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 swap = {["["] = "(", ["("] = "["}
   7
   8 local function startof(node) return node.start end
   9 local function finishof(node) return node.finish end
  10 local function is_comment(node) return node.is_comment end
  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                 local firstarg_delta = base_indent + parent[1].finish + 2 - pstart - s.indent - op_adj - (indent_adj or 0)
  46                 if last_distinguished and i > 1 then
  47                         delta = delta + 1
  48                         if i - 1 <= last_distinguished then
  49                                 if parent[first_argument + 1].indent then
  50                                         delta = delta + 2
  51                                 else
  52                                         delta = firstarg_delta
  53                                 end
  54                         elseif last_distinguished < 0
  55                                 and i > first_argument + 1 and not parent[first_argument + 1].indent then
  56                                 delta = firstarg_delta
  57                         end
  58                 elseif i == 1 then
  59                         -- remove leading space
  60                         delta = -(s.start - pstart)
  61                 elseif                               -- align further arguments below the second one
  62                         parent.d == "("              -- [] and {} contain data, so no arguments
  63                         and not parent[1].is_string  -- a string can't have arguments
  64                         --and not parent[1].is_list  -- wrong, GNU Emacs compatible behaviour
  65                         then
  66                         if i > first_argument + 1 and not parent[first_argument + 1].indent then
  67                                 delta = firstarg_delta
  68                         end
  69                         if delta < 0 then delta = math.max(-s.indent, delta) end
  70                 end
  71                 if delta ~= 0 then
  72                         table.insert(deltas, {s.start, delta})
  73                 end
  74                 adj = adj - delta
  75         end
  76         return adj
  77 end
  78
  79 function M.new(parser, walker, fmt, write, delete, eol_at)
  80
  81         local function refmt_list(parent, base_indent, padj, deltas, keep_electric_space)
  82                 local adj = 0
  83                 local op_adj = 0
  84                 local indent_adj = 0
  85                 local pstart = parent.start + (parent.p and #parent.p or 0) + #parent.d
  86                 if parent.is_empty then
  87                         normalize_spacing(pstart, parent.finish - pstart, deltas)
  88                         return deltas
  89                 end
  90                 local last_distinguished = fmt:last_distinguished(parent)
  91                 local first_argument = 1
  92                 if #parent > 2 and parent[1].is_list and #parent[1] > 1 then
  93                         local op = parent[1]
  94                         local nearest_indented = op[#op].indent and op[#op] or walker.indented_before(op[#op])
  95                         indent_adj = nearest_indented.start - pstart - nearest_indented.indent + 1
  96                 end
  97                 for i, s in ipairs(parent) do
  98                         adj = s.indent and 0 or adj
  99                         if last_distinguished then
 100                                 -- do not let early comments influence the indentation of real expressions:
 101                                 if i <= last_distinguished and s.is_comment then
 102                                         last_distinguished = last_distinguished + 1
 103                                 end
 104                                 -- s is the name of a named let. account for it:
 105                                 if i == last_distinguished + 1 and not s.is_list and parent[1].text == "let" then
 106                                         last_distinguished = last_distinguished + 1
 107                                 end
 108                                 -- do not let early comments influence the indentation of real expressions:
 109                         elseif i <= first_argument + 1 and s.is_comment then
 110                                 first_argument = first_argument + 1
 111                         end
 112                         local has_eol = s.is_line_comment
 113                         adj = leading_space(s, deltas, adj, parent, i, pstart, has_eol)
 114                         adj = trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
 115                         adj = indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
 116                                 op_adj, indent_adj)
 117                         if i == 1 then
 118                                 op_adj = adj
 119                         end
 120                         if s.is_list then
 121                                 local nearest_indented = s.indent and s or walker.indented_before(s)
 122                                 local parent_column = nearest_indented and
 123                                         nearest_indented.indent + (s.start + (s.p and #s.p or 0) + #s.d) - nearest_indented.start
 124                                         or base_indent + (s.start + (s.p and #s.p or 0) + #s.d) - pstart
 125                                 refmt_list(s, parent_column - adj, padj + adj, deltas, keep_electric_space)
 126                         end
 127                 end
 128                 return deltas
 129         end
 130
 131         local function path_from(range)
 132                 local _, parent_at, m = walker.sexp_at(range, true)
 133                 local path
 134                 if parent_at[m] then
 135                         path = walker.sexp_path(parent_at[m])
 136                         local base = parent_at[m]
 137                         if range.finish == base.finish + 1 then
 138                                 path.after_finish = 0  -- lists can end up with a different length
 139                         else
 140                                 path.after_start = range.start - base.start
 141                         end
 142                 else
 143                         local s = parent_at[#parent_at]
 144                         if not s or range.start >= s.finish + 1 + (s.is_line_comment and 1 or 0) then
 145                                 path = walker.sexp_path(parent_at)
 146                                 path.at_pfinish = true
 147                         else
 148                                 local prev, n = parent_at.before(range.start, finishof)
 149                                 if prev then
 150                                         path = walker.sexp_path(prev)
 151                                         local nxt = parent_at[n + 1]
 152                                         path.after_finish = nxt and not nxt.indent and 1 or range.finish - prev.finish - 1
 153                                 else
 154                                         path = walker.sexp_path(parent_at[1])
 155                                         path.after_start = 0
 156                                 end
 157                         end
 158                 end
 159                 return path
 160         end
 161
 162         local function pos_from(path, range)
 163                 local sexp, parentng, n = walker.goto_path(path)
 164                 if sexp then
 165                         if path.after_finish then
 166                                 local nxt = n and parentng[n + 1]
 167                                 local max = nxt and nxt.start - sexp.finish - 1
 168                                 return sexp.finish + 1 - (range.finish - range.start) +
 169                                         (max and math.min(path.after_finish, max) or path.after_finish)
 170                         elseif path.at_pfinish then
 171                                 return sexp.finish
 172                         else
 173                                 return sexp.start + path.after_start
 174                         end
 175                 end
 176         end
 177
 178         local function refmt_at(scope, range, keep_electric_space)
 179                 if not range or not scope or scope.is_root or (scope.finish - scope.start < 2) then return range.start end
 180                 local parent = walker.sexp_at(scope, true)
 181                 if not (parent and parent.is_list) then return range.start end
 182                 local path = path_from(range)
 183                 local indented_parent = parent.indent and parent or parent.is_list and walker.indented_before(parent)
 184                 local parent_column = indented_parent and (indented_parent.indent + parent.start - indented_parent.start +
 185                         (parent.p and #parent.p or 0) + #parent.d) or
 186                         0
 187                 local deltas = refmt_list(parent, parent_column, 0, {}, keep_electric_space)
 188                 table.sort(deltas, function(d1, d2) return d1[1] > d2[1] end)
 189                 for _, pair in ipairs(deltas) do
 190                         local offset, delta = unpack(pair)
 191                         if delta > 0 then
 192                                 write(offset, string.rep(" ", delta))
 193                         elseif delta < 0 then
 194                                 delete(offset + delta, -delta)
 195                         end
 196                 end
 197                 parser.tree.rewind(parent.start or 0)
 198                 return path and pos_from(path, range) or range.start
 199         end
 200
 201         local function splice(pos, sexps, skip, backwards, action)
 202                 local spliced
 203                 local sexp = walker.sexp_at(skip, true)
 204                 local start = sexp.start + (sexp.p and #sexp.p or 0)
 205                 -- XXX: don't splice empty line comments _yet_. See _join_or_splice
 206                 local tosplice = action.splice or action.wrap or not sexp.is_line_comment and sexp.is_empty
 207                 local opening = (sexp.p or "")..sexp.d
 208                 local closing = parser.opposite[sexp.d]
 209                 local real_start = tosplice and sexp.start or start + #sexp.d
 210                 local splice_closing = not sexp.is_line_comment or sexp.is_empty
 211                 local real_finish = sexp.finish + 1 - (tosplice and splice_closing and 0 or #closing)
 212                 local first = backwards and
 213                         {start = real_start, finish = math.max(pos, start + #sexp.d)} or
 214                         {start = real_start, finish = sexp.is_empty and pos or start + #sexp.d}
 215                 local second = backwards and
 216                         {start = sexp.is_empty and pos or sexp.finish + 1 - #closing, finish = real_finish} or
 217                         {start = math.min(pos, sexp.finish + 1 - #closing), finish = real_finish}
 218                 action.func(second)
 219                 action.func(first)
 220                 spliced = tosplice
 221                 if action.kill then
 222                         local ndeleted = first.finish - first.start + second.finish - second.start
 223                         if ndeleted > 0 then
 224                                 sexps.rewind(sexp.start)
 225                         end
 226                 end
 227                 return first.finish - first.start, spliced, opening, closing
 228         end
 229
 230         -- If you try to delete some part of indentation, this function joins the current line with
 231         -- the previous one, unless the latter is a line comment.
 232         -- it does this by
 233         -- a) extending or shrinking the range that is to be deleted
 234         -- b) returning a truthy value to trick pick_out to glide the cursor, but refmt to restore the deleted spaces
 235         -- c) both a) and b)
 236         local function delete_indentation(range, pos)
 237                 local node, parent = walker.sexp_at(range)
 238                 if node or not parent.is_list then return end
 239                 local prev = parent.before(pos, finishof)
 240                 local nxt = parent.after(pos, startof)
 241                 if prev and prev.finish >= range.start or nxt and nxt.start < range.finish then return end
 242                 local backwards = pos == range.finish
 243                 local adj = 0
 244                 local eol = eol_at(pos)
 245                 local on_empty_line = not nxt or eol and nxt.start > eol
 246                 local empty_line_after_comment = prev and prev.is_line_comment
 247                         and on_empty_line
 248                 if nxt and nxt.indent then
 249                         if backwards and prev then
 250                                 range.start = prev.finish + (empty_line_after_comment and 0 or 1)
 251                                 if not prev.d then
 252                                         range.finish = range.start + 1
 253                                         adj = (on_empty_line and 0 or 1)
 254                                 end
 255                         end
 256                         return adj
 257                 end
 258                 if not nxt and prev then
 259                         range.start = prev.finish + 1
 260                         range.finish = parent.finish
 261                 elseif nxt and nxt.start == range.finish and (not prev or prev.finish + 1 == range.start) then
 262                         if prev and prev.d or nxt and nxt.d then
 263                                 -- don't delete spaces near delimiters, just slide the cursor:
 264                                 if backwards then
 265                                         range.finish = range.start
 266                                 else
 267                                         range.start = range.finish
 268                                 end
 269                         end
 270                         return adj
 271                 end
 272         end
 273
 274         local function big_enough_parent(pos1, pos2)
 275                 -- since the pos1-pos2 range can cross list boundaries, find which list contains both pos1 and pos2
 276                 local _, p1, p2
 277                 _, p1 = walker.sexp_at({start = pos1, finish = pos1}, true)
 278                 if p1.is_root or not (p1.start < pos1 and p1.finish > pos2) then
 279                         _, p2 = walker.sexp_at({start = pos2, finish = pos2}, true)
 280                 end
 281                 return p2 and not p2.is_root and p2 or p1
 282         end
 283
 284         local function extend_overlap(range)
 285                 local rnode = walker.sexp_at({start = range.finish, finish = range.finish})
 286                 if rnode and rnode.p and rnode.p:find";"
 287                         and range.finish > rnode.start and range.finish < rnode.start + #rnode.p then
 288                         return {start = range.start, finish = rnode.start + #rnode.p}
 289                 end
 290                 return range
 291         end
 292
 293         local function pick_out(range, pos, action)
 294                 local ndeleted = 0
 295                 if range.start == range.finish then return ndeleted end
 296                 local sexps = parser.tree
 297                 local skips = sexps.unbalanced_delimiters(range)
 298                 -- handle splice and kill-splice of forms and strings:
 299                 if #skips == 1 then
 300                         local sexp = walker.sexp_at(skips[1], true)
 301                         local backward_splice = skips[1].opening and pos >= sexp.start + (sexp.p and #sexp.p or 0) + #sexp.d
 302                                 and range.start >= sexp.start
 303                         local forward_splice = skips[1].closing and pos <= sexp.finish + 1 - #parser.opposite[sexp.d]
 304                                 and range.finish <= sexp.finish + 1
 305                         if backward_splice or forward_splice then
 306                                 return splice(backward_splice and range.finish or range.start, sexps, sexp, backward_splice, action)
 307                         end
 308                 end
 309                 local node, parent = walker.sexp_at({start = range.finish, finish = range.finish})
 310                 -- if the range ends with a line comment, don't delete its closing newline:
 311                 local drop_eol = action.kill and node and
 312                         node.finish + 1 == range.finish and node.is_line_comment
 313                 local par = big_enough_parent(range.start, range.finish)
 314                 local operator_changed = par[1] and par[1].finish >= range.start
 315                 local refmt = #skips == 0 and delete_indentation(range, pos) or operator_changed and 0
 316                 table.sort(skips, function(a, b) return a.start < b.start end)
 317                 table.insert(skips, {start = range.finish - (drop_eol and 1 or 0)})
 318                 table.insert(skips, 1, {finish = range.start})
 319                 ndeleted = ndeleted + (drop_eol and 1 or 0)
 320                 for i = #skips - 1, 1, -1 do
 321                         local region = {start = skips[i].finish, finish = skips[i + 1].start}
 322                         if skips[i].closing and skips[i + 1].opening then
 323                                 -- leave out some of the space between adjacent lists
 324                                 local _, rparent = walker.sexp_at(region)
 325                                 local nxt = rparent.after(region.start, startof)
 326                                 region.start = nxt and nxt.start or region.start
 327                         end
 328                         if action then
 329                                 action.func(region)
 330                                 ndeleted = ndeleted + (region.finish - region.start)
 331                         end
 332                 end
 333                 -- if parent[#parent + 1] is nil, we are at EOF
 334                 if ndeleted > 0 and (not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1]) then
 335                         sexps.rewind(range.start)
 336                 end
 337                 return ndeleted - (refmt or 0), nil, nil, nil, refmt
 338         end
 339
 340         local function raise_sexp(range, pos)
 341                 local sexp, parent = walker.sexp_at(range, true)
 342                 if sexp and parent and parent.is_list then
 343                         delete(sexp.finish + 1, parent.finish - sexp.finish)
 344                         delete(parent.start, sexp.start - parent.start)
 345                         parser.tree.rewind(parent.start)
 346                         range.start = parent.start + pos - sexp.start
 347                         range.finish = range.start
 348                         local _, nodes = walker.sexp_path(range)
 349                         local grandparent = nodes[#nodes - 2]
 350                         return grandparent and refmt_at(grandparent, range) or range.start
 351                 end
 352         end
 353
 354         local function slurp_sexp(range, forward)
 355                 local _, parent = walker.sexp_at(range, true)
 356                 local seeker = forward and walker.finish_after or walker.start_before
 357                 if not parent or not parent.is_list then return range.start end
 358                 local r = {start = parent.start, finish = parent.finish + 1}
 359                 local newpos = seeker(r, is_comment)
 360                 if not newpos then return range.start end
 361                 local opening = (parent.p or "")..parent.d
 362                 local closing = parser.opposite[parent.d]
 363                 local delimiter = forward and closing or opening
 364                 if forward then
 365                         write(newpos, delimiter)
 366                 end
 367                 delete(forward and parent.finish or parent.start, #delimiter)
 368                 if not forward then
 369                         write(newpos, delimiter)
 370                 end
 371                 parser.tree.rewind(math.min(parent.start, newpos))
 372                 return refmt_at(big_enough_parent(newpos, range.start), range)
 373         end
 374
 375         local function barf_sexp(range, forward)
 376                 local _, parent, m = walker.sexp_at(range, true)
 377                 local seeker = forward and walker.finish_before or walker.start_after
 378                 -- TODO: barfing out of strings requires calling the parser on them
 379                 if not parent or not parent.is_list or parent.is_empty then return range.start end
 380                 local opening = (parent.p or "")..parent.d
 381                 local pstart = parent.start + #opening
 382                 local r = {start = forward and parent.finish - 1 or pstart, finish = forward and parent.finish or pstart + 1}
 383                 local newpos = seeker(r, is_comment) or forward and pstart or parent.finish
 384                 local closing = parser.opposite[parent.d]
 385                 local delimiter = forward and closing or opening
 386                 if not forward then
 387                         write(newpos, delimiter)
 388                 end
 389                 delete(forward and parent.finish or parent.start, #delimiter)
 390                 if forward then
 391                         write(newpos, delimiter)
 392                 end
 393                 parser.tree.rewind(math.min(parent.start, newpos))
 394                 local drag = forward and (newpos < range.finish) or not forward and (newpos > range.start)
 395                 local keep_inside = forward and m > 1 and range.finish > range.start and 1 or 0
 396                 newpos = drag and newpos - keep_inside or range.start
 397                 local rangeng = {start = newpos, finish = newpos}
 398                 return refmt_at(big_enough_parent(newpos, parent.finish + 1), rangeng)
 399         end
 400
 401         local function splice_sexp(range, _, no_refmt)
 402                 local _, parent = walker.sexp_at(range)
 403                 if not parent or not parent.d then return end
 404                 local opening = (parent.p or "")..parent.d
 405                 local closing = parser.opposite[parent.d]
 406                 local finish = parent.finish + 1 - #closing
 407                 if not parent.is_line_comment then
 408                         delete(finish, #closing)
 409                 end
 410                 -- TODO: (un)escape special characters, if necessary
 411                 delete(parent.start, parent.is_empty and (finish - parent.start) or #opening)
 412                 parser.tree.rewind(parent.start)
 413                 range.start = range.start - #opening
 414                 range.finish = range.start
 415                 local _, parentng = walker.sexp_at(range, true)
 416                 return not no_refmt and refmt_at(parentng, range) or range.start
 417         end
 418
 419         local function rewrap(parent, kind)
 420                 local pstart = parent.start + #((parent.p or "")..parent.d) - 1
 421                 delete(parent.finish, 1)
 422                 write(parent.finish, parser.opposite[kind])
 423                 delete(pstart, #parent.d)
 424                 write(pstart, kind)
 425                 parser.tree.rewind(parent.start)
 426         end
 427
 428         local function cycle_wrap(range, pos)
 429                 local _, parent = walker.sexp_at(range)
 430                 if not parent or not parent.is_list then return end
 431                 local next_kind = {["("] = "[", ["["] = "{", ["{"] = "("}
 432                 rewrap(parent, next_kind[parent.d])
 433                 return pos
 434         end
 435
 436         local function split_sexp(range)
 437                 local _, parent = walker.sexp_at(range)
 438                 if not (parent and parent.d) then return end
 439                 local new_finish, new_start
 440                 if parent.is_list then
 441                         local prev = parent.before(range.start, finishof, is_comment)
 442                         new_finish = prev and prev.finish + 1
 443                         -- XXX: do not skip comments here, so they end up in the second list
 444                         -- and are not separated from their target expression:
 445                         local nxt = new_finish and parent.after(new_finish, startof)
 446                         new_start = nxt and nxt.start
 447                 else
 448                         new_start = range.start
 449                         new_finish = range.start
 450                 end
 451                 if not (new_start and new_finish) then return end
 452                 local opening = (parent.p or "")..parent.d
 453                 local closing = parser.opposite[parent.d]
 454                 write(new_start, opening)
 455                 local sep = parent.is_line_comment and ""  -- line comments already have a separator
 456                         or new_finish == new_start and " "  -- only add a separator if there was none before
 457                         or ""
 458                 write(new_finish, closing..sep)
 459                 parser.tree.rewind(parent.start)
 460                 range.start = new_start + (parent.is_list and 0 or #opening + #closing)
 461                 range.finish = range.start
 462                 local _, nodes = walker.sexp_path(range)
 463                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 464                 local scope = parentng and not parentng.is_root and parentng or grandparent
 465                 return refmt_at(scope, range)
 466         end
 467
 468         local function join_sexps(range)
 469                 local node, parent = walker.sexp_at(range, true)
 470                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 471                 local second = first ~= node and node or parent.after(range.start, startof)
 472                 if not (first and second and first.d and
 473                         -- don't join line comments to margin comments:
 474                         (not first.is_line_comment or first.indent and second.indent) and
 475                         (first.d == second.d or
 476                                 -- join line comments even when their delimiters differ slightly
 477                                 -- (different number of semicolons, existence/lack of a space after them)
 478                                 parser.opposite[first.d] == parser.opposite[second.d])) then
 479                         return
 480                 end
 481                 local opening = (second.p or "")..second.d
 482                 local closing = parser.opposite[first.d]
 483                 local pos
 484                 if not first.is_list then
 485                         pos = first.finish + 1 - #closing
 486                         delete(pos, second.start + #opening - pos)
 487                 else
 488                         delete(second.start, #opening)
 489                         delete(first.finish, #closing)
 490                         pos = second.start - #closing
 491                 end
 492                 parser.tree.rewind(first.start)
 493                 range.start = pos
 494                 range.finish = range.start
 495                 local _, nodes = walker.sexp_path(range)
 496                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 497                 local scope = parentng and not parentng.is_root and parentng or grandparent
 498                 return refmt_at(scope, range)
 499         end
 500
 501         local function delete_splicing(range, pos, splicing, delete_and_yank)
 502                 local action = {kill = true, wrap = splicing, splice = splicing, func = delete_and_yank}
 503                 local sexp, parent, n = walker.sexp_at(range, true)
 504                 range = extend_overlap(range)
 505                 local ndeleted, spliced = pick_out(range, pos, action)
 506                 local closing = spliced and parser.opposite[sexp.d]
 507                 local inner_list_len = spliced and sexp.finish - sexp.start + 1 - #sexp.d - #closing
 508                 local range_len = range.finish - range.start
 509                 local backwards = pos == range.finish
 510                 local whole_object = sexp and
 511                         (sexp.start == range.start and sexp.finish + 1 == range.finish
 512                         or spliced and (inner_list_len <= (backwards and range_len + ndeleted or range_len)))
 513                 local in_head_atom = sexp and not sexp.d and n == 1 and #parent > 1
 514                 local in_whitespace = not sexp
 515                 if whole_object or in_whitespace or in_head_atom then
 516                         local cur = whole_object and sexp.start or range.start
 517                         -- if parent[#parent + 1] is nil, we are at EOF
 518                         if not parent.is_root or parent.is_parsed(cur) or parent[#parent + 1] then
 519                                 parser.tree.rewind(cur)
 520                         end
 521                         local r = {start = cur, finish = cur}
 522                         local _, parentng = walker.sexp_at(r, true)
 523                         return refmt_at(parentng, r)
 524                 end
 525                 return spliced and (backwards and sexp.start or range.start - ndeleted)
 526                         or not backwards and ndeleted <= 0 and range.finish - ndeleted
 527                         or backwards and ndeleted <= 0 and range.start + ndeleted
 528                         or range.start
 529         end
 530
 531         local function transpose(range, first, second)
 532                 if not (first and second) then return end
 533                 local copy1 = first.text
 534                 local copy2 = second.text
 535                 delete(second.start, second.finish + 1 - second.start)
 536                 write(second.start, copy1)
 537                 delete(first.start, first.finish + 1 - first.start)
 538                 write(first.start, copy2)
 539                 parser.tree.rewind(first.start)
 540                 range.start = second.finish + 1
 541                 range.finish = range.start
 542                 return refmt_at(big_enough_parent(first.start, second.finish), range)
 543         end
 544
 545         local function transpose_sexps(range)
 546                 local node, parent = walker.sexp_at(range, true)
 547                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 548                 local second = first ~= node and node or parent.after(range.start, startof)
 549                 return transpose(range, first, second)
 550         end
 551
 552         local function transpose_words(range)
 553                 local _, first = walker.start_float_before(range)
 554                 local _, second = walker.finish_float_after(range)
 555                 if first and second and first.start == second.start then
 556                         _, first = walker.start_float_before(first)
 557                 end
 558                 return transpose(range, first, second)
 559         end
 560
 561         local function transpose_chars(range)
 562                 local node, parent, i = walker.sexp_at(range)
 563                 local nxt = i and parent[i + 1]
 564                 local pstart = not parent.is_root and parent.start + (parent.p and #parent.p or 0) + #parent.d
 565                 local pfinish = not parent.is_root and parent.finish
 566                 local npref = node and node.p and node.start + #node.p
 567                 -- only allow transposing while inside atoms/words and prefixes
 568                 if node and ((npref and (range.start <= npref and range.start > node.start) or
 569                         node.d and range.start > node.finish + 1) or not node.d and (not pstart or range.start > pstart)) then
 570                         local start = range.start -
 571                                 ((range.start == pfinish or range.start == npref or
 572                                 range.start == node.finish + 1 and (parent.is_list or parent.is_root) and (not nxt or nxt.indent)) and 1 or 0)
 573                         local str_start = start - node.start + 1
 574                         local char = node.text:sub(str_start, str_start)
 575                         delete(start, 1)
 576                         write(start - 1, #char > 0 and char or " ")
 577                         parser.tree.rewind(start)
 578                         local in_head_atom = i == 1 and #parent > 1
 579                         return parent.is_list and in_head_atom and refmt_at(parent, {start = start + 1, finish = start + 1}) or start + 1
 580                 end
 581         end
 582
 583         local function _join_or_splice(parent, n, range, pos)
 584                 local sexp = parent[n]
 585                 local nxt = parent[n + 1]
 586                 local is_last = not nxt or not nxt.is_line_comment
 587                 local newpos = not (is_last and sexp.is_empty) and join_sexps(range)
 588                 if not newpos and sexp.is_empty then
 589                         newpos = splice_sexp({start = pos, finish = pos}, nil, true)
 590                 end
 591                 return newpos or pos
 592         end
 593
 594         local function delete_nonsplicing(range, pos, delete_maybe_yank)
 595                 local action = {kill = true, wrap = false, splice = false, func = delete_maybe_yank}
 596                 range = extend_overlap(range)
 597                 local ndeleted, spliced, opening, _, refmt = pick_out(range, pos, action)
 598                 local backwards = pos == range.finish
 599                 if opening then
 600                         if spliced then
 601                                 return pos - ndeleted
 602                         else
 603                                 if ndeleted == 0 then
 604                                         local closing = parser.opposite[opening] -- XXX: why don't I use the pick_out return value?
 605                                         if closing == "\n" then
 606                                                 local sexp, parent, n = walker.sexp_at(range)
 607                                                 if pos == sexp.start + #sexp.d and backwards then
 608                                                         return _join_or_splice(parent, n, range, pos)
 609                                                 elseif pos == sexp.finish then
 610                                                         local r = {start = pos + #closing, finish = pos + #closing}
 611                                                         return _join_or_splice(parent, n, r, pos)
 612                                                 end
 613                                         end
 614                                 end
 615                                 return backwards and (range.finish - ndeleted) or range.start
 616                         end
 617                 else
 618                         local newpos = backwards and range.start + (ndeleted <= 0 and ndeleted or 0) or (range.finish - ndeleted)
 619                         if refmt then
 620                                 local r = {start = newpos, finish = newpos}
 621                                 return refmt_at(big_enough_parent(range.start, range.finish - ndeleted), r, true)
 622                         end
 623                         return newpos
 624                 end
 625         end
 626
 627         local function insert_pair(range, delimiter, shiftless, auto_square)
 628                 local indices, nodes = walker.sexp_path(range)
 629                 local sexp = nodes[#nodes]
 630                 local right_after_prefix = sexp and sexp.p and range.start == sexp.start + #sexp.p
 631                 -- XXX: here I assume that # is a valid prefix for the dialect
 632                 local mb_closing = (delimiter == "|") and right_after_prefix and parser.opposite[sexp.p .. delimiter]
 633                 local closing = mb_closing or parser.opposite[delimiter]
 634                 local squarewords = fmt.squarewords
 635                 if squarewords and not right_after_prefix
 636                         and not (closing == "]" and shiftless and not auto_square)
 637                         and (auto_square or squarewords.not_optional)
 638                         and not fmt:adjust_bracket_p(indices, nodes, range) then
 639                                 delimiter, closing = "[", "]"
 640                 end
 641                 write(range.finish, closing)
 642                 write(range.start, delimiter)
 643                 if right_after_prefix or parser.tree.is_parsed(range.start) then
 644                         parser.tree.rewind(right_after_prefix and sexp.start or range.start)
 645                 end
 646                 return range.start + #delimiter
 647         end
 648
 649         local function make_wrap(kind)
 650                 return function(range, pos, shiftless, auto_square)
 651                         local opening = shiftless and swap[kind] or kind
 652                         local function _wrap(r)
 653                                 if not (r.finish > r.start) then return end
 654                                 insert_pair(r, opening, false, auto_square)
 655                         end
 656                         local action = {kill = false, wrap = false, splice = false, func = _wrap}
 657                         pick_out(range, pos, action)
 658                         local rangeng = {start = pos + #opening, finish = range.finish}
 659                         local _, parentng = walker.sexp_at(range)  -- TODO: range.finish is wrong. use sexp_path and big_enough_parent
 660                         return refmt_at(parentng, rangeng)
 661                 end
 662         end
 663
 664         local function newline(parent, range)
 665                 local line_comment = parent.is_line_comment
 666                 -- do not autoextend margin comments:
 667                 if line_comment and range.start < parent.finish + (parent.indent and 1 or 0)  then
 668                         local newpos = split_sexp(range)
 669                         if newpos then
 670                                 return newpos
 671                         end
 672                 end
 673                 if not parent.is_list and not line_comment then
 674                         -- if parent[#parent + 1] is nil, we are at EOF
 675                         if not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1] then
 676                                 parser.tree.rewind(parent.start or range.start)
 677                         end
 678                         local newpos = range.start
 679                         write(newpos, "\n")
 680                         return newpos + 1
 681                 end
 682                 if not parent.is_list then
 683                         local _
 684                         _, parent = walker.sexp_at(parent, true)
 685                 end
 686                 local last_nonblank_in_list = not parent.is_empty and parent[#parent].finish - (line_comment and 1 or 0)
 687                 local nxt = parent.after(range.start, startof)
 688                 local last_on_line = range.start == eol_at(range.start)
 689                 local margin = nxt and not nxt.indent and nxt.is_line_comment and nxt.finish
 690                 local after_last = last_nonblank_in_list and range.start > last_nonblank_in_list
 691                 local in_indent = nxt and nxt.indent and range.start <= nxt.start and range.start >= (nxt.start - nxt.indent)
 692                 local placeholder = "asdf"
 693                 local newpos = margin or range.start
 694                 if not parent.is_empty then
 695                         if in_indent then
 696                                 write(newpos, (placeholder.."\n"))
 697                         else
 698                                 write(newpos, "\n"..((after_last or last_on_line or margin) and placeholder or ""))
 699                         end
 700                 end
 701                 parser.tree.rewind(parent.start or newpos)
 702                 -- move the cursor onto the placeholder, so refmt_at can restore the position:
 703                 local r = {start = newpos, finish = newpos}
 704                 newpos = walker.start_after(r) or newpos
 705                 local rangeng = {start = newpos, finish = newpos}
 706                 newpos = refmt_at(parent, rangeng)
 707                 local _, parentng = walker.sexp_at({start = newpos, finish = newpos}, true)
 708                 if after_last then
 709                         local autoindent = parentng[#parentng].indent
 710                         write(parentng.finish, "\n"..string.rep(" ", autoindent or 0))
 711                 end
 712                 if after_last or last_on_line or margin or in_indent then
 713                         delete(newpos, #placeholder)
 714                 end
 715                 parser.tree.rewind(parentng.start or newpos)
 716                 return newpos
 717         end
 718
 719         local function close_and_newline(range, closing)
 720                 local opening = closing and parser.opposite[closing]
 721                 local parent = walker.quasilist_at(range, opening)
 722                 if parent then
 723                         local has_eol = parent.is_line_comment
 724                         local r = {start = parent.finish, finish = parent.finish}
 725                         local newpos = refmt_at(parent, r)
 726                         r = {start = newpos + (has_eol and 0 or 1), finish = newpos + (has_eol and 0 or 1)}
 727                         local list, parentng = walker.sexp_at(r)
 728                         newpos = list and list.finish + 1 or r.start
 729                         newpos = newline(parentng, {start = newpos, finish = newpos})
 730                         if not newpos then
 731                                 newpos = r.finish + 1
 732                                 write(newpos, "\n")
 733                                 parser.tree.rewind(parentng.start or list.start)
 734                         end
 735                         return newpos
 736                 elseif closing == "\n" then
 737                         local eol = eol_at(range.start)
 738                         local _, parentng = walker.sexp_at({start = eol, finish = eol})
 739                         local newpos = newline(parentng, {start = eol, finish = eol})
 740                         return newpos
 741                 end
 742                 return range.start
 743         end
 744
 745         local function join_line(_, pos)
 746                 local eol = eol_at(pos)
 747                 local r = {start = eol, finish = eol + 1}
 748                 return delete_nonsplicing(r, r.start, delete)
 749         end
 750
 751         local wrap_doublequote = make_wrap'"'
 752
 753         local function meta_doublequote(range, pos, auto_square)
 754                 local escaped = walker.escaped_at(range)
 755                 if not escaped then
 756                         return wrap_doublequote(range, pos, nil, auto_square)
 757                 elseif escaped.is_string then
 758                         return close_and_newline(range, '"')
 759                 end
 760                 return pos
 761         end
 762
 763         local block_comment_start
 764         for o, c in pairs(parser.opposite) do
 765                 if #c > 1 then
 766                         block_comment_start = o
 767                         break
 768                 end
 769         end
 770
 771         local wrap_comment = make_wrap(block_comment_start)
 772
 773         return {
 774                 delete_splicing = delete_splicing,
 775                 delete_nonsplicing = delete_nonsplicing,
 776                 refmt_at = refmt_at,
 777                 pick_out = pick_out,
 778                 raise_sexp = raise_sexp,
 779                 slurp_sexp = slurp_sexp,
 780                 barf_sexp = barf_sexp,
 781                 splice_sexp = splice_sexp,
 782                 wrap_round = make_wrap"(",
 783                 wrap_square = make_wrap"[",
 784                 wrap_curly = make_wrap"{",
 785                 meta_doublequote = meta_doublequote,
 786                 wrap_comment = wrap_comment,
 787                 insert_pair = insert_pair,
 788                 newline = newline,
 789                 join_line = join_line,
 790                 close_and_newline = close_and_newline,
 791                 cycle_wrap = cycle_wrap,
 792                 split_sexp = split_sexp,
 793                 join_sexps = join_sexps,
 794                 transpose_sexps = transpose_sexps,
 795                 transpose_words = transpose_words,
 796                 transpose_chars = transpose_chars,
 797         }
 798 end
 799
 800 return M