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#pragma once
#include <limits>
#include <nall/function.hpp>
#include <nall/serializer.hpp>
#include <nall/utility.hpp>
namespace nall {
template<typename type_t> auto priority_queue_nocallback(type_t) -> void {}
//priority queue implementation using binary min-heap array;
//does not require normalize() function.
//O(1) find (tick)
//O(log n) append (enqueue)
//O(log n) remove (dequeue)
template<typename type_t> struct priority_queue {
priority_queue(unsigned size, function<void (type_t)> callback = &priority_queue_nocallback<type_t>) : callback(callback) {
heap = new heap_t[size];
heapcapacity = size;
reset();
}
~priority_queue() {
delete[] heap;
}
priority_queue(const priority_queue&) = delete;
auto operator=(const priority_queue&) -> priority_queue& = delete;
inline auto tick(unsigned ticks) -> void {
basecounter += ticks;
while(heapsize && gte(basecounter, heap[0].counter)) callback(dequeue());
}
//counter is relative to current time (eg enqueue(64, ...) fires in 64 ticks);
//counter cannot exceed std::numeric_limits<unsigned>::max() >> 1.
auto enqueue(unsigned counter, type_t event) -> void {
unsigned child = heapsize++;
counter += basecounter;
while(child) {
unsigned parent = (child - 1) >> 1;
if(gte(counter, heap[parent].counter)) break;
heap[child].counter = heap[parent].counter;
heap[child].event = heap[parent].event;
child = parent;
}
heap[child].counter = counter;
heap[child].event = event;
}
auto dequeue() -> type_t {
type_t event(heap[0].event);
unsigned parent = 0;
unsigned counter = heap[--heapsize].counter;
while(true) {
unsigned child = (parent << 1) + 1;
if(child >= heapsize) break;
if(child + 1 < heapsize && gte(heap[child].counter, heap[child + 1].counter)) child++;
if(gte(heap[child].counter, counter)) break;
heap[parent].counter = heap[child].counter;
heap[parent].event = heap[child].event;
parent = child;
}
heap[parent].counter = counter;
heap[parent].event = heap[heapsize].event;
return event;
}
auto reset() -> void {
basecounter = 0;
heapsize = 0;
}
auto serialize(serializer& s) -> void {
s.integer(basecounter);
s.integer(heapsize);
for(unsigned n = 0; n < heapcapacity; n++) {
s.integer(heap[n].counter);
s.integer(heap[n].event);
}
}
private:
function<void (type_t)> callback;
unsigned basecounter;
unsigned heapsize;
unsigned heapcapacity;
struct heap_t {
unsigned counter;
type_t event;
} *heap;
//return true if x is greater than or equal to y
inline auto gte(unsigned x, unsigned y) -> bool {
return x - y < (std::numeric_limits<unsigned>::max() >> 1);
}
};
}
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