ladybird/Kernel/Queue.h
2019-01-31 17:31:23 +01:00

96 lines
2.2 KiB
C++

#pragma once
#include "types.h"
template<typename T>
class Queue {
public:
struct Node {
explicit Node(T&& value)
: value(move(value))
{ }
Node* next { nullptr };
Node* prev { nullptr };
T value;
};
Queue() { }
~Queue()
{
while (!is_empty())
dequeue();
}
bool is_empty() const { return !m_head; }
void enqueue(T&& item)
{
auto* new_node = new Node(move(item));
if (!m_head) {
m_head = new_node;
m_tail = new_node;
} else if (m_tail) {
new_node->prev = m_tail;
m_tail->next = new_node;
m_tail = new_node;
}
dump("enqueue");
}
T dequeue()
{
ASSERT(m_head);
T value = move(m_head->value);
auto* oldHead = m_head;
if (oldHead->next) {
oldHead->next->prev = nullptr;
m_head = oldHead->next;
} else {
m_head = nullptr;
}
if (m_tail == oldHead)
m_tail = nullptr;
delete oldHead;
dump("dequeue");
//asm volatile("cli;hlt");
return value;
}
Node* head() { return m_head; }
T take(Node& node)
{
T value = move(node.value);
if (node.prev) {
node.prev->next = node.next;
} else {
m_head = node.next;
}
if (node.next) {
node.next->prev = node.prev;
} else {
m_tail = node.prev;
}
delete &node;
dump("take");
return value;
}
private:
void dump(const char* op)
{
return;
asm volatile("cli");
ASSERT(m_head != (void*)0xaaaaaaaa);
ASSERT(m_tail != (void*)0xaaaaaaaa);
kprintf("Queue %p after %s: {m_head=%p, m_tail=%p}\n", this, op, m_head, m_tail);
for (auto* node = m_head; node; node = node->next) {
kprintf(" Queue::Node %p%s%s next=%p prev=%p\n", node, node == m_head ? " (head)" : "", node == m_tail ? " (tail)" : "", node->next, node->prev);
}
asm volatile("sti");
}
Node* m_head { nullptr };
Node* m_tail { nullptr };
};