feat: support ordered bullet continuations

lua/bullets/actions.lua

@@ -1,4 +1,6 @@
 local M = {}
+local config = require("bullets.config")
+local ordinal = require("bullets.ordinal")
 
 local function feed(keys)
   vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes(keys, true, false, true), "n", false)
@@ -18,6 +20,127 @@ local function parse_standard(line)
   }
 end
 
+local function parse_numeric(line)
+  local indent, marker, closure, spacing, text = line:match("^(%s*)(%d+)([.)])(%s+)(.*)$")
+  if not marker then
+    return nil
+  end
+
+  return {
+    type = "num",
+    indent = indent,
+    marker = marker,
+    closure = closure,
+    spacing = spacing,
+    text = text,
+  }
+end
+
+local function parse_alpha(line)
+  local max = config.options.max_alpha_characters
+  if max == 0 then
+    return nil
+  end
+
+  local indent, marker, closure, spacing, text = line:match("^(%s*)(%a+)([.)])(%s+)(.*)$")
+  if not marker or #marker > max or not (marker == marker:lower() or marker == marker:upper()) then
+    return nil
+  end
+
+  return {
+    type = "abc",
+    indent = indent,
+    marker = marker,
+    closure = closure,
+    spacing = spacing,
+    text = text,
+  }
+end
+
+local function parse_roman(line)
+  if not config.options.enable_roman_list then
+    return nil
+  end
+
+  local indent, marker, closure, spacing, text = line:match("^(%s*)(%a+)([.)])(%s+)(.*)$")
+  if not marker or not (marker == marker:lower() or marker == marker:upper()) or not ordinal.is_roman(marker) then
+    return nil
+  end
+
+  return {
+    type = "rom",
+    indent = indent,
+    marker = marker,
+    closure = closure,
+    spacing = spacing,
+    text = text,
+  }
+end
+
+local function parse_line(line)
+  local standard = parse_standard(line)
+  if standard then
+    standard.type = "std"
+    return { standard }
+  end
+
+  local numeric = parse_numeric(line)
+  if numeric then
+    return { numeric }
+  end
+
+  local alpha = parse_alpha(line)
+  local roman = parse_roman(line)
+
+  return vim.tbl_filter(function(item)
+    return item ~= nil
+  end, { alpha, roman })
+end
+
+local resolve_bullet
+
+local function previous_ordered_type(lnum, indent)
+  for row = lnum - 1, 1, -1 do
+    local line = vim.api.nvim_buf_get_lines(0, row - 1, row, false)[1]
+    if line == "" then
+      return nil
+    end
+
+    local bullet = resolve_bullet(parse_line(line), row)
+    if bullet and bullet.indent == indent and (bullet.type == "abc" or bullet.type == "rom") then
+      return bullet.type
+    end
+  end
+
+  return nil
+end
+
+function resolve_bullet(bullets, lnum)
+  if #bullets == 0 then
+    return nil
+  end
+  if #bullets == 1 then
+    return bullets[1]
+  end
+
+  local previous_type = previous_ordered_type(lnum, bullets[1].indent)
+  if previous_type then
+    for _, bullet in ipairs(bullets) do
+      if bullet.type == previous_type then
+        return bullet
+      end
+    end
+  end
+
+  for _, bullet in ipairs(bullets) do
+    if bullet.type == "rom" then
+      return bullet
+    end
+  end
+
+  return bullets[1]
+end
+
 local function at_eol(line)
   return vim.fn.col(".") == #line + 1
 end
@@ -27,11 +150,52 @@ local function insert_line(lnum, line)
   vim.api.nvim_win_set_cursor(0, { lnum + 1, #line })
 end
 
+local function pad_right(prefix, width)
+  if not config.options.pad_right or #prefix >= width then
+    return prefix
+  end
+
+  return prefix .. string.rep(" ", width - #prefix)
+end
+
+local function next_marker(bullet)
+  if bullet.type == "num" then
+    return tostring(tonumber(bullet.marker) + 1)
+  end
+  if bullet.type == "abc" then
+    local marker =
+      ordinal.number_to_abc(ordinal.abc_to_number(bullet.marker) + 1, bullet.marker == bullet.marker:lower())
+    if #marker > config.options.max_alpha_characters then
+      return nil
+    end
+    return marker
+  end
+  if bullet.type == "rom" then
+    return ordinal.number_to_roman(ordinal.roman_to_number(bullet.marker) + 1, bullet.marker == bullet.marker:lower())
+  end
+
+  return bullet.marker
+end
+
+local function next_prefix(bullet)
+  local marker = next_marker(bullet)
+  if not marker then
+    return nil
+  end
+
+  if bullet.type == "std" then
+    return bullet.indent .. marker .. bullet.spacing
+  end
+
+  local prefix = marker .. bullet.closure .. " "
+  return bullet.indent .. pad_right(prefix, #bullet.marker + #bullet.closure + #bullet.spacing)
+end
+
 function M.insert_new_bullet()
   local mode = vim.fn.mode()
   local lnum = vim.api.nvim_win_get_cursor(0)[1]
   local line = vim.api.nvim_get_current_line()
-  local bullet = parse_standard(line)
+  local bullet = resolve_bullet(parse_line(line), lnum)
 
   if mode ~= "n" and not at_eol(line) then
     feed("<CR>")
@@ -48,7 +212,13 @@ function M.insert_new_bullet()
     return ""
   end
 
-  insert_line(lnum, bullet.indent .. bullet.marker .. bullet.spacing)
+  local prefix = next_prefix(bullet)
+  if not prefix then
+    feed("<CR>")
+    return ""
+  end
+
+  insert_line(lnum, prefix)
 
   if mode == "n" then
     vim.cmd.startinsert({ bang = true })

lua/bullets/ordinal.lua

@@ -0,0 +1,95 @@
+local M = {}
+
+local roman_values = {
+  { 1000, "m" },
+  { 900, "cm" },
+  { 500, "d" },
+  { 400, "cd" },
+  { 100, "c" },
+  { 90, "xc" },
+  { 50, "l" },
+  { 40, "xl" },
+  { 10, "x" },
+  { 9, "ix" },
+  { 5, "v" },
+  { 4, "iv" },
+  { 1, "i" },
+}
+
+function M.abc_to_number(value)
+  local result = 0
+  local lower = value:lower()
+
+  for i = 1, #lower do
+    result = result * 26 + lower:byte(i) - string.byte("a") + 1
+  end
+
+  return result
+end
+
+function M.number_to_abc(value, lower)
+  local base = lower and string.byte("a") or string.byte("A")
+  local result = ""
+
+  while value > 0 do
+    value = value - 1
+    result = string.char(base + value % 26) .. result
+    value = math.floor(value / 26)
+  end
+
+  return result
+end
+
+function M.roman_to_number(value)
+  local roman = value:lower()
+  local result = 0
+  local index = 1
+
+  while index <= #roman do
+    local matched = false
+    for _, pair in ipairs(roman_values) do
+      local number, letters = pair[1], pair[2]
+      if roman:sub(index, index + #letters - 1) == letters then
+        result = result + number
+        index = index + #letters
+        matched = true
+        break
+      end
+    end
+
+    if not matched then
+      return nil
+    end
+  end
+
+  return result
+end
+
+function M.number_to_roman(value, lower)
+  local result = ""
+
+  for _, pair in ipairs(roman_values) do
+    local number, letters = pair[1], pair[2]
+    while value >= number do
+      result = result .. letters
+      value = value - number
+    end
+  end
+
+  if lower then
+    return result
+  end
+
+  return result:upper()
+end
+
+function M.is_roman(value)
+  local number = M.roman_to_number(value)
+  if not number then
+    return false
+  end
+
+  return M.number_to_roman(number, value == value:lower()) == value
+end
+
+return M

test/alphabetic_bullets_spec.lua

@@ -1,4 +1,5 @@
 local helpers = require("test.helpers")
+local active_it = it
 local it = pending
 
 describe("Bullets.vim", function()
@@ -7,7 +8,7 @@ describe("Bullets.vim", function()
       helpers.reset_config()
     end)
 
-    it("adds a new upper case bullet", function()
+    active_it("adds a new upper case bullet", function()
       helpers.new_buffer({
         "# Hello there",
         "A. this is the first bullet",
@@ -31,7 +32,7 @@ describe("Bullets.vim", function()
       }, helpers.get_lines())
     end)
 
-    it("adds a new lower case bullet", function()
+    active_it("adds a new lower case bullet", function()
       helpers.new_buffer({
         "# Hello there",
         "a. this is the first bullet",
@@ -56,7 +57,7 @@ describe("Bullets.vim", function()
     end)
 
     it("adds a new bullet and loops at z", function()
-      vim.g.bullets_renumber_on_change = 0
+      require("bullets").setup({ renumber_on_change = false })
       helpers.new_buffer({
         "# Hello there",
         "y. this is the first bullet",
@@ -80,7 +81,7 @@ describe("Bullets.vim", function()
       }, helpers.get_lines())
     end)
 
-    it("does not add a new bullet when mixed case", function()
+    active_it("does not add a new bullet when mixed case", function()
       -- "Ab." is mixed case so the plugin doesn't recognise it as a bullet.
       -- CR is therefore deferred via feedkeys('n'); the 'tx' flag in our outer
       -- feedkeys drains that deferred CR, leaving normal mode on a new empty line.
@@ -99,8 +100,8 @@ describe("Bullets.vim", function()
     end)
 
     describe("g:bullets_max_alpha_characters", function()
-      it("stops adding items after configured max (default 2)", function()
-        vim.g.bullets_renumber_on_change = 0
+      active_it("stops adding items after configured max (default 2)", function()
+        require("bullets").setup({ renumber_on_change = false })
         helpers.new_buffer({
           "# Hello there",
           "zy. this is the first bullet",
@@ -120,8 +121,8 @@ describe("Bullets.vim", function()
         }, helpers.get_lines())
       end)
 
-      it("does not bullets if configured as 0", function()
-        vim.g.bullets_max_alpha_characters = 0
+      active_it("does not bullets if configured as 0", function()
+        require("bullets").setup({ max_alpha_characters = 0 })
         helpers.new_buffer({
           "# Hello there",
           "a. this is the first bullet",