99 lines
3.1 KiB
Lua
99 lines
3.1 KiB
Lua
-- 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
|
|
|
|
-- makes a copy of lines on every single keystroke; will be inefficient with really long lines.
|
|
-- TODO: highlight stuff inserted by any undo/redo operation
|
|
-- TODO: coalesce multiple similar operations
|
|
|
|
function record_undo_event(State, data)
|
|
State.history[State.next_history] = data
|
|
State.next_history = State.next_history+1
|
|
for i=State.next_history,#State.history do
|
|
State.history[i] = nil
|
|
end
|
|
end
|
|
|
|
function undo_event(State)
|
|
if State.next_history > 1 then
|
|
--? print('moving to history', State.next_history-1)
|
|
State.next_history = State.next_history-1
|
|
local result = State.history[State.next_history]
|
|
return result
|
|
end
|
|
end
|
|
|
|
function redo_event(State)
|
|
if State.next_history <= #State.history then
|
|
--? print('restoring history', State.next_history+1)
|
|
local result = State.history[State.next_history]
|
|
State.next_history = State.next_history+1
|
|
return result
|
|
end
|
|
end
|
|
|
|
-- Copy all relevant global state.
|
|
-- Make copies of objects; the rest of the app may mutate them in place, but undo requires immutable histories.
|
|
function snapshot(State, s,e)
|
|
-- Snapshot everything by default, but subset if requested.
|
|
assert(s, 'failed to snapshot operation for undo history')
|
|
if e == nil then
|
|
e = s
|
|
end
|
|
assert(#State.lines > 0, 'failed to snapshot operation for undo history')
|
|
if s < 1 then s = 1 end
|
|
if s > #State.lines then s = #State.lines end
|
|
if e < 1 then e = 1 end
|
|
if e > #State.lines then e = #State.lines end
|
|
-- compare with App.initialize_globals
|
|
local event = {
|
|
screen_top=deepcopy(State.screen_top1),
|
|
selection=deepcopy(State.selection1),
|
|
cursor=deepcopy(State.cursor1),
|
|
current_drawing_mode=Drawing_mode,
|
|
previous_drawing_mode=State.previous_drawing_mode,
|
|
lines={},
|
|
start_line=s,
|
|
end_line=e,
|
|
-- no filename; undo history is cleared when filename changes
|
|
}
|
|
for i=s,e do
|
|
table.insert(event.lines, deepcopy(State.lines[i]))
|
|
end
|
|
return event
|
|
end
|
|
|
|
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, 'failed to patch undo operation')
|
|
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, 'failed to patch undo operation')
|
|
for i=1,#to.lines do
|
|
table.insert(lines, to.start_line+i-1, to.lines[i])
|
|
end
|
|
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
|
|
|
|
function minmax(a, b)
|
|
return math.min(a,b), math.max(a,b)
|
|
end
|