REWRITE

plugin/virt-column.lua

@@ -0,0 +1,115 @@
+--- vim.g.virtcolumn: equal to global colorcolumn
+--- vim.b.virtcolumn: equal to local colorcolumn
+--- vim.g.virtcolumn_char: ▕ by default
+
+local api = vim.api
+local fn = vim.fn
+local ffi = require "ffi"
+
+ffi.cdef "int curwin_col_off(void);"
+---@diagnostic disable-next-line: undefined-field
+local curwin_col_off = ffi.C.curwin_col_off
+
+local NS = api.nvim_create_namespace "virt-column"
+
+local function _refresh()
+    local bufnr = api.nvim_get_current_buf()
+    if not api.nvim_buf_is_loaded(bufnr) then
+        return
+    end
+
+    local textwidth = vim.opt.textwidth:get()
+    local virtcolumns = vim.split(vim.b.virtcolumn or vim.g.virtcolumn or vim.o.cc, ",")
+
+    ---@type number[]
+    local items = {}
+
+    for _, virtcolumn in ipairs(virtcolumns) do
+        if virtcolumn and virtcolumn ~= "" then
+            if vim.startswith(virtcolumn, "+") then
+                if textwidth ~= 0 then
+                    table.insert(items, textwidth + tonumber(virtcolumn:sub(2)))
+                end
+            elseif vim.startswith(virtcolumn, "-") then
+                if textwidth ~= 0 then
+                    table.insert(items, textwidth - tonumber(virtcolumn:sub(2)))
+                end
+            else
+                table.insert(items, tonumber(virtcolumn))
+            end
+        end
+    end
+    table.sort(items, function(a, b)
+        return a > b
+    end)
+
+    api.nvim_buf_clear_namespace(bufnr, NS, 0, -1)
+
+    if #items == 0 then
+        return
+    end
+
+    local win_lines = vim.o.lines
+    local offset = vim.fn.line "w0"
+    -- Avoid flickering caused by winscrolled_timer
+    offset = offset <= win_lines and 1 or offset - win_lines
+
+    --                                                  Avoid flickering caused by winscrolled_timer
+    --                                                                       ↓↓↓↓↓↓↓↓↓↓↓
+    local lines = api.nvim_buf_get_lines(bufnr, offset - 1, vim.fn.line "w$" + win_lines, false)
+    local width = api.nvim_win_get_width(0) - curwin_col_off()
+    local tabstop = vim.opt.tabstop:get()
+    local char = vim.g.virtcolumn_char or "▕"
+
+    for i = 1, #lines do
+        for _, item in ipairs(items) do
+            local line = lines[i]:gsub("\t", string.rep(" ", tabstop))
+            if width > item and api.nvim_strwidth(line) < item then
+                api.nvim_buf_set_extmark(bufnr, NS, i + offset - 2, 0, {
+                    virt_text = { { char, "VirtColumn" } },
+                    virt_text_pos = "overlay",
+                    hl_mode = "combine",
+                    virt_text_win_col = item - 1,
+                    priority = 0,
+                })
+            end
+        end
+    end
+end
+
+-- Avoid unnecessary refreshing as much as possible
+local winscrolled_timer
+local function refresh(args)
+    ---@type string
+    local event = args.event or ""
+    if event == "WinScrolled" then
+        if winscrolled_timer and winscrolled_timer:is_active() then
+            winscrolled_timer:stop()
+            winscrolled_timer:close()
+        end
+        winscrolled_timer = vim.defer_fn(_refresh, 100)
+    elseif event:match "TextChanged" then
+        local lines_count = fn.line "$"
+        local need_refresh = vim.b.virtcolumn_lines_count ~= lines_count
+        vim.b.virtcolumn_lines_count = lines_count
+        if need_refresh then
+            _refresh()
+        end
+    end
+end
+
+local function set_hl()
+    vim.cmd [[
+      hi clear ColorColumn
+      hi default link VirtColumn NonText
+    ]]
+end
+set_hl()
+
+local group = api.nvim_create_augroup("virtcolumn", {})
+api.nvim_create_autocmd(
+    { "WinScrolled", "TextChanged", "TextChangedI", "BufWinEnter", "InsertLeave" },
+    { group = group, callback = refresh }
+)
+api.nvim_create_autocmd("OptionSet", { group = group, callback = refresh, pattern = "colorcolumn" })
+api.nvim_create_autocmd("ColorScheme", { group = group, callback = set_hl })