1 files changed, 399 insertions, 0 deletions
diff --git a/scripts/util.lua b/scripts/util.lua
new file mode 100644
index 0000000000..5940221abe
--- /dev/null
+++ b/scripts/util.lua
@@ -0,0 +1,399 @@
+-- TODO(justinmk): move most of this to `vim.text`.
+
+local fmt = string.format
+
+--- @class nvim.util.MDNode
+--- @field [integer] nvim.util.MDNode
+--- @field type string
+--- @field text? string
+
+local INDENTATION = 4
+
+local NBSP = string.char(160)
+
+local M = {}
+
+local function contains(t, xs)
+  return vim.tbl_contains(xs, t)
+end
+
+-- Map of api_level:version, by inspection of:
+--    :lua= vim.mpack.decode(vim.fn.readfile('test/functional/fixtures/api_level_9.mpack','B')).version
+M.version_level = {
+  [13] = '0.11.0',
+  [12] = '0.10.0',
+  [11] = '0.9.0',
+  [10] = '0.8.0',
+  [9] = '0.7.0',
+  [8] = '0.6.0',
+  [7] = '0.5.0',
+  [6] = '0.4.0',
+  [5] = '0.3.2',
+  [4] = '0.3.0',
+  [3] = '0.2.1',
+  [2] = '0.2.0',
+  [1] = '0.1.0',
+}
+
+--- @param txt string
+--- @param srow integer
+--- @param scol integer
+--- @param erow? integer
+--- @param ecol? integer
+--- @return string
+local function slice_text(txt, srow, scol, erow, ecol)
+  local lines = vim.split(txt, '\n')
+
+  if srow == erow then
+    return lines[srow + 1]:sub(scol + 1, ecol)
+  end
+
+  if erow then
+    -- Trim the end
+    for _ = erow + 2, #lines do
+      table.remove(lines, #lines)
+    end
+  end
+
+  -- Trim the start
+  for _ = 1, srow do
+    table.remove(lines, 1)
+  end
+
+  lines[1] = lines[1]:sub(scol + 1)
+  lines[#lines] = lines[#lines]:sub(1, ecol)
+
+  return table.concat(lines, '\n')
+end
+
+--- @param text string
+--- @return nvim.util.MDNode
+local function parse_md_inline(text)
+  local parser = vim.treesitter.languagetree.new(text, 'markdown_inline')
+  local root = parser:parse(true)[1]:root()
+
+  --- @param node TSNode
+  --- @return nvim.util.MDNode?
+  local function extract(node)
+    local ntype = node:type()
+
+    if ntype:match('^%p$') then
+      return
+    end
+
+    --- @type table<any,any>
+    local ret = { type = ntype }
+    ret.text = vim.treesitter.get_node_text(node, text)
+
+    local row, col = 0, 0
+
+    for child, child_field in node:iter_children() do
+      local e = extract(child)
+      if e and ntype == 'inline' then
+        local srow, scol = child:start()
+        if (srow == row and scol > col) or srow > row then
+          local t = slice_text(ret.text, row, col, srow, scol)
+          if t and t ~= '' then
+            table.insert(ret, { type = 'text', j = true, text = t })
+          end
+        end
+        row, col = child:end_()
+      end
+
+      if child_field then
+        ret[child_field] = e
+      else
+        table.insert(ret, e)
+      end
+    end
+
+    if ntype == 'inline' and (row > 0 or col > 0) then
+      local t = slice_text(ret.text, row, col)
+      if t and t ~= '' then
+        table.insert(ret, { type = 'text', text = t })
+      end
+    end
+
+    return ret
+  end
+
+  return extract(root) or {}
+end
+
+--- @param text string
+--- @return nvim.util.MDNode
+local function parse_md(text)
+  local parser = vim.treesitter.languagetree.new(text, 'markdown', {
+    injections = { markdown = '' },
+  })
+
+  local root = parser:parse(true)[1]:root()
+
+  local EXCLUDE_TEXT_TYPE = {
+    list = true,
+    list_item = true,
+    section = true,
+    document = true,
+    fenced_code_block = true,
+    fenced_code_block_delimiter = true,
+  }
+
+  --- @param node TSNode
+  --- @return nvim.util.MDNode?
+  local function extract(node)
+    local ntype = node:type()
+
+    if ntype:match('^%p$') or contains(ntype, { 'block_continuation' }) then
+      return
+    end
+
+    --- @type table<any,any>
+    local ret = { type = ntype }
+
+    if not EXCLUDE_TEXT_TYPE[ntype] then
+      ret.text = vim.treesitter.get_node_text(node, text)
+    end
+
+    if ntype == 'inline' then
+      ret = parse_md_inline(ret.text)
+    end
+
+    for child, child_field in node:iter_children() do
+      local e = extract(child)
+      if child_field then
+        ret[child_field] = e
+      else
+        table.insert(ret, e)
+      end
+    end
+
+    return ret
+  end
+
+  return extract(root) or {}
+end
+
+--- Prefixes each line in `text`.
+---
+--- Does not wrap, not important for "meta" files? (You probably want md_to_vimdoc instead.)
+---
+--- @param text string
+--- @param prefix_ string
+function M.prefix_lines(prefix_, text)
+  local r = ''
+  for _, l in ipairs(vim.split(text, '\n', { plain = true })) do
+    r = r .. vim.trim(prefix_ .. l) .. '\n'
+  end
+  return r
+end
+
+--- @param x string
+--- @param start_indent integer
+--- @param indent integer
+--- @param text_width integer
+--- @return string
+function M.wrap(x, start_indent, indent, text_width)
+  local words = vim.split(vim.trim(x), '%s+')
+  local parts = { string.rep(' ', start_indent) } --- @type string[]
+  local count = indent
+
+  for i, w in ipairs(words) do
+    if count > indent and count + #w > text_width - 1 then
+      parts[#parts + 1] = '\n'
+      parts[#parts + 1] = string.rep(' ', indent)
+      count = indent
+    elseif i ~= 1 then
+      parts[#parts + 1] = ' '
+      count = count + 1
+    end
+    count = count + #w
+    parts[#parts + 1] = w
+  end
+
+  return (table.concat(parts):gsub('%s+\n', '\n'):gsub('\n+$', ''))
+end
+
+--- @param node nvim.util.MDNode
+--- @param start_indent integer
+--- @param indent integer
+--- @param text_width integer
+--- @param level integer
+--- @return string[]
+local function render_md(node, start_indent, indent, text_width, level, is_list)
+  local parts = {} --- @type string[]
+
+  -- For debugging
+  local add_tag = false
+  -- local add_tag = true
+
+  local ntype = node.type
+
+  if add_tag then
+    parts[#parts + 1] = '<' .. ntype .. '>'
+  end
+
+  if ntype == 'text' then
+    parts[#parts + 1] = node.text
+  elseif ntype == 'html_tag' then
+    error('html_tag: ' .. node.text)
+  elseif ntype == 'inline_link' then
+    vim.list_extend(parts, { '*', node[1].text, '*' })
+  elseif ntype == 'shortcut_link' then
+    if node[1].text:find('^<.*>$') then
+      parts[#parts + 1] = node[1].text
+    elseif node[1].text:find('^%d+$') then
+      vim.list_extend(parts, { '[', node[1].text, ']' })
+    else
+      vim.list_extend(parts, { '|', node[1].text, '|' })
+    end
+  elseif ntype == 'backslash_escape' then
+    parts[#parts + 1] = node.text
+  elseif ntype == 'emphasis' then
+    parts[#parts + 1] = node.text:sub(2, -2)
+  elseif ntype == 'code_span' then
+    vim.list_extend(parts, { '`', node.text:sub(2, -2):gsub(' ', NBSP), '`' })
+  elseif ntype == 'inline' then
+    if #node == 0 then
+      local text = assert(node.text)
+      parts[#parts + 1] = M.wrap(text, start_indent, indent, text_width)
+    else
+      for _, child in ipairs(node) do
+        vim.list_extend(parts, render_md(child, start_indent, indent, text_width, level + 1))
+      end
+    end
+  elseif ntype == 'paragraph' then
+    local pparts = {}
+    for _, child in ipairs(node) do
+      vim.list_extend(pparts, render_md(child, start_indent, indent, text_width, level + 1))
+    end
+    parts[#parts + 1] = M.wrap(table.concat(pparts), start_indent, indent, text_width)
+    parts[#parts + 1] = '\n'
+  elseif ntype == 'code_fence_content' then
+    local lines = vim.split(node.text:gsub('\n%s*$', ''), '\n')
+
+    local cindent = indent + INDENTATION
+    if level > 3 then
+      -- The tree-sitter markdown parser doesn't parse the code blocks indents
+      -- correctly in lists. Fudge it!
+      lines[1] = '    ' .. lines[1] -- ¯\_(ツ)_/¯
+      cindent = indent - level
+      local _, initial_indent = lines[1]:find('^%s*')
+      initial_indent = initial_indent + cindent
+      if initial_indent < indent then
+        cindent = indent - INDENTATION
+      end
+    end
+
+    for _, l in ipairs(lines) do
+      if #l > 0 then
+        parts[#parts + 1] = string.rep(' ', cindent)
+        parts[#parts + 1] = l
+      end
+      parts[#parts + 1] = '\n'
+    end
+  elseif ntype == 'fenced_code_block' then
+    parts[#parts + 1] = '>'
+    for _, child in ipairs(node) do
+      if child.type == 'info_string' then
+        parts[#parts + 1] = child.text
+        break
+      end
+    end
+    parts[#parts + 1] = '\n'
+    for _, child in ipairs(node) do
+      if child.type ~= 'info_string' then
+        vim.list_extend(parts, render_md(child, start_indent, indent, text_width, level + 1))
+      end
+    end
+    parts[#parts + 1] = '<\n'
+  elseif ntype == 'html_block' then
+    local text = node.text:gsub('^<pre>help', '')
+    text = text:gsub('</pre>%s*$', '')
+    parts[#parts + 1] = text
+  elseif ntype == 'list_marker_dot' then
+    parts[#parts + 1] = node.text
+  elseif contains(ntype, { 'list_marker_minus', 'list_marker_star' }) then
+    parts[#parts + 1] = '• '
+  elseif ntype == 'list_item' then
+    parts[#parts + 1] = string.rep(' ', indent)
+    local offset = node[1].type == 'list_marker_dot' and 3 or 2
+    for i, child in ipairs(node) do
+      local sindent = i <= 2 and 0 or (indent + offset)
+      vim.list_extend(
+        parts,
+        render_md(child, sindent, indent + offset, text_width, level + 1, true)
+      )
+    end
+  else
+    if node.text then
+      error(fmt('cannot render:\n%s', vim.inspect(node)))
+    end
+    for i, child in ipairs(node) do
+      local start_indent0 = i == 1 and start_indent or indent
+      vim.list_extend(
+        parts,
+        render_md(child, start_indent0, indent, text_width, level + 1, is_list)
+      )
+      if ntype ~= 'list' and i ~= #node then
+        if (node[i + 1] or {}).type ~= 'list' then
+          parts[#parts + 1] = '\n'
+        end
+      end
+    end
+  end
+
+  if add_tag then
+    parts[#parts + 1] = '</' .. ntype .. '>'
+  end
+
+  return parts
+end
+
+--- @param text_width integer
+local function align_tags(text_width)
+  --- @param line string
+  --- @return string
+  return function(line)
+    local tag_pat = '%s*(%*.+%*)%s*$'
+    local tags = {}
+    for m in line:gmatch(tag_pat) do
+      table.insert(tags, m)
+    end
+
+    if #tags > 0 then
+      line = line:gsub(tag_pat, '')
+      local tags_str = ' ' .. table.concat(tags, ' ')
+      --- @type integer
+      local conceal_offset = select(2, tags_str:gsub('%*', '')) - 2
+      local pad = string.rep(' ', text_width - #line - #tags_str + conceal_offset)
+      return line .. pad .. tags_str
+    end
+
+    return line
+  end
+end
+
+--- @param text string
+--- @param start_indent integer
+--- @param indent integer
+--- @param is_list? boolean
+--- @return string
+function M.md_to_vimdoc(text, start_indent, indent, text_width, is_list)
+  -- Add an extra newline so the parser can properly capture ending ```
+  local parsed = parse_md(text .. '\n')
+  local ret = render_md(parsed, start_indent, indent, text_width, 0, is_list)
+
+  local lines = vim.split(table.concat(ret):gsub(NBSP, ' '), '\n')
+
+  lines = vim.tbl_map(align_tags(text_width), lines)
+
+  local s = table.concat(lines, '\n')
+
+  -- Reduce whitespace in code-blocks
+  s = s:gsub('\n+%s*>([a-z]+)\n', ' >%1\n')
+  s = s:gsub('\n+%s*>\n?\n', ' >\n')
+
+  return s
+end
+
+return M