only problem is that prestate is going to be the key name during the loop (its what were returning - k), its not (necesarily) going to be an index/number that you can increment. the original way works fine.
Ah yes, you are correct, so storing t.i is still necessary.
question: in the iter function do i have to do a table.wipe( t ) or can i just get away with t.data = nil? the rest are just numbers and strings so should de-reference and get gc'd fairly quickly only the source table would hang around for ages and stop this table from being gc'd.
table.wipe(t) is needed if you are using a table pool that is used across your entire addon. t.data = nil is fine if you are using a local table pool that only your iterator will use.
local function pairsByKey (t, f)
local a = {}
for n in pairs(t) do table.insert(a, n) end
table.sort(a, f)
local i = 0 -- iterator variable
local iter = function () -- iterator function
i = i + 1
if a[i] == nil then return nil
else return a[i], t[a[i]]
end
end
return iter
end
...
function foo()
local bar = {
["key1"]="value1",
["key2"]="value2",
["key3"]="value3",
}
for k, v in pairsByKey(bar) do
dostuffwith(k, v)
end
end
I have no idea if what I do leads to a lot of garbage or not, it does a nice job of hiding the complexity in the iterator so that the code itself looks simple...It has the added advantage of allowing for a sorter to be passed as a second argument.
Similarly I use the same principle to iterate over a raid/party :
local function RaidIterator()
local i = 0
return function ()
i = i + 1
local unit
if UnitInRaid("player") and i<=GetNumRaidMembers() then
return "raid"..i
else
numPartyMembers = GetNumPartyMembers()
if i<= numPartyMembers then
return "party"..i
elseif i==numPartyMembers+1 then
return "player"
end
end
end
end
local function pairsByKey (t, f)
local a = {}
for n in pairs(t) do table.insert(a, n) end
table.sort(a, f)
local i = 0 -- iterator variable
local iter = function () -- iterator function
i = i + 1
if a[i] == nil then return nil
else return a[i], t[a[i]]
end
end
return iter
end
...
function foo()
local bar = {
["key1"]="value1",
["key2"]="value2",
["key3"]="value3",
}
for k, v in pairsByKey(bar) do
dostuffwith(k, v)
end
end
I have no idea if what I do leads to a lot of garbage or not
It creates a table and a function everytime it's called, depending on how you use it, it could produce some quite a bit of garbage. Something like this will only create the required iteration function and sorted array when required.
[SIZE=2]
[SIZE=2]local pairsByKeys; do[/SIZE]
[SIZE=2]local sortedtbl, iter[/SIZE]
[SIZE=2]function pairsByKeys(tbl, f)[/SIZE]
[SIZE=2] if sortedtbl then[/SIZE]
[SIZE=2] wipe(sortedtbl)[/SIZE]
[SIZE=2] else[/SIZE]
[SIZE=2] sortedtbl = {}[/SIZE]
[SIZE=2] function iter(tbl, i)[/SIZE]
[SIZE=2] i = i + 1[/SIZE]
[SIZE=2] if sortedtbl[i] == nil then[/SIZE]
[SIZE=2] return nil, nil, nil[/SIZE]
[SIZE=2] else[/SIZE]
[SIZE=2] return i, sortedtbl[i], tbl[sortedtbl[i]][/SIZE]
[SIZE=2] end[/SIZE]
[SIZE=2] end[/SIZE]
[SIZE=2] end[/SIZE]
[SIZE=2] for k, v in pairs(tbl) do[/SIZE]
[SIZE=2] table.insert(sortedtbl, k)[/SIZE]
[SIZE=2] end[/SIZE]
[SIZE=2] table.sort(sortedtbl, f)[/SIZE]
[SIZE=2] return iter, tbl, 0[/SIZE]
[SIZE=2]end[/SIZE]
[SIZE=2]end[/SIZE]
[SIZE=2]local tbl = {[/SIZE]
[SIZE=2]key1 = "val1",[/SIZE]
[SIZE=2]key2 = "val2",[/SIZE]
[SIZE=2]key3 = "val3",[/SIZE]
[SIZE=2]key4 = "val4",[/SIZE]
[SIZE=2]key5 = "val5",[/SIZE]
[SIZE=2]key6 = "val6",[/SIZE]
[SIZE=2]}[/SIZE]
[SIZE=2]for i, k, v in pairsByKeys(tbl) do[/SIZE]
[SIZE=2]print(k, v)[/SIZE]
[SIZE=2]end[/SIZE]
[/SIZE]
Slakah, your code is using the same "sortedtbl" for all iterators, so you can't include two loops at the same time.
I think Xinhuan's code is the best but changed to the following to have the prestate "stored" outside the table :
local spairs
do
local function iter(state, index)
index = index + 1
local key = state[index]
if key ~= nil then
return index, key, state.t[key]
end
end
function spairs(t, sortFunc)
local state = {}
local index = 1
for k in pairs(t) do
state[index] = k
index = index + 1
end
table.sort(state, sortFunc)
state.t = t
return iter, state, 0
end
end
-- Sample usage:
for index, key, value in spairs(t) do
-- Do something with key, value
end
Honestly, there oare few cases when you want to iterate through sorted keys so you could do it "manually" instead of using such an iterator.
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Curse PremiumAh yes, you are correct, so storing t.i is still necessary.
table.wipe(t) is needed if you are using a table pool that is used across your entire addon. t.data = nil is fine if you are using a local table pool that only your iterator will use.
local function pairsByKey (t, f) local a = {} for n in pairs(t) do table.insert(a, n) end table.sort(a, f) local i = 0 -- iterator variable local iter = function () -- iterator function i = i + 1 if a[i] == nil then return nil else return a[i], t[a[i]] end end return iter end ... function foo() local bar = { ["key1"]="value1", ["key2"]="value2", ["key3"]="value3", } for k, v in pairsByKey(bar) do dostuffwith(k, v) end endI have no idea if what I do leads to a lot of garbage or not, it does a nice job of hiding the complexity in the iterator so that the code itself looks simple...It has the added advantage of allowing for a sorter to be passed as a second argument.
Similarly I use the same principle to iterate over a raid/party :
local function RaidIterator() local i = 0 return function () i = i + 1 local unit if UnitInRaid("player") and i<=GetNumRaidMembers() then return "raid"..i else numPartyMembers = GetNumPartyMembers() if i<= numPartyMembers then return "party"..i elseif i==numPartyMembers+1 then return "player" end end end endIt creates a table and a function everytime it's called, depending on how you use it, it could produce some quite a bit of garbage. Something like this will only create the required iteration function and sorted array when required.
[SIZE=2] [SIZE=2]local pairsByKeys; do[/SIZE] [SIZE=2]local sortedtbl, iter[/SIZE] [SIZE=2]function pairsByKeys(tbl, f)[/SIZE] [SIZE=2] if sortedtbl then[/SIZE] [SIZE=2] wipe(sortedtbl)[/SIZE] [SIZE=2] else[/SIZE] [SIZE=2] sortedtbl = {}[/SIZE] [SIZE=2] function iter(tbl, i)[/SIZE] [SIZE=2] i = i + 1[/SIZE] [SIZE=2] if sortedtbl[i] == nil then[/SIZE] [SIZE=2] return nil, nil, nil[/SIZE] [SIZE=2] else[/SIZE] [SIZE=2] return i, sortedtbl[i], tbl[sortedtbl[i]][/SIZE] [SIZE=2] end[/SIZE] [SIZE=2] end[/SIZE] [SIZE=2] end[/SIZE] [SIZE=2] for k, v in pairs(tbl) do[/SIZE] [SIZE=2] table.insert(sortedtbl, k)[/SIZE] [SIZE=2] end[/SIZE] [SIZE=2] table.sort(sortedtbl, f)[/SIZE] [SIZE=2] return iter, tbl, 0[/SIZE] [SIZE=2]end[/SIZE] [SIZE=2]end[/SIZE] [SIZE=2]local tbl = {[/SIZE] [SIZE=2]key1 = "val1",[/SIZE] [SIZE=2]key2 = "val2",[/SIZE] [SIZE=2]key3 = "val3",[/SIZE] [SIZE=2]key4 = "val4",[/SIZE] [SIZE=2]key5 = "val5",[/SIZE] [SIZE=2]key6 = "val6",[/SIZE] [SIZE=2]}[/SIZE] [SIZE=2]for i, k, v in pairsByKeys(tbl) do[/SIZE] [SIZE=2]print(k, v)[/SIZE] [SIZE=2]end[/SIZE] [/SIZE]-
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Curse PremiumI think Xinhuan's code is the best but changed to the following to have the prestate "stored" outside the table :
local spairs do local function iter(state, index) index = index + 1 local key = state[index] if key ~= nil then return index, key, state.t[key] end end function spairs(t, sortFunc) local state = {} local index = 1 for k in pairs(t) do state[index] = k index = index + 1 end table.sort(state, sortFunc) state.t = t return iter, state, 0 end end -- Sample usage: for index, key, value in spairs(t) do -- Do something with key, value endHonestly, there oare few cases when you want to iterate through sorted keys so you could do it "manually" instead of using such an iterator.