: ubuntu-latest
     env:
       XDG_CONFIG_HOME: ${{ github.workspace }}/.config/
     steps:
       - uses: actions/checkout@v4
-      - uses: rhysd/action-setup-vim@v1
+      - uses: cachix/install-nix-action@v31
         with:
-          neovim: true
+          nix_path: nixpkgs=channel:nixos-unstable
-          version: v0.11.0
+
-          arch: 'x86_64'
+      - name: Populate Nix store
-      - run: make test
+        run:
+          nix-shell --pure --run 'true'
+
+      - name: Type-check
+        run:
+          nix-shell --pure --run 'make lint'
+
+      - name: Check formatting with stylua
+        run:
+          nix-shell --pure --run 'make fmt-check'
+
+      - name: Run busted tests
+        run:
+          nix-shell --pure --run 'make test'

.gitignore

@@ -1,4 +1,3 @@
-/.lux/
-lux.lock
 *.src.rock
 *.aider*
+luacov.*.out

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "library/busted"]
+	path = library/busted
+	url = https://github.com/LuaCATS/busted
+	branch = main

.luacheckrc

@@ -1,2 +0,0 @@
--- :vim set ft=lua
-globals = { "vim" }

.luacov

@@ -0,0 +1,6 @@
+return {
+  include = {
+    'lua/u/',
+  },
+  tick = true,
+}

.woodpecker/ci.yaml

@@ -0,0 +1,10 @@
+when:
+  - event: push
+
+steps:
+  - name: build
+    image: nixos/nix
+    commands:
+      - nix-shell --pure --run 'make lint'
+      - nix-shell --pure --run 'make fmt-check'
+      - nix-shell --pure --run 'make test'

Makefile

@@ -1,16 +1,26 @@
-PLENARY_DIR=~/.local/share/nvim/site/pack/test/opt/plenary.nvim
+export VIMRUNTIME := $(shell nvim -u NORC --headless +'echo $$VIMRUNTIME' +'quitall' 2>&1)
 
-all: lint test
+all: lint fmt-check test
 
 lint:
-	lua-language-server --check=lua/u/ --checklevel=Error
+	@echo "## Typechecking"
-	lx check
+	@emmylua_check .
+
+fmt-check:
+	@echo "## Checking code format"
+	@stylua --check .
 
 fmt:
-	stylua .
+	@echo "## Formatting code"
+	@stylua .
 
-test: $(PLENARY_DIR)
+test:
-	NVIM_APPNAME=noplugstest nvim -u NORC --headless -c 'set packpath+=~/.local/share/nvim/site' -c 'packadd plenary.nvim' -c "PlenaryBustedDirectory spec/"
+	@rm -f luacov.*.out
+	@echo "## Running tests"
+	@busted --coverage --verbose
+	@echo "## Generating coverage report"
+	@luacov
+	@awk '/^Summary$$/{flag=1;next} flag{print}' luacov.report.out
 
-$(PLENARY_DIR):
+watch:
-	git clone https://github.com/nvim-lua/plenary.nvim/ $(PLENARY_DIR)
+	@watchexec -c -e lua make

examples/counter.lua

@@ -1,5 +1,5 @@
-local tracker = require 'u.tracker'
 local Buffer = require 'u.buffer'
+local tracker = require 'u.tracker'
 local h = require('u.renderer').h
 
 -- Create an buffer for the UI

examples/filetree.lua

@@ -10,10 +10,10 @@
 --   change on the underlying filesystem.
 --------------------------------------------------------------------------------
 
---- @alias FsDir { kind: 'dir'; path: string; expanded: boolean; children: FsNode[] }
+--- @alias u.examples.FsDir { kind: 'dir', path: string, expanded: boolean, children: u.examples.FsNode[] }
---- @alias FsFile { kind: 'file'; path: string }
+--- @alias u.examples.FsFile { kind: 'file', path: string }
---- @alias FsNode FsDir | FsFile
+--- @alias u.examples.FsNode u.examples.FsDir | u.examples.FsFile
---- @alias ShowOpts { root_path?: string, width?: number, focus_path?: string }
+--- @alias u.examples.ShowOpts { root_path?: string, width?: number, focus_path?: string }
 
 local Buffer = require 'u.buffer'
 local Renderer = require('u.renderer').Renderer
@@ -58,13 +58,13 @@ function H.relative(path, base)
 end
 
 --- @param root_path string
---- @return { tree: FsDir; path_to_node: table<string, FsNode> }
+--- @return { tree: u.examples.FsDir, path_to_node: table<string, u.examples.FsNode> }
 function H.get_tree_inf(root_path)
   logger:info { 'get_tree_inf', root_path }
-  --- @type table<string, FsNode>
+  --- @type table<string, u.examples.FsNode>
   local path_to_node = {}
 
-  --- @type FsDir
+  --- @type u.examples.FsDir
   local tree = {
     kind = 'dir',
     path = H.normalize(root_path or '.'),
@@ -77,8 +77,8 @@ function H.get_tree_inf(root_path)
   return { tree = tree, path_to_node = path_to_node }
 end
 
---- @param tree FsDir
+--- @param tree u.examples.FsDir
---- @param path_to_node table<string, FsNode>
+--- @param path_to_node table<string, u.examples.FsNode>
 function H.populate_dir_children(tree, path_to_node)
   tree.children = {}
 
@@ -113,10 +113,10 @@ function H.populate_dir_children(tree, path_to_node)
 end
 
 --- @param opts {
----   bufnr: number;
+---   bufnr: number,
----   prev_winnr: number;
+---   prev_winnr: number,
----   root_path: string;
+---   root_path: string,
----   focus_path?: string;
+---   focus_path?: string
 --- }
 ---
 --- @return { expand: fun(path: string), collapse: fun(path: string) }
@@ -135,7 +135,7 @@ local function _render_in_buffer(opts)
       local parts = H.split_path(H.relative(focused_path, tree_inf.tree.path))
       local path_to_node = tree_inf.path_to_node
 
-      --- @param node FsDir
+      --- @param node u.examples.FsDir
       --- @param child_names string[]
       local function expand_to(node, child_names)
         if #child_names == 0 then return end
@@ -310,7 +310,7 @@ local function _render_in_buffer(opts)
   --
   local renderer = Renderer.new(opts.bufnr)
   tracker.create_effect(function()
-    --- @type { tree: FsDir; path_to_node: table<string, FsNode> }
+    --- @type { tree: u.examples.FsDir, path_to_node: table<string, u.examples.FsNode> }
     local tree_inf = s_tree_inf:get()
     local tree = tree_inf.tree
 
@@ -329,7 +329,7 @@ local function _render_in_buffer(opts)
 
     --- Since the filesystem is a recursive tree of nodes, we need to
     --- recursively render each node. This function does just that:
-    --- @param node FsNode
+    --- @param node u.examples.FsNode
     --- @param level number
     local function render_node(node, level)
       local name = vim.fs.basename(node.path)
@@ -407,14 +407,14 @@ end
 --------------------------------------------------------------------------------
 
 --- @type {
----   bufnr: number;
+---   bufnr: number,
----   winnr: number;
+---   winnr: number,
----   controller: { expand: fun(path: string), collapse: fun(path: string) };
+---   controller: { expand: fun(path: string), collapse: fun(path: string) }
 --- } | nil
 local current_inf = nil
 
 --- Show the filetree:
---- @param opts? ShowOpts
+--- @param opts? u.examples.ShowOpts
 function M.show(opts)
   if current_inf ~= nil then return current_inf.controller end
   opts = opts or {}
@@ -456,7 +456,7 @@ function M.hide()
 end
 
 --- Toggle the filetree:
---- @param opts? ShowOpts
+--- @param opts? u.examples.ShowOpts
 function M.toggle(opts)
   if current_inf == nil then
     M.show(opts)

examples/form.lua

@@ -0,0 +1,117 @@
+-- form.lua:
+--
+-- This is a runnable example of a form. Open this file in Neovim, and execute
+-- `:luafile %` to run it. It will create a new buffer to the side, and render
+-- an interactive form. Edit the "inputs" between the `[...]` brackets, and
+-- watch the buffer react immediately to your changes.
+--
+
+local Renderer = require('u.renderer').Renderer
+local h = require('u.renderer').h
+local tracker = require 'u.tracker'
+
+-- Create a new, temporary, buffer to the side:
+vim.cmd.vnew()
+vim.bo.buftype = 'nofile'
+vim.bo.bufhidden = 'wipe'
+vim.bo.buflisted = false
+local renderer = Renderer.new()
+
+-- Create two signals:
+local s_name = tracker.create_signal 'whoever-you-are'
+local s_age = tracker.create_signal 'ideally-a-number'
+
+-- We can create derived information from the signals above. Say we want to do
+-- some validation on the input for `age`: we can do that with a memo:
+local s_age_info = tracker.create_memo(function()
+  local age_raw = s_age:get()
+  local age_digits = age_raw:match '^%s*(%d+)%s*$'
+  local age_n = age_digits and tonumber(age_digits) or nil
+  return {
+    type = age_n and 'number' or 'string',
+    raw = age_raw,
+    n = age_n,
+    n1 = age_n and age_n + 1 or nil,
+  }
+end)
+
+-- This is the render effect that depends on the signals created above. This
+-- will re-run every time one of the signals changes.
+tracker.create_effect(function()
+  local name = s_name:get()
+  local age = s_age:get()
+  local age_info = s_age_info:get()
+
+  -- Each time the signals change, we re-render the buffer:
+  renderer:render {
+    h.Type({}, '# Form Example'),
+    '\n\n',
+
+    -- We can also listen for when specific locations in the buffer change, on
+    -- a tag-by-tag basis. This gives us two-way data-binding between the
+    -- buffer and the signals.
+    {
+      'Name: ',
+      h.Structure({
+        on_change = function(text) s_name:set(text) end,
+      }, name),
+    },
+    {
+      '\nAge: ',
+      h.Structure({
+        on_change = function(text) s_age:set(text) end,
+      }, age),
+    },
+
+    '\n\n',
+
+    -- Show the values of the signals here, too, so that we can see the
+    -- reactivity in action. If you change the values in the tags above, you
+    -- can see the changes reflected here immediately.
+    { 'Hello, "', name, '"!' },
+
+    --
+    -- A more complex example: we can do much more complex rendering, based on
+    -- the state. For example, if you type different values into the `age`
+    -- field, you can see not only the displayed information change, but also
+    -- the color of the highlights in this section will adapt to the type of
+    -- information that has been detected.
+    --
+    -- If string input is detected, values below are shown in the
+    -- `String`/`ErrorMsg` highlight groups.
+    --
+    -- If number input is detected, values below are shown in the `Number`
+    -- highlight group.
+    --
+    -- If a valid number is entered, then this section also displays how old
+    -- you willl be next year (`n + 1`).
+    --
+
+    '\n\n',
+    h.Type({}, '## Computed Information (derived from `age`)'),
+    '\n\n',
+    {
+      'Type: ',
+      h('text', {
+        hl = age_info.type == 'number' and 'Number' or 'String',
+      }, age_info.type),
+    },
+    { '\nRaw input: ', h.String({}, '"' .. age_info.raw .. '"') },
+    {
+      '\nCurrent age: ',
+      age_info.n
+          -- Show the age:
+          and h.Number({}, tostring(age_info.n))
+        -- Show an error-placeholder if the age is invalid:
+        or h.ErrorMsg({}, '(?)'),
+    },
+
+    -- This part is shown conditionally, i.e., only if the age next year can be
+    -- computed:
+    age_info.n1
+      and {
+        '\nAge next year: ',
+        h.Number({}, tostring(age_info.n1)),
+      },
+  }
+end)

examples/notify.lua

@@ -1,8 +1,7 @@
-local Buffer = require 'u.buffer'
+local Renderer = require('u.renderer').Renderer
 local TreeBuilder = require('u.renderer').TreeBuilder
 local tracker = require 'u.tracker'
 local utils = require 'u.utils'
-local Window = require 'my.window'
 
 local TIMEOUT = 4000
 local ICONS = {
@@ -14,15 +13,25 @@ local ICONS = {
 }
 local DEFAULT_ICON = { text = '', group = 'DiagnosticSignOk' }
 
---- @alias Notification {
+local S_EDITOR_DIMENSIONS =
----   kind: number;
+  tracker.create_signal(utils.get_editor_dimensions(), 's:editor_dimensions')
----   id: number;
+vim.api.nvim_create_autocmd('VimResized', {
----   text: string;
+  callback = function()
+    local new_dim = utils.get_editor_dimensions()
+    S_EDITOR_DIMENSIONS:set(new_dim)
+  end,
+})
+
+--- @alias u.examples.Notification {
+---   kind: number,
+---   id: number,
+---   text: string,
+---   timer: uv.uv_timer_t
 --- }
 
 local M = {}
 
---- @type Window | nil
+--- @type { win: integer, buf: integer, renderer: u.renderer.Renderer } | nil
 local notifs_w
 
 local s_notifications_raw = tracker.create_signal {}
@@ -30,44 +39,49 @@ local s_notifications = s_notifications_raw:debounce(50)
 
 -- Render effect:
 tracker.create_effect(function()
-  --- @type Notification[]
+  --- @type u.examples.Notification[]
   local notifs = s_notifications:get()
+  --- @type { width: integer, height: integer }
+  local editor_size = S_EDITOR_DIMENSIONS:get()
 
   if #notifs == 0 then
     if notifs_w then
-      notifs_w:close(true)
+      if vim.api.nvim_win_is_valid(notifs_w.win) then vim.api.nvim_win_close(notifs_w.win, true) end
       notifs_w = nil
     end
     return
   end
 
+  local avail_width = editor_size.width
+  local float_width = 40
+  local float_height = math.min(#notifs, editor_size.height - 3)
+  local win_config = {
+    relative = 'editor',
+    anchor = 'NE',
+    row = 0,
+    col = avail_width,
+    width = float_width,
+    height = float_height,
+    border = 'single',
+    focusable = false,
+    zindex = 900,
+  }
   vim.schedule(function()
-    local editor_size = utils.get_editor_dimensions()
-    local avail_width = editor_size.width
-    local float_width = 40
-    local win_config = {
-      relative = 'editor',
-      anchor = 'NE',
-      row = 0,
-      col = avail_width,
-      width = float_width,
-      height = math.min(#notifs, editor_size.height - 3),
-      border = 'single',
-      focusable = false,
-    }
     if not notifs_w or not vim.api.nvim_win_is_valid(notifs_w.win) then
-      notifs_w = Window.new(Buffer.create(false, true), win_config)
+      local b = vim.api.nvim_create_buf(false, true)
-      vim.wo[notifs_w.win].cursorline = false
+      local w = vim.api.nvim_open_win(b, false, win_config)
-      vim.wo[notifs_w.win].list = false
+      vim.wo[w].cursorline = false
-      vim.wo[notifs_w.win].listchars = ''
+      vim.wo[w].list = false
-      vim.wo[notifs_w.win].number = false
+      vim.wo[w].listchars = ''
-      vim.wo[notifs_w.win].relativenumber = false
+      vim.wo[w].number = false
-      vim.wo[notifs_w.win].wrap = false
+      vim.wo[w].relativenumber = false
+      vim.wo[w].wrap = false
+      notifs_w = { win = w, buf = b, renderer = Renderer.new(b) }
     else
-      notifs_w:set_config(win_config)
+      vim.api.nvim_win_set_config(notifs_w.win, win_config)
     end
 
-    notifs_w:render(TreeBuilder.new()
+    notifs_w.renderer:render(TreeBuilder.new()
       :nest(function(tb)
         for idx, notif in ipairs(notifs) do
           if idx > 1 then tb:put '\n' end
@@ -79,48 +93,81 @@ tracker.create_effect(function()
       end)
       :tree())
     vim.api.nvim_win_call(notifs_w.win, function()
-      -- scroll to bottom:
+      vim.fn.winrestview {
-      vim.cmd.normal 'G'
+        -- scroll all the way left:
-      -- scroll all the way to the left:
+        leftcol = 0,
-      vim.cmd.normal '9999zh'
+        -- set the bottom line to be at the bottom of the window:
+        topline = vim.api.nvim_buf_line_count(notifs_w.buf) - win_config.height + 1,
+      }
     end)
   end)
 end)
 
+--- @param id number
+local function _delete_notif(id)
+  --- @param notifs u.examples.Notification[]
+  s_notifications_raw:schedule_update(function(notifs)
+    for i, notif in ipairs(notifs) do
+      if notif.id == id then
+        notif.timer:stop()
+        notif.timer:close()
+        table.remove(notifs, i)
+        break
+      end
+    end
+    return notifs
+  end)
+end
+
 local _orig_notify
 
 --- @param msg string
 --- @param level integer|nil
---- @param opts table|nil
+--- @param opts? { id: number }
-local function my_notify(msg, level, opts)
+function M.notify(msg, level, opts)
-  vim.schedule(function() _orig_notify(msg, level, opts) end)
   if level == nil then level = vim.log.levels.INFO end
-  if level < vim.log.levels.INFO then return end
 
-  local id = math.random(math.huge)
+  opts = opts or {}
+  local id = opts.id or math.random(999999999)
 
-  --- @param notifs Notification[]
+  --- @type u.examples.Notification?
-  s_notifications_raw:schedule_update(function(notifs)
+  local notif = vim.iter(s_notifications_raw:get()):find(function(n) return n.id == id end)
-    table.insert(notifs, { kind = level, id = id, text = msg })
+  if not notif then
-    return notifs
+    -- Create a new notification (maybe):
-  end)
+    if vim.trim(msg) == '' then return id end
+    if level < vim.log.levels.INFO then return id end
 
-  vim.defer_fn(function()
+    local timer = assert((vim.uv or vim.loop).new_timer(), 'could not create timer')
-    --- @param notifs Notification[]
+    timer:start(TIMEOUT, 0, function() _delete_notif(id) end)
+    notif = {
+      id = id,
+      kind = level,
+      text = msg,
+      timer = timer,
+    }
+    --- @param notifs u.examples.Notification[]
     s_notifications_raw:schedule_update(function(notifs)
-      for i, notif in ipairs(notifs) do
+      table.insert(notifs, notif)
-        if notif.id == id then
-          table.remove(notifs, i)
-          break
-        end
-      end
       return notifs
     end)
-  end, TIMEOUT)
+  else
+    -- Update an existing notification:
+    s_notifications_raw:schedule_update(function(notifs)
+      -- We already have a copy-by-reference of the notif we want to modify:
+      notif.timer:stop()
+      notif.text = msg
+      notif.kind = level
+      notif.timer:start(TIMEOUT, 0, function() _delete_notif(id) end)
+
+      return notifs
+    end)
+  end
+
+  return id
 end
 
 local _once_msgs = {}
-local function my_notify_once(msg, level, opts)
+function M.notify_once(msg, level, opts)
   if vim.tbl_contains(_once_msgs, msg) then return false end
   table.insert(_once_msgs, msg)
   vim.notify(msg, level, opts)
@@ -130,8 +177,8 @@ end
 function M.setup()
   if _orig_notify == nil then _orig_notify = vim.notify end
 
-  vim.notify = my_notify
+  vim.notify = M.notify
-  vim.notify_once = my_notify_once
+  vim.notify_once = M.notify_once
 end
 
 return M

examples/picker.lua

@@ -1,5 +1,5 @@
-local utils = require 'u.utils'
 local Buffer = require 'u.buffer'
+local utils = require 'u.utils'
 local Renderer = require('u.renderer').Renderer
 local h = require('u.renderer').h
 local TreeBuilder = require('u.renderer').TreeBuilder
@@ -44,26 +44,26 @@ local function shallow_copy_arr(arr) return vim.iter(arr):totable() end
 --    shortest portion of this function.
 --------------------------------------------------------------------------------
 
---- @alias SelectController {
+--- @alias u.examples.SelectController<T> {
----   get_items: fun(): T[];
+---   get_items: fun(): T[],
----   set_items: fun(items: T[]);
+---   set_items: fun(items: T[]),
----   set_filter_text: fun(filter_text: string);
+---   set_filter_text: fun(filter_text: string),
----   get_selected_indices: fun(): number[];
+---   get_selected_indices: fun(): number[],
----   get_selected_items: fun(): T[];
+---   get_selected_items: fun(): T[],
----   set_selected_indices: fun(indicies: number[], ephemeral?: boolean);
+---   set_selected_indices: fun(indicies: number[], ephemeral?: boolean),
----   close: fun();
+---   close: fun()
 --- }
---- @alias SelectOpts<T> {
+--- @alias u.examples.SelectOpts<T> {
----   items: `T`[];
+---   items: `T`[],
----   multi?: boolean;
+---   multi?: boolean,
----   format_item?: fun(item: T): Tree;
+---   format_item?: (fun(item: T): u.renderer.Tree),
----   on_finish?: fun(items: T[], indicies: number[]);
+---   on_finish?: (fun(items: T[], indicies: number[])),
----   on_selection_changed?: fun(items: T[], indicies: number[]);
+---   on_selection_changed?: fun(items: T[], indicies: number[]),
----   mappings?: table<string, fun(select: SelectController)>;
+---   mappings?: table<string, fun(select: u.examples.SelectController)>
 --- }
 
 --- @generic T
---- @param opts SelectOpts<T>
+--- @param opts u.examples.SelectOpts<T>
 function M.create_picker(opts) -- {{{
   local is_in_insert_mode = vim.api.nvim_get_mode().mode:sub(1, 1) == 'i'
   local stopinsert = not is_in_insert_mode
@@ -326,7 +326,7 @@ function M.create_picker(opts) -- {{{
     safe_wrap(function()
       local items = s_items:get()
       local selected_indices = s_selected_indices:get()
-      --- @type { orig_idx: number; item: T }[]
+      --- @type { orig_idx: number, item: T }[]
       local filtered_items = s_filtered_items:get()
       local cursor_index = s_cursor_index:get()
       local indices = shallow_copy_arr(selected_indices)
@@ -477,7 +477,7 @@ function M.create_picker(opts) -- {{{
       local selected_indices = s_selected_indices:get()
       local top_offset = s_top_offset:get()
       local cursor_index = s_cursor_index:get()
-      --- @type { filtered_idx: number; orig_idx: number; item: T; formatted: string }[]
+      --- @type { filtered_idx: number, orig_idx: number, item: T, formatted: string }[]
       local visible_items = s_visible_items:get()
 
       -- The above has to run in the execution context for the signaling to work, but
@@ -557,7 +557,7 @@ function M.create_picker(opts) -- {{{
     return safe_run(function() H.finish(true) end)
   end
 
-  return controller --[[@as SelectController]]
+  return controller --[[@as u.examples.SelectController]]
 end -- }}}
 
 --------------------------------------------------------------------------------
@@ -791,14 +791,14 @@ function M.buffers() -- {{{
   -- ensure that `cwd` ends with a trailing slash:
   if cwd[#cwd] ~= '/' then cwd = cwd .. '/' end
 
-  --- @type { name: string; changed: number; bufnr: number }[]
+  --- @type { name: string, changed: number, bufnr: number }[]
   local bufs = vim.fn.getbufinfo { buflisted = 1 }
 
   M.create_picker {
     multi = true,
     items = bufs,
 
-    --- @param item { name: string; changed: number; bufnr: number }
+    --- @param item { name: string, changed: number, bufnr: number }
     format_item = function(item)
       local item_name = item.name
       if item_name == '' then item_name = '[No Name]' end

examples/splitjoin.lua

@@ -1,6 +1,6 @@
-local vim_repeat = require 'u.repeat'
 local CodeWriter = require 'u.codewriter'
 local Range = require 'u.range'
+local vim_repeat = require 'u.repeat'
 
 local M = {}
 

examples/surround.lua

@@ -1,7 +1,7 @@
-local vim_repeat = require 'u.repeat'
-local Range = require 'u.range'
 local Buffer = require 'u.buffer'
 local CodeWriter = require 'u.codewriter'
+local Range = require 'u.range'
+local vim_repeat = require 'u.repeat'
 
 local M = {}
 
@@ -21,10 +21,10 @@ local surrounds = {
   ['`'] = { left = '`', right = '`' },
 }
 
---- @type { left: string; right: string } | nil
+--- @type { left: string, right: string } | nil
 local CACHED_BOUNDS = nil
 
---- @return { left: string; right: string }|nil
+--- @return { left: string, right: string }|nil
 local function prompt_for_bounds()
   if vim_repeat.is_repeating() then
     -- If we are repeating, we don't want to prompt for bounds, because
@@ -55,7 +55,7 @@ local function prompt_for_bounds()
 end
 
 --- @param range u.Range
---- @param bounds { left: string; right: string }
+--- @param bounds { left: string, right: string }
 local function do_surround(range, bounds)
   local left = bounds.left
   local right = bounds.right

examples/text-objects.lua

@@ -1,7 +1,7 @@
-local txtobj = require 'u.txtobj'
+local Buffer = require 'u.buffer'
 local Pos = require 'u.pos'
 local Range = require 'u.range'
-local Buffer = require 'u.buffer'
+local txtobj = require 'u.txtobj'
 
 local M = {}
 

lua/u/buffer.lua

@@ -2,10 +2,10 @@ local Range = require 'u.range'
 local Renderer = require('u.renderer').Renderer
 
 --- @class u.Buffer
---- @field bufnr number
+--- @field bufnr integer
 --- @field b vim.var_accessor
 --- @field bo vim.bo
---- @field private renderer u.Renderer
+--- @field renderer u.renderer.Renderer
 local Buffer = {}
 Buffer.__index = Buffer
 
@@ -62,19 +62,22 @@ end
 function Buffer:lines(start, stop) return Range.from_lines(self.bufnr, start, stop) end
 
 --- @param motion string
---- @param opts? { contains_cursor?: boolean; pos?: u.Pos }
+--- @param opts? { contains_cursor?: boolean, pos?: u.Pos }
 function Buffer:motion(motion, opts)
   opts = vim.tbl_extend('force', opts or {}, { bufnr = self.bufnr })
   return Range.from_motion(motion, opts)
 end
 
---- @param event string|string[]
+--- @param event vim.api.keyset.events|vim.api.keyset.events[]
 --- @diagnostic disable-next-line: undefined-doc-name
 --- @param opts vim.api.keyset.create_autocmd
 function Buffer:autocmd(event, opts)
   vim.api.nvim_create_autocmd(event, vim.tbl_extend('force', opts, { buffer = self.bufnr }))
 end
 
+--- @param fn function
+function Buffer:call(fn) return vim.api.nvim_buf_call(self.bufnr, fn) end
+
 --- @param tree u.renderer.Tree
 function Buffer:render(tree) return self.renderer:render(tree) end
 

lua/u/codewriter.lua

@@ -32,7 +32,7 @@ end
 --- @param line string
 --- @param bufnr? number
 function CodeWriter.from_line(line, bufnr)
-  if bufnr == nil then bufnr = vim.api.nvim_get_current_buf() end
+  if bufnr == nil or bufnr == 0 then bufnr = vim.api.nvim_get_current_buf() end
 
   local ws = line:match '^%s*'
   local expandtab = vim.api.nvim_get_option_value('expandtab', { buf = bufnr })

lua/u/extmark.lua

@@ -0,0 +1,71 @@
+local Pos = require 'u.pos'
+
+---@class u.Extmark
+---@field bufnr integer
+---@field id integer
+---@field nsid integer
+local Extmark = {}
+Extmark.__index = Extmark
+
+--- @param bufnr integer
+--- @param nsid integer
+--- @param id integer
+function Extmark.new(bufnr, nsid, id)
+  return setmetatable({
+    bufnr = bufnr,
+    nsid = nsid,
+    id = id,
+  }, Extmark)
+end
+
+--- @param range u.Range
+--- @param nsid integer
+function Extmark.from_range(range, nsid)
+  local r = range:to_charwise()
+  local stop = r.stop or r.start
+  local end_row = stop.lnum - 1
+  local end_col = stop.col
+  if range.mode == 'V' then
+    end_row = end_row + 1
+    end_col = 0
+  end
+  local id = vim.api.nvim_buf_set_extmark(r.start.bufnr, nsid, r.start.lnum - 1, r.start.col - 1, {
+    right_gravity = false,
+    end_right_gravity = true,
+    end_row = end_row,
+    end_col = end_col,
+  })
+  return Extmark.new(r.start.bufnr, nsid, id)
+end
+
+function Extmark:range()
+  local Range = require 'u.range'
+
+  local raw_extmark =
+    vim.api.nvim_buf_get_extmark_by_id(self.bufnr, self.nsid, self.id, { details = true })
+  local start_row0, start_col0, details = unpack(raw_extmark)
+
+  --- @type u.Pos
+  local start = Pos.from00(self.bufnr, start_row0, start_col0)
+  --- @type u.Pos?
+  local stop = details
+    and details.end_row
+    and details.end_col
+    and Pos.from01(self.bufnr, details.end_row, details.end_col)
+
+  local n_buf_lines = vim.api.nvim_buf_line_count(self.bufnr)
+  if stop and stop.lnum > n_buf_lines then
+    stop.lnum = n_buf_lines
+    stop = stop:eol()
+  end
+  if stop and stop.col == 0 then
+    stop.col = 1
+    stop = stop:next(-1)
+  end
+
+  return Range.new(start, stop, 'v')
+end
+
+function Extmark:delete() vim.api.nvim_buf_del_extmark(self.bufnr, self.nsid, self.id) end
+
+return Extmark

lua/u/logger.lua

@@ -1,9 +1,9 @@
 local M = {}
 
+local LOG_ROOT = vim.fs.joinpath(vim.fn.stdpath 'cache', 'u.log')
+
 --- @params name string
-function M.file_for_name(name)
+function M.file_for_name(name) return vim.fs.joinpath(LOG_ROOT, name .. '.log.jsonl') end
-  return vim.fs.joinpath(vim.fn.stdpath 'cache', 'u.log', name .. '.log.jsonl')
-end
 
 --------------------------------------------------------------------------------
 -- Logger class
@@ -11,7 +11,6 @@ end
 
 --- @class u.Logger
 --- @field name string
---- @field private fd number
 local Logger = {}
 Logger.__index = Logger
 M.Logger = Logger
@@ -20,10 +19,7 @@ M.Logger = Logger
 function Logger.new(name)
   local file_path = M.file_for_name(name)
   vim.fn.mkdir(vim.fs.dirname(file_path), 'p')
-  local self = setmetatable({
+  local self = setmetatable({ name = name }, Logger)
-    name = name,
-    fd = (vim.uv or vim.loop).fs_open(file_path, 'a', tonumber('644', 8)),
-  }, Logger)
   return self
 end
 
@@ -32,10 +28,12 @@ end
 function Logger:write(level, ...)
   local data = { ... }
   if #data == 1 then data = data[1] end
-  (vim.uv or vim.loop).fs_write(
+  local f = assert(io.open(M.file_for_name(self.name), 'a'), 'could not open file')
-    self.fd,
+  assert(
-    vim.json.encode { ts = os.date(), level = level, data = data } .. '\n'
+    f:write(vim.json.encode { ts = os.date(), level = level, data = data } .. '\n'),
+    'could not write to file'
   )
+  f:close()
 end
 
 function Logger:trace(...) self:write('INFO', ...) end
@@ -64,6 +62,12 @@ function M.setup()
     vim.cmd.terminal('tail -f "' .. log_file_path .. '"')
     vim.cmd.startinsert()
   end, { nargs = '*' })
+
+  vim.api.nvim_create_user_command(
+    'Logroot',
+    function() vim.api.nvim_echo({ { LOG_ROOT } }, false, {}) end,
+    {}
+  )
 end
 
 return M

lua/u/opkeymap.lua

@@ -5,7 +5,6 @@ local __U__OpKeymapOpFunc_rhs = nil
 
 --- This is the global utility function used for operatorfunc
 --- in opkeymap
---- @type nil|fun(range: u.Range): fun():any|nil
 --- @param ty 'line'|'char'|'block'
 -- selene: allow(unused_variable)
 function _G.__U__OpKeymapOpFunc(ty)

lua/u/pos.lua

@@ -7,9 +7,9 @@ local function line_text(bufnr, lnum)
 end
 
 --- @class u.Pos
---- @field bufnr number buffer number
+--- @field bufnr integer buffer number
---- @field lnum number 1-based line index
+--- @field lnum integer 1-based line index
---- @field col number 1-based column index
+--- @field col integer 1-based column index
 --- @field off number
 local Pos = {}
 Pos.__index = Pos
@@ -31,16 +31,33 @@ end
 function Pos.new(bufnr, lnum, col, off)
   if bufnr == nil or bufnr == 0 then bufnr = vim.api.nvim_get_current_buf() end
   if off == nil then off = 0 end
-  local pos = {
+  --- @type u.Pos
+  return setmetatable({
     bufnr = bufnr,
     lnum = lnum,
     col = col,
     off = off,
-  }
+  }, Pos)
-  setmetatable(pos, Pos)
-  return pos
 end
 
+--- @param bufnr? number
+--- @param lnum0 number 1-based
+--- @param col0 number 1-based
+--- @param off? number
+function Pos.from00(bufnr, lnum0, col0, off) return Pos.new(bufnr, lnum0 + 1, col0 + 1, off) end
+
+--- @param bufnr? number
+--- @param lnum0 number 1-based
+--- @param col1 number 1-based
+--- @param off? number
+function Pos.from01(bufnr, lnum0, col1, off) return Pos.new(bufnr, lnum0 + 1, col1, off) end
+
+--- @param bufnr? number
+--- @param lnum1 number 1-based
+--- @param col0 number 1-based
+--- @param off? number
+function Pos.from10(bufnr, lnum1, col0, off) return Pos.new(bufnr, lnum1, col0 + 1, off) end
+
 function Pos.invalid() return Pos.new(0, 0, 0, 0) end
 
 function Pos.__lt(a, b) return a.lnum < b.lnum or (a.lnum == b.lnum and a.col < b.col) end
@@ -67,6 +84,15 @@ function Pos.__sub(x, y)
   return x:next(-y)
 end
 
+--- @param bufnr number
+--- @param lnum number
+function Pos.from_eol(bufnr, lnum)
+  if bufnr == nil or bufnr == 0 then bufnr = vim.api.nvim_get_current_buf() end
+  local pos = Pos.new(bufnr, lnum, 0)
+  pos.col = pos:line():len()
+  return pos
+end
+
 --- @param name string
 --- @return u.Pos
 function Pos.from_pos(name)
@@ -96,9 +122,16 @@ end
 
 function Pos:as_vim() return { self.bufnr, self.lnum, self.col, self.off } end
 
+function Pos:eol() return Pos.from_eol(self.bufnr, self.lnum) end
+
 --- @param pos string
 function Pos:save_to_pos(pos) vim.fn.setpos(pos, { self.bufnr, self.lnum, self.col, self.off }) end
 
+--- @param winnr? integer
+function Pos:save_to_cursor(winnr)
+  vim.api.nvim_win_set_cursor(winnr or 0, { self.lnum, self.col - 1 })
+end
+
 --- @param mark string
 function Pos:save_to_mark(mark)
   local p = self:as_real()

lua/u/range.lua

@@ -1,14 +1,8 @@
+local Extmark = require 'u.extmark'
 local Pos = require 'u.pos'
 
--- Certain functions in the Range class yank text. In order to prevent unwanted
+local ESC = vim.api.nvim_replace_termcodes('<Esc>', true, false, true)
--- highlighting, we intercept and discard some calls to the `on_yank` callback.
+local NS = vim.api.nvim_create_namespace 'u.range'
-local orig_on_yank = vim.hl.on_yank
-local on_yank_enabled = true
---- @diagnostic disable-next-line: duplicate-set-field
-function vim.hl.on_yank(opts)
-  if not on_yank_enabled then return end
-  return orig_on_yank(opts)
-end
 
 --- @class u.Range
 --- @field start u.Pos
@@ -118,12 +112,12 @@ function Range.from_lines(bufnr, start_line, stop_line)
 end
 
 --- @param motion string
---- @param opts? { bufnr?: number; contains_cursor?: boolean; pos?: u.Pos, user_defined?: boolean }
+--- @param opts? { bufnr?: number, contains_cursor?: boolean, pos?: u.Pos, user_defined?: boolean }
 --- @return u.Range|nil
 function Range.from_motion(motion, opts)
   -- Options handling:
   opts = opts or {}
-  if opts.bufnr == nil then opts.bufnr = vim.api.nvim_get_current_buf() end
+  if opts.bufnr == nil or opts.bufnr == 0 then opts.bufnr = vim.api.nvim_get_current_buf() end
   if opts.contains_cursor == nil then opts.contains_cursor = false end
   if opts.user_defined == nil then opts.user_defined = false end
 
@@ -133,10 +127,6 @@ function Range.from_motion(motion, opts)
   local is_txtobj = scope == 'a' or scope == 'i'
   local is_quote_txtobj = is_txtobj and vim.tbl_contains({ "'", '"', '`' }, motion_rest)
 
-  --- @type u.Pos
-  local start
-  --- @type u.Pos
-  local stop
   -- Capture the original state of the buffer for restoration later.
   local original_state = {
     winview = vim.fn.winsaveview(),
@@ -144,59 +134,88 @@ function Range.from_motion(motion, opts)
     cursor = vim.fn.getpos '.',
     pos_lbrack = vim.fn.getpos "'[",
     pos_rbrack = vim.fn.getpos "']",
+    opfunc = vim.go.operatorfunc,
+    prev_captured_range = _G.Range__from_motion_opfunc_captured_range,
+    prev_mode = vim.fn.mode(),
+    vinf = Range.from_vtext(),
   }
+  --- @type u.Range|nil
+  _G.Range__from_motion_opfunc_captured_range = nil
+
   vim.api.nvim_buf_call(opts.bufnr, function()
     if opts.pos ~= nil then opts.pos:save_to_pos '.' end
 
-    Pos.invalid():save_to_pos "'["
+    _G.Range__from_motion_opfunc = function(ty)
-    Pos.invalid():save_to_pos "']"
+      _G.Range__from_motion_opfunc_captured_range = Range.from_op_func(ty)
-
+    end
-    local prev_on_yank_enabled = on_yank_enabled
+    local old_eventignore = vim.o.eventignore
-    on_yank_enabled = false
+    vim.o.eventignore = 'all'
+    vim.go.operatorfunc = 'v:lua.Range__from_motion_opfunc'
     vim.cmd {
       cmd = 'normal',
       bang = not opts.user_defined,
-      args = { '""y' .. motion },
+      args = { ESC .. 'g@' .. motion },
       mods = { silent = true },
     }
-    on_yank_enabled = prev_on_yank_enabled
+    vim.o.eventignore = old_eventignore
-
-    start = Pos.from_pos "'["
-    stop = Pos.from_pos "']"
   end)
+  local captured_range = _G.Range__from_motion_opfunc_captured_range
+
   -- Restore original state:
   vim.fn.winrestview(original_state.winview)
   vim.fn.setreg('"', original_state.regquote)
   vim.fn.setpos('.', original_state.cursor)
   vim.fn.setpos("'[", original_state.pos_lbrack)
   vim.fn.setpos("']", original_state.pos_rbrack)
+  if original_state.prev_mode ~= 'n' then original_state.vinf:set_visual_selection() end
+  vim.go.operatorfunc = original_state.opfunc
+  _G.Range__from_motion_opfunc_captured_range = original_state.prev_captured_range
 
-  if start == stop and start:is_invalid() then return nil end
+  if not captured_range then return nil end
 
   -- Fixup the bounds:
   if
     -- I have no idea why, but when yanking `i"`, the stop-mark is
     -- placed on the ending quote. For other text-objects, the stop-
     -- mark is placed before the closing character.
-    (is_quote_txtobj and scope == 'i' and stop:char() == motion_rest)
+    (is_quote_txtobj and scope == 'i' and captured_range.stop:char() == motion_rest)
     -- *Sigh*, this also sometimes happens for `it` as well.
-    or (motion == 'it' and stop:char() == '<')
+    or (motion == 'it' and captured_range.stop:char() == '<')
   then
-    stop = stop:next(-1) or stop
+    captured_range.stop = captured_range.stop:next(-1) or captured_range.stop
   end
   if is_quote_txtobj and scope == 'a' then
-    start = start:find_next(1, motion_rest) or start
+    captured_range.start = captured_range.start:find_next(1, motion_rest) or captured_range.start
-    stop = stop:find_next(-1, motion_rest) or stop
+    captured_range.stop = captured_range.stop:find_next(-1, motion_rest) or captured_range.stop
   end
 
   if
-    opts.contains_cursor
+    opts.contains_cursor and not captured_range:contains(Pos.new(unpack(original_state.cursor)))
-    and not Range.new(start, stop):contains(Pos.new(unpack(original_state.cursor)))
   then
     return nil
   end
 
-  return Range.new(start, stop)
+  return captured_range
+end
+
+--- @param opts? { contains_cursor?: boolean }
+function Range.from_tsquery_caps(bufnr, query, opts)
+  opts = opts or { contains_cursor = true }
+
+  local ranges = Range.from_buf_text(bufnr):tsquery(query)
+  if not ranges then return end
+  if not opts.contains_cursor then return ranges end
+
+  local cursor = Pos.from_pos '.'
+  return vim.tbl_map(function(cap_ranges)
+    return vim
+      .iter(cap_ranges)
+      :filter(
+        --- @param r u.Range
+        function(r) return r:contains(cursor) end
+      )
+      :totable()
+  end, ranges)
 end
 
 --- Get range information from the currently selected visual text.
@@ -226,19 +245,22 @@ end
 --- @param args unknown
 --- @return u.Range|nil
 function Range.from_cmd_args(args)
-  --- @type 'v'|'V'
+  if args.range == 0 then return nil end
-  local mode
+
-  --- @type nil|u.Pos
+  local bufnr = vim.api.nvim_get_current_buf()
-  local start
+  if args.range == 1 then
-  local stop
+    return Range.new(Pos.new(bufnr, args.line1, 1), Pos.new(bufnr, args.line1, Pos.MAX_COL), 'V')
-  if args.range == 0 then
+  end
-    return nil
+
-  else
+  local is_visual = vim.fn.histget('cmd', -1):sub(1, 5) == [['<,'>]]
-    start = Pos.from_pos "'<"
+  --- @type 'v'|'V'
-    stop = Pos.from_pos "'>"
+  local mode = is_visual and vim.fn.visualmode() or 'V'
-    mode = stop:is_col_max() and 'V' or 'v'
+
+  if is_visual then
+    return Range.new(Pos.from_pos "'<", Pos.from_pos "'>", mode)
+  else
+    return Range.new(Pos.new(bufnr, args.line1, 1), Pos.new(bufnr, args.line2, Pos.MAX_COL), mode)
   end
-  return Range.new(start, stop, mode)
 end
 
 function Range.find_nearest_brackets()
@@ -278,6 +300,13 @@ function Range:to_linewise()
   return r
 end
 
+function Range:to_charwise()
+  local r = self:clone()
+  r.mode = 'v'
+  if r.stop:is_col_max() then r.stop = r.stop:as_real() end
+  return r
+end
+
 --- @param x u.Pos | u.Range
 function Range:contains(x)
   if getmetatable(x) == Pos then
@@ -319,27 +348,19 @@ end
 --- @param left string
 --- @param right string
 function Range:save_to_pos(left, right)
-  if self:is_empty() then
+  self.start:save_to_pos(left);
-    self.start:save_to_pos(left)
+  (self:is_empty() and self.start or self.stop):save_to_pos(right)
-    self.start:save_to_pos(right)
-  else
-    self.start:save_to_pos(left)
-    self.stop:save_to_pos(right)
-  end
 end
 
 --- @param left string
 --- @param right string
 function Range:save_to_marks(left, right)
-  if self:is_empty() then
+  self.start:save_to_mark(left);
-    self.start:save_to_mark(left)
+  (self:is_empty() and self.start or self.stop):save_to_mark(right)
-    self.start:save_to_mark(right)
-  else
-    self.start:save_to_mark(left)
-    self.stop:save_to_mark(right)
-  end
 end
 
+function Range:save_to_extmark() return Extmark.from_range(self, NS) end
+
 function Range:set_visual_selection()
   if self:is_empty() then return end
   if vim.api.nvim_get_current_buf() ~= self.start.bufnr then
@@ -354,14 +375,46 @@ function Range:set_visual_selection()
   self.stop:save_to_pos '.'
 end
 
---------------------------------------------------------------------------------
--- Range.from_* functions:
---------------------------------------------------------------------------------
-
 --------------------------------------------------------------------------------
 -- Text access/manipulation utilities:
 --------------------------------------------------------------------------------
 
+--- @param query string
+function Range:tsquery(query)
+  local bufnr = self.start.bufnr
+
+  local lang = vim.treesitter.language.get_lang(vim.bo[bufnr].filetype)
+  if lang == nil then return end
+  local parser = vim.treesitter.get_parser(bufnr, lang)
+  if parser == nil then return end
+  local tree = parser:parse()[1]
+  if tree == nil then return end
+
+  local root = tree:root()
+  local q = vim.treesitter.query.parse(lang, query)
+  --- @type table<string, u.Range[]>
+  local ranges = {}
+  for id, match, _meta in
+    q:iter_captures(root, bufnr, self.start.lnum - 1, (self.stop or self.start).lnum)
+  do
+    local start_row0, start_col0, stop_row0, stop_col0 = match:range()
+    local range = Range.new(
+      Pos.new(bufnr, start_row0 + 1, start_col0 + 1),
+      Pos.new(bufnr, stop_row0 + 1, stop_col0),
+      'v'
+    )
+    if range.stop.lnum > vim.api.nvim_buf_line_count(bufnr) then
+      range.stop = range.stop:must_next(-1)
+    end
+
+    local capture_name = q.captures[id]
+    if not ranges[capture_name] then ranges[capture_name] = {} end
+    if self:contains(range) then table.insert(ranges[capture_name], range) end
+  end
+
+  return ranges
+end
+
 function Range:length()
   if self:is_empty() then return 0 end
 
@@ -460,7 +513,7 @@ function Range:text() return vim.fn.join(self:lines(), '\n') end
 
 --- @param l number
 -- luacheck: ignore
---- @return { line: string; idx0: { start: number; stop: number; }; lnum: number; range: fun():u.Range; text: fun():string }|nil
+--- @return { line: string, idx0: { start: number, stop: number }, lnum: number, range: (fun():u.Range), text: fun():string }|nil
 function Range:line(l)
   if l < 0 then l = self:line_count() + l + 1 end
   if l > self:line_count() then return end

lua/u/tracker.lua

@@ -6,19 +6,19 @@ M.debug = false
 -- class Signal
 --------------------------------------------------------------------------------
 
---- @class u.Signal
+--- @class u.Signal<T>
 --- @field name? string
 --- @field private changing boolean
---- @field private value any
+--- @field private value T
 --- @field private subscribers table<function, boolean>
 --- @field private on_dispose_callbacks function[]
 local Signal = {}
 M.Signal = Signal
 Signal.__index = Signal
 
---- @param value any
+--- @param value `T`
 --- @param name? string
---- @return u.Signal
+--- @return u.Signal<T>
 function Signal:new(value, name)
   local obj = setmetatable({
     name = name,
@@ -30,7 +30,7 @@ function Signal:new(value, name)
   return obj
 end
 
---- @param value any
+--- @param value T
 function Signal:set(value)
   self.value = value
 
@@ -67,11 +67,12 @@ function Signal:set(value)
   end
 end
 
+--- @param value T
 function Signal:schedule_set(value)
   vim.schedule(function() self:set(value) end)
 end
 
---- @return any
+--- @return T
 function Signal:get()
   local ctx = M.ExecutionContext.current()
   if ctx then ctx:track(self) end
@@ -85,8 +86,8 @@ function Signal:update(fn) self:set(fn(self.value)) end
 function Signal:schedule_update(fn) self:schedule_set(fn(self.value)) end
 
 --- @generic U
---- @param fn fun(value: T): U
+--- @param fn fun(value: T): `U`
---- @return u.Signal --<U>
+--- @return u.Signal<U>
 function Signal:map(fn)
   local mapped_signal = M.create_memo(function()
     local value = self:get()
@@ -95,13 +96,13 @@ function Signal:map(fn)
   return mapped_signal
 end
 
---- @return u.Signal
+--- @return u.Signal<T>
 function Signal:clone()
   return self:map(function(x) return x end)
 end
 
 --- @param fn fun(value: T): boolean
---- @return u.Signal -- <T>
+--- @return u.Signal<T>
 function Signal:filter(fn)
   local filtered_signal = M.create_signal(nil, self.name and self.name .. ':filtered' or nil)
   local unsubscribe_from_self = self:subscribe(function(value)
@@ -112,10 +113,10 @@ function Signal:filter(fn)
 end
 
 --- @param ms number
---- @return u.Signal -- <T>
+--- @return u.Signal<T>
 function Signal:debounce(ms)
   local function set_timeout(timeout, callback)
-    local timer = (vim.uv or vim.loop).new_timer()
+    local timer = assert((vim.uv or vim.loop).new_timer(), 'could not create new timer')
     timer:start(timeout, 0, function()
       timer:stop()
       timer:close()
@@ -127,7 +128,7 @@ function Signal:debounce(ms)
   local filtered = M.create_signal(self.value, self.name and self.name .. ':debounced' or nil)
 
   --- @diagnostic disable-next-line: undefined-doc-name
-  --- @type { queued: { value: T, ts: number }[]; timer?: uv_timer_t; }
+  --- @type { queued: { value: T, ts: number }[], timer?: uv.uv_timer_t }
   local state = { queued = {}, timer = nil }
   local function clear_timeout()
     if state.timer == nil then return end
@@ -202,6 +203,7 @@ end
 -- class ExecutionContext
 --------------------------------------------------------------------------------
 
+--- @type u.ExecutionContext|nil
 local CURRENT_CONTEXT = nil
 
 --- @class u.ExecutionContext
@@ -262,16 +264,18 @@ end
 -- Helpers
 --------------------------------------------------------------------------------
 
---- @param value any
+--- @generic T
+--- @param value `T`
 --- @param name? string
---- @return u.Signal
+--- @return u.Signal<T>
 function M.create_signal(value, name) return Signal:new(value, name) end
 
---- @param fn function
+--- @generic T
+--- @param fn fun(): `T`
 --- @param name? string
 --- @return u.Signal
 function M.create_memo(fn, name)
-  --- @type u.Signal
+  --- @type u.Signal<T> | nil
   local result
   local unsubscribe = M.create_effect(function()
     local value = fn()
@@ -282,8 +286,8 @@ function M.create_memo(fn, name)
       result = M.create_signal(value, name and ('m.s:' .. name) or nil)
     end
   end, name)
-  result:on_dispose(unsubscribe)
+  assert(result):on_dispose(unsubscribe)
-  return result
+  return assert(result)
 end
 
 --- @param fn function

lua/u/utils.lua

@@ -4,15 +4,63 @@ local M = {}
 -- Types
 --
 
---- @alias QfItem { col: number, filename: string, kind: string, lnum: number, text: string }
+--- @class u.utils.QfItem
---- @alias KeyMaps table<string, fun(): any | string> }
+--- @field col number
--- luacheck: ignore
+--- @field filename string
---- @alias CmdArgs { args: string; bang: boolean; count: number; fargs: string[]; line1: number; line2: number; mods: string; name: string; range: 0|1|2; reg: string; smods: any; info: u.Range|nil }
+--- @field kind string
+--- @field lnum number
+--- @field text string
 
+--- @class u.utils.RawCmdArgs
+--- @field args string
+--- @field bang boolean
+--- @field count number
+--- @field fargs string[]
+--- @field line1 number
+--- @field line2 number
+--- @field mods string
+--- @field name string
+--- @field range 0|1|2
+--- @field reg string
+--- @field smods any
+
+--- @class u.utils.CmdArgs: u.utils.RawCmdArgs
+--- @field info u.Range|nil
+
+--- @class u.utils.UcmdArgs
+--- @field nargs? 0|1|'*'|'?'|'+'
+--- @field range? boolean|'%'|number
+--- @field count? boolean|number
+--- @field addr? string
+--- @field completion? string
+--- @field force? boolean
+--- @field preview? fun(opts: u.utils.UcmdArgs, ns: integer, buf: integer):0|1|2
+
+--
+-- Functions
+--
+
+--- Debug utility that prints a value and returns it unchanged.
+--- Useful for debugging in the middle of expressions or function chains.
+---
 --- @generic T
---- @param x `T`
+--- @param x `T` The value to debug print
---- @param message? string
+--- @param message? string Optional message to print alongside the value
---- @return T
+--- @return T The original value, unchanged
+---
+--- @usage
+--- ```lua
+--- -- Debug a value in the middle of a chain:
+--- local result = some_function()
+---   :map(utils.dbg)  -- prints the intermediate value
+---   :filter(predicate)
+---
+--- -- Debug with a custom message:
+--- local config = utils.dbg(get_config(), "Current config:")
+---
+--- -- Debug return values:
+--- return utils.dbg(calculate_result(), "Final result")
+--- ```
 function M.dbg(x, message)
   local t = {}
   if message ~= nil then table.insert(t, message) end
@@ -21,22 +69,37 @@ function M.dbg(x, message)
   return x
 end
 
---- A utility for creating user commands that also pre-computes useful information
+--- Creates a user command with enhanced argument processing.
---- and attaches it to the arguments.
+--- Automatically computes range information and attaches it as `args.info`.
 ---
+--- @param name string The command name (without the leading colon)
+--- @param cmd string | fun(args: u.utils.CmdArgs): any Command implementation
+--- @param opts? u.utils.UcmdArgs Command options (nargs, range, etc.)
+---
+--- @usage
 --- ```lua
---- -- Example:
+--- -- Create a command that works with visual selections:
---- ucmd('MyCmd', function(args)
+--- utils.ucmd('MyCmd', function(args)
----   -- print the visually selected text:
+---   -- Print the visually selected text:
 ---   vim.print(args.info:text())
----   -- or get the vtext as an array of lines:
+---   -- Or get the selection as an array of lines:
 ---   vim.print(args.info:lines())
 --- end, { nargs = '*', range = true })
+---
+--- -- Create a command that processes the current line:
+--- utils.ucmd('ProcessLine', function(args)
+---   local line_text = args.info:text()
+---   -- Process the line...
+--- end, { range = '%' })
+---
+--- -- Create a command with arguments:
+--- utils.ucmd('SearchReplace', function(args)
+---   local pattern, replacement = args.fargs[1], args.fargs[2]
+---   local text = args.info:text()
+---   -- Perform search and replace...
+--- end, { nargs = 2, range = true })
 --- ```
---- @param name string
---- @param cmd string | fun(args: CmdArgs): any
 -- luacheck: ignore
---- @param opts? { nargs?: 0|1|'*'|'?'|'+'; range?: boolean|'%'|number; count?: boolean|number, addr?: string; completion?: string }
 function M.ucmd(name, cmd, opts)
   local Range = require 'u.range'
 
@@ -48,9 +111,81 @@ function M.ucmd(name, cmd, opts)
       return cmd(args)
     end
   end
-  vim.api.nvim_create_user_command(name, cmd2, opts or {})
+  vim.api.nvim_create_user_command(name, cmd2, opts or {} --[[@as any]])
 end
 
+--- Creates command arguments for delegating from one command to another.
+--- Preserves all relevant context (range, modifiers, bang, etc.) when
+--- implementing a derived command in terms of a base command.
+---
+--- @param current_args vim.api.keyset.create_user_command.command_args|u.utils.RawCmdArgs The arguments from the current command
+--- @return vim.api.keyset.cmd Arguments suitable for vim.cmd() calls
+---
+--- @usage
+--- ```lua
+--- -- Implement :MyEdit in terms of :edit, preserving all context:
+--- utils.ucmd('MyEdit', function(args)
+---   local delegated_args = utils.create_delegated_cmd_args(args)
+---   -- Add custom logic here...
+---   vim.cmd.edit(delegated_args)
+--- end, { nargs = '*', range = true, bang = true })
+---
+--- -- Implement :MySubstitute that delegates to :substitute:
+--- utils.ucmd('MySubstitute', function(args)
+---   -- Pre-process arguments
+---   local pattern = preprocess_pattern(args.fargs[1])
+---
+---   local delegated_args = utils.create_delegated_cmd_args(args)
+---   delegated_args.args = { pattern, args.fargs[2] }
+---
+---   vim.cmd.substitute(delegated_args)
+--- end, { nargs = 2, range = true, bang = true })
+--- ```
+function M.create_delegated_cmd_args(current_args)
+  --- @type vim.api.keyset.cmd
+  local args = {
+    range = current_args.range == 1 and { current_args.line1 }
+      or current_args.range == 2 and { current_args.line1, current_args.line2 }
+      or nil,
+    count = (current_args.count ~= -1 and current_args.range == 0) and current_args.count or nil,
+    reg = current_args.reg ~= '' and current_args.reg or nil,
+    bang = current_args.bang or nil,
+    args = #current_args.fargs > 0 and current_args.fargs or nil,
+    mods = current_args.smods,
+  }
+  return args
+end
+
+--- Gets the current editor dimensions.
+--- Useful for positioning floating windows or calculating layout sizes.
+---
+--- @return { width: number, height: number } The editor dimensions in columns and lines
+---
+--- @usage
+--- ```lua
+--- -- Center a floating window:
+--- local dims = utils.get_editor_dimensions()
+--- local win_width = 80
+--- local win_height = 20
+--- local col = math.floor((dims.width - win_width) / 2)
+--- local row = math.floor((dims.height - win_height) / 2)
+---
+--- vim.api.nvim_open_win(bufnr, true, {
+---   relative = 'editor',
+---   width = win_width,
+---   height = win_height,
+---   col = col,
+---   row = row,
+--- })
+---
+--- -- Check if editor is wide enough for side-by-side layout:
+--- local dims = utils.get_editor_dimensions()
+--- if dims.width >= 160 then
+---   -- Use side-by-side layout
+--- else
+---   -- Use stacked layout
+--- end
+--- ```
 function M.get_editor_dimensions() return { width = vim.go.columns, height = vim.go.lines } end
 
 return M

lux.toml

@@ -1,19 +0,0 @@
-package = "u.nvim"
-version = "0.2.0"
-lua = ">=5.1"
-
-[description]
-summary = ""
-maintainer = "jrop"
-labels = [ "library", "neovim", "neovim-plugin", "range", "utility" ]
-
-
-[dependencies]
-# Add your dependencies here
-# `busted = ">=2.0"`
-
-[run]
-args = [ "src/main.lua" ]
-
-[build]
-type = "builtin"

selene.toml

@@ -1,4 +0,0 @@
-std = "vim"
-
-[lints]
-multiple_statements = "allow"

shell.nix

@@ -0,0 +1,23 @@
+{
+  pkgs ?
+    import
+      # nixos-unstable (neovim@0.11.4):
+      (fetchTarball {
+        url = "https://github.com/nixos/nixpkgs/archive/0b4defa2584313f3b781240b29d61f6f9f7e0df3.tar.gz";
+        sha256 = "0p3rrd8wwlk0iwgzm7frkw1k98ywrh0avi7fqjjk87i68n3inxrs";
+      })
+      { },
+}:
+pkgs.mkShell {
+  packages = [
+    pkgs.git
+    pkgs.gnumake
+    pkgs.emmylua-check
+    pkgs.lua51Packages.busted
+    pkgs.lua51Packages.luacov
+    pkgs.lua51Packages.luarocks
+    pkgs.neovim
+    pkgs.stylua
+    pkgs.watchexec
+  ];
+}

spec/range_spec.lua

@@ -1,5 +1,5 @@
-local Range = require 'u.range'
 local Pos = require 'u.pos'
+local Range = require 'u.range'
 local withbuf = loadfile './spec/withbuf.lua'()
 
 describe('Range', function()
@@ -238,6 +238,128 @@ describe('Range', function()
     end)
   end)
 
+  it('from_tsquery_caps', function()
+    withbuf({
+      '-- a comment',
+      '',
+      'function foo(bar) end',
+      '',
+      '-- a middle comment',
+      '',
+      'function bar(baz) end',
+      '',
+      '-- another comment',
+    }, function()
+      vim.cmd.setfiletype 'lua'
+
+      --- @param contains_cursor? boolean
+      local function get_caps(contains_cursor)
+        if contains_cursor == nil then contains_cursor = true end
+        return (Range.from_tsquery_caps(
+          0,
+          '(function_declaration) @f',
+          { contains_cursor = contains_cursor }
+        )).f or {}
+      end
+
+      local caps = get_caps(false)
+      assert.are.same(#caps, 2)
+      assert.are.same(vim.iter(caps):map(function(c) return c:text() end):totable(), {
+        'function foo(bar) end',
+        'function bar(baz) end',
+      })
+
+      Pos.new(0, 1, 1):save_to_pos '.'
+      caps = get_caps()
+      assert.are.same(#caps, 0)
+
+      Pos.new(0, 3, 18):save_to_pos '.'
+      caps = get_caps()
+      assert.are.same(#caps, 1)
+      assert.are.same(caps[1]:text(), 'function foo(bar) end')
+
+      Pos.new(0, 5, 1):save_to_pos '.'
+      caps = get_caps()
+      assert.are.same(#caps, 0)
+
+      Pos.new(0, 7, 1):save_to_pos '.'
+      caps = get_caps()
+      assert.are.same(#caps, 1)
+      assert.are.same(caps[1]:text(), 'function bar(baz) end')
+    end)
+  end)
+
+  it('from_tsquery_caps with string array filter', function()
+    withbuf({
+      '{',
+      '  sample_key1 = "sample-value1",',
+      '  sample_key2 = "sample-value2",',
+      '}',
+    }, function()
+      vim.cmd.setfiletype 'lua'
+
+      -- Place cursor in "sample-value1"
+      Pos.new(0, 2, 25):save_to_pos '.'
+
+      -- Query that captures both keys and values in pairs
+      local query = [[
+        (field
+          name: _ @key
+          value: _ @value)
+      ]]
+
+      local ranges = Range.from_line(0, 2):tsquery(query)
+
+      -- Should have both @key and @value captures for the first pair only
+      -- (since cursor is in sample-value1)
+      assert(ranges, 'Range should not be nil')
+      assert(ranges.key, 'Range.key should not be nil')
+      assert(ranges.value, 'Range.value should not be nil')
+
+      -- Should have exactly one key and one value
+      assert.are.same(#ranges.key, 1)
+      assert.are.same(#ranges.value, 1)
+
+      -- Check that we got sample-key1 and sample-value1
+      assert.are.same(ranges.key[1]:text(), 'sample_key1')
+      assert.are.same(ranges.value[1]:text(), '"sample-value1"')
+    end)
+
+    -- Make sure this works when the match is on the last line:
+    withbuf({
+      '{sample_key1= "sample-value1",',
+      'sample_key2= "sample-value2"}',
+    }, function()
+      vim.cmd.setfiletype 'lua'
+
+      -- Place cursor in "sample-value1"
+      Pos.new(0, 2, 25):save_to_pos '.'
+
+      -- Query that captures both keys and values in pairs
+      local query = [[
+        (field
+          name: _ @key
+          value: _ @value)
+      ]]
+
+      local ranges = Range.from_line(0, 2):tsquery(query)
+
+      -- Should have both @key and @value captures for the first pair only
+      -- (since cursor is in sample-value1)
+      assert(ranges, 'Range should not be nil')
+      assert(ranges.key, 'Range.key should not be nil')
+      assert(ranges.value, 'Range.value should not be nil')
+
+      -- Should have exactly one key and one value
+      assert.are.same(#ranges.key, 1)
+      assert.are.same(#ranges.value, 1)
+
+      -- Check that we got sample-key2 and sample-value2
+      assert.are.same(ranges.key[1]:text(), 'sample_key2')
+      assert.are.same(ranges.value[1]:text(), '"sample-value2"')
+    end)
+  end)
+
   it('should get nearest block', function()
     withbuf({
       'this is a {',
@@ -318,18 +440,89 @@ describe('Range', function()
     end)
   end)
 
-  it('from_cmd_args', function()
+  it('from_cmd_args: range=0', function()
-    local args = { range = 1 }
+    local args = { range = 0 }
+    withbuf(
+      { 'line one', 'and line two' },
+      function() assert.are.same(Range.from_cmd_args(args), nil) end
+    )
+  end)
+
+  it('from_cmd_args: range=1', function()
+    local args = { range = 1, line1 = 1 }
     withbuf({ 'line one', 'and line two' }, function()
       local a = Pos.new(nil, 1, 1)
-      local b = Pos.new(nil, 2, 2)
+      local b = Pos.new(nil, 1, Pos.MAX_COL)
+
+      local range = Range.from_cmd_args(args) --[[@as u.Range]]
+      assert.are.same(range.start, a)
+      assert.are.same(range.stop, b)
+      assert.are.same(range.mode, 'V')
+      assert.are.same(range:text(), 'line one')
+    end)
+  end)
+
+  it('from_cmd_args: range=2: no-visual', function()
+    local args = { range = 2, line1 = 1, line2 = 2 }
+    withbuf({ 'line one', 'and line two' }, function()
+      local range = Range.from_cmd_args(args) --[[@as u.Range]]
+      assert.are.same(range.start, Pos.new(nil, 1, 1))
+      assert.are.same(range.stop, Pos.new(nil, 2, Pos.MAX_COL))
+      assert.are.same(range.mode, 'V')
+      assert.are.same(range:text(), 'line one\nand line two')
+    end)
+  end)
+
+  it('from_cmd_args: range=2: visual: linewise', function()
+    local args = { range = 2, line1 = 1, line2 = 2 }
+    withbuf({ 'line one', 'and line two' }, function()
+      local a = Pos.new(nil, 1, 1)
+      local b = Pos.new(nil, 2, Pos.MAX_COL)
       a:save_to_pos "'<"
       b:save_to_pos "'>"
+      local range = Range.from_cmd_args(args) --[[@as u.Range]]
+      assert.are.same(range.start, a)
+      assert.are.same(range.stop, b)
+      assert.are.same(range.mode, 'V')
+      assert.are.same(range:text(), 'line one\nand line two')
+    end)
+  end)
 
-      local range = Range.from_cmd_args(args)
+  it('from_cmd_args: range=2: visual: charwise', function()
+    local args = { range = 2, line1 = 1, line2 = 1 }
+    withbuf({ 'line one', 'and line two' }, function()
+      -- Simulate a visual selection:
+      local a = Pos.new(nil, 1, 1)
+      local b = Pos.new(nil, 1, 4)
+      a:save_to_pos "'<"
+      b:save_to_pos "'>"
+      Range.new(a, b, 'v'):set_visual_selection()
+      assert.are.same(vim.fn.mode(), 'v')
+
+      -- In this simulated setup, we need to force visualmode() to return
+      -- 'v' and histget() to return [['<,'>]]:
+
+      -- visualmode()
+      local orig_visualmode = vim.fn.visualmode
+      --- @diagnostic disable-next-line: duplicate-set-field
+      function vim.fn.visualmode() return 'v' end
+      assert.are.same(vim.fn.visualmode(), 'v')
+
+      -- histget()
+      local orig_histget = vim.fn.histget
+      --- @diagnostic disable-next-line: duplicate-set-field
+      function vim.fn.histget(x, y) return [['<,'>]] end
+
+      -- Now run the test:
+      local range = Range.from_cmd_args(args) --[[@as u.Range]]
       assert.are.same(range.start, a)
       assert.are.same(range.stop, b)
       assert.are.same(range.mode, 'v')
+      assert.are.same(range:text(), 'line')
+
+      -- Reset visualmode() and histget():
+      vim.fn.visualmode = orig_visualmode
+      vim.fn.histget = orig_histget
     end)
   end)
 
@@ -617,4 +810,86 @@ describe('Range', function()
       }, vim.api.nvim_buf_get_lines(b, 0, -1, false))
     end)
   end)
+
+  it('can save to extmark', function()
+    withbuf({
+      'The quick brown',
+      'fox',
+      'jumps',
+      'over',
+      'the lazy dog',
+    }, function()
+      -- Construct a range over 'fox jumps'
+      local r = Range.new(Pos.new(nil, 2, 1), Pos.new(nil, 3, 5), 'v')
+      local extrange = r:save_to_extmark()
+      assert.are.same({ 'fox', 'jumps' }, extrange:range():lines())
+      -- change 'jumps' to 'leaps':
+      vim.api.nvim_buf_set_text(extrange.bufnr, 2, 0, 2, 4, { 'leap' })
+      assert.are.same({
+        'The quick brown',
+        'fox',
+        'leaps',
+        'over',
+        'the lazy dog',
+      }, vim.api.nvim_buf_get_lines(extrange.bufnr, 0, -1, false))
+      assert.are.same({ 'fox', 'leaps' }, extrange:range():lines())
+    end)
+  end)
+
+  it('can save linewise extmark', function()
+    withbuf({
+      'The quick brown',
+      'fox',
+      'jumps',
+      'over',
+      'the lazy dog',
+    }, function()
+      -- Construct a range over 'fox jumps'
+      local r = Range.new(Pos.new(nil, 2, 1), Pos.new(nil, 3, Pos.MAX_COL), 'V')
+      local extrange = r:save_to_extmark()
+      assert.are.same({ 'fox', 'jumps' }, extrange:range():lines())
+
+      local extmark = vim.api.nvim_buf_get_extmark_by_id(
+        extrange.bufnr,
+        vim.api.nvim_create_namespace 'u.range',
+        extrange.id,
+        { details = true }
+      )
+      local row0, col0, details = unpack(extmark)
+      assert.are.same({ 1, 0 }, { row0, col0 })
+      assert.are.same({ 3, 0 }, { details.end_row, details.end_col })
+    end)
+  end)
+
+  it('discerns range bounds from extmarks beyond the end of the buffer', function()
+    local Buffer = require 'u.buffer'
+
+    vim.cmd.vnew()
+    local left = Buffer.current()
+    left:set_tmp_options()
+    vim.cmd.vnew()
+    local right = Buffer.current()
+    right:set_tmp_options()
+
+    left:all():replace {
+      'one',
+      'two',
+      'three',
+    }
+    local left_all_ext = left:all():save_to_extmark()
+
+    right:all():replace {
+      'foo',
+      'bar',
+    }
+
+    vim.api.nvim_set_current_buf(right.bufnr)
+    vim.cmd [[normal! ggyG]]
+    vim.api.nvim_set_current_buf(left.bufnr)
+    vim.cmd [[normal! ggVGp]]
+
+    assert.are.same({ 'foo', 'bar' }, left_all_ext:range():lines())
+    vim.api.nvim_buf_delete(left.bufnr, { force = true })
+    vim.api.nvim_buf_delete(right.bufnr, { force = true })
+  end)
 end)

spec/renderer_spec.lua

@@ -83,13 +83,13 @@ describe('Renderer', function()
   end)
 
   --
-  -- get_pos_infos
+  -- get_tags_at
   --
 
   it('should return no extmarks for an empty buffer', function()
     withbuf({}, function()
       local r = R.Renderer.new(0)
-      local pos_infos = r:get_pos_infos { 0, 0 }
+      local pos_infos = r:get_tags_at { 0, 0 }
       assert.are.same(pos_infos, {})
     end)
   end)
@@ -102,12 +102,28 @@ describe('Renderer', function()
         R.h('text', { hl = 'HighlightGroup2' }, ' World'),
       }
 
-      local pos_infos = r:get_pos_infos { 0, 2 }
+      local pos_infos = r:get_tags_at { 0, 2 }
-
       assert.are.same(#pos_infos, 1)
       assert.are.same(pos_infos[1].tag.attributes.hl, 'HighlightGroup1')
       assert.are.same(pos_infos[1].extmark.start, { 0, 0 })
       assert.are.same(pos_infos[1].extmark.stop, { 0, 5 })
+      pos_infos = r:get_tags_at { 0, 4 }
+      assert.are.same(#pos_infos, 1)
+      assert.are.same(pos_infos[1].tag.attributes.hl, 'HighlightGroup1')
+      assert.are.same(pos_infos[1].extmark.start, { 0, 0 })
+      assert.are.same(pos_infos[1].extmark.stop, { 0, 5 })
+
+      pos_infos = r:get_tags_at { 0, 5 }
+      assert.are.same(#pos_infos, 1)
+      assert.are.same(pos_infos[1].tag.attributes.hl, 'HighlightGroup2')
+      assert.are.same(pos_infos[1].extmark.start, { 0, 5 })
+      assert.are.same(pos_infos[1].extmark.stop, { 0, 11 })
+
+      -- In insert mode, bounds are eagerly included:
+      pos_infos = r:get_tags_at({ 0, 5 }, 'i')
+      assert.are.same(#pos_infos, 2)
+      assert.are.same(pos_infos[1].tag.attributes.hl, 'HighlightGroup1')
+      assert.are.same(pos_infos[2].tag.attributes.hl, 'HighlightGroup2')
     end)
   end)
 
@@ -125,11 +141,252 @@ describe('Renderer', function()
         }),
       }
 
-      local pos_infos = r:get_pos_infos { 0, 5 }
+      local pos_infos = r:get_tags_at { 0, 5 }
 
       assert.are.same(#pos_infos, 2)
       assert.are.same(pos_infos[1].tag.attributes.hl, 'HighlightGroup2')
       assert.are.same(pos_infos[2].tag.attributes.hl, 'HighlightGroup1')
     end)
   end)
+
+  it('repeated patch_lines calls should not change the buffer content', function()
+    local lines = {
+      [[{ {]],
+      [[    bounds = {]],
+      [[      start1 = { 1, 1 },]],
+      [[      stop1 = { 4, 1 }]],
+      [[    },]],
+      [[    end_right_gravity = true,]],
+      [[    id = 1,]],
+      [[    ns_id = 623,]],
+      [[    ns_name = "my.renderer:91",]],
+      [[    right_gravity = false]],
+      [[  } }]],
+      [[]],
+    }
+    withbuf(lines, function()
+      local Buffer = require 'u.buffer'
+      R.Renderer.patch_lines(0, nil, lines)
+      assert.are.same(Buffer.current():all():lines(), lines)
+
+      R.Renderer.patch_lines(0, lines, lines)
+      assert.are.same(Buffer.current():all():lines(), lines)
+
+      R.Renderer.patch_lines(0, lines, lines)
+      assert.are.same(Buffer.current():all():lines(), lines)
+    end)
+  end)
+
+  it('should fire text-changed events', function()
+    withbuf({}, function()
+      local Buffer = require 'u.buffer'
+      local buf = Buffer.current()
+      local r = R.Renderer.new(0)
+      local captured_changed_text = ''
+      r:render {
+        R.h('text', {
+          on_change = function(txt) captured_changed_text = txt end,
+        }, {
+          'one\n',
+          'two\n',
+          'three\n',
+        }),
+      }
+
+      vim.fn.setreg('"', 'bleh')
+      vim.cmd [[normal! ggVGp]]
+      -- For some reason, the autocmd does not fire in the busted environment.
+      -- We'll call the handler ourselves:
+      r:_on_text_changed()
+
+      assert.are.same(buf:all():text(), 'bleh')
+      assert.are.same(captured_changed_text, 'bleh')
+
+      vim.fn.setreg('"', '')
+      vim.cmd [[normal! ggdG]]
+      -- We'll call the handler ourselves:
+      r:_on_text_changed()
+
+      assert.are.same(buf:all():text(), '')
+      assert.are.same(captured_changed_text, '')
+    end)
+
+    withbuf({}, function()
+      local Buffer = require 'u.buffer'
+      local buf = Buffer.current()
+      local r = R.Renderer.new(0)
+      --- @type string?
+      local captured_changed_text = nil
+      r:render {
+        'prefix:',
+        R.h('text', {
+          on_change = function(txt) captured_changed_text = txt end,
+        }, {
+          'one',
+        }),
+        'suffix',
+      }
+
+      vim.fn.setreg('"', 'bleh')
+      vim.api.nvim_win_set_cursor(0, { 1, 9 })
+      vim.cmd [[normal! vhhd]]
+      -- For some reason, the autocmd does not fire in the busted environment.
+      -- We'll call the handler ourselves:
+      r:_on_text_changed()
+
+      assert.are.same(buf:all():text(), 'prefix:suffix')
+      assert.are.same(captured_changed_text, '')
+    end)
+  end)
+
+  it('should find tags by position', function()
+    withbuf({}, function()
+      local r = R.Renderer.new(0)
+      r:render {
+        'pre',
+        R.h('text', {
+          id = 'outer',
+        }, {
+          'inner-pre',
+          R.h('text', {
+            id = 'inner',
+          }, {
+            'inner-text',
+          }),
+          'inner-post',
+        }),
+        'post',
+      }
+
+      local tags = r:get_tags_at { 0, 11 }
+      assert.are.same(#tags, 1)
+      assert.are.same(tags[1].tag.attributes.id, 'outer')
+
+      tags = r:get_tags_at { 0, 12 }
+      assert.are.same(#tags, 2)
+      assert.are.same(tags[1].tag.attributes.id, 'inner')
+      assert.are.same(tags[2].tag.attributes.id, 'outer')
+    end)
+  end)
+
+  it('should find tags by id', function()
+    withbuf({}, function()
+      local r = R.Renderer.new(0)
+      r:render {
+        R.h('text', {
+          id = 'outer',
+        }, {
+          'inner-pre',
+          R.h('text', {
+            id = 'inner',
+          }, {
+            'inner-text',
+          }),
+          'inner-post',
+        }),
+        'post',
+      }
+
+      local bounds = r:get_tag_bounds 'outer'
+      assert.are.same(bounds, { start = { 0, 0 }, stop = { 0, 29 } })
+
+      bounds = r:get_tag_bounds 'inner'
+      assert.are.same(bounds, { start = { 0, 9 }, stop = { 0, 19 } })
+    end)
+  end)
+
+  it('should mount and rerender components', function()
+    withbuf({}, function()
+      --- @type any
+      local leaked_state = { app = {}, c1 = {}, c2 = {} }
+
+      --- @param ctx u.renderer.FnComponentContext<any, { phase: string, count: integer }>
+      local function Counter(ctx)
+        if ctx.phase == 'mount' then ctx.state = { phase = ctx.phase, count = 1 } end
+        local state = assert(ctx.state)
+        state.phase = ctx.phase
+        leaked_state[ctx.props.id].ctx = ctx
+
+        return {
+          { 'Value: ', R.h.Number({}, tostring(state.count)) },
+        }
+      end
+
+      --- @param ctx u.renderer.FnComponentContext<any, {
+      ---   toggle1: boolean,
+      ---   show2: boolean
+      --- }>
+      function App(ctx)
+        if ctx.phase == 'mount' then ctx.state = { toggle1 = false, show2 = true } end
+        local state = assert(ctx.state)
+        leaked_state.app.ctx = ctx
+
+        return {
+          state.toggle1 and 'Toggle1' or R.h(Counter, { id = 'c1' }, {}),
+          '\n',
+
+          state.show2 and {
+            '\n',
+            R.h(Counter, { id = 'c2' }, {}),
+          },
+        }
+      end
+
+      local renderer = R.Renderer.new()
+      renderer:mount(R.h(App, {}, {}))
+
+      local Buffer = require 'u.buffer'
+      local buf = Buffer.current()
+      assert.are.same(buf:all():lines(), {
+        'Value: 1',
+        '',
+        'Value: 1',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'mount')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'mount')
+      leaked_state.app.ctx:update_immediate { toggle1 = true, show2 = true }
+      assert.are.same(buf:all():lines(), {
+        'Toggle1',
+        '',
+        'Value: 1',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'unmount')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'update')
+
+      leaked_state.app.ctx:update_immediate { toggle1 = true, show2 = false }
+      assert.are.same(buf:all():lines(), {
+        'Toggle1',
+        '',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'unmount')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'unmount')
+
+      leaked_state.app.ctx:update_immediate { toggle1 = false, show2 = true }
+      assert.are.same(buf:all():lines(), {
+        'Value: 1',
+        '',
+        'Value: 1',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'mount')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'mount')
+
+      leaked_state.c1.ctx:update_immediate { count = 2 }
+      assert.are.same(buf:all():lines(), {
+        'Value: 2',
+        '',
+        'Value: 1',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'update')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'update')
+
+      leaked_state.c2.ctx:update_immediate { count = 3 }
+      assert.are.same(buf:all():lines(), {
+        'Value: 2',
+        '',
+        'Value: 3',
+      })
+      assert.are.same(leaked_state.c1.ctx.state.phase, 'update')
+      assert.are.same(leaked_state.c2.ctx.state.phase, 'update')
+    end)
+  end)
 end)

spec/withbuf.lua

@@ -1,3 +1,4 @@
+require 'luacov'
 local function withbuf(lines, f)
   vim.go.swapfile = false
 

stylua.toml

@@ -1,6 +1,10 @@
+syntax = "LuaJIT"
 call_parentheses = "None"
 collapse_simple_statement = "Always"
 column_width = 100
 indent_type = "Spaces"
 indent_width = 2
 quote_style = "AutoPreferSingle"
+
+[sort_requires]
+enabled = true

vim.yml

@@ -1,36 +0,0 @@
----
-base: lua51
-globals:
-  vim:
-    any: true
-  assert.are.same:
-    args:
-      - type: any
-      - type: any
-  assert.are_not.same:
-    args:
-      - type: any
-      - type: any
-  assert.has.error:
-    args:
-      - type: any
-      - type: any
-  assert.is_true:
-    args:
-      - type: any
-      - type: any
-  assert.is_false:
-    args:
-      - type: any
-      - type: any
-  describe:
-    args:
-      - type: string
-      - type: function
-  it:
-    args:
-      - type: string
-      - type: function
-  before_each:
-    args:
-      - type: function