edit.lua

   1 local M = {}
   2
   3 -- XXX: in Lua 5.2 unpack() was moved into table
   4 local unpack = unpack or table.unpack
   5
   6 local function startof(node) return node.start end
   7 local function finishof(node) return node.finish end
   8 local function is_comment(node) return node.is_comment end
   9
  10 function M.new(parser, walker, fmt, write, delete, eol_at)
  11
  12         local function normalize_spacing(start, delta, list)
  13                 if delta > 0 then
  14                         table.insert(list, {start + delta, -delta})
  15                 elseif delta < 0 then
  16                         table.insert(list, {start, -delta})
  17                 end
  18                 return delta
  19         end
  20
  21         local function leading_space(s, deltas, adj, parent, i, pstart, has_eol)
  22                 local prev = parent[i - 1]
  23                 if not s.indent and not (prev and (s.d == "|" or prev.d == "|")) and not has_eol then
  24                         local off = prev and prev.finish + 1 or pstart
  25                         adj = adj + normalize_spacing(off, s.start - off - (prev and 1 or 0), deltas)
  26                 end
  27                 return adj
  28         end
  29
  30         local function trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
  31                 local nxt = parent[i + 1]
  32                 local is_last = not nxt
  33                 if (is_last and not keep_electric_space) or nxt and nxt.indent then
  34                         local off = is_last and parent.finish - (has_eol and i < #parent and 1 or 0) or nxt.start - nxt.indent - 1
  35                         local finish = s.finish + (has_eol and i < #parent and 0 or 1)
  36                         normalize_spacing(finish, off - finish, deltas)
  37                 end
  38                 return adj
  39         end
  40
  41         local function indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
  42                 op_adj, indent_adj)
  43                 if s.indent then
  44                         local delta = base_indent - s.indent
  45                         if last_distinguished and i > 1 then
  46                                 delta = delta + 1
  47                                 if i - 1 <= last_distinguished then
  48                                         delta = delta + 2
  49                                 end
  50                         elseif i == 1 then
  51                                 -- remove leading space, if any
  52                                 delta = -(s.start - pstart)
  53                         elseif                               -- align further arguments below the second one
  54                                 parent.d == "("              -- [] and {} contain data, so no arguments
  55                                 and not parent[1].is_string  -- a string can't have arguments
  56                                 --and not parent[1].is_list  -- wrong, GNU Emacs compatible behaviour
  57                                 then
  58                                 if i > first_argument + 1 and not parent[first_argument + 1].indent then
  59                                         delta = base_indent + parent[1].finish + 2 - pstart - s.indent - op_adj - (indent_adj or 0)
  60                                 end
  61                                 if delta < 0 then delta = math.max(-s.indent, delta) end
  62                         end
  63                         if delta ~= 0 then
  64                                 table.insert(deltas, {s.start, delta})
  65                         end
  66                         adj = adj - delta
  67                 end
  68                 return adj
  69         end
  70
  71         local function refmt_list(parent, base_indent, padj, deltas, keep_electric_space)
  72                 local adj = 0
  73                 local op_adj = 0
  74                 local indent_adj = 0
  75                 local pstart = parent.start + (parent.p and #parent.p or 0) + #parent.d
  76                 if parent.is_empty then
  77                         normalize_spacing(pstart, parent.finish - pstart, deltas)
  78                         return deltas
  79                 end
  80                 local last_distinguished = fmt:last_distinguished(parent)
  81                 local first_argument = 1
  82                 if parent[1].is_list and #parent > 2 then
  83                         local op = parent[1]
  84                         local nearest_indented = op[#op].indent and op[#op] or walker.indented_before(op[#op])
  85                         indent_adj = nearest_indented.start - pstart - nearest_indented.indent + 1
  86                 end
  87                 for i, s in ipairs(parent) do
  88                         adj = s.indent and 0 or adj
  89                         if last_distinguished then
  90                                 -- do not let early comments influence the indentation of real expressions:
  91                                 if i <= last_distinguished and s.is_comment then
  92                                         last_distinguished = last_distinguished + 1
  93                                 end
  94                                 -- s is the name of a named let. account for it:
  95                                 if i == last_distinguished + 1 and not s.is_list and parent[1].text == "let" then
  96                                         last_distinguished = last_distinguished + 1
  97                                 end
  98                                 -- do not let early comments influence the indentation of real expressions:
  99                         elseif i <= first_argument + 1 and s.is_comment then
 100                                 first_argument = first_argument + 1
 101                         end
 102                         local has_eol = s.is_comment and parser.opposite[s.d] == "\n"
 103                         adj = leading_space(s, deltas, adj, parent, i, pstart, has_eol)
 104                         adj = trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
 105                         adj = indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
 106                                 op_adj, indent_adj)
 107                         if i == 1 then
 108                                 op_adj = adj
 109                         end
 110                         if s.is_list then
 111                                 local nearest_indented = s.indent and s or walker.indented_before(s)
 112                                 local parent_column = nearest_indented and
 113                                         nearest_indented.indent + (s.start + (s.p and #s.p or 0) + #s.d) - nearest_indented.start
 114                                         or base_indent + (s.start + (s.p and #s.p or 0) + #s.d) - pstart
 115                                 refmt_list(s, parent_column - adj, padj + adj, deltas, keep_electric_space)
 116                         end
 117                 end
 118                 return deltas
 119         end
 120
 121         local function refmt_at(scope, range, keep_electric_space)
 122                 if not range or not scope or scope.is_root then return end
 123                 local parent = walker.sexp_at(scope, true)
 124                 if not (parent and parent.is_list) then return end
 125                 local _, parent_at, m = walker.sexp_at(range, true)
 126                 if not m then
 127                         _, m = parent_at.after(range.start, startof)
 128                         if not m then
 129                                 m = #parent_at
 130                         end
 131                 end
 132                 local base = parent_at[m] or parent_at
 133                 local path = walker.sexp_path(base)
 134                 local after_start, at_pfinish
 135                 if parent_at[m] then
 136                         local s = parent_at[#parent_at]
 137                         local has_eol = s.is_comment and parser.opposite[s.d] == "\n"
 138                         if range.start >= s.finish + 1 + (has_eol and 1 or 0) then
 139                                 at_pfinish = true
 140                         else
 141                                 after_start = range.start < base.start and 0 or range.start - base.start
 142                         end
 143                 else
 144                         after_start = (parent_at.p and #parent_at.p or 0) + #parent_at.d
 145                 end
 146                 local indented_parent = parent.indent and parent or parent.is_list and walker.indented_before(parent)
 147                 local parent_column = indented_parent and (indented_parent.indent + parent.start - indented_parent.start +
 148                         (parent.p and #parent.p or 0) + #parent.d) or
 149                         0
 150                 local deltas = refmt_list(parent, parent_column, 0, {}, keep_electric_space)
 151                 table.sort(deltas, function(d1, d2) return d1[1] > d2[1] end)
 152                 for _, pair in ipairs(deltas) do
 153                         local offset, delta = unpack(pair)
 154                         if delta > 0 then
 155                                 write(offset, string.rep(" ", delta))
 156                         elseif delta < 0 then
 157                                 delete(offset + delta, -delta)
 158                         end
 159                 end
 160                 parser.tree.rewind(parent.start or 0)
 161                 if path then
 162                         local sexp, parentng = walker.goto_path(path)
 163                         if sexp then
 164                                 if at_pfinish then
 165                                         return parentng.finish
 166                                 else
 167                                         return sexp.start + after_start
 168                                 end
 169                         end
 170                 end
 171                 return range.start
 172         end
 173
 174         local function splice(pos, sexps, skip, backwards, action)
 175                 local spliced
 176                 local sexp = walker.sexp_at(skip, true)
 177                 local start = sexp.start + (sexp.p and #sexp.p or 0)
 178                 local is_line_comment = sexp.is_comment and parser.opposite[sexp.d] == "\n"
 179                 -- XXX: don't splice empty line comments _yet_; see _join_or_splice
 180                 local tosplice = action.splice or action.wrap or not is_line_comment and sexp.is_empty
 181                 local opening = (sexp.p or '')..sexp.d
 182                 local closing = parser.opposite[sexp.d]
 183                 local real_start = tosplice and sexp.start or start + #sexp.d
 184                 local splice_closing = closing ~= "\n" or sexp.is_empty
 185                 local real_finish = sexp.finish + 1 - (tosplice and splice_closing and 0 or #closing)
 186                 local first = backwards and
 187                         {start = real_start, finish = math.max(pos, start + #sexp.d)} or
 188                         {start = real_start, finish = sexp.is_empty and pos or start + #sexp.d}
 189                 local second = backwards and
 190                         {start = sexp.is_empty and pos or sexp.finish + 1 - #closing, finish = real_finish} or
 191                         {start = math.min(pos, sexp.finish + 1 - #closing), finish = real_finish}
 192                 action.func(second)
 193                 action.func(first)
 194                 spliced = tosplice
 195                 if action.kill then
 196                         local ndeleted = first.finish - first.start + second.finish - second.start
 197                         if ndeleted > 0 then
 198                                 sexps.rewind(sexp.start)
 199                         end
 200                 end
 201                 return first.finish - first.start, spliced, opening, closing
 202         end
 203
 204         -- If you try to delete some part of indentation, this function joins the current line with
 205         -- the previous one, unless the latter is a line comment.
 206         -- it does this by
 207         -- a) extending or shrinking the range that is to be deleted
 208         -- b) returning a truthy value to trick pick_out to glide the cursor, but refmt to restore the deleted spaces
 209         -- c) both a) and b)
 210         local function delete_indentation(range, pos)
 211                 local node, parent = walker.sexp_at(range)
 212                 if node or not parent.is_list then return end
 213                 local prev = parent.before(pos, finishof)
 214                 local nxt = parent.after(pos, startof)
 215                 if prev and prev.finish >= range.start or nxt and nxt.start < range.finish then return end
 216                 local backwards = pos == range.finish
 217                 local adj = 0
 218                 local eol = eol_at(pos)
 219                 local on_empty_line = not nxt or eol and nxt.start > eol
 220                 local empty_line_after_comment = prev and prev.is_comment and parser.opposite[prev.d] == "\n"
 221                         and on_empty_line
 222                 if nxt and nxt.indent then
 223                         if backwards and prev then
 224                                 range.start = prev.finish + (empty_line_after_comment and 0 or 1)
 225                                 if not prev.d then
 226                                         range.finish = range.start + 1
 227                                         adj = (on_empty_line and 0 or 1)
 228                                 end
 229                         end
 230                         return adj
 231                 end
 232                 if not nxt and prev then
 233                         range.start = prev.finish + 1
 234                         range.finish = parent.finish
 235                 elseif nxt and nxt.start == range.finish and (not prev or prev.finish + 1 == range.start) then
 236                         if prev and prev.d or nxt and nxt.d then
 237                                 -- don't delete spaces near delimiters, just slide the cursor:
 238                                 if backwards then
 239                                         range.finish = range.start
 240                                 else
 241                                         range.start = range.finish
 242                                 end
 243                         end
 244                         return adj
 245                 end
 246         end
 247
 248         local function big_enough_parent(pos1, pos2)
 249                 -- since the pos1-pos2 range can cross list boundaries, find which list contains both pos1 and pos2
 250                 local _, p1, p2
 251                 _, p1 = walker.sexp_at({start = pos1, finish = pos1}, true)
 252                 if p1.is_root or not (p1.start < pos1 and p1.finish > pos2) then
 253                         _, p2 = walker.sexp_at({start = pos2, finish = pos2}, true)
 254                 end
 255                 return p2 and not p2.is_root and p2 or p1
 256         end
 257
 258         local function pick_out(range, pos, action)
 259                 local ndeleted = 0
 260                 if range.start == range.finish then return ndeleted end
 261                 local sexps = parser.tree
 262                 local skips = sexps.unbalanced_delimiters(range)
 263                 -- handle splice and kill-splice of forms and strings:
 264                 if #skips == 1 then
 265                         local sexp = walker.sexp_at(skips[1], true)
 266                         local backward_splice = skips[1].opening and pos >= sexp.start + (sexp.p and #sexp.p or 0) + #sexp.d
 267                                 and range.start >= sexp.start
 268                         local forward_splice = skips[1].closing and pos <= sexp.finish + 1 - #parser.opposite[sexp.d]
 269                                 and range.finish <= sexp.finish + 1
 270                         if backward_splice or forward_splice then
 271                                 return splice(backward_splice and range.finish or range.start, sexps, sexp, backward_splice, action)
 272                         end
 273                 end
 274                 local node, parent = walker.sexp_at({start = range.finish, finish = range.finish})
 275                 local drop_eol = node and node.finish + 1 == range.finish and node.is_comment and parser.opposite[node.d] == "\n"
 276                 local par = big_enough_parent(range.start, range.finish)
 277                 local operator_changed = par[1] and par[1].finish >= range.start
 278                 local refmt = #skips == 0 and delete_indentation(range, pos) or operator_changed and 0
 279                 table.sort(skips, function(a, b) return a.start < b.start end)
 280                 table.insert(skips, {start = range.finish - (drop_eol and 1 or 0)})
 281                 table.insert(skips, 1, {finish = range.start})
 282                 ndeleted = ndeleted + (drop_eol and 1 or 0)
 283                 for i = #skips - 1, 1, -1 do
 284                         local region = {start = skips[i].finish, finish = skips[i + 1].start}
 285                         if skips[i].closing and skips[i + 1].opening then
 286                                 -- leave out some of the space between adjacent lists
 287                                 local _, rparent = walker.sexp_at(region)
 288                                 local nxt = rparent.after(region.start, startof)
 289                                 region.start = nxt and nxt.start or region.start
 290                         end
 291                         if action then
 292                                 action.func(region)
 293                                 ndeleted = ndeleted + (region.finish - region.start)
 294                         end
 295                 end
 296                 -- if parent[#parent + 1] is nil, we are at EOF
 297                 if ndeleted > 0 and (not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1]) then
 298                         sexps.rewind(range.start)
 299                 end
 300                 return ndeleted - (refmt or 0), nil, nil, nil, refmt
 301         end
 302
 303         local function raise_sexp(range, pos)
 304                 local sexp, parent = walker.sexp_at(range, true)
 305                 if sexp and parent and parent.is_list then
 306                         delete(sexp.finish + 1, parent.finish - sexp.finish)
 307                         delete(parent.start, sexp.start - parent.start)
 308                         parser.tree.rewind(parent.start)
 309                         range.start = parent.start + pos - sexp.start
 310                         range.finish = range.start
 311                         local _, nodes = walker.sexp_path(range)
 312                         local grandparent = nodes[#nodes - 2]
 313                         return grandparent and refmt_at(grandparent, range) or range.start
 314                 end
 315         end
 316
 317         local function slurp_sexp(range, forward)
 318                 local _, parent = walker.sexp_at(range, true)
 319                 local seeker = forward and walker.finish_after or walker.start_before
 320                 if not parent or not parent.is_list then return range.start end
 321                 local r = {start = parent.start, finish = parent.finish + 1}
 322                 local newpos = seeker(r, is_comment)
 323                 if not newpos then return range.start end
 324                 local opening = (parent.p or '')..parent.d
 325                 local closing = parser.opposite[parent.d]
 326                 local delimiter = forward and closing or opening
 327                 if forward then
 328                         write(newpos, delimiter)
 329                 end
 330                 delete(forward and parent.finish or parent.start, #delimiter)
 331                 if not forward then
 332                         write(newpos, delimiter)
 333                 end
 334                 parser.tree.rewind(math.min(parent.start, newpos))
 335                 return refmt_at(big_enough_parent(newpos, range.start), range) or range.start
 336         end
 337
 338         local function barf_sexp(range, forward)
 339                 local _, parent, m = walker.sexp_at(range, true)
 340                 local seeker = forward and walker.finish_before or walker.start_after
 341                 -- TODO: barfing out of strings requires calling the parser on them
 342                 if not parent or not parent.is_list then return range.start end
 343                 local opening = (parent.p or '')..parent.d
 344                 local pstart = parent.start + #opening
 345                 local r = {start = forward and parent.finish - 1 or pstart, finish = forward and parent.finish or pstart + 1}
 346                 local newpos = seeker(r, is_comment) or forward and pstart or parent.finish
 347                 if not newpos then return range.start end
 348                 local closing = parser.opposite[parent.d]
 349                 local delimiter = forward and closing or opening
 350                 if not forward then
 351                         write(newpos, delimiter)
 352                 end
 353                 delete(forward and parent.finish or parent.start, #delimiter)
 354                 if forward then
 355                         write(newpos, delimiter)
 356                 end
 357                 parser.tree.rewind(math.min(parent.start, newpos))
 358                 local barfed_cursor_backward = m == 1 and not forward
 359                 local barfed_cursor_forward = m == #parent and forward
 360                 range.start = range.start + #delimiter * (barfed_cursor_backward and -1 or barfed_cursor_forward and 1 or 0)
 361                 return refmt_at(big_enough_parent(newpos, parent.finish + 1), range) or range.start
 362         end
 363
 364         local function splice_sexp(range, _, no_refmt)
 365                 local _, parent = walker.sexp_at(range)
 366                 if not parent or not parent.d then return end
 367                 local opening = (parent.p or '')..parent.d
 368                 local closing = parser.opposite[parent.d]
 369                 local finish = parent.finish + 1 - #closing
 370                 if closing ~= "\n" then
 371                         delete(finish, #closing)
 372                 end
 373                 -- TODO: (un)escape special characters, if necessary
 374                 delete(parent.start, parent.is_empty and (finish - parent.start) or #opening)
 375                 parser.tree.rewind(parent.start)
 376                 range.start = range.start - #opening
 377                 range.finish = range.start
 378                 local _, parentng = walker.sexp_at(range, true)
 379                 return not no_refmt and refmt_at(parentng, range) or range.start
 380         end
 381
 382         local function rewrap(parent, kind)
 383                 local pstart = parent.start + #((parent.p or '')..parent.d) - 1
 384                 delete(parent.finish, 1)
 385                 write(parent.finish, parser.opposite[kind])
 386                 delete(pstart, #parent.d)
 387                 write(pstart, kind)
 388                 parser.tree.rewind(parent.start)
 389         end
 390
 391         local function cycle_wrap(range, pos)
 392                 local _, parent = walker.sexp_at(range)
 393                 if not parent or not parent.is_list then return end
 394                 local next_kind = {["("] = "[", ["["] = "{", ["{"] = "("}
 395                 rewrap(parent, next_kind[parent.d])
 396                 return pos
 397         end
 398
 399         local function split_sexp(range)
 400                 local _, parent = walker.sexp_at(range)
 401                 if not (parent and parent.d) then return end
 402                 local new_finish, new_start
 403                 if parent.is_list then
 404                         local prev = parent.before(range.start, finishof, is_comment)
 405                         new_finish = prev and prev.finish + 1
 406                         -- XXX: do not skip comments here, so they end up in the second list
 407                         -- and are not separated from their target expression:
 408                         local nxt = new_finish and parent.after(new_finish, startof)
 409                         new_start = nxt and nxt.start
 410                 else
 411                         new_start = range.start
 412                         new_finish = range.start
 413                 end
 414                 if not (new_start and new_finish) then return end
 415                 local opening = (parent.p or '')..parent.d
 416                 local closing = parser.opposite[parent.d]
 417                 write(new_start, opening)
 418                 local sep = parser.opposite[parent.d] == "\n" and ""  -- line comments already have a separator
 419                         or new_finish == new_start and " "  -- only add a separator if there was none before
 420                         or ""
 421                 write(new_finish, closing..sep)
 422                 parser.tree.rewind(parent.start)
 423                 range.start = new_start + (parent.is_list and 0 or #opening + #closing)
 424                 range.finish = range.start
 425                 local _, nodes = walker.sexp_path(range)
 426                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 427                 local scope = parentng and not parentng.is_root and parentng or grandparent
 428                 return refmt_at(scope, range) or range.start
 429         end
 430
 431         local function join_sexps(range)
 432                 local node, parent = walker.sexp_at(range, true)
 433                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 434                 local second = first ~= node and node or parent.after(range.start, startof)
 435                 if not (first and second and first.d and
 436                         -- don't join line comments to margin comments:
 437                         (parser.opposite[first.d] ~= "\n" or first.indent and second.indent) and
 438                         (first.d == second.d or
 439                                 -- join line comments even when their delimiters differ slightly
 440                                 -- (different number of semicolons, existence/lack of a space after them)
 441                                 parser.opposite[first.d] == parser.opposite[second.d])) then
 442                         return
 443                 end
 444                 local opening = (second.p or '')..second.d
 445                 local closing = parser.opposite[first.d]
 446                 local pos
 447                 if not first.is_list then
 448                         pos = first.finish + 1 - #closing
 449                         delete(pos, second.start + #opening - pos)
 450                 else
 451                         delete(second.start, #opening)
 452                         delete(first.finish, #closing)
 453                         pos = second.start - #closing
 454                 end
 455                 parser.tree.rewind(first.start)
 456                 range.start = pos
 457                 range.finish = range.start
 458                 local _, nodes = walker.sexp_path(range)
 459                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 460                 local scope = parentng and not parentng.is_root and parentng or grandparent
 461                 return refmt_at(scope, range) or range.start
 462         end
 463
 464         local function delete_splicing(range, pos, splicing, delete_and_yank)
 465                 local action = {kill = true, wrap = splicing, splice = splicing, func = delete_and_yank}
 466                 local sexp, parent, n = walker.sexp_at(range, true)
 467                 local ndeleted, spliced = pick_out(range, pos, action)
 468                 local closing = spliced and parser.opposite[sexp.d]
 469                 local inner_list_len = spliced and sexp.finish - sexp.start + 1 - #sexp.d - #closing
 470                 local range_len = range.finish - range.start
 471                 local backwards = pos == range.finish
 472                 local whole_object = sexp and
 473                         (sexp.start == range.start and sexp.finish + 1 == range.finish
 474                         or spliced and (inner_list_len <= (backwards and range_len + ndeleted or range_len)))
 475                 local in_head_atom = sexp and not sexp.d and n == 1 and #parent > 1
 476                 local in_whitespace = not sexp
 477                 if whole_object or in_whitespace or in_head_atom then
 478                         local cur = whole_object and sexp.start or range.start
 479                         -- if parent[#parent + 1] is nil, we are at EOF
 480                         if not parent.is_root or parent.is_parsed(cur) or parent[#parent + 1] then
 481                                 parser.tree.rewind(cur)
 482                         end
 483                         local r = {start = cur, finish = cur}
 484                         local _, parentng = walker.sexp_at(r, true)
 485                         local newpos = refmt_at(parentng, r)
 486                         return newpos or cur
 487                 end
 488                 return spliced and (backwards and sexp.start or range.start - ndeleted)
 489                         or not backwards and ndeleted <= 0 and range.finish - ndeleted
 490                         or range.start
 491         end
 492
 493         local function transpose(range, first, second)
 494                 if not (first and second) then return end
 495                 local copy1 = first.text
 496                 local copy2 = second.text
 497                 delete(second.start, second.finish + 1 - second.start)
 498                 write(second.start, copy1)
 499                 delete(first.start, first.finish + 1 - first.start)
 500                 write(first.start, copy2)
 501                 parser.tree.rewind(first.start)
 502                 range.start = second.finish + 1
 503                 range.finish = range.start
 504                 return refmt_at(big_enough_parent(first.start, second.finish), range) or range.start
 505         end
 506
 507         local function transpose_sexps(range)
 508                 local node, parent = walker.sexp_at(range, true)
 509                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 510                 local second = first ~= node and node or parent.after(range.start, startof)
 511                 return transpose(range, first, second)
 512         end
 513
 514         local function transpose_words(range)
 515                 local _, first = walker.start_float_before(range)
 516                 local _, second = walker.finish_float_after(range)
 517                 if first and second and first.start == second.start then
 518                         _, first = walker.start_float_before(first)
 519                 end
 520                 return transpose(range, first, second)
 521         end
 522
 523         local function transpose_chars(range)
 524                 local node, parent, i = walker.sexp_at(range)
 525                 local nxt = i and parent[i + 1]
 526                 local pstart = not parent.is_root and parent.start + (parent.p and #parent.p or 0) + #parent.d
 527                 local pfinish = not parent.is_root and parent.finish
 528                 local npref = node and node.p and node.start + #node.p
 529                 -- only allow transposing while inside atoms/words and prefixes
 530                 if node and ((npref and (range.start <= npref and range.start > node.start) or
 531                         node.d and range.start > node.finish + 1) or not node.d and (not pstart or range.start > pstart)) then
 532                         local start = range.start -
 533                                 ((range.start == pfinish or range.start == npref or
 534                                 range.start == node.finish + 1 and (parent.is_list or parent.is_root) and (not nxt or nxt.indent)) and 1 or 0)
 535                         local str_start = start - node.start + 1
 536                         local char = node.text:sub(str_start, str_start)
 537                         delete(start, 1)
 538                         write(start - 1, #char > 0 and char or " ")
 539                         parser.tree.rewind(start)
 540                         local in_head_atom = i == 1 and #parent > 1
 541                         return parent.is_list and in_head_atom
 542                                 and refmt_at(parent, {start = start + 1, finish = start + 1})
 543                                 or start + 1
 544                 end
 545         end
 546
 547         local function _join_or_splice(parent, n, range, pos)
 548                 local sexp = parent[n]
 549                 local nxt = parent[n + 1]
 550                 local is_last = not nxt or parser.opposite[nxt.d] ~= "\n"
 551                 local newpos = not (is_last and sexp.is_empty) and join_sexps(range)
 552                 if not newpos and sexp.is_empty then
 553                         newpos = splice_sexp({start = pos, finish = pos}, nil, true)
 554                 end
 555                 return newpos or pos
 556         end
 557
 558         local function delete_nonsplicing(range, pos, delete_maybe_yank)
 559                 local action = {kill = true, wrap = false, splice = false, func = delete_maybe_yank}
 560                 local ndeleted, spliced, opening, _, refmt = pick_out(range, pos, action)
 561                 local backwards = pos == range.finish
 562                 if opening then
 563                         if spliced then
 564                                 return pos - ndeleted
 565                         else
 566                                 if ndeleted == 0 then
 567                                         local closing = parser.opposite[opening] -- XXX: why don't I use the pick_out return value?
 568                                         if closing == "\n" then
 569                                                 local sexp, parent, n = walker.sexp_at(range)
 570                                                 if pos == sexp.start + #sexp.d and backwards then
 571                                                         return _join_or_splice(parent, n, range, pos)
 572                                                 elseif pos == sexp.finish then
 573                                                         local r = {start = pos + #closing, finish = pos + #closing}
 574                                                         return _join_or_splice(parent, n, r, pos)
 575                                                 end
 576                                         end
 577                                 end
 578                                 return backwards and (range.finish - ndeleted) or range.start
 579                         end
 580                 else
 581                         local newpos = backwards and range.start or (range.finish - ndeleted)
 582                         if refmt then
 583                                 local r = {start = newpos, finish = newpos}
 584                                 return refmt_at(big_enough_parent(range.start, range.finish - ndeleted), r, true)
 585                         end
 586                         return newpos
 587                 end
 588         end
 589
 590         local function insert_pair(range, delimiter, shiftless, auto_square)
 591                 local indices, nodes = walker.sexp_path(range)
 592                 local sexp = nodes[#nodes]
 593                 local right_after_prefix = sexp and sexp.p and range.start == sexp.start + #sexp.p
 594                 -- XXX: here I assume that # is a valid prefix for the dialect
 595                 local mb_closing = (delimiter == "|") and right_after_prefix and parser.opposite[sexp.p .. delimiter]
 596                 local closing = mb_closing or parser.opposite[delimiter]
 597                 local squarewords = fmt.squarewords
 598                 if squarewords and not right_after_prefix
 599                         and not (closing == "]" and shiftless and not auto_square)
 600                         and (auto_square or squarewords.not_optional)
 601                         and not fmt:adjust_bracket_p(indices, nodes, range) then
 602                                 delimiter, closing = "[", "]"
 603                 end
 604                 write(range.finish, closing)
 605                 write(range.start, delimiter)
 606                 if right_after_prefix or parser.tree.is_parsed(range.start) then
 607                         parser.tree.rewind(right_after_prefix and sexp.start or range.start)
 608                 end
 609                 return range.start + #delimiter
 610         end
 611
 612         local function make_wrap(kind)
 613                 return function(range, pos, auto_square)
 614                         local opening = kind
 615                         local function _wrap(r)
 616                                 if not (r.finish > r.start) then return end
 617                                 insert_pair(r, opening, false, auto_square)
 618                         end
 619                         local action = {kill = false, wrap = false, splice = false, func = _wrap}
 620                         pick_out(range, pos, action)
 621                         range.start = range.start + #opening
 622                         return refmt_at(big_enough_parent(range.start - #opening, range.start), range) or range.start
 623                 end
 624         end
 625
 626         local function newline(parent, range)
 627                 local line_comment = parent.d and parser.opposite[parent.d] == "\n"
 628                 -- do not autoextend margin comments:
 629                 if line_comment and range.start < parent.finish + (parent.indent and 1 or 0)  then
 630                         local newpos = split_sexp(range)
 631                         if newpos then
 632                                 return newpos
 633                         end
 634                 end
 635                 if not parent.is_list and not line_comment then
 636                         -- if parent[#parent + 1] is nil, we are at EOF
 637                         if not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1] then
 638                                 parser.tree.rewind(parent.start or range.start)
 639                         end
 640                         return
 641                 end
 642                 if not parent.is_list then
 643                         local _
 644                         _, parent = walker.sexp_at(parent, true)
 645                 end
 646                 local last_nonblank_in_list = not parent.is_empty and parent[#parent].finish - (line_comment and 1 or 0)
 647                 local nxt = parent.after(range.start, startof)
 648                 local last_on_line = not nxt or nxt and nxt.indent and nxt.start > range.start
 649                 local margin = nxt and not nxt.indent and nxt.is_comment and parser.opposite[nxt.d] == "\n" and nxt.finish
 650                 local after_last = last_nonblank_in_list and range.start > last_nonblank_in_list
 651                 local in_indent = nxt and nxt.indent and range.start <= nxt.start and range.start >= (nxt.start - nxt.indent)
 652                 local placeholder = "asdf"
 653                 local newpos = margin or range.start
 654                 if not parent.is_empty then
 655                         if in_indent then
 656                                 write(newpos, (placeholder.."\n"))
 657                         else
 658                                 write(newpos, "\n"..((after_last or last_on_line or margin) and placeholder or ""))
 659                         end
 660                 end
 661                 parser.tree.rewind(parent.start or newpos)
 662                 -- move the cursor onto the placeholder, so refmt_at can restore the position:
 663                 local r = {start = newpos, finish = newpos}
 664                 newpos = walker.start_after(r) or newpos
 665                 local rangeng = {start = newpos, finish = newpos}
 666                 newpos = refmt_at(parent, rangeng) or rangeng.start
 667                 local _, parentng = walker.sexp_at({start = newpos, finish = newpos}, true)
 668                 if after_last then
 669                         local autoindent = parentng[#parentng].indent
 670                         write(parentng.finish, "\n"..string.rep(" ", autoindent or 0))
 671                 end
 672                 if after_last or last_on_line or margin or in_indent then
 673                         delete(newpos, #placeholder)
 674                 end
 675                 parser.tree.rewind(parentng.start or newpos)
 676                 return newpos
 677         end
 678
 679         local function close_and_newline(range)
 680                 local _, parent = walker.sexp_at(range)
 681                 if parent and not parent.is_root then
 682                         local r = {start = parent.finish, finish = parent.finish}
 683                         local newpos = refmt_at(parent, r)
 684                         r = {start = (newpos or r.finish) + 1, finish = (newpos or r.finish) + 1}
 685                         local list, parentng = walker.sexp_at(r)
 686                         newpos = newline(parentng, {start = list.finish + 1, finish = list.finish + 1})
 687                         if not newpos then
 688                                 newpos = list.finish + 1
 689                                 write(newpos, "\n")
 690                         end
 691                         return newpos
 692                 end
 693                 return range.start
 694         end
 695
 696         local function join_line(_, pos)
 697                 local eol = eol_at(pos)
 698                 local r = {start = eol, finish = eol + 1}
 699                 return delete_nonsplicing(r, r.start, delete)
 700         end
 701
 702         local function meta_doublequote(range, pos, auto_square)
 703                 local escaped = walker.escaped_at(range)
 704                 if not escaped then
 705                         local _, parent = walker.sexp_at(range)
 706                         local newpos = insert_pair(range, '"', false, auto_square)
 707                         return refmt_at(parent, {start = newpos, finish = newpos}) or newpos
 708                 elseif escaped.is_string then
 709                         return close_and_newline(range)
 710                 end
 711                 return pos
 712         end
 713
 714         return {
 715                 delete_splicing = delete_splicing,
 716                 delete_nonsplicing = delete_nonsplicing,
 717                 refmt_at = refmt_at,
 718                 pick_out = pick_out,
 719                 raise_sexp = raise_sexp,
 720                 slurp_sexp = slurp_sexp,
 721                 barf_sexp = barf_sexp,
 722                 splice_sexp = splice_sexp,
 723                 wrap_round = make_wrap"(",
 724                 wrap_square = make_wrap"[",
 725                 wrap_curly = make_wrap"{",
 726                 meta_doublequote = meta_doublequote,
 727                 insert_pair = insert_pair,
 728                 newline = newline,
 729                 join_line = join_line,
 730                 close_and_newline = close_and_newline,
 731                 cycle_wrap = cycle_wrap,
 732                 split_sexp = split_sexp,
 733                 join_sexps = join_sexps,
 734                 transpose_sexps = transpose_sexps,
 735                 transpose_words = transpose_words,
 736                 transpose_chars = transpose_chars,
 737         }
 738 end
 739
 740 return M