fix(tohtml): support ranges again

4 files changed, 94 insertions, 42 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index 57796a4716..c1ffc41c24 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -4412,7 +4412,7 @@ vim.text.hexencode({str})                               *vim.text.hexencode()*
 Lua module: tohtml                                                *vim.tohtml*
 
 
-:TOhtml {file}                                                       *:TOhtml*
+:[range]TOhtml {file}                                                *:TOhtml*
 Converts the buffer shown in the current window to HTML, opens the generated
 HTML in a new split window, and saves its contents to {file}. If {file} is not
 given, a temporary file (created by |tempname()|) is used.
@@ -4434,6 +4434,8 @@ tohtml.tohtml({winid}, {opt})                         *tohtml.tohtml.tohtml()*
                  • {width}? (`integer`, default: 'textwidth' if non-zero or
                    window width otherwise) Width used for items which are
                    either right aligned or repeat a character infinitely.
+                 • {range}? (`integer[]`, default: entire buffer) Range of
+                   rows to use.
 
     Return: ~
         (`string[]`)
diff --git a/runtime/lua/tohtml.lua b/runtime/lua/tohtml.lua
index 7bb4a26ad6..a4b5a741bc 100644
--- a/runtime/lua/tohtml.lua
+++ b/runtime/lua/tohtml.lua
@@ -1,6 +1,6 @@
 --- @brief
 ---<pre>help
----:TOhtml {file}                                                       *:TOhtml*
+---:[range]TOhtml {file}                                                *:TOhtml*
 ---Converts the buffer shown in the current window to HTML, opens the generated
 ---HTML in a new split window, and saves its contents to {file}. If {file} is not
 ---given, a temporary file (created by |tempname()|) is used.
@@ -40,7 +40,8 @@
 --- @field winid integer
 --- @field bufnr integer
 --- @field width integer
---- @field buflen integer
+--- @field start integer
+--- @field end_ integer
 
 --- @class (private) vim.tohtml.styletable
 --- @field [integer] vim.tohtml.line (integer: (1-index, exclusive))
@@ -393,7 +394,7 @@ end
 
 --- @param state vim.tohtml.state
 local function styletable_syntax(state)
-  for row = 1, state.buflen do
+  for row = state.start, state.end_ do
     local prev_id = 0
     local prev_col = nil
     for col = 1, #vim.fn.getline(row) + 1 do
@@ -413,7 +414,7 @@ end
 --- @param state vim.tohtml.state
 local function styletable_diff(state)
   local styletable = state.style
-  for row = 1, state.buflen do
+  for row = state.start, state.end_ do
     local style_line = styletable[row]
     local filler = vim.fn.diff_filler(row)
     if filler ~= 0 then
@@ -423,7 +424,7 @@ local function styletable_diff(state)
         { { fill:rep(state.width), register_hl(state, 'DiffDelete') } }
       )
     end
-    if row == state.buflen + 1 then
+    if row == state.end_ + 1 then
       break
     end
     local prev_id = 0
@@ -465,7 +466,9 @@ local function styletable_treesitter(state)
     if not query then
       return
     end
-    for capture, node, metadata in query:iter_captures(root, buf_highlighter.bufnr, 0, state.buflen) do
+    for capture, node, metadata in
+      query:iter_captures(root, buf_highlighter.bufnr, state.start - 1, state.end_)
+    do
       local srow, scol, erow, ecol = node:range()
       --- @diagnostic disable-next-line: invisible
       local c = q._query.captures[capture]
@@ -519,7 +522,7 @@ local function _styletable_extmarks_virt_text(state, extmark, namespaces)
   --- @type integer,integer
   local row, col = extmark[2], extmark[3]
   if
-    row < state.buflen
+    row < vim.api.nvim_buf_line_count(state.bufnr)
     and (
       extmark[4].virt_text_pos == 'inline'
       or extmark[4].virt_text_pos == 'eol'
@@ -628,7 +631,7 @@ end
 local function styletable_folds(state)
   local styletable = state.style
   local has_folded = false
-  for row = 1, state.buflen do
+  for row = state.start, state.end_ do
     if vim.fn.foldclosed(row) > 0 then
       has_folded = true
       styletable[row].hide = true
@@ -650,7 +653,7 @@ end
 local function styletable_conceal(state)
   local bufnr = state.bufnr
   vim._with({ buf = bufnr }, function()
-    for row = 1, state.buflen do
+    for row = state.start, state.end_ do
       --- @type table<integer,[integer,integer,string]>
       local conceals = {}
       local line_len_exclusive = #vim.fn.getline(row) + 1
@@ -768,7 +771,7 @@ local function styletable_statuscolumn(state)
       local max = tonumber(foldcolumn:match('^%w-:(%d)')) or 1
       local maxfold = 0
       vim._with({ buf = state.bufnr }, function()
-        for row = 1, vim.api.nvim_buf_line_count(state.bufnr) do
+        for row = state.start, state.end_ do
           local foldlevel = vim.fn.foldlevel(row)
           if foldlevel > maxfold then
             maxfold = foldlevel
@@ -783,7 +786,7 @@ local function styletable_statuscolumn(state)
 
   --- @type table<integer,any>
   local statuses = {}
-  for row = 1, state.buflen do
+  for row = state.start, state.end_ do
     local status = vim.api.nvim_eval_statusline(
       statuscolumn,
       { winid = state.winid, use_statuscol_lnum = row, highlights = true }
@@ -833,7 +836,7 @@ local function styletable_listchars(state)
   })
 
   if listchars.eol then
-    for row = 1, state.buflen do
+    for row = state.start, state.end_ do
       local style_line = state.style[row]
       style_line_insert_overlay_char(
         style_line,
@@ -1127,16 +1130,22 @@ end
 local function extend_pre(out, state)
   local styletable = state.style
   table.insert(out, '<pre>')
+  local out_start = #out
   local hide_count = 0
   --- @type integer[]
   local stack = {}
 
+  local before = ''
+  local after = ''
   local function loop(row)
+    local inside = row <= state.end_ and row >= state.start
     local style_line = styletable[row]
     if style_line.hide and (styletable[row - 1] or {}).hide then
       return
     end
-    _extend_virt_lines(out, state, row)
+    if inside then
+      _extend_virt_lines(out, state, row)
+    end
     --Possible improvement (altermo):
     --Instead of looping over all the buffer characters per line,
     --why not loop over all the style_line cells,
@@ -1146,7 +1155,9 @@ local function extend_pre(out, state)
     end
     local line = vim.api.nvim_buf_get_lines(state.bufnr, row - 1, row, false)[1] or ''
     local s = ''
-    s = s .. _pre_text_to_html(state, row)
+    if inside then
+      s = s .. _pre_text_to_html(state, row)
+    end
     local true_line_len = #line + 1
     for k in pairs(style_line) do
       if type(k) == 'number' and k > true_line_len then
@@ -1193,7 +1204,7 @@ local function extend_pre(out, state)
           end
         end
 
-        if cell[3] then
+        if cell[3] and inside then
           s = s .. _virt_text_to_html(state, cell)
         end
 
@@ -1204,7 +1215,7 @@ local function extend_pre(out, state)
         break
       end
 
-      if hide_count == 0 then
+      if hide_count == 0 and inside then
         s = s
           .. _char_to_html(
             state,
@@ -1213,12 +1224,20 @@ local function extend_pre(out, state)
           )
       end
     end
-    table.insert(out, s)
+    if row > state.end_ + 1 then
+      after = after .. s
+    elseif row < state.start then
+      before = s .. before
+    else
+      table.insert(out, s)
+    end
   end
 
-  for row = 1, state.buflen + 1 do
+  for row = 1, vim.api.nvim_buf_line_count(state.bufnr) + 1 do
     loop(row)
   end
+  out[out_start] = out[out_start] .. before
+  out[#out] = out[#out] .. after
   assert(#stack == 0, 'an open HTML tag was never closed')
   table.insert(out, '</pre>')
 end
@@ -1250,6 +1269,7 @@ local function global_state_to_state(winid, global_state)
   if not width or width < 1 then
     width = vim.api.nvim_win_get_width(winid)
   end
+  local range = opt.range or { 1, vim.api.nvim_buf_line_count(bufnr) }
   local state = setmetatable({
     winid = winid == 0 and vim.api.nvim_get_current_win() or winid,
     opt = vim.wo[winid],
@@ -1257,7 +1277,8 @@ local function global_state_to_state(winid, global_state)
     bufnr = bufnr,
     tabstop = (' '):rep(vim.bo[bufnr].tabstop),
     width = width,
-    buflen = vim.api.nvim_buf_line_count(bufnr),
+    start = range[1],
+    end_ = range[2],
   }, { __index = global_state })
   return state --[[@as vim.tohtml.state]]
 end
@@ -1316,35 +1337,22 @@ local function state_generate_style(state)
   end)
 end
 
---- @param winid integer[]|integer
+--- @param winid integer
 --- @param opt? vim.tohtml.opt
 --- @return string[]
 local function win_to_html(winid, opt)
-  if type(winid) == 'number' then
-    winid = { winid }
-  end
-  --- @cast winid integer[]
-  assert(#winid > 0, 'no window specified')
   opt = opt or {}
-  local title = table.concat(
-    vim.tbl_map(vim.api.nvim_buf_get_name, vim.tbl_map(vim.api.nvim_win_get_buf, winid)),
-    ','
-  )
+  local title = vim.api.nvim_buf_get_name(vim.api.nvim_win_get_buf(winid))
+
   local global_state = opt_to_global_state(opt, title)
-  --- @type vim.tohtml.state[]
-  local states = {}
-  for _, i in ipairs(winid) do
-    local state = global_state_to_state(i, global_state)
-    state_generate_style(state)
-    table.insert(states, state)
-  end
+  local state = global_state_to_state(winid, global_state)
+  state_generate_style(state)
+
   local html = {}
   extend_html(html, function()
     extend_head(html, global_state)
     extend_body(html, function()
-      for _, state in ipairs(states) do
-        extend_pre(html, state)
-      end
+      extend_pre(html, state)
     end)
   end)
   return html
@@ -1371,6 +1379,10 @@ local M = {}
 --- infinitely.
 --- (default: 'textwidth' if non-zero or window width otherwise)
 --- @field width? integer
+---
+--- Range of rows to use.
+--- (default: entire buffer)
+--- @field range? integer[]
 
 --- Converts the buffer shown in the window {winid} to HTML and returns the output as a list of string.
 --- @param winid? integer Window to convert (defaults to current window)
diff --git a/runtime/plugin/tohtml.lua b/runtime/plugin/tohtml.lua
index 79f2794a40..0cb4562938 100644
--- a/runtime/plugin/tohtml.lua
+++ b/runtime/plugin/tohtml.lua
@@ -5,8 +5,8 @@ vim.g.loaded_2html_plugin = true
 
 vim.api.nvim_create_user_command('TOhtml', function(args)
   local outfile = args.args ~= '' and args.args or vim.fn.tempname() .. '.html'
-  local html = require('tohtml').tohtml()
+  local html = require('tohtml').tohtml(0, { range = { args.line1, args.line2 } })
   vim.fn.writefile(html, outfile)
   vim.cmd.split(outfile)
   vim.bo.filetype = 'html'
-end, { bar = true, nargs = '?' })
+end, { bar = true, nargs = '?', range = '%' })
diff --git a/test/functional/plugin/tohtml_spec.lua b/test/functional/plugin/tohtml_spec.lua
index be5bada901..827db8c0f3 100644
--- a/test/functional/plugin/tohtml_spec.lua
+++ b/test/functional/plugin/tohtml_spec.lua
@@ -176,6 +176,44 @@ describe(':TOhtml', function()
     }, fn.readfile(out_file))
   end)
 
+  it('expected internal html generated from range', function()
+    insert([[
+    line1
+    line2
+    line3
+    ]])
+    local ns = api.nvim_create_namespace ''
+    api.nvim_buf_set_extmark(0, ns, 0, 0, { end_col = 1, end_row = 1, hl_group = 'Visual' })
+    exec('set termguicolors')
+    local bg = fn.synIDattr(fn.hlID('Normal'), 'bg#', 'gui')
+    local fg = fn.synIDattr(fn.hlID('Normal'), 'fg#', 'gui')
+    exec_lua [[
+    local html = vim.cmd'2,2TOhtml'
+    ]]
+    local out_file = api.nvim_buf_get_name(api.nvim_get_current_buf())
+    eq({
+      '<!DOCTYPE html>',
+      '<html>',
+      '<head>',
+      '<meta charset="UTF-8">',
+      '<title></title>',
+      ('<meta name="colorscheme" content="%s"></meta>'):format(api.nvim_get_var('colors_name')),
+      '<style>',
+      '* {font-family: monospace}',
+      ('body {background-color: %s; color: %s}'):format(bg, fg),
+      '.Visual {background-color: #9b9ea4}',
+      '</style>',
+      '</head>',
+      '<body style="display: flex">',
+      '<pre><span class="Visual">',
+      'l</span>ine2',
+      '',
+      '</pre>',
+      '</body>',
+      '</html>',
+    }, fn.readfile(out_file))
+  end)
+
   it('highlight attributes generated', function()
     --Make sure to uncomment the attribute in `html_syntax_match()`
     exec('hi LINE gui=' .. table.concat({