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perf: call mapper as-is in mapped()

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littensy 2026-04-01 05:29:55 -07:00
parent 27c7f5a6fd
commit c52f55a55e
2 changed files with 42 additions and 53 deletions
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38
packages/charm/src/init.luau
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@ -914,22 +914,9 @@ end
@see https://github.com/littensy/charm?tab=readme-ov-file#mappedgetter-mapper
]]
local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI, KI) -> (VO, KO)): Getter<{ [KO]: VO }>
local map = noYield(mapper)
local nextInput: { [KI]: VI } = {}
local keyMap: { [KI]: KO } = {}
local function mapUntracked(value: VI, key: KI): (VO, KO)
local prevSub = setActiveSub(nil)
local success, valueOut, keyOut = pcall(map, value, key)
activeSub = prevSub
if not success then
error(`mapped() transform function failed: {valueOut}`, 0)
end
return valueOut, if keyOut == nil then key :: any else keyOut
end
return computed(function(lastOutput: { [KO]: VO }?): { [KO]: VO }
local nextOutput: { [KO]: VO } = lastOutput or {}
local prevInput = nextInput
@ -937,19 +924,19 @@ local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI,
-- For keys that were removed from the input, remove the corresponding
-- keys from the output.
for prevKeyIn in prevInput do
if nextInput[prevKeyIn] ~= nil then
for keyIn in prevInput do
if nextInput[keyIn] ~= nil then
continue
end
local prevKeyOut = keyMap[prevKeyIn]
local keyOut = keyMap[keyIn]
if prevKeyOut ~= nil then
if keyOut ~= nil then
if nextOutput == lastOutput then
nextOutput = table.clone(nextOutput)
end
nextOutput[prevKeyOut] = nil
keyMap[prevKeyIn] = nil
nextOutput[keyOut] = nil
keyMap[keyIn] = nil
end
end
@ -957,13 +944,14 @@ local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI,
-- the output. If the mapper returns a new key that is different from
-- the previous call, the old mapped key should be removed from the
-- output.
for nextKeyIn, nextValueIn in nextInput do
if nextValueIn == prevInput[nextKeyIn] then
for keyIn, nextValueIn in nextInput do
if nextValueIn == prevInput[keyIn] then
continue
end
local nextValueOut, nextKeyOut = mapUntracked(nextValueIn, nextKeyIn)
local prevKeyOut = keyMap[nextKeyIn]
local nextValueOut, keyOutOrNil = mapper(nextValueIn, keyIn)
local nextKeyOut: KO = if keyOutOrNil ~= nil then keyOutOrNil else keyIn :: any
local prevKeyOut = keyMap[keyIn]
if prevKeyOut ~= nil and prevKeyOut ~= nextKeyOut then
if nextOutput == lastOutput then
@ -971,13 +959,13 @@ local function mapped<KI, VI, KO, VO>(getter: Getter<{ [KI]: VI }>, mapper: (VI,
end
nextOutput[prevKeyOut] = nil
nextOutput[nextKeyOut] = nextValueOut
keyMap[nextKeyIn] = nextKeyOut
keyMap[keyIn] = nextKeyOut
elseif nextOutput[nextKeyOut] ~= nextValueOut then
if nextOutput == lastOutput then
nextOutput = table.clone(nextOutput)
end
nextOutput[nextKeyOut] = nextValueOut
keyMap[nextKeyIn] = nextKeyOut
keyMap[keyIn] = nextKeyOut
end
end