88 lines
2.2 KiB
C++
88 lines
2.2 KiB
C++
#pragma once
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#include <cstdint>
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#include <new>
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#include <utility>
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template <typename T, int N>
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struct callback_list {
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struct node {
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alignas(T) uint8_t storage[sizeof(T)];
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node* prev = nullptr;
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node* next = nullptr;
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bool active = false;
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T& value() { return *reinterpret_cast<T*>(storage); }
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const T& value() const { return *reinterpret_cast<const T*>(storage); }
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};
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node nodes[N];
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node* free_head = &nodes[0];
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node sentinel;
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callback_list() {
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for (int i = 0; i < N - 1; i++) nodes[i].next = &nodes[i + 1];
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nodes[N - 1].next = nullptr;
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sentinel.prev = &sentinel;
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sentinel.next = &sentinel;
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}
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bool empty() const { return sentinel.next == &sentinel; }
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node* insert(T value) {
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if (!free_head) return nullptr;
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node* n = alloc(std::move(value));
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link_before(&sentinel, n);
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return n;
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}
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template <typename Less>
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node* insert_sorted(T value, Less&& less) {
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if (!free_head) return nullptr;
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node* n = alloc(std::move(value));
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node* pos = sentinel.next;
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while (pos != &sentinel && !less(n->value(), pos->value()))
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pos = pos->next;
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link_before(pos, n);
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return n;
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}
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void remove(node* n) {
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if (!n || !n->active) return;
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n->prev->next = n->next;
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n->next->prev = n->prev;
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n->active = false;
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n->value().~T();
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n->next = free_head;
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n->prev = nullptr;
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free_head = n;
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}
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node* front() { return sentinel.next != &sentinel ? sentinel.next : nullptr; }
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template <typename Fn>
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void for_each(Fn&& fn) {
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node* cur = sentinel.next;
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while (cur != &sentinel) {
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node* next = cur->next;
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fn(cur);
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cur = next;
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}
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}
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private:
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node* alloc(T value) {
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node* n = free_head;
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free_head = n->next;
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new (n->storage) T(std::move(value));
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n->active = true;
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return n;
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}
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void link_before(node* pos, node* n) {
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n->prev = pos->prev;
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n->next = pos;
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pos->prev->next = n;
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pos->prev = n;
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}
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};
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