edit.lua

   1 local M = {}
   2
   3 -- XXX: in Lua 5.2 unpack() was moved into table
   4 local unpack = table.unpack or 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 local function is_lone_prefix(node)
  78         return node and node.p and (#node.p == node.finish - node.start + 1)
  79 end
  80
  81 function M.new(parser, walker, fmt, write, delete, eol_at)
  82
  83         local function refmt_list(parent, base_indent, padj, deltas, keep_electric_space)
  84                 local adj = 0
  85                 local op_adj = 0
  86                 local indent_adj = 0
  87                 local pstart = parent.start + (parent.p and #parent.p or 0) + #parent.d
  88                 if parent.is_empty then
  89                         normalize_spacing(pstart, parent.finish - pstart, deltas)
  90                         return deltas
  91                 end
  92                 local last_distinguished = fmt:last_distinguished(parent)
  93                 local first_argument = 1
  94                 if #parent > 2 and parent[1].is_list and #parent[1] > 1 then
  95                         local op = parent[1]
  96                         local nearest_indented = op[#op].indent and op[#op] or walker.indented_before(op[#op])
  97                         indent_adj = nearest_indented.start - pstart - nearest_indented.indent + 1
  98                 end
  99                 for i, s in ipairs(parent) do
 100                         adj = s.indent and 0 or adj
 101                         if last_distinguished then
 102                                 -- do not let early comments influence the indentation of real expressions:
 103                                 if i <= last_distinguished and s.is_comment then
 104                                         last_distinguished = last_distinguished + 1
 105                                 end
 106                                 -- s is the name of a named let. account for it:
 107                                 if i == last_distinguished + 1 and not s.is_list and parent[1].text == "let" then
 108                                         last_distinguished = last_distinguished + 1
 109                                 end
 110                                 -- do not let early comments influence the indentation of real expressions:
 111                         elseif i <= first_argument + 1 and s.is_comment then
 112                                 first_argument = first_argument + 1
 113                         end
 114                         local has_eol = s.is_line_comment
 115                         adj = leading_space(s, deltas, adj, parent, i, pstart, has_eol)
 116                         adj = trailing_space(s, deltas, adj, parent, i, has_eol, keep_electric_space)
 117                         adj = indentation(s, deltas, adj, parent, i, pstart, base_indent, last_distinguished, first_argument,
 118                                 op_adj, indent_adj)
 119                         if i == 1 then
 120                                 op_adj = adj
 121                         end
 122                         if s.is_list then
 123                                 local nearest_indented = s.indent and s or walker.indented_before(s)
 124                                 local parent_column = nearest_indented and
 125                                         nearest_indented.indent + (s.start + (s.p and #s.p or 0) + #s.d) - nearest_indented.start
 126                                         or base_indent + (s.start + (s.p and #s.p or 0) + #s.d) - pstart
 127                                 refmt_list(s, parent_column - adj, padj + adj, deltas, keep_electric_space)
 128                         end
 129                 end
 130                 return deltas
 131         end
 132
 133         local function path_from(range)
 134                 local _, parent_at, m = walker.sexp_at(range, true)
 135                 local path
 136                 if parent_at[m] then
 137                         path = walker.sexp_path(parent_at[m])
 138                         local base = parent_at[m]
 139                         if range.finish == base.finish + 1 then
 140                                 path.after_finish = 0  -- lists can end up with a different length
 141                         else
 142                                 path.after_start = range.start - base.start
 143                         end
 144                 else
 145                         local s = parent_at[#parent_at]
 146                         if not s or range.start >= s.finish + 1 + (s.is_line_comment and 1 or 0) then
 147                                 path = walker.sexp_path(parent_at)
 148                                 path.at_pfinish = true
 149                         else
 150                                 local prev, n = parent_at.before(range.start, finishof)
 151                                 if prev then
 152                                         path = walker.sexp_path(prev)
 153                                         local nxt = parent_at[n + 1]
 154                                         path.after_finish = nxt and not nxt.indent and 1 or range.finish - prev.finish - 1
 155                                 else
 156                                         path = walker.sexp_path(parent_at[1])
 157                                         path.after_start = 0
 158                                 end
 159                         end
 160                 end
 161                 return path
 162         end
 163
 164         local function pos_from(path, range)
 165                 local sexp, parentng, n = walker.goto_path(path)
 166                 if sexp then
 167                         if path.after_finish then
 168                                 local nxt = n and parentng[n + 1]
 169                                 local max = nxt and nxt.start - sexp.finish - 1
 170                                 return sexp.finish + 1 - (range.finish - range.start) +
 171                                         (max and math.min(path.after_finish, max) or path.after_finish)
 172                         elseif path.at_pfinish then
 173                                 return sexp.finish
 174                         else
 175                                 return sexp.start + path.after_start
 176                         end
 177                 end
 178         end
 179
 180         local function refmt_at(scope, range, keep_electric_space)
 181                 if not range or not scope or scope.is_root or (scope.finish - scope.start < 2) then return range.start end
 182                 local parent = walker.sexp_at(scope, true)
 183                 if not (parent and parent.is_list) then return range.start end
 184                 local path = path_from(range)
 185                 local indented_parent = parent.indent and parent or parent.is_list and walker.indented_before(parent)
 186                 local parent_column = indented_parent and (indented_parent.indent + parent.start - indented_parent.start +
 187                         (parent.p and #parent.p or 0) + #parent.d) or
 188                         0
 189                 local deltas = refmt_list(parent, parent_column, 0, {}, keep_electric_space)
 190                 table.sort(deltas, function(d1, d2) return d1[1] > d2[1] end)
 191                 for _, pair in ipairs(deltas) do
 192                         local offset, delta = unpack(pair)
 193                         if delta > 0 then
 194                                 write(offset, string.rep(" ", delta))
 195                         elseif delta < 0 then
 196                                 delete(offset + delta, -delta)
 197                         end
 198                 end
 199                 parser.tree.rewind(parent.start or 0)
 200                 return path and pos_from(path, range) or range.start
 201         end
 202
 203         local function splice(pos, sexps, skip, backwards, action)
 204                 local spliced
 205                 local sexp = walker.sexp_at(skip, true)
 206                 local start = sexp.start + (sexp.p and #sexp.p or 0)
 207                 -- XXX: don't splice empty line comments _yet_. See _join_or_splice
 208                 local tosplice = action.splice or action.wrap or not sexp.is_line_comment and sexp.is_empty
 209                 local opening = (sexp.p or "")..sexp.d
 210                 local closing = parser.opposite[sexp.d]
 211                 local real_start = tosplice and sexp.start or start + #sexp.d
 212                 local splice_closing = not sexp.is_line_comment or sexp.is_empty
 213                 local real_finish = sexp.finish + 1 - (tosplice and splice_closing and 0 or #closing)
 214                 local first = backwards and
 215                         {start = real_start, finish = math.max(pos, start + #sexp.d)} or
 216                         {start = real_start, finish = sexp.is_empty and pos or start + #sexp.d}
 217                 local second = backwards and
 218                         {start = sexp.is_empty and pos or sexp.finish + 1 - #closing, finish = real_finish} or
 219                         {start = math.min(pos, sexp.finish + 1 - #closing), finish = real_finish}
 220                 action.func(second)
 221                 action.func(first)
 222                 spliced = tosplice
 223                 if action.kill then
 224                         local ndeleted = first.finish - first.start + second.finish - second.start
 225                         if ndeleted > 0 then
 226                                 sexps.rewind(sexp.start)
 227                         end
 228                 end
 229                 return first.finish - first.start, spliced, opening, closing
 230         end
 231
 232
 233         -- This function handles some whitespace-only deletion corner cases magically.
 234         -- It does so by
 235         -- a) extending or shrinking the range that is to be deleted
 236         -- b) returning an integer to trick pick_out to glide the cursor, but calling refmt to restore the deleted spaces
 237         -- c) both a) and b)
 238         local function delete_whitespace_only(range, pos)
 239                 local node, parent = walker.sexp_at(range)
 240                 if node or not parent.is_list then return end
 241                 local prev = parent.before(pos, finishof)
 242                 local nxt = parent.after(pos, startof)
 243                 if prev and prev.finish >= range.start or nxt and nxt.start < range.finish then return end
 244                 local backwards = pos == range.finish
 245                 local adj = 0
 246                 local eol = eol_at(pos)
 247                 local on_empty_line = not nxt or eol and nxt.start > eol
 248                 local empty_line_after_comment = prev and prev.is_line_comment
 249                         and on_empty_line
 250                 if nxt and nxt.indent then
 251                         if backwards and prev then
 252                                 -- join current line with the previous one, unless the latter is a line comment
 253                                 range.start = prev.finish + (empty_line_after_comment and 0 or 1)
 254                                 if not prev.d then
 255                                         range.finish = range.start + 1
 256                                         adj = (on_empty_line and 0 or 1)
 257                                 end
 258                         else
 259                                 adj = nxt.start - range.finish
 260                         end
 261                         return adj
 262                 end
 263                 if not nxt and prev then
 264                         -- clean up trailing whitespace (e.g. electric RET)
 265                         range.start = prev.finish + 1
 266                         range.finish = parent.finish
 267                 elseif nxt and nxt.start == range.finish and (not prev or prev.finish + 1 == range.start) then
 268                         if prev and prev.d or nxt and nxt.d and not is_lone_prefix(prev) then
 269                                 -- don't delete spaces near delimiters, just slide the cursor:
 270                                 if backwards then
 271                                         range.finish = range.start
 272                                 else
 273                                         range.start = range.finish
 274                                 end
 275                         end
 276                         return adj
 277                 end
 278         end
 279
 280         local function big_enough_parent(pos1, pos2)
 281                 -- since the pos1-pos2 range can cross list boundaries, find which list contains both pos1 and pos2
 282                 local _, p1, p2
 283                 _, p1 = walker.sexp_at({start = pos1, finish = pos1}, true)
 284                 if p1.is_root or not (p1.start < pos1 and p1.finish > pos2) then
 285                         _, p2 = walker.sexp_at({start = pos2, finish = pos2}, true)
 286                 end
 287                 return p2 and not p2.is_root and p2 or p1
 288         end
 289
 290         local function extend_overlap(range)
 291                 local rnode = walker.sexp_at({start = range.finish, finish = range.finish})
 292                 if rnode and rnode.p and rnode.p:find";"
 293                         and range.finish > rnode.start and range.finish < rnode.start + #rnode.p then
 294                         return {start = range.start, finish = rnode.start + #rnode.p}
 295                 end
 296                 return range
 297         end
 298
 299         local function pick_out(range, pos, action)
 300                 local ndeleted = 0
 301                 if range.start == range.finish then return ndeleted end
 302                 local sexps = parser.tree
 303                 local skips = sexps.unbalanced_delimiters(range)
 304                 -- handle splice and kill-splice of forms and strings:
 305                 if #skips == 1 then
 306                         local sexp = walker.sexp_at(skips[1], true)
 307                         local backward_splice = skips[1].opening and pos >= sexp.start + (sexp.p and #sexp.p or 0) + #sexp.d
 308                                 and range.start >= sexp.start
 309                         local forward_splice = skips[1].closing and pos <= sexp.finish + 1 - #parser.opposite[sexp.d]
 310                                 and range.finish <= sexp.finish + 1
 311                         if backward_splice or forward_splice then
 312                                 return splice(backward_splice and range.finish or range.start, sexps, sexp, backward_splice, action)
 313                         end
 314                 end
 315                 local node, parent = walker.sexp_at({start = range.finish, finish = range.finish})
 316                 -- if the range ends with a line comment, don't delete its closing newline:
 317                 local drop_eol = action.kill and node and
 318                         node.finish + 1 == range.finish and node.is_line_comment
 319                 local par = big_enough_parent(range.start, range.finish)
 320                 local operator_changed = par[1] and par[1].finish >= range.start
 321                 local refmt = #skips == 0 and delete_whitespace_only(range, pos) or operator_changed and 0
 322                 table.sort(skips, function(a, b) return a.start < b.start end)
 323                 table.insert(skips, {start = range.finish - (drop_eol and 1 or 0)})
 324                 table.insert(skips, 1, {finish = range.start})
 325                 ndeleted = ndeleted + (drop_eol and 1 or 0)
 326                 for i = #skips - 1, 1, -1 do
 327                         local region = {start = skips[i].finish, finish = skips[i + 1].start}
 328                         if skips[i].closing and skips[i + 1].opening then
 329                                 -- leave out some of the space between adjacent lists
 330                                 local _, rparent = walker.sexp_at(region)
 331                                 local nxt = rparent.after(region.start, startof)
 332                                 region.start = nxt and nxt.start or region.start
 333                         end
 334                         if action then
 335                                 action.func(region)
 336                                 ndeleted = ndeleted + (region.finish - region.start)
 337                         end
 338                 end
 339                 -- if parent[#parent + 1] is nil, we are at EOF
 340                 if ndeleted > 0 and (not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1]) then
 341                         sexps.rewind(range.start)
 342                 end
 343                 return ndeleted - (refmt or 0), nil, nil, nil, refmt
 344         end
 345
 346         local function raise_sexp(range, pos)
 347                 local sexp, parent = walker.sexp_at(range, true)
 348                 if sexp and parent and parent.is_list then
 349                         delete(sexp.finish + 1, parent.finish - sexp.finish)
 350                         delete(parent.start, sexp.start - parent.start)
 351                         parser.tree.rewind(parent.start)
 352                         range.start = parent.start + pos - sexp.start
 353                         range.finish = range.start
 354                         local _, nodes = walker.sexp_path(range)
 355                         local grandparent = nodes[#nodes - 2]
 356                         return grandparent and refmt_at(grandparent, range) or range.start
 357                 end
 358         end
 359
 360         local function slurp_sexp(range, forward)
 361                 local _, parent = walker.sexp_at(range, true)
 362                 local seeker = forward and walker.finish_after or walker.start_before
 363                 if not parent or not parent.is_list then return range.start end
 364                 local r = {start = parent.start, finish = parent.finish + 1}
 365                 local newpos = seeker(r, is_comment)
 366                 if not newpos then return range.start end
 367                 local opening = (parent.p or "")..parent.d
 368                 local closing = parser.opposite[parent.d]
 369                 local delimiter = forward and closing or opening
 370                 if forward then
 371                         write(newpos, delimiter)
 372                 end
 373                 delete(forward and parent.finish or parent.start, #delimiter)
 374                 if not forward then
 375                         write(newpos, delimiter)
 376                 end
 377                 parser.tree.rewind(math.min(parent.start, newpos))
 378                 return refmt_at(big_enough_parent(newpos, range.start), range)
 379         end
 380
 381         local function barf_sexp(range, forward)
 382                 local _, parent = walker.sexp_at(range, true)
 383                 local seeker = forward and walker.finish_before or walker.start_after
 384                 -- TODO: barfing out of strings requires calling the parser on them
 385                 if not parent or not parent.is_list or parent.is_empty then return range.start end
 386                 local opening = (parent.p or "")..parent.d
 387                 local pstart = parent.start + #opening
 388                 local r = {start = forward and parent.finish - 1 or pstart, finish = forward and parent.finish or pstart + 1}
 389                 local newpos = seeker(r, is_comment) or forward and pstart or parent.finish
 390                 local closing = parser.opposite[parent.d]
 391                 local delimiter = forward and closing or opening
 392                 if not forward then
 393                         write(newpos, delimiter)
 394                 end
 395                 delete(forward and parent.finish or parent.start, #delimiter)
 396                 if forward then
 397                         write(newpos, delimiter)
 398                 end
 399                 parser.tree.rewind(math.min(parent.start, newpos))
 400                 local drag = forward and (newpos < range.finish) or not forward and (newpos > range.start)
 401                 local keep_inside = forward and #parent > 1 and range.finish > range.start and 1 or 0
 402                 newpos = drag and newpos - keep_inside or range.start
 403                 local rangeng = {start = newpos, finish = newpos}
 404                 return refmt_at(big_enough_parent(newpos, parent.finish + 1), rangeng)
 405         end
 406
 407         local function splice_sexp(range, _, no_refmt)
 408                 local _, parent = walker.sexp_at(range)
 409                 if not parent or not parent.d then return end
 410                 local opening = (parent.p or "")..parent.d
 411                 local closing = parser.opposite[parent.d]
 412                 local finish = parent.finish + 1 - #closing
 413                 if not parent.is_line_comment then
 414                         delete(finish, #closing)
 415                 end
 416                 -- TODO: (un)escape special characters, if necessary
 417                 delete(parent.start, parent.is_empty and (finish - parent.start) or #opening)
 418                 parser.tree.rewind(parent.start)
 419                 range.start = range.start - #opening
 420                 range.finish = range.start
 421                 local _, parentng = walker.sexp_at(range, true)
 422                 return not no_refmt and refmt_at(parentng, range) or range.start
 423         end
 424
 425         local function rewrap(parent, kind)
 426                 local pstart = parent.start + #((parent.p or "")..parent.d) - 1
 427                 delete(parent.finish, 1)
 428                 write(parent.finish, parser.opposite[kind])
 429                 delete(pstart, #parent.d)
 430                 write(pstart, kind)
 431                 parser.tree.rewind(parent.start)
 432         end
 433
 434         local function cycle_wrap(range, pos)
 435                 local _, parent = walker.sexp_at(range)
 436                 if not parent or not parent.is_list then return end
 437                 local next_kind = {["("] = "[", ["["] = "{", ["{"] = "("}
 438                 rewrap(parent, next_kind[parent.d])
 439                 return pos
 440         end
 441
 442         local function split_sexp(range)
 443                 local _, parent = walker.sexp_at(range)
 444                 if not (parent and parent.d) then return end
 445                 local new_finish, new_start
 446                 if parent.is_list then
 447                         local prev = parent.before(range.start, finishof, is_comment)
 448                         new_finish = prev and prev.finish + 1
 449                         -- XXX: do not skip comments here, so they end up in the second list
 450                         -- and are not separated from their target expression:
 451                         local nxt = new_finish and parent.after(new_finish, startof)
 452                         new_start = nxt and nxt.start
 453                 else
 454                         new_start = range.start
 455                         new_finish = range.start
 456                 end
 457                 if not (new_start and new_finish) then return end
 458                 local opening = (parent.p or "")..parent.d
 459                 local closing = parser.opposite[parent.d]
 460                 write(new_start, opening)
 461                 local sep = parent.is_line_comment and ""  -- line comments already have a separator
 462                         or new_finish == new_start and " "  -- only add a separator if there was none before
 463                         or ""
 464                 write(new_finish, closing..sep)
 465                 parser.tree.rewind(parent.start)
 466                 range.start = new_start + (parent.is_list and 0 or #opening + #closing)
 467                 range.finish = range.start
 468                 local _, nodes = walker.sexp_path(range)
 469                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 470                 local scope = parentng and not parentng.is_root and parentng or grandparent
 471                 return refmt_at(scope, range)
 472         end
 473
 474         local function join_sexps(range)
 475                 local node, parent = walker.sexp_at(range, true)
 476                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 477                 local second = first ~= node and node or parent.after(range.start, startof)
 478                 if not (first and second and first.d and
 479                         -- don't join line comments to margin comments:
 480                         (not first.is_line_comment or first.indent and second.indent) and
 481                         (first.d == second.d or
 482                                 -- join line comments even when their delimiters differ slightly
 483                                 -- (different number of semicolons, existence/lack of a space after them)
 484                                 parser.opposite[first.d] == parser.opposite[second.d])) then
 485                         return
 486                 end
 487                 local opening = (second.p or "")..second.d
 488                 local closing = parser.opposite[first.d]
 489                 local pos
 490                 if not first.is_list then
 491                         pos = first.finish + 1 - #closing
 492                         delete(pos, second.start + #opening - pos)
 493                 else
 494                         delete(second.start, #opening)
 495                         delete(first.finish, #closing)
 496                         pos = second.start - #closing
 497                 end
 498                 parser.tree.rewind(first.start)
 499                 range.start = pos
 500                 range.finish = range.start
 501                 local _, nodes = walker.sexp_path(range)
 502                 local parentng, grandparent = nodes[#nodes - 1], nodes[#nodes - 2]
 503                 local scope = parentng and not parentng.is_root and parentng or grandparent
 504                 return refmt_at(scope, range)
 505         end
 506
 507         local function delete_splicing(range, pos, splicing, delete_and_yank)
 508                 local action = {kill = true, wrap = splicing, splice = splicing, func = delete_and_yank}
 509                 local sexp, parent, n = walker.sexp_at(range)
 510                 local nxt = n and parent[n + 1]
 511                 local prev = n and parent[n - 1]
 512                 range = extend_overlap(range)
 513                 local ndeleted, spliced, opening, closing = pick_out(range, pos, action)
 514                 local inner_list_len = spliced and sexp.finish - sexp.start + 1 - #opening - #closing
 515                 local range_len = range.finish - range.start
 516                 local backwards = pos == range.finish
 517                 local whole_object = sexp and
 518                         (sexp.start == range.start and sexp.finish + 1 == range.finish
 519                         or spliced and inner_list_len <= range_len - (backwards and #opening or #closing))
 520                 local in_head_atom = sexp and not sexp.d and n == 1 and #parent > 1
 521                 local in_whitespace = not sexp
 522                 if whole_object or spliced or in_whitespace or in_head_atom then
 523                         local cur = (whole_object or spliced) and (prev and prev.finish or sexp.start) or range.start
 524                         -- if parent[#parent + 1] is nil, we are at EOF
 525                         if not parent.is_root or parent.is_parsed(cur) or parent[#parent + 1] then
 526                                 parser.tree.rewind(cur)
 527                         end
 528                         -- make sure the cursor is not left in whitespace:
 529                         if whole_object and nxt then
 530                                 cur = nxt.start - range_len - (spliced and (backwards and #closing or #opening) or 0)
 531                         elseif whole_object and prev then
 532                                 cur = prev.finish
 533                         elseif whole_object and parent.d and not parent.is_list then
 534                                 local _, parentng = walker.sexp_at({start = cur, finish = cur})
 535                                 local trailing = parentng.spaces_after(sexp.start)
 536                                 local leading = not trailing and parentng.spaces_before(sexp.start)
 537                                 if trailing then
 538                                         delete(sexp.start, trailing - sexp.start)
 539                                         parser.tree.rewind(sexp.start)
 540                                 elseif leading then
 541                                         delete(leading, sexp.start - leading)
 542                                         parser.tree.rewind(leading)
 543                                         cur = leading
 544                                 end
 545                         elseif spliced then
 546                                 cur = (backwards and sexp.start or (nxt and nxt.start - range_len or range.start) - ndeleted)
 547                         end
 548                         local r = {start = cur, finish = cur + 1}
 549                         local _, parentng = walker.sexp_at(r, true)
 550                         return refmt_at(parentng, r)
 551                 end
 552                 return not backwards and ndeleted <= 0 and range.finish - ndeleted
 553                         or backwards and ndeleted <= 0 and range.start + ndeleted
 554                         or range.start
 555         end
 556
 557         local function transpose(range, first, second)
 558                 if not (first and second) then return end
 559                 local copy1 = first.text
 560                 local copy2 = second.text
 561                 delete(second.start, second.finish + 1 - second.start)
 562                 write(second.start, copy1)
 563                 delete(first.start, first.finish + 1 - first.start)
 564                 write(first.start, copy2)
 565                 parser.tree.rewind(first.start)
 566                 range.start = second.finish + 1
 567                 range.finish = range.start
 568                 return refmt_at(big_enough_parent(first.start, second.finish), range)
 569         end
 570
 571         local function transpose_sexps(range)
 572                 local node, parent = walker.sexp_at(range, true)
 573                 local first = node and node.finish + 1 == range.start and node or parent.before(range.start, finishof)
 574                 local second = first ~= node and node or parent.after(range.start, startof)
 575                 return transpose(range, first, second)
 576         end
 577
 578         local function transpose_words(range)
 579                 local first, second, _
 580                 first = walker.sexp_at(range)
 581                 if not first or first.d or first.start == range.finish then
 582                         _, first = walker.start_float_before(range)
 583                 end
 584                 if first then
 585                         _, second = walker.finish_float_after({start = first.finish + 1, finish = first.finish + 1})
 586                 end
 587                 return transpose(range, first, second)
 588         end
 589
 590         local function transpose_chars(range)
 591                 local node, parent, i = walker.sexp_at(range)
 592                 local nxt = i and parent[i + 1]
 593                 local pstart = not parent.is_root and parent.start + (parent.p and #parent.p or 0) + #parent.d
 594                 local pfinish = not parent.is_root and parent.finish
 595                 local npref = node and node.p and node.start + #node.p
 596                 -- only allow transposing while inside atoms/words and prefixes
 597                 if node and ((npref and (range.start <= npref and range.start > node.start) or
 598                         node.d and range.start > node.finish + 1) or not node.d and (not pstart or range.start > pstart)) then
 599                         local start = range.start -
 600                                 ((range.start == pfinish or range.start == npref or
 601                                 range.start == node.finish + 1 and (parent.is_list or parent.is_root) and (not nxt or nxt.indent)) and 1 or 0)
 602                         local str_start = start - node.start + 1
 603                         local char = node.text:sub(str_start, str_start)
 604                         delete(start, 1)
 605                         write(start - 1, #char > 0 and char or " ")
 606                         parser.tree.rewind(start)
 607                         local in_head_atom = i == 1 and #parent > 1
 608                         return parent.is_list and in_head_atom and refmt_at(parent, {start = start + 1, finish = start + 1}) or start + 1
 609                 end
 610         end
 611
 612         local function _join_or_splice(parent, n, range, pos)
 613                 local sexp = parent[n]
 614                 local nxt = parent[n + 1]
 615                 local is_last = not nxt or not nxt.is_line_comment
 616                 local newpos = not (is_last and sexp.is_empty) and join_sexps(range)
 617                 if not newpos and sexp.is_empty then
 618                         newpos = splice_sexp({start = pos, finish = pos}, nil, true)
 619                 end
 620                 return newpos or pos
 621         end
 622
 623         local function delete_nonsplicing(range, pos, delete_maybe_yank)
 624                 local action = {kill = true, wrap = false, splice = false, func = delete_maybe_yank}
 625                 range = extend_overlap(range)
 626                 local ndeleted, spliced, opening, _, refmt = pick_out(range, pos, action)
 627                 local backwards = pos == range.finish
 628                 if opening then
 629                         if spliced then
 630                                 return pos - ndeleted
 631                         else
 632                                 if ndeleted == 0 then
 633                                         local closing = parser.opposite[opening] -- XXX: why don't I use the pick_out return value?
 634                                         if closing == "\n" then
 635                                                 local sexp, parent, n = walker.sexp_at(range)
 636                                                 if pos == sexp.start + #sexp.d and backwards then
 637                                                         return _join_or_splice(parent, n, range, pos)
 638                                                 elseif pos == sexp.finish then
 639                                                         local r = {start = pos + #closing, finish = pos + #closing}
 640                                                         return _join_or_splice(parent, n, r, pos)
 641                                                 end
 642                                         end
 643                                 end
 644                                 return backwards and (range.finish - ndeleted) or range.start
 645                         end
 646                 else
 647                         local newpos = backwards and range.start + (ndeleted <= 0 and ndeleted or 0) or (range.finish - ndeleted)
 648                         if refmt then
 649                                 local r = {start = newpos, finish = newpos}
 650                                 return refmt_at(big_enough_parent(range.start, range.finish - ndeleted), r, true)
 651                         end
 652                         return newpos
 653                 end
 654         end
 655
 656         local function insert_pair(range, delimiter, auto_square)
 657                 local indices, nodes = walker.sexp_path(range)
 658                 local sexp = nodes[#nodes]
 659                 local right_after_prefix = sexp and sexp.p and range.start == sexp.start + #sexp.p
 660                 -- XXX: here I assume that # is a valid prefix for the dialect
 661                 local mb_closing = (delimiter == "|") and right_after_prefix and parser.opposite[sexp.p .. delimiter]
 662                 local closing = mb_closing or parser.opposite[delimiter]
 663                 local squarewords = fmt.squarewords
 664                 if squarewords and not right_after_prefix
 665                         and (auto_square or squarewords.not_optional)
 666                         and not fmt:adjust_bracket_p(indices, nodes, range) then
 667                                 delimiter, closing = "[", "]"
 668                 end
 669                 write(range.finish, closing)
 670                 write(range.start, delimiter)
 671                 if right_after_prefix or parser.tree.is_parsed(range.start) then
 672                         parser.tree.rewind(right_after_prefix and sexp.start or range.start)
 673                 end
 674                 return range.start + #delimiter
 675         end
 676
 677         local function make_wrap(opening)
 678                 return parser.opposite[opening] and function(range, pos, auto_square)
 679                         local function _wrap(r)
 680                                 if not (r.finish > r.start) then return end
 681                                 insert_pair(r, opening, false, auto_square)
 682                         end
 683                         local action = {kill = false, wrap = false, splice = false, func = _wrap}
 684                         pick_out(range, pos, action)
 685                         local rangeng = {start = pos + #opening, finish = range.finish}
 686                         local _, parentng = walker.sexp_at(range)  -- TODO: range.finish is wrong. use sexp_path and big_enough_parent
 687                         return refmt_at(parentng, rangeng)
 688                 end
 689         end
 690
 691         local function newline(parent, range)
 692                 local line_comment = parent.is_line_comment
 693                 -- do not autoextend margin comments:
 694                 if line_comment and range.start < parent.finish + (parent.indent and 1 or 0)  then
 695                         local newpos = split_sexp(range)
 696                         if newpos then
 697                                 return newpos
 698                         end
 699                 end
 700                 if not parent.is_list and not line_comment then
 701                         -- if parent[#parent + 1] is nil, we are at EOF
 702                         if not parent.is_root or parent.is_parsed(range.start) or parent[#parent + 1] then
 703                                 parser.tree.rewind(parent.start or range.start)
 704                         end
 705                         local newpos = range.start
 706                         write(newpos, "\n")
 707                         return newpos + 1
 708                 end
 709                 if not parent.is_list then
 710                         local _
 711                         _, parent = walker.sexp_at(parent, true)
 712                 end
 713                 local last_nonblank_in_list = not parent.is_empty and parent[#parent].finish - (line_comment and 1 or 0)
 714                 local nxt = parent.after(range.start, startof)
 715                 local last_on_line = range.start == eol_at(range.start)
 716                 local margin = nxt and not nxt.indent and nxt.is_line_comment and nxt.finish
 717                 local after_last = last_nonblank_in_list and range.start > last_nonblank_in_list
 718                 local in_indent = nxt and nxt.indent and range.start <= nxt.start and range.start >= (nxt.start - nxt.indent)
 719                 local placeholder = "asdf"
 720                 local newpos = margin or range.start
 721                 if not parent.is_empty then
 722                         if in_indent then
 723                                 write(newpos, (placeholder.."\n"))
 724                         else
 725                                 write(newpos, "\n"..((after_last or last_on_line or margin) and placeholder or ""))
 726                         end
 727                 end
 728                 parser.tree.rewind(parent.start or newpos)
 729                 -- move the cursor onto the placeholder, so refmt_at can restore the position:
 730                 local r = {start = newpos, finish = newpos}
 731                 newpos = walker.start_after(r) or newpos
 732                 local rangeng = {start = newpos, finish = newpos}
 733                 newpos = refmt_at(parent, rangeng)
 734                 local _, parentng = walker.sexp_at({start = newpos, finish = newpos}, true)
 735                 if after_last then
 736                         local autoindent = parentng[#parentng].indent
 737                         write(parentng.finish, "\n"..string.rep(" ", autoindent or 0))
 738                 end
 739                 if after_last or last_on_line or margin or in_indent then
 740                         delete(newpos, #placeholder)
 741                 end
 742                 parser.tree.rewind(parentng.start or newpos)
 743                 return newpos
 744         end
 745
 746         local function close_and_newline(range, closing)
 747                 local opening = closing and parser.opposite[closing]
 748                 local parent = walker.list_at(range, opening)
 749                 if parent then
 750                         local has_eol = parent.is_line_comment
 751                         local r = {start = parent.finish, finish = parent.finish}
 752                         local newpos = refmt_at(parent, r)
 753                         r = {start = newpos + (has_eol and 0 or 1), finish = newpos + (has_eol and 0 or 1)}
 754                         local list, parentng = walker.sexp_at(r)
 755                         newpos = list and list.finish + 1 or r.start
 756                         newpos = newline(parentng, {start = newpos, finish = newpos})
 757                         if not newpos then
 758                                 newpos = r.finish + 1
 759                                 write(newpos, "\n")
 760                                 parser.tree.rewind(parentng.start or list.start)
 761                         end
 762                         return newpos
 763                 elseif closing == "\n" then
 764                         local eol = eol_at(range.start)
 765                         local _, parentng = walker.sexp_at({start = eol, finish = eol})
 766                         local newpos = newline(parentng, {start = eol, finish = eol})
 767                         return newpos
 768                 end
 769                 return range.start
 770         end
 771
 772         local function join_line(_, pos)
 773                 local eol = eol_at(pos)
 774                 local r = {start = eol, finish = eol + 1}
 775                 return delete_nonsplicing(r, r.start, delete)
 776         end
 777
 778         local wrap_doublequote = make_wrap'"'
 779
 780         local function meta_doublequote(range, pos, auto_square)
 781                 local escaped = walker.escaped_at(range)
 782                 if not escaped then
 783                         return wrap_doublequote(range, pos, nil, auto_square)
 784                 elseif escaped.is_string then
 785                         return close_and_newline(range, '"')
 786                 end
 787                 return pos
 788         end
 789
 790         local block_comment_start
 791         for o, c in pairs(parser.opposite) do
 792                 if #c > 1 then
 793                         block_comment_start = o
 794                         break
 795                 end
 796         end
 797
 798         local wrap_comment = make_wrap(block_comment_start)
 799
 800         return {
 801                 delete_splicing = delete_splicing,
 802                 delete_nonsplicing = delete_nonsplicing,
 803                 refmt_at = refmt_at,
 804                 pick_out = pick_out,
 805                 raise_sexp = raise_sexp,
 806                 slurp_sexp = slurp_sexp,
 807                 barf_sexp = barf_sexp,
 808                 splice_sexp = splice_sexp,
 809                 wrap_round = make_wrap"(",
 810                 wrap_square = make_wrap"[",
 811                 wrap_curly = make_wrap"{",
 812                 meta_doublequote = meta_doublequote,
 813                 wrap_comment = wrap_comment,
 814                 insert_pair = insert_pair,
 815                 newline = newline,
 816                 join_line = join_line,
 817                 close_and_newline = close_and_newline,
 818                 cycle_wrap = cycle_wrap,
 819                 split_sexp = split_sexp,
 820                 join_sexps = join_sexps,
 821                 transpose_sexps = transpose_sexps,
 822                 transpose_words = transpose_words,
 823                 transpose_chars = transpose_chars,
 824         }
 825 end
 826
 827 return M