v0.1.3: Performance & stability improvements

- Fix: Removed duplicate line assignment in state.lua
- Fix: Cleaned up unused variables (bufnr in editor.lua, skipped_count in ui.lua)
- Perf: Replaced vim.deepcopy() with shallow copies for cursor positions
- Perf: Added O(1) hash-based lookups (cursor_set, skipped_set) for position checks
- Add: Buffer validity check in finder.find_matches()
- Add: editor.cleanup() for proper module state reset
- Add: keymaps.clear_global_keymaps() for plugin unload
- Remove: Unused 'current' highlight configuration

Author: khoido2003

CHANGELOG.md

@@ -2,8 +2,19 @@
 
 ## [0.1.3] - 2026-01-14
 
+### Fixed
+- **Duplicate Line Bug**: Removed duplicate assignment of `original_pos` in `state.lua`
+- **Unused Variables**: Cleaned up unused `bufnr` variables in `editor.lua` and `skipped_count` in `ui.lua`
+
+### Improved
+- **Memory Efficiency**: Replaced `vim.deepcopy()` with shallow copies in `state.lua` for cursor position tables (reduces allocation overhead)
+- **O(1) Position Lookups**: Added hash sets (`cursor_set`, `skipped_set`) for instant position checks instead of O(n) array scans - significant speedup with many matches
+- **Buffer Safety**: Added buffer validity check in `finder.find_matches()` to prevent errors on invalid buffers
+- **Resource Cleanup**: Added `editor.cleanup()` function to properly reset module state
+- **Keymap Management**: Added `keymaps.clear_global_keymaps()` for proper plugin unload cleanup
+
 ### Removed
-- **Unused `current` Highlight**: Removed the `current` highlight configuration (was defined but never used in highlighting logic). This simplifies the config without affecting functionality.
+- **Unused `current` Highlight**: Removed the `current` highlight configuration (was defined but never used)
 
 ---
 

lua/multiple-cursor/editor.lua

@@ -24,6 +24,15 @@ local function debug(msg)
   end
 end
 
+---Cleanup function to reset module state (prevents memory leaks)
+function M.cleanup()
+  edit_positions = {}
+  applying_changes = false
+  last_primary_length = 0
+  last_line_len = 0
+  pcall(vim.api.nvim_del_augroup_by_name, augroup_name)
+end
+
 ---Start editing mode - positions cursor at current word, does NOT delete
 function M.start_editing_mode()
   local bufnr = state.get_bufnr()
@@ -379,7 +388,6 @@ end
 
 ---Start editing at the start of all words (for 'I' key)
 function M.start_editing_at_start()
-  local bufnr = state.get_bufnr()
   local cursors = state.get_cursors()
 
   if #cursors == 0 then
@@ -397,7 +405,6 @@ end
 
 ---Start editing at the end of all words (for 'A' key)
 function M.start_editing_at_end()
-  local bufnr = state.get_bufnr()
   local cursors = state.get_cursors()
 
   if #cursors == 0 then

lua/multiple-cursor/finder.lua

@@ -51,6 +51,11 @@ function M.find_matches(word, bufnr)
     return matches
   end
 
+  -- Validate buffer before accessing
+  if not vim.api.nvim_buf_is_valid(bufnr) then
+    return matches
+  end
+
   local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
 
   -- Build search pattern

lua/multiple-cursor/keymaps.lua

@@ -94,6 +94,11 @@ function M.setup_global_keymaps(start_callback)
   local keys = opts.keymaps
 
   if keys.start_next and keys.start_next ~= false then
+    -- Track global keymaps for cleanup
+    M._global_keymaps = M._global_keymaps or {}
+    table.insert(M._global_keymaps, { mode = "n", lhs = keys.start_next })
+    table.insert(M._global_keymaps, { mode = "v", lhs = keys.start_next })
+
     vim.keymap.set("n", keys.start_next, start_callback, {
       noremap = true,
       silent = true,
@@ -114,4 +119,14 @@ function M.setup_global_keymaps(start_callback)
   end
 end
 
+---Clear global keymaps (for plugin unload)
+function M.clear_global_keymaps()
+  if M._global_keymaps then
+    for _, keymap in ipairs(M._global_keymaps) do
+      pcall(vim.keymap.del, keymap.mode, keymap.lhs)
+    end
+    M._global_keymaps = {}
+  end
+end
+
 return M

lua/multiple-cursor/state.lua

@@ -17,6 +17,12 @@
 
 local M = {}
 
+-- Helper to create a unique numeric key from line and col_start
+-- Using multiplication to create a unique key (supports up to 1M columns per line)
+local function make_key(line, col_start)
+  return line * 1000000 + col_start
+end
+
 ---@type MultipleCursor.State
 M.state = {
   active = false,
@@ -25,6 +31,9 @@ M.state = {
   cursors = {},
   matches = {},
   skipped = {},
+  -- Hash sets for O(1) lookups
+  cursor_set = {},
+  skipped_set = {},
   current_idx = 0,
   namespace = 0,
   original_pos = {},
@@ -45,6 +54,8 @@ function M.reset()
   M.state.cursors = {}
   M.state.matches = {}
   M.state.skipped = {}
+  M.state.cursor_set = {}
+  M.state.skipped_set = {}
   M.state.current_idx = 0
   M.state.original_pos = {}
 end
@@ -72,9 +83,10 @@ function M.start(word, bufnr, matches)
   M.state.matches = matches
   M.state.cursors = {}
   M.state.skipped = {}
+  M.state.cursor_set = {}
+  M.state.skipped_set = {}
   M.state.current_idx = 1
   M.state.original_pos = vim.api.nvim_win_get_cursor(0)
-  M.state.original_pos = vim.api.nvim_win_get_cursor(0)
 end
 
 ---Update matches and current word (e.g. after editing)
@@ -86,43 +98,48 @@ function M.update_matches(word, matches)
   -- Current cursors remain selected; we don't reset them
 end
 
----Add a cursor at the current match
----@return boolean success
 function M.add_cursor()
   if M.state.current_idx > #M.state.matches then
     return false
   end
 
   local match = M.state.matches[M.state.current_idx]
-  table.insert(M.state.cursors, vim.deepcopy(match))
+  -- Shallow copy is sufficient since CursorPosition only contains primitives
+  table.insert(M.state.cursors, { line = match.line, col_start = match.col_start, col_end = match.col_end })
+  -- Update hash set
+  M.state.cursor_set[make_key(match.line, match.col_start)] = true
   M.state.current_idx = M.state.current_idx + 1
   return true
 end
 
----Skip the current match
----@return boolean success
 function M.skip_current()
   if M.state.current_idx > #M.state.matches then
     return false
   end
 
   -- Store the skipped match for potential re-selection
   local skipped_match = M.state.matches[M.state.current_idx]
-  table.insert(M.state.skipped, vim.deepcopy(skipped_match))
+  table.insert(
+    M.state.skipped,
+    { line = skipped_match.line, col_start = skipped_match.col_start, col_end = skipped_match.col_end }
+  )
+  -- Update hash set
+  M.state.skipped_set[make_key(skipped_match.line, skipped_match.col_start)] = true
 
   M.state.current_idx = M.state.current_idx + 1
   return true
 end
 
----Re-select the last skipped match
----@return boolean success
 function M.reselect_last()
   if #M.state.skipped == 0 then
     return false
   end
 
   -- Get the last skipped match
   local last_skipped = table.remove(M.state.skipped)
+  -- Update hash sets
+  M.state.skipped_set[make_key(last_skipped.line, last_skipped.col_start)] = nil
+  M.state.cursor_set[make_key(last_skipped.line, last_skipped.col_start)] = true
 
   -- Add it to cursors
   table.insert(M.state.cursors, last_skipped)
@@ -136,25 +153,26 @@ function M.get_skipped()
   return M.state.skipped
 end
 
----Remove the last added cursor (does NOT add to skipped - just removes)
----@return boolean success
 function M.remove_last()
   if #M.state.cursors == 0 then
     return false
   end
 
-  table.remove(M.state.cursors)
+  local removed = table.remove(M.state.cursors)
+  -- Update hash set
+  M.state.cursor_set[make_key(removed.line, removed.col_start)] = nil
   return true
 end
 
----Remove the last added cursor AND add it to skipped list
----@return boolean success
 function M.remove_last_to_skipped()
   if #M.state.cursors == 0 then
     return false
   end
 
   local removed = table.remove(M.state.cursors)
+  -- Update hash sets
+  M.state.cursor_set[make_key(removed.line, removed.col_start)] = nil
+  M.state.skipped_set[make_key(removed.line, removed.col_start)] = true
   table.insert(M.state.skipped, removed)
   return true
 end
@@ -172,28 +190,38 @@ function M.get_match_at_position(line, col)
   return nil, nil
 end
 
----Check if position is already in cursors (selected)
+---Check if position is already in cursors (selected) - O(1) lookup
 ---@param line number
 ---@param col_start number
----@return boolean, number? is_selected and index in cursors
+---@return boolean, number? is_selected and index in cursors (index only if needed)
 function M.is_position_selected(line, col_start)
-  for i, cursor in ipairs(M.state.cursors) do
-    if cursor.line == line and cursor.col_start == col_start then
-      return true, i
+  local key = make_key(line, col_start)
+  if M.state.cursor_set[key] then
+    -- Only compute index if needed (for removal operations)
+    for i, cursor in ipairs(M.state.cursors) do
+      if cursor.line == line and cursor.col_start == col_start then
+        return true, i
+      end
     end
+    return true, nil
   end
   return false, nil
 end
 
----Check if position is in skipped list
+---Check if position is in skipped list - O(1) lookup
 ---@param line number
 ---@param col_start number
----@return boolean, number? is_skipped and index in skipped
+---@return boolean, number? is_skipped and index in skipped (index only if needed)
 function M.is_position_skipped(line, col_start)
-  for i, skip in ipairs(M.state.skipped) do
-    if skip.line == line and skip.col_start == col_start then
-      return true, i
+  local key = make_key(line, col_start)
+  if M.state.skipped_set[key] then
+    -- Only compute index if needed (for removal operations)
+    for i, skip in ipairs(M.state.skipped) do
+      if skip.line == line and skip.col_start == col_start then
+        return true, i
+      end
     end
+    return true, nil
   end
   return false, nil
 end
@@ -208,52 +236,64 @@ function M.add_cursor_at_position(line, col)
     return false
   end
 
-  if M.is_position_selected(match.line, match.col_start) then
+  local key = make_key(match.line, match.col_start)
+  if M.state.cursor_set[key] then
     return false
   end
 
-  local is_skipped, skip_idx = M.is_position_skipped(match.line, match.col_start)
-  if is_skipped and skip_idx then
-    table.remove(M.state.skipped, skip_idx)
+  -- Remove from skipped if present
+  if M.state.skipped_set[key] then
+    M.state.skipped_set[key] = nil
+    for i, skip in ipairs(M.state.skipped) do
+      if skip.line == match.line and skip.col_start == match.col_start then
+        table.remove(M.state.skipped, i)
+        break
+      end
+    end
   end
 
-  table.insert(M.state.cursors, vim.deepcopy(match))
+  table.insert(M.state.cursors, { line = match.line, col_start = match.col_start, col_end = match.col_end })
+  M.state.cursor_set[key] = true
   return true
 end
 
----Skip/remove cursor at specific position
----@param line number
----@param col number
----@return boolean success, string action ("skipped" or "removed" or nil)
 function M.skip_at_position(line, col)
   local match, _ = M.get_match_at_position(line, col)
   if not match then
     return false, nil
   end
 
-  local is_selected, cursor_idx = M.is_position_selected(match.line, match.col_start)
-  if is_selected and cursor_idx then
-    local removed = table.remove(M.state.cursors, cursor_idx)
-    table.insert(M.state.skipped, removed)
-    return true, "removed"
+  local key = make_key(match.line, match.col_start)
+
+  -- If selected, move to skipped
+  if M.state.cursor_set[key] then
+    M.state.cursor_set[key] = nil
+    for i, cursor in ipairs(M.state.cursors) do
+      if cursor.line == match.line and cursor.col_start == match.col_start then
+        local removed = table.remove(M.state.cursors, i)
+        table.insert(M.state.skipped, removed)
+        M.state.skipped_set[key] = true
+        return true, "removed"
+      end
+    end
   end
 
-  if not M.is_position_skipped(match.line, match.col_start) then
-    table.insert(M.state.skipped, vim.deepcopy(match))
+  -- If not skipped, add to skipped
+  if not M.state.skipped_set[key] then
+    table.insert(M.state.skipped, { line = match.line, col_start = match.col_start, col_end = match.col_end })
+    M.state.skipped_set[key] = true
     return true, "skipped"
   end
 
   return false, nil
 end
 
----Select all remaining matches
 function M.select_all()
   for _, match in ipairs(M.state.matches) do
-    if
-      not M.is_position_selected(match.line, match.col_start)
-      and not M.is_position_skipped(match.line, match.col_start)
-    then
-      table.insert(M.state.cursors, vim.deepcopy(match))
+    local key = make_key(match.line, match.col_start)
+    if not M.state.cursor_set[key] and not M.state.skipped_set[key] then
+      table.insert(M.state.cursors, { line = match.line, col_start = match.col_start, col_end = match.col_end })
+      M.state.cursor_set[key] = true
     end
   end
 end

lua/multiple-cursor/ui.lua

@@ -314,7 +314,7 @@ function M.update_highlights()
   end
 
   -- Add virtual text showing count
-  local total, selected, skipped_count = state.get_counts()
+  local total, selected, _skipped_count = state.get_counts()
   local status_text = string.format(" [%d/%d] selected", selected, total)
 
   -- Show status in virtual text at the end of current line