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 local function normalize_spacing(start, delta, list)
  11         if delta > 0 then
  12                 table.insert(list, {start + delta, -delta})
  13         elseif delta < 0 then
  14                 table.insert(list, {start, -delta})
  15         end
  16         return delta
  17 end
  18
  19 local function leading_space(s, deltas, adj, parent, i, pstart, has_eol)
  20         local prev = parent[i - 1]
  21         if not s.indent and not (prev and (s.d == "|" or prev.d == "|")) and not has_eol then
  22                 local off = prev and prev.finish + 1 or pstart
  23                 adj = adj + normalize_spacing(off, s.start - off - (prev and 1 or 0), deltas)
  24         end
  25         return adj
  26 end
  27
  28 local function trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
  29         local nxt = parent[i + 1]
  30         local is_last = not nxt
  31         if (is_last and not keep_electric_space) or nxt and nxt.indent then
  32                 local off = is_last and parent.finish - (has_eol and i < #parent and 1 or 0) or nxt.start - nxt.indent - 1
  33                 local finish = s.finish + (has_eol and i < #parent and 0 or 1)
  34                 normalize_spacing(finish, off - finish, deltas)
  35         end
  36         return adj
  37 end
  38
  39 local function indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
  40         op_adj, indent_adj)
  41         if s.indent then
  42                 local delta = base_indent - s.indent
  43                 local firstarg_delta = base_indent + parent[1].finish + 2 - pstart - s.indent - op_adj - (indent_adj or 0)
  44                 if last_distinguished and i > 1 then
  45                         delta = delta + 1
  46                         if i - 1 <= last_distinguished then
  47                                 if parent[first_argument + 1].indent then
  48                                         delta = delta + 2
  49                                 else
  50                                         delta = firstarg_delta
  51                                 end
  52                         elseif last_distinguished < 0
  53                                 and i > first_argument + 1 and not parent[first_argument + 1].indent then
  54                                 delta = firstarg_delta
  55                         end
  56                 elseif i == 1 then
  57                         -- remove leading space
  58                         delta = -(s.start - pstart)
  59                 elseif                               -- align further arguments below the second one
  60                         parent.d == "("              -- [] and {} contain data, so no arguments
  61                         and not parent[1].is_string  -- a string can't have arguments
  62                         --and not parent[1].is_list  -- wrong, GNU Emacs compatible behaviour
  63                         then
  64                         if i > first_argument + 1 and not parent[first_argument + 1].indent then
  65                                 delta = firstarg_delta
  66                         end
  67                         if delta < 0 then delta = math.max(-s.indent, delta) end
  68                 end
  69                 if delta ~= 0 then
  70                         table.insert(deltas, {s.start, delta})
  71                 end
  72                 adj = adj - delta
  73         end
  74         return adj
  75 end
  76
  77 function M.new(parser, walker, fmt, write, delete, eol_at)
  78
  79         local function refmt_list(parent, base_indent, padj, deltas, keep_electric_space)
  80                 local adj = 0
  81                 local op_adj = 0
  82                 local indent_adj = 0
  83                 local pstart = parent.start + (parent.p and #parent.p or 0) + #parent.d
  84                 if parent.is_empty then
  85                         normalize_spacing(pstart, parent.finish - pstart, deltas)
  86                         return deltas
  87                 end
  88                 local last_distinguished = fmt:last_distinguished(parent)
  89                 local first_argument = 1
  90                 if #parent > 2 and parent[1].is_list and #parent[1] > 1 then
  91                         local op = parent[1]
  92                         local nearest_indented = op[#op].indent and op[#op] or walker.indented_before(op[#op])
  93                         indent_adj = nearest_indented.start - pstart - nearest_indented.indent + 1
  94                 end
  95                 for i, s in ipairs(parent) do
  96                         adj = s.indent and 0 or adj
  97                         if last_distinguished then
  98                                 -- do not let early comments influence the indentation of real expressions:
  99                                 if i <= last_distinguished and s.is_comment then
 100                                         last_distinguished = last_distinguished + 1
 101                                 end
 102                                 -- s is the name of a named let. account for it:
 103                                 if i == last_distinguished + 1 and not s.is_list and parent[1].text == "let" then
 104                                         last_distinguished = last_distinguished + 1
 105                                 end
 106                                 -- do not let early comments influence the indentation of real expressions:
 107                         elseif i <= first_argument + 1 and s.is_comment then
 108                                 first_argument = first_argument + 1
 109                         end
 110                         local has_eol = s.is_line_comment
 111                         adj = leading_space(s, deltas, adj, parent, i, pstart, has_eol)
 112                         adj = trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
 113                         adj = indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
 114                                 op_adj, indent_adj)
 115                         if i == 1 then
 116                                 op_adj = adj
 117                         end
 118                         if s.is_list then
 119                                 local nearest_indented = s.indent and s or walker.indented_before(s)
 120                                 local parent_column = nearest_indented and
 121                                         nearest_indented.indent + (s.start + (s.p and #s.p or 0) + #s.d) - nearest_indented.start
 122                                         or base_indent + (s.start + (s.p and #s.p or 0) + #s.d) - pstart
 123                                 refmt_list(s, parent_column - adj, padj + adj, deltas, keep_electric_space)
 124                         end
 125                 end
 126                 return deltas
 127         end
 128
 129         local function path_from(range)
 130                 local _, parent_at, m = walker.sexp_at(range, true)
 131                 local path
 132                 if parent_at[m] then
 133                         path = walker.sexp_path(parent_at[m])
 134                         local base = parent_at[m]
 135                         if range.finish == base.finish + 1 then
 136                                 path.after_finish = 0  -- lists can end up with a different length
 137                         else
 138                                 path.after_start = range.start - base.start
 139                         end
 140                 else
 141                         local s = parent_at[#parent_at]
 142                         if not s or range.start >= s.finish + 1 + (s.is_line_comment and 1 or 0) then
 143                                 path = walker.sexp_path(parent_at)
 144                                 path.at_pfinish = true
 145                         else
 146                                 local prev, n = parent_at.before(range.start, finishof)
 147                                 if prev then
 148                                         path = walker.sexp_path(prev)
 149                                         local nxt = parent_at[n + 1]
 150                                         path.after_finish = nxt and not nxt.indent and 1 or range.finish - prev.finish - 1
 151                                 else
 152                                         path = walker.sexp_path(parent_at[1])
 153                                         path.after_start = 0
 154                                 end
 155                         end
 156                 end
 157                 return path
 158         end
 159
 160         local function pos_from(path, range)
 161                 local sexp, parentng, n = walker.goto_path(path)
 162                 if sexp then
 163                         if path.after_finish then
 164                                 local nxt = n and parentng[n + 1]
 165                                 local max = nxt and nxt.start - sexp.finish - 1
 166                                 return sexp.finish + 1 - (range.finish - range.start) +
 167                                         (max and math.min(path.after_finish, max) or path.after_finish)
 168                         elseif path.at_pfinish then
 169                                 return sexp.finish
 170                         else
 171                                 return sexp.start + path.after_start
 172                         end
 173                 end
 174         end
 175
 176         local function refmt_at(scope, range, keep_electric_space)
 177                 if not range or not scope or scope.is_root or (scope.finish - scope.start < 2) then return range.start end
 178                 local parent = walker.sexp_at(scope, true)
 179                 if not (parent and parent.is_list) then return range.start end
 180                 local path = path_from(range)
 181                 local indented_parent = parent.indent and parent or parent.is_list and walker.indented_before(parent)
 182                 local parent_column = indented_parent and (indented_parent.indent + parent.start - indented_parent.start +
 183                         (parent.p and #parent.p or 0) + #parent.d) or
 184                         0
 185                 local deltas = refmt_list(parent, parent_column, 0, {}, keep_electric_space)
 186                 table.sort(deltas, function(d1, d2) return d1[1] > d2[1] end)
 187                 for _, pair in ipairs(deltas) do
 188                         local offset, delta = unpack(pair)
 189                         if delta > 0 then
 190                                 write(offset, string.rep(" ", delta))
 191                         elseif delta < 0 then
 192                                 delete(offset + delta, -delta)
 193                         end
 194                 end
 195                 parser.tree.rewind(parent.start or 0)
 196                 return path and pos_from(path, range) or range.start
 197         end
 198
 199         local function splice(pos, sexps, skip, backwards, action)
 200                 local spliced
 201                 local sexp = walker.sexp_at(skip, true)
 202                 local start = sexp.start + (sexp.p and #sexp.p or 0)
 203                 -- XXX: don't splice empty line comments _yet_. See _join_or_splice
 204                 local tosplice = action.splice or action.wrap or not sexp.is_line_comment and sexp.is_empty
 205                 local opening = (sexp.p or "")..sexp.d
 206                 local closing = parser.opposite[sexp.d]
 207                 local real_start = tosplice and sexp.start or start + #sexp.d
 208                 local splice_closing = not sexp.is_line_comment or sexp.is_empty
 209                 local real_finish = sexp.finish + 1 - (tosplice and splice_closing and 0 or #closing)
 210                 local first = backwards and
 211                         {start = real_start, finish = math.max(pos, start + #sexp.d)} or
 212                         {start = real_start, finish = sexp.is_empty and pos or start + #sexp.d}
 213                 local second = backwards and
 214                         {start = sexp.is_empty and pos or sexp.finish + 1 - #closing, finish = real_finish} or
 215                         {start = math.min(pos, sexp.finish + 1 - #closing), finish = real_finish}
 216                 action.func(second)
 217                 action.func(first)
 218                 spliced = tosplice
 219                 if action.kill then
 220                         local ndeleted = first.finish - first.start + second.finish - second.start
 221                         if ndeleted > 0 then
 222                                 sexps.rewind(sexp.start)
 223                         end
 224                 end
 225                 return first.finish - first.start, spliced, opening, closing
 226         end
 227
 228         -- If you try to delete some part of indentation, this function joins the current line with
 229         -- the previous one, unless the latter is a line comment.
 230         -- it does this by
 231         -- a) extending or shrinking the range that is to be deleted
 232         -- b) returning a truthy value to trick pick_out to glide the cursor, but refmt to restore the deleted spaces
 233         -- c) both a) and b)
 234         local function delete_indentation(range, pos)
 235                 local node, parent = walker.sexp_at(range)
 236                 if node or not parent.is_list then return end
 237                 local prev = parent.before(pos, finishof)
 238                 local nxt = parent.after(pos, startof)
 239                 if prev and prev.finish >= range.start or nxt and nxt.start < range.finish then return end
 240                 local backwards = pos == range.finish
 241                 local adj = 0
 242                 local eol = eol_at(pos)
 243                 local on_empty_line = not nxt or eol and nxt.start > eol
 244                 local empty_line_after_comment = prev and prev.is_line_comment
 245                         and on_empty_line
 246                 if nxt and nxt.indent then
 247                         if backwards and prev then
 248                                 range.start = prev.finish + (empty_line_after_comment and 0 or 1)
 249                                 if not prev.d then
 250                                         range.finish = range.start + 1
 251                                         adj = (on_empty_line and 0 or 1)
 252                                 end
 253                         end
 254                         return adj
 255                 end
 256                 if not nxt and prev then
 257                         range.start = prev.finish + 1
 258                         range.finish = parent.finish
 259                 elseif nxt and nxt.start == range.finish and (not prev or prev.finish + 1 == range.start) then
 260                         if prev and prev.d or nxt and nxt.d then
 261                                 -- don't delete spaces near delimiters, just slide the cursor:
 262                                 if backwards then
 263                                         range.finish = range.start
 264                                 else
 265                                         range.start = range.finish
 266                                 end
 267                         end
 268                         return adj
 269                 end
 270         end
 271
 272         local function big_enough_parent(pos1, pos2)
 273                 -- since the pos1-pos2 range can cross list boundaries, find which list contains both pos1 and pos2
 274                 local _, p1, p2
 275                 _, p1 = walker.sexp_at({start = pos1, finish = pos1}, true)
 276                 if p1.is_root or not (p1.start < pos1 and p1.finish > pos2) then
 277                         _, p2 = walker.sexp_at({start = pos2, finish = pos2}, true)
 278                 end
 279                 return p2 and not p2.is_root and p2 or p1
 280         end
 281
 282         local function extend_overlap(range)
 283                 local rnode = walker.sexp_at({start = range.finish, finish = range.finish})
 284                 if rnode and rnode.p and rnode.p:find";"
 285                         and range.finish > rnode.start and range.finish < rnode.start + #rnode.p then
 286                         return {start = range.start, finish = rnode.start + #rnode.p}
 287                 end
 288                 return range
 289         end
 290
 291         local function pick_out(range, pos, action)
 292                 local ndeleted = 0
 293                 if range.start == range.finish then return ndeleted end
 294                 local sexps = parser.tree
 295                 local skips = sexps.unbalanced_delimiters(range)
 296                 -- handle splice and kill-splice of forms and strings:
 297                 if #skips == 1 then
 298                         local sexp = walker.sexp_at(skips[1], true)
 299                         local backward_splice = skips[1].opening and pos >= sexp.start + (sexp.p and #sexp.p or 0) + #sexp.d
 300                                 and range.start >= sexp.start
 301                         local forward_splice = skips[1].closing and pos <= sexp.finish + 1 - #parser.opposite[sexp.d]
 302                                 and range.finish <= sexp.finish + 1
 303                         if backward_splice or forward_splice then
 304                                 return splice(backward_splice and range.finish or range.start, sexps, sexp, backward_splice, action)
 305                         end
 306                 end
 307                 local node, parent = walker.sexp_at({start = range.finish, finish = range.finish})
 308                 -- if the range ends with a line comment, don't delete its closing newline:
 309                 local drop_eol = action.kill and node and
 310                         node.finish + 1 == range.finish and node.is_line_comment
 311                 local par = big_enough_parent(range.start, range.finish)
 312                 local operator_changed = par[1] and par[1].finish >= range.start
 313                 local refmt = #skips == 0 and delete_indentation(range, pos) or operator_changed and 0
 314                 table.sort(skips, function(a, b) return a.start < b.start end)
 315                 table.insert(skips, {start = range.finish - (drop_eol and 1 or 0)})
 316                 table.insert(skips, 1, {finish = range.start})
 317                 ndeleted = ndeleted + (drop_eol and 1 or 0)
 318                 for i = #skips - 1, 1, -1 do
 319                         local region = {start = skips[i].finish, finish = skips[i + 1].start}
 320                         if skips[i].closing and skips[i + 1].opening then
 321                                 -- leave out some of the space between adjacent lists
 322                                 local _, rparent = walker.sexp_at(region)
 323                                 local nxt = rparent.after(region.start, startof)
 324                                 region.start = nxt and nxt.start or region.start
 325                         end
 326                         if action then
 327                                 action.func(region)
 328                                 ndeleted = ndeleted + (region.finish - region.start)
 329                         end
 330                 end
 331                 -- if parent[#parent + 1] is nil, we are at EOF
 332                 if ndeleted > 0 and (not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1]) then
 333                         sexps.rewind(range.start)
 334                 end
 335                 return ndeleted - (refmt or 0), nil, nil, nil, refmt
 336         end
 337
 338         local function raise_sexp(range, pos)
 339                 local sexp, parent = walker.sexp_at(range, true)
 340                 if sexp and parent and parent.is_list then
 341                         delete(sexp.finish + 1, parent.finish - sexp.finish)
 342                         delete(parent.start, sexp.start - parent.start)
 343                         parser.tree.rewind(parent.start)
 344                         range.start = parent.start + pos - sexp.start
 345                         range.finish = range.start
 346                         local _, nodes = walker.sexp_path(range)
 347                         local grandparent = nodes[#nodes - 2]
 348                         return grandparent and refmt_at(grandparent, range) or range.start
 349                 end
 350         end
 351
 352         local function slurp_sexp(range, forward)
 353                 local _, parent = walker.sexp_at(range, true)
 354                 local seeker = forward and walker.finish_after or walker.start_before
 355                 if not parent or not parent.is_list then return range.start end
 356                 local r = {start = parent.start, finish = parent.finish + 1}
 357                 local newpos = seeker(r, is_comment)
 358                 if not newpos then return range.start end
 359                 local opening = (parent.p or "")..parent.d
 360                 local closing = parser.opposite[parent.d]
 361                 local delimiter = forward and closing or opening
 362                 if forward then
 363                         write(newpos, delimiter)
 364                 end
 365                 delete(forward and parent.finish or parent.start, #delimiter)
 366                 if not forward then
 367                         write(newpos, delimiter)
 368                 end
 369                 parser.tree.rewind(math.min(parent.start, newpos))
 370                 return refmt_at(big_enough_parent(newpos, range.start), range)
 371         end
 372
 373         local function barf_sexp(range, forward)
 374                 local _, parent, m = walker.sexp_at(range, true)
 375                 local seeker = forward and walker.finish_before or walker.start_after
 376                 -- TODO: barfing out of strings requires calling the parser on them
 377                 if not parent or not parent.is_list then return range.start end
 378                 local opening = (parent.p or "")..parent.d
 379                 local pstart = parent.start + #opening
 380                 local r = {start = forward and parent.finish - 1 or pstart, finish = forward and parent.finish or pstart + 1}
 381                 local newpos = seeker(r, is_comment) or forward and pstart or parent.finish
 382                 if not newpos then return range.start end
 383                 local closing = parser.opposite[parent.d]
 384                 local delimiter = forward and closing or opening
 385                 if not forward then
 386                         write(newpos, delimiter)
 387                 end
 388                 delete(forward and parent.finish or parent.start, #delimiter)
 389                 if forward then
 390                         write(newpos, delimiter)
 391                 end
 392                 parser.tree.rewind(math.min(parent.start, newpos))
 393                 local barfed_cursor_backward = m == 1 and not forward
 394                 local barfed_cursor_forward = m == #parent and forward
 395                 range.start = range.start + #delimiter * (barfed_cursor_backward and -1 or barfed_cursor_forward and 1 or 0)
 396                 return refmt_at(big_enough_parent(newpos, parent.finish + 1), range)
 397         end
 398
 399         local function splice_sexp(range, _, no_refmt)
 400                 local _, parent = walker.sexp_at(range)
 401                 if not parent or not parent.d then return end
 402                 local opening = (parent.p or "")..parent.d
 403                 local closing = parser.opposite[parent.d]
 404                 local finish = parent.finish + 1 - #closing
 405                 if not parent.is_line_comment then
 406                         delete(finish, #closing)
 407                 end
 408                 -- TODO: (un)escape special characters, if necessary
 409                 delete(parent.start, parent.is_empty and (finish - parent.start) or #opening)
 410                 parser.tree.rewind(parent.start)
 411                 range.start = range.start - #opening
 412                 range.finish = range.start
 413                 local _, parentng = walker.sexp_at(range, true)
 414                 return not no_refmt and refmt_at(parentng, range) or range.start
 415         end
 416
 417         local function rewrap(parent, kind)
 418                 local pstart = parent.start + #((parent.p or "")..parent.d) - 1
 419                 delete(parent.finish, 1)
 420                 write(parent.finish, parser.opposite[kind])
 421                 delete(pstart, #parent.d)
 422                 write(pstart, kind)
 423                 parser.tree.rewind(parent.start)
 424         end
 425
 426         local function cycle_wrap(range, pos)
 427                 local _, parent = walker.sexp_at(range)
 428                 if not parent or not parent.is_list then return end
 429                 local next_kind = {["("] = "[", ["["] = "{", ["{"] = "("}
 430                 rewrap(parent, next_kind[parent.d])
 431                 return pos
 432         end
 433
 434         local function split_sexp(range)
 435                 local _, parent = walker.sexp_at(range)
 436                 if not (parent and parent.d) then return end
 437                 local new_finish, new_start
 438                 if parent.is_list then
 439                         local prev = parent.before(range.start, finishof, is_comment)
 440                         new_finish = prev and prev.finish + 1
 441                         -- XXX: do not skip comments here, so they end up in the second list
 442                         -- and are not separated from their target expression:
 443                         local nxt = new_finish and parent.after(new_finish, startof)
 444                         new_start = nxt and nxt.start
 445                 else
 446                         new_start = range.start
 447                         new_finish = range.start
 448                 end
 449                 if not (new_start and new_finish) then return end
 450                 local opening = (parent.p or "")..parent.d
 451                 local closing = parser.opposite[parent.d]
 452                 write(new_start, opening)
 453                 local sep = parent.is_line_comment and ""  -- line comments already have a separator
 454                         or new_finish == new_start and " "  -- only add a separator if there was none before
 455                         or ""
 456                 write(new_finish, closing..sep)
 457                 parser.tree.rewind(parent.start)
 458                 range.start = new_start + (parent.is_list and 0 or #opening + #closing)
 459                 range.finish = range.start
 460                 local _, nodes = walker.sexp_path(range)
 461                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 462                 local scope = parentng and not parentng.is_root and parentng or grandparent
 463                 return refmt_at(scope, range)
 464         end
 465
 466         local function join_sexps(range)
 467                 local node, parent = walker.sexp_at(range, true)
 468                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 469                 local second = first ~= node and node or parent.after(range.start, startof)
 470                 if not (first and second and first.d and
 471                         -- don't join line comments to margin comments:
 472                         (not first.is_line_comment or first.indent and second.indent) and
 473                         (first.d == second.d or
 474                                 -- join line comments even when their delimiters differ slightly
 475                                 -- (different number of semicolons, existence/lack of a space after them)
 476                                 parser.opposite[first.d] == parser.opposite[second.d])) then
 477                         return
 478                 end
 479                 local opening = (second.p or "")..second.d
 480                 local closing = parser.opposite[first.d]
 481                 local pos
 482                 if not first.is_list then
 483                         pos = first.finish + 1 - #closing
 484                         delete(pos, second.start + #opening - pos)
 485                 else
 486                         delete(second.start, #opening)
 487                         delete(first.finish, #closing)
 488                         pos = second.start - #closing
 489                 end
 490                 parser.tree.rewind(first.start)
 491                 range.start = pos
 492                 range.finish = range.start
 493                 local _, nodes = walker.sexp_path(range)
 494                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 495                 local scope = parentng and not parentng.is_root and parentng or grandparent
 496                 return refmt_at(scope, range)
 497         end
 498
 499         local function delete_splicing(range, pos, splicing, delete_and_yank)
 500                 local action = {kill = true, wrap = splicing, splice = splicing, func = delete_and_yank}
 501                 local sexp, parent, n = walker.sexp_at(range, true)
 502                 range = extend_overlap(range)
 503                 local ndeleted, spliced = pick_out(range, pos, action)
 504                 local closing = spliced and parser.opposite[sexp.d]
 505                 local inner_list_len = spliced and sexp.finish - sexp.start + 1 - #sexp.d - #closing
 506                 local range_len = range.finish - range.start
 507                 local backwards = pos == range.finish
 508                 local whole_object = sexp and
 509                         (sexp.start == range.start and sexp.finish + 1 == range.finish
 510                         or spliced and (inner_list_len <= (backwards and range_len + ndeleted or range_len)))
 511                 local in_head_atom = sexp and not sexp.d and n == 1 and #parent > 1
 512                 local in_whitespace = not sexp
 513                 if whole_object or in_whitespace or in_head_atom then
 514                         local cur = whole_object and sexp.start or range.start
 515                         -- if parent[#parent + 1] is nil, we are at EOF
 516                         if not parent.is_root or parent.is_parsed(cur) or parent[#parent + 1] then
 517                                 parser.tree.rewind(cur)
 518                         end
 519                         local r = {start = cur, finish = cur}
 520                         local _, parentng = walker.sexp_at(r, true)
 521                         return refmt_at(parentng, r)
 522                 end
 523                 return spliced and (backwards and sexp.start or range.start - ndeleted)
 524                         or not backwards and ndeleted <= 0 and range.finish - ndeleted
 525                         or backwards and ndeleted <= 0 and range.start + ndeleted
 526                         or range.start
 527         end
 528
 529         local function transpose(range, first, second)
 530                 if not (first and second) then return end
 531                 local copy1 = first.text
 532                 local copy2 = second.text
 533                 delete(second.start, second.finish + 1 - second.start)
 534                 write(second.start, copy1)
 535                 delete(first.start, first.finish + 1 - first.start)
 536                 write(first.start, copy2)
 537                 parser.tree.rewind(first.start)
 538                 range.start = second.finish + 1
 539                 range.finish = range.start
 540                 return refmt_at(big_enough_parent(first.start, second.finish), range)
 541         end
 542
 543         local function transpose_sexps(range)
 544                 local node, parent = walker.sexp_at(range, true)
 545                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 546                 local second = first ~= node and node or parent.after(range.start, startof)
 547                 return transpose(range, first, second)
 548         end
 549
 550         local function transpose_words(range)
 551                 local _, first = walker.start_float_before(range)
 552                 local _, second = walker.finish_float_after(range)
 553                 if first and second and first.start == second.start then
 554                         _, first = walker.start_float_before(first)
 555                 end
 556                 return transpose(range, first, second)
 557         end
 558
 559         local function transpose_chars(range)
 560                 local node, parent, i = walker.sexp_at(range)
 561                 local nxt = i and parent[i + 1]
 562                 local pstart = not parent.is_root and parent.start + (parent.p and #parent.p or 0) + #parent.d
 563                 local pfinish = not parent.is_root and parent.finish
 564                 local npref = node and node.p and node.start + #node.p
 565                 -- only allow transposing while inside atoms/words and prefixes
 566                 if node and ((npref and (range.start <= npref and range.start > node.start) or
 567                         node.d and range.start > node.finish + 1) or not node.d and (not pstart or range.start > pstart)) then
 568                         local start = range.start -
 569                                 ((range.start == pfinish or range.start == npref or
 570                                 range.start == node.finish + 1 and (parent.is_list or parent.is_root) and (not nxt or nxt.indent)) and 1 or 0)
 571                         local str_start = start - node.start + 1
 572                         local char = node.text:sub(str_start, str_start)
 573                         delete(start, 1)
 574                         write(start - 1, #char > 0 and char or " ")
 575                         parser.tree.rewind(start)
 576                         local in_head_atom = i == 1 and #parent > 1
 577                         return parent.is_list and in_head_atom and refmt_at(parent, {start = start + 1, finish = start + 1}) or start + 1
 578                 end
 579         end
 580
 581         local function _join_or_splice(parent, n, range, pos)
 582                 local sexp = parent[n]
 583                 local nxt = parent[n + 1]
 584                 local is_last = not nxt or not nxt.is_line_comment
 585                 local newpos = not (is_last and sexp.is_empty) and join_sexps(range)
 586                 if not newpos and sexp.is_empty then
 587                         newpos = splice_sexp({start = pos, finish = pos}, nil, true)
 588                 end
 589                 return newpos or pos
 590         end
 591
 592         local function delete_nonsplicing(range, pos, delete_maybe_yank)
 593                 local action = {kill = true, wrap = false, splice = false, func = delete_maybe_yank}
 594                 range = extend_overlap(range)
 595                 local ndeleted, spliced, opening, _, refmt = pick_out(range, pos, action)
 596                 local backwards = pos == range.finish
 597                 if opening then
 598                         if spliced then
 599                                 return pos - ndeleted
 600                         else
 601                                 if ndeleted == 0 then
 602                                         local closing = parser.opposite[opening] -- XXX: why don't I use the pick_out return value?
 603                                         if closing == "\n" then
 604                                                 local sexp, parent, n = walker.sexp_at(range)
 605                                                 if pos == sexp.start + #sexp.d and backwards then
 606                                                         return _join_or_splice(parent, n, range, pos)
 607                                                 elseif pos == sexp.finish then
 608                                                         local r = {start = pos + #closing, finish = pos + #closing}
 609                                                         return _join_or_splice(parent, n, r, pos)
 610                                                 end
 611                                         end
 612                                 end
 613                                 return backwards and (range.finish - ndeleted) or range.start
 614                         end
 615                 else
 616                         local newpos = backwards and range.start + (ndeleted <= 0 and ndeleted or 0) or (range.finish - ndeleted)
 617                         if refmt then
 618                                 local r = {start = newpos, finish = newpos}
 619                                 return refmt_at(big_enough_parent(range.start, range.finish - ndeleted), r, true)
 620                         end
 621                         return newpos
 622                 end
 623         end
 624
 625         local function insert_pair(range, delimiter, shiftless, auto_square)
 626                 local indices, nodes = walker.sexp_path(range)
 627                 local sexp = nodes[#nodes]
 628                 local right_after_prefix = sexp and sexp.p and range.start == sexp.start + #sexp.p
 629                 -- XXX: here I assume that # is a valid prefix for the dialect
 630                 local mb_closing = (delimiter == "|") and right_after_prefix and parser.opposite[sexp.p .. delimiter]
 631                 local closing = mb_closing or parser.opposite[delimiter]
 632                 local squarewords = fmt.squarewords
 633                 if squarewords and not right_after_prefix
 634                         and not (closing == "]" and shiftless and not auto_square)
 635                         and (auto_square or squarewords.not_optional)
 636                         and not fmt:adjust_bracket_p(indices, nodes, range) then
 637                                 delimiter, closing = "[", "]"
 638                 end
 639                 write(range.finish, closing)
 640                 write(range.start, delimiter)
 641                 if right_after_prefix or parser.tree.is_parsed(range.start) then
 642                         parser.tree.rewind(right_after_prefix and sexp.start or range.start)
 643                 end
 644                 return range.start + #delimiter
 645         end
 646
 647         local function make_wrap(kind)
 648                 return function(range, pos, auto_square)
 649                         local opening = kind
 650                         local function _wrap(r)
 651                                 if not (r.finish > r.start) then return end
 652                                 insert_pair(r, opening, false, auto_square)
 653                         end
 654                         local action = {kill = false, wrap = false, splice = false, func = _wrap}
 655                         pick_out(range, pos, action)
 656                         local rangeng = {start = pos + #opening, finish = range.finish}
 657                         local _, parentng = walker.sexp_at(range)  -- TODO: range.finish is wrong. use sexp_path and big_enough_parent
 658                         return refmt_at(parentng, rangeng)
 659                 end
 660         end
 661
 662         local function newline(parent, range)
 663                 local line_comment = parent.is_line_comment
 664                 -- do not autoextend margin comments:
 665                 if line_comment and range.start < parent.finish + (parent.indent and 1 or 0)  then
 666                         local newpos = split_sexp(range)
 667                         if newpos then
 668                                 return newpos
 669                         end
 670                 end
 671                 if not parent.is_list and not line_comment then
 672                         -- if parent[#parent + 1] is nil, we are at EOF
 673                         if not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1] then
 674                                 parser.tree.rewind(parent.start or range.start)
 675                         end
 676                         local newpos = range.start
 677                         write(newpos, "\n")
 678                         return newpos + 1
 679                 end
 680                 if not parent.is_list then
 681                         local _
 682                         _, parent = walker.sexp_at(parent, true)
 683                 end
 684                 local last_nonblank_in_list = not parent.is_empty and parent[#parent].finish - (line_comment and 1 or 0)
 685                 local nxt = parent.after(range.start, startof)
 686                 local last_on_line = range.start == eol_at(range.start)
 687                 local margin = nxt and not nxt.indent and nxt.is_line_comment and nxt.finish
 688                 local after_last = last_nonblank_in_list and range.start > last_nonblank_in_list
 689                 local in_indent = nxt and nxt.indent and range.start <= nxt.start and range.start >= (nxt.start - nxt.indent)
 690                 local placeholder = "asdf"
 691                 local newpos = margin or range.start
 692                 if not parent.is_empty then
 693                         if in_indent then
 694                                 write(newpos, (placeholder.."\n"))
 695                         else
 696                                 write(newpos, "\n"..((after_last or last_on_line or margin) and placeholder or ""))
 697                         end
 698                 end
 699                 parser.tree.rewind(parent.start or newpos)
 700                 -- move the cursor onto the placeholder, so refmt_at can restore the position:
 701                 local r = {start = newpos, finish = newpos}
 702                 newpos = walker.start_after(r) or newpos
 703                 local rangeng = {start = newpos, finish = newpos}
 704                 newpos = refmt_at(parent, rangeng)
 705                 local _, parentng = walker.sexp_at({start = newpos, finish = newpos}, true)
 706                 if after_last then
 707                         local autoindent = parentng[#parentng].indent
 708                         write(parentng.finish, "\n"..string.rep(" ", autoindent or 0))
 709                 end
 710                 if after_last or last_on_line or margin or in_indent then
 711                         delete(newpos, #placeholder)
 712                 end
 713                 parser.tree.rewind(parentng.start or newpos)
 714                 return newpos
 715         end
 716
 717         local function close_and_newline(range, closing)
 718                 local opening = closing and parser.opposite[closing]
 719                 local parent = walker.quasilist_at(range, opening)
 720                 if parent then
 721                         local has_eol = parent.is_line_comment
 722                         local r = {start = parent.finish, finish = parent.finish}
 723                         local newpos = refmt_at(parent, r)
 724                         r = {start = newpos + (has_eol and 0 or 1), finish = newpos + (has_eol and 0 or 1)}
 725                         local list, parentng = walker.sexp_at(r)
 726                         newpos = list and list.finish + 1 or r.start
 727                         newpos = newline(parentng, {start = newpos, finish = newpos})
 728                         if not newpos then
 729                                 newpos = r.finish + 1
 730                                 write(newpos, "\n")
 731                                 parser.tree.rewind(parentng.start or list.start)
 732                         end
 733                         return newpos
 734                 elseif closing == "\n" then
 735                         local eol = eol_at(range.start)
 736                         local _, parentng = walker.sexp_at({start = eol, finish = eol})
 737                         local newpos = newline(parentng, {start = eol, finish = eol})
 738                         return newpos
 739                 end
 740                 return range.start
 741         end
 742
 743         local function join_line(_, pos)
 744                 local eol = eol_at(pos)
 745                 local r = {start = eol, finish = eol + 1}
 746                 return delete_nonsplicing(r, r.start, delete)
 747         end
 748
 749         local wrap_doublequote = make_wrap'"'
 750
 751         local function meta_doublequote(range, pos, auto_square)
 752                 local escaped = walker.escaped_at(range)
 753                 if not escaped then
 754                         return wrap_doublequote(range, pos, auto_square)
 755                 elseif escaped.is_string then
 756                         return close_and_newline(range, '"')
 757                 end
 758                 return pos
 759         end
 760
 761         local block_comment_start
 762         for o, c in pairs(parser.opposite) do
 763                 if #c > 1 then
 764                         block_comment_start = o
 765                         break
 766                 end
 767         end
 768
 769         local wrap_comment = make_wrap(block_comment_start)
 770
 771         return {
 772                 delete_splicing = delete_splicing,
 773                 delete_nonsplicing = delete_nonsplicing,
 774                 refmt_at = refmt_at,
 775                 pick_out = pick_out,
 776                 raise_sexp = raise_sexp,
 777                 slurp_sexp = slurp_sexp,
 778                 barf_sexp = barf_sexp,
 779                 splice_sexp = splice_sexp,
 780                 wrap_round = make_wrap"(",
 781                 wrap_square = make_wrap"[",
 782                 wrap_curly = make_wrap"{",
 783                 meta_doublequote = meta_doublequote,
 784                 wrap_comment = wrap_comment,
 785                 insert_pair = insert_pair,
 786                 newline = newline,
 787                 join_line = join_line,
 788                 close_and_newline = close_and_newline,
 789                 cycle_wrap = cycle_wrap,
 790                 split_sexp = split_sexp,
 791                 join_sexps = join_sexps,
 792                 transpose_sexps = transpose_sexps,
 793                 transpose_words = transpose_words,
 794                 transpose_chars = transpose_chars,
 795         }
 796 end
 797
 798 return M