more efficient undo/redo

Dependencies

• [2] 4QQBMWLL regression: typing uppercase letters in text
• [3] N6V6UJ3P this implementation undo load-tests quite poorly
• [4] SQLVYKVJ rename
• [5] XNFTJHC4 split keyboard handling between Text and Drawing
• [6] 2ZYV7D3W handle tab characters
• [7] CG3264MM move
• [8] HMODUNJE scroll on backspace
• [9] 2RXZ3PGO beginning of a new approach to scroll+wrap
• [10] PHFWIFYK scroll on enter
• [11] A2TQYJ6J .
• [12] 2POFQQLW keep cursor on screen when pressing 'down'
• [13] DAENUOGV eliminate assumptions that line length == size in bytes
• [14] DHI6IJCN selecting text and deleting selections
• [15] 73OCE2MC after much struggle, a brute-force undo
• [16] G6OYAYHU paste in text with M-v
• [17] WY3JD6W6 bugfix
• [18] 537TQ2QN some more logging
• [19] SLLR6KKI bugfix for non-ASCII
• [20] QVDQMJXV avoid scrolling down if possible
• [21] AYE2VEGJ extract a couple of methods
• [22] JY4VK7L2 rename
• [23] IDGP4BJZ new known issue with drawings
• [*] BULPIBEG beginnings of a module for the text editor
• [*] FS2ITYYH record a known issue

Change contents

• edit in undo.lua at line 35
  [5.1004]

  [5.1004]
  + -- Copy all relevant global state.
• replacement in undo.lua at line 37
  [5.1116]→[4.1:21](∅→∅)
  − function snapshot()
  [5.1116]

  [5.1147]
  + function snapshot(s,e)

  + -- Snapshot everything by default, but subset if requested.

  + if s == nil and e == nil then

  + s = 1

  + e = #Lines

  + elseif e == nil then

  + e = s

  + end
• edit in undo.lua at line 54
  [5.1427]

  [5.1427]
  + start_line=s,

  + end_line=e,
• replacement in undo.lua at line 59
  [5.1559]→[5.1559:1592](∅→∅)
  − for _,line in ipairs(Lines) do
  [5.1559]

  [5.1592]
  + for i=s,e do

  + local line = Lines[i]
• edit in undo.lua at line 78
  [5.2322]

  [5.2322]
  + function patch(lines, from, to)

  + --? if #from.lines == 1 and #to.lines == 1 then

  + --? assert(from.start_line == from.end_line)

  + --? assert(to.start_line == to.end_line)

  + --? assert(from.start_line == to.start_line)

  + --? lines[from.start_line] = to.lines[1]

  + --? return

  + --? end

  + assert(from.start_line == to.start_line)

  + for i=from.end_line,from.start_line,-1 do

  + table.remove(lines, i)

  + end

  + assert(#to.lines == to.end_line-to.start_line+1)

  + for i=1,#to.lines do

  + table.insert(lines, to.start_line+i-1, to.lines[i])

  + end

  + end

  +
• edit in undo.lua at line 108
  [5.2739]
  +

  + function minmax(a, b)

  + return math.min(a,b), math.max(a,b)

  + end
• edit in text.lua at line 135
  [5.2657]

  [5.2657]
  + local minl,maxl = minmax(Selection1.line, Cursor1.line)

  + local before = snapshot(minl, maxl)

  + Text.delete_selection_without_undo()

  + record_undo_event({before=before, after=snapshot(Cursor1.line)})

  + end

  +

  + function Text.delete_selection_without_undo()
• edit in text.lua at line 1178
  [5.6254]→[3.2:614](∅→∅)
  − end

  −

  − function test_zzz_undo_load_test()

  − print('\n\nTesting a 10KB file')

  − -- create a large list of lines

  − local lines = {}

  − -- 10k characters, hundred lines, 2k words

  − for i=1,100 do

  − local line = ''

  − for c=1,20 do

  − line = line..'abcd '

  − end

  − end

  − Lines = load_array(lines)

  − -- perform 1000 mutations

  − print('are the dots printing quickly and without any pauses?')

  − for i=1,1000 do

  − if i%50 == 0 then

  − App.run_after_keychord('return')

  − else

  − App.run_after_textinput('a')

  − end

  − if i%10 == 0 then

  − io.write(i)

  − io.write(' ')

  − io.flush()

  − end

  − end
• replacement in text.lua at line 1225
  [2.74]→[5.42:78](∅→∅),[5.42]→[5.42:78](∅→∅)
  − local down = love.keyboard.isDown
  [2.74]

  [5.1]
  + if Selection1.line then

  + Text.delete_selection()

  + end

  + local before = snapshot(Cursor1.line)
• edit in text.lua at line 1230
  [5.28]

  [5.60]
  + record_undo_event({before=before, after=snapshot(Cursor1.line)})
• edit in text.lua at line 1234
  [5.99]→[5.1:55](∅→∅),[5.55]→[5.6260:6318](∅→∅),[5.6318]→[4.23:51](∅→∅)
  − if Selection1.line then Text.delete_selection() end

  − -- Collect what you did in an event that can be undone.

  − local before = snapshot()
• edit in text.lua at line 1244
  [5.763]→[5.6358:6383](∅→∅),[5.6383]→[4.52:107](∅→∅)
  − -- finalize undo event

  − record_undo_event({before=before, after=snapshot()})
• replacement in text.lua at line 1251
  [5.655]→[4.108:138](∅→∅)
  − local before = snapshot()
  [5.655]

  [5.764]
  + local before_line = Cursor1.line

  + local before = snapshot(before_line)
• replacement in text.lua at line 1265
  [5.1648]→[4.139:196](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
  [5.1648]

  [5.134]
  + record_undo_event({before=before, after=snapshot(before_line, Cursor1.line)})
• replacement in text.lua at line 1267
  [5.163]→[4.197:227](∅→∅)
  − local before = snapshot()
  [5.163]

  [5.163]
  + local before = snapshot(Cursor1.line)
• replacement in text.lua at line 1270
  [5.1006]→[4.228:285](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
  [5.1006]

  [5.2046]
  + record_undo_event({before=before, after=snapshot(Cursor1.line)})
• edit in text.lua at line 1272
  [5.2081]→[4.286:316](∅→∅)
  − local before = snapshot()
• edit in text.lua at line 1275
  [5.6750]→[4.317:376](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
• edit in text.lua at line 1277
  [5.8474]

  [5.1902]
  + local before
• edit in text.lua at line 1279
  [5.1930]

  [5.1930]
  + before = snapshot(Cursor1.line)

  + else

  + before = snapshot(Cursor1.line-1, Cursor1.line)

  + end

  + if Cursor1.pos > 1 then
• replacement in text.lua at line 1314
  [5.3034]→[4.377:434](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
  [5.3034]

  [5.3034]
  + record_undo_event({before=before, after=snapshot(Cursor1.line)})
• edit in text.lua at line 1316
  [5.3066]→[4.435:465](∅→∅)
  − local before = snapshot()
• edit in text.lua at line 1319
  [5.6968]→[4.466:525](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
• edit in text.lua at line 1320
  [5.8546]

  [5.8546]
  + end

  + local before

  + if Cursor1.pos <= utf8.len(Lines[Cursor1.line].data) then

  + before = snapshot(Cursor1.line)

  + else

  + before = snapshot(Cursor1.line, Cursor1.line+1)
• replacement in text.lua at line 1350
  [5.3956]→[4.526:583](∅→∅)
  − record_undo_event({before=before, after=snapshot()})
  [5.3956]

  [5.7107]
  + record_undo_event({before=before, after=snapshot(Cursor1.line)})
• replacement in text.lua at line 1360
  [5.7450]→[5.7450:7520](∅→∅)
  − if src.lines then

  − Lines = deepcopy(src.lines)

  − end
  [5.7450]

  [5.7520]
  + patch(Lines, event.after, event.before)
• replacement in text.lua at line 1369
  [5.7761]→[5.7761:8113](∅→∅)
  − if src.lines then

  − Lines = deepcopy(src.lines)

  − --? for _,line in ipairs(Lines) do

  − --? if line.mode == 'drawing' then

  − --? print('restoring', line.points, 'with', #line.points, 'points')

  − --? print('restoring', line.shapes, 'with', #line.shapes, 'shapes')

  − --? end

  − --? end

  − end
  [5.7761]

  [5.8113]
  + patch(Lines, event.before, event.after)
• edit in text.lua at line 1383
  [5.76]

  [5.76]
  + local before_line = Cursor1.line

  + local before = snapshot(before_line)
• edit in text.lua at line 1389
  [5.209]

  [5.209]
  + record_undo_event({before=before, after=snapshot(before_line, Cursor1.line)})
• replacement in README.md at line 9
  [5.8364]→[5.8364:8558](∅→∅)
  − * Undo is extremely inefficient in space. While this app is extremely unlikely

  − to lose the current state of a file at any moment, undo history is volatile

  − and should be considered unstable.
  [5.8364]

  [5.14]
  + * Undo/redo can be sluggish in large files. If things get sluggish, killing

  + the process can lose data.