after much struggle, a brute-force undo

[?]

Jun 2, 2022, 10:45 PM

73OCE2MCBJJZZMN2KYPJTBOUCKBZAOQ2QIAMTGCNOOJ2AJAXFT2AC

Dependencies

[2] AD34IX2Z couple more tests
[3] PHFWIFYK scroll on enter
[4] SLLR6KKI bugfix for non-ASCII
[5] DHI6IJCN selecting text and deleting selections
[*] R5QXEHUI somebody stop me
[*] BULPIBEG beginnings of a module for the text editor
[*] XNFTJHC4 split keyboard handling between Text and Drawing
[*] H2DPLWMV snapshot: wrapping long lines at word boundaries
[*] PFT5Y2ZY move
[*] 2RXZ3PGO beginning of a new approach to scroll+wrap
[*] 2ZYV7D3W handle tab characters
[*] CG3264MM move
[*] OTIBCAUJ love2d scaffold
[*] AVTNUQYR basic test-enabled framework
[*] AVQ5MC5D finish uppercasing all globals
[*] BLWAYPKV extract a module
[*] HYEAFRZ2 split mouse_pressed events between Text and Drawing
[*] 6DE7RBZ6 move mouse_released events to Drawing
[*] VHQCNMAR several more modules
[*] FS2ITYYH record a known issue
[*] A2TQYJ6J .
[*] IDGP4BJZ new known issue with drawings

Change contents

file addition: undo.lua (----------)

[7.2]

-- undo/redo by managing the sequence of events in the current session
-- based on https://github.com/akkartik/mu1/blob/master/edit/012-editor-undo.mu

-- Incredibly inefficient; we make a copy of lines on every single keystroke.
-- The hope here is that we're either editing small files or just reading large files.
-- TODO: highlight stuff inserted by any undo/redo operation
-- TODO: coalesce multiple similar operations

function record_undo_event(data)
History[Next_history] = data
Next_history = Next_history+1
for i=Next_history,#History do
History[i] = nil
end
end

function undo_event()
if Next_history > 1 then
--? print('moving to history', Next_history-1)
Next_history = Next_history-1
local result = History[Next_history]
return result
end
end

function redo_event()
if Next_history <= #History then
--? print('restoring history', Next_history+1)
local result = History[Next_history]
Next_history = Next_history+1
return result
end
end

-- Make copies of objects; the rest of the app may mutate them in place, but undo requires immutable histories.
function snapshot_everything()
-- compare with App.initialize_globals
local event = {
screen_top=deepcopy(Screen_top1),
selection=deepcopy(Selection1),
cursor=deepcopy(Cursor1),
current_drawing_mode=Drawing_mode,
previous_drawing_mode=Previous_drawing_mode,
zoom=Zoom,
lines={},
-- no filename; undo history is cleared when filename changes
}
-- deep copy lines without cached stuff like text fragments
for _,line in ipairs(Lines) do
if line.mode == 'text' then
table.insert(event.lines, {mode='text', data=line.data})
elseif line.mode == 'drawing' then
local points=deepcopy(line.points)
--? print('copying', line.points, 'with', #line.points, 'points into', points)
local shapes=deepcopy(line.shapes)
--? print('copying', line.shapes, 'with', #line.shapes, 'shapes into', shapes)
table.insert(event.lines, {mode='drawing', y=line.y, h=line.h, points=points, shapes=shapes, pending={}})
--? table.insert(event.lines, {mode='drawing', y=line.y, h=line.h, points=deepcopy(line.points), shapes=deepcopy(line.shapes), pending={}})
else
print(line.mode)
assert(false)
end
end
return event
end

-- https://stackoverflow.com/questions/640642/how-do-you-copy-a-lua-table-by-value/26367080#26367080
function deepcopy(obj, seen)
if type(obj) ~= 'table' then return obj end
if seen and seen[obj] then return seen[obj] end
local s = seen or {}
local result = setmetatable({}, getmetatable(obj))
s[obj] = result
for k,v in pairs(obj) do
result[deepcopy(k, s)] = deepcopy(v, s)
end
return result
end
edit in text.lua at line 5

[9.30]

[10.1567]

require 'undo'
edit in text.lua at line 1096

[5.8374]

[11.1]

function test_undo_insert_text()
io.write('\ntest_undo_insert_text')
App.screen.init{width=120, height=60}
Lines = load_array{'abc', 'def', 'xyz'}
Line_width = App.screen.width
Cursor1 = {line=2, pos=4}
Screen_top1 = {line=1, pos=1}
Screen_bottom1 = {}
Zoom = 1
-- insert a character
App.run_after_textinput('g')
check_eq(Cursor1.line, 2, 'F - test_undo_insert_text/baseline/cursor:line')
check_eq(Cursor1.pos, 5, 'F - test_undo_insert_text/baseline/cursor:pos')
check_nil(Selection1.line, 'F - test_undo_insert_text/baseline/selection:line')
check_nil(Selection1.pos, 'F - test_undo_insert_text/baseline/selection:pos')
local screen_top_margin = 15 -- pixels
local line_height = 15 -- pixels
local y = screen_top_margin
App.screen.check(y, 'abc', 'F - test_undo_insert_text/baseline/screen:1')
y = y + line_height
App.screen.check(y, 'defg', 'F - test_undo_insert_text/baseline/screen:2')
y = y + line_height
App.screen.check(y, 'xyz', 'F - test_undo_insert_text/baseline/screen:3')
-- undo
App.run_after_keychord('M-z')
check_eq(Cursor1.line, 2, 'F - test_undo_insert_text/cursor:line')
check_eq(Cursor1.pos, 4, 'F - test_undo_insert_text/cursor:pos')
check_nil(Selection1.line, 'F - test_undo_insert_text/selection:line')
check_nil(Selection1.pos, 'F - test_undo_insert_text/selection:pos')
y = screen_top_margin
App.screen.check(y, 'abc', 'F - test_undo_insert_text/screen:1')
y = y + line_height
App.screen.check(y, 'def', 'F - test_undo_insert_text/screen:2')
y = y + line_height
App.screen.check(y, 'xyz', 'F - test_undo_insert_text/screen:3')
end

function test_undo_delete_text()
io.write('\ntest_undo_delete_text')
App.screen.init{width=120, height=60}
Lines = load_array{'abc', 'defg', 'xyz'}
Line_width = App.screen.width
Cursor1 = {line=2, pos=5}
Screen_top1 = {line=1, pos=1}
Screen_bottom1 = {}
Zoom = 1
-- delete a character
App.run_after_keychord('backspace')
check_eq(Cursor1.line, 2, 'F - test_undo_delete_text/baseline/cursor:line')
check_eq(Cursor1.pos, 4, 'F - test_undo_delete_text/baseline/cursor:pos')
check_nil(Selection1.line, 'F - test_undo_delete_text/baseline/selection:line')
check_nil(Selection1.pos, 'F - test_undo_delete_text/baseline/selection:pos')
local screen_top_margin = 15 -- pixels
local line_height = 15 -- pixels
local y = screen_top_margin
App.screen.check(y, 'abc', 'F - test_undo_delete_text/baseline/screen:1')
y = y + line_height
App.screen.check(y, 'def', 'F - test_undo_delete_text/baseline/screen:2')
y = y + line_height
App.screen.check(y, 'xyz', 'F - test_undo_delete_text/baseline/screen:3')
-- undo
--? -- after undo, the backspaced key is selected
App.run_after_keychord('M-z')
check_eq(Cursor1.line, 2, 'F - test_undo_delete_text/cursor:line')
check_eq(Cursor1.pos, 5, 'F - test_undo_delete_text/cursor:pos')
check_nil(Selection1.line, 'F - test_undo_delete_text/selection:line')
check_nil(Selection1.pos, 'F - test_undo_delete_text/selection:pos')
--? check_eq(Selection1.line, 2, 'F - test_undo_delete_text/selection:line')
--? check_eq(Selection1.pos, 4, 'F - test_undo_delete_text/selection:pos')
y = screen_top_margin
App.screen.check(y, 'abc', 'F - test_undo_delete_text/screen:1')
y = y + line_height
App.screen.check(y, 'defg', 'F - test_undo_delete_text/screen:2')
y = y + line_height
App.screen.check(y, 'xyz', 'F - test_undo_delete_text/screen:3')
end
edit in text.lua at line 1224

[4.55]

[9.171]

-- Collect what you did in an event that can be undone.
local before = snapshot_everything()
edit in text.lua at line 1236

[12.763]

[9.513]

-- finalize undo event
record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1245

[9.655]

[12.764]

local before = snapshot_everything()
edit in text.lua at line 1258

[3.1648]

[13.134]

record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1260

[13.163]

[13.163]

local before = snapshot_everything()
edit in text.lua at line 1263

[9.1006]

[9.2046]

record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1265

[9.2081]

[5.8395]

local before = snapshot_everything()
edit in text.lua at line 1268

[5.8453]

[5.8453]

save_to_disk(Lines, Filename)
record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1303

[9.3034]

[9.3034]

record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1305

[9.3066]

[5.8475]

local before = snapshot_everything()
edit in text.lua at line 1308

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[5.8533]

save_to_disk(Lines, Filename)
record_undo_event({before=before, after=snapshot_everything()})
edit in text.lua at line 1335

[9.3956]

[14.36]

record_undo_event({before=before, after=snapshot_everything()})
-- undo/redo really belongs in main.lua, but it's here so I can test the
-- text-specific portions of it
elseif chord == 'M-z' then
local event = undo_event()
if event then
local src = event.before
Screen_top1 = deepcopy(src.screen_top)
Cursor1 = deepcopy(src.cursor)
Selection1 = deepcopy(src.selection)
if src.lines then
Lines = deepcopy(src.lines)
end
end
elseif chord == 'M-y' then
local event = redo_event()
if event then
local src = event.after
Screen_top1 = deepcopy(src.screen_top)
Cursor1 = deepcopy(src.cursor)
Selection1 = deepcopy(src.selection)
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
end
edit in main.lua at line 68

[2.1568]

[2.1568]

-- undo
History = {}
Next_history = 1
edit in main.lua at line 109

[16.1352]

[17.747]

App.initialize_globals() -- in particular, forget all undo history
edit in drawing.lua at line 209

[19.853]

[19.853]

Drawing.before = snapshot_everything()
edit in drawing.lua at line 351

[20.3159]

[21.19072]

record_undo_event({before=Drawing.before, after=snapshot_everything()})
edit in README.md at line 8

[23.148]

[24.14]

* 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.