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fulpstation/code/__HELPERS/heap.dm
2024-11-13 14:48:48 +00:00

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//////////////////////
//datum/heap object
//////////////////////
/datum/heap
var/list/L
var/cmp
/datum/heap/New(compare)
L = new()
cmp = compare
/datum/heap/Destroy(force)
for(var/i in L) // because this is before the list helpers are loaded
qdel(i)
L = null
return ..()
/datum/heap/proc/is_empty()
return !length(L)
//insert and place at its position a new node in the heap
/datum/heap/proc/insert(A)
L.Add(A)
swim(length(L))
//removes and returns the first element of the heap
//(i.e the max or the min dependent on the comparison function)
/datum/heap/proc/pop()
if(!length(L))
return 0
. = L[1]
L[1] = L[length(L)]
L.Cut(length(L))
if(length(L))
sink(1)
//Get a node up to its right position in the heap
/datum/heap/proc/swim(index)
var/parent = round(index * 0.5)
while(parent > 0 && (call(cmp)(L[index],L[parent]) > 0))
L.Swap(index,parent)
index = parent
parent = round(index * 0.5)
//Get a node down to its right position in the heap
/datum/heap/proc/sink(index)
var/g_child = get_greater_child(index)
while(g_child > 0 && (call(cmp)(L[index],L[g_child]) < 0))
L.Swap(index,g_child)
index = g_child
g_child = get_greater_child(index)
//Returns the greater (relative to the comparison proc) of a node children
//or 0 if there's no child
/datum/heap/proc/get_greater_child(index)
if(index * 2 > length(L))
return 0
if(index * 2 + 1 > length(L))
return index * 2
if(call(cmp)(L[index * 2],L[index * 2 + 1]) < 0)
return index * 2 + 1
else
return index * 2
//Replaces a given node so it verify the heap condition
/datum/heap/proc/resort(A)
var/index = L.Find(A)
swim(index)
sink(index)
/datum/heap/proc/List()
. = L.Copy()