void close(const F& f) {
clear_cached_elements(f);
if (fetch_new_data(nullptr)) {
clear_cached_elements(f);
}
cache_.clear(f);
}
pointer take_head() {
if (m_head != nullptr || fetch_new_data()) {
auto result = m_head;
m_head = m_head->next;
return result;
}
return nullptr;
}
pointer take_head() {
if (head_ != nullptr || fetch_new_data()) {
auto result = head_;
head_ = head_->next;
return result;
}
return nullptr;
}
size_t count(size_t max_count = std::numeric_limits<size_t>::max()) {
size_t res = cache_.count(max_count);
if (res >= max_count) {
return res;
}
fetch_new_data();
auto ptr = head_;
while (ptr && res < max_count) {
ptr = ptr->next;
++res;
}
return res;
}
void remove_if(UnaryPredicate f) {
pointer head = m_head;
pointer last = nullptr;
pointer p = m_head;
auto loop = [&]() -> bool {
while (p) {
if (f(*p)) {
if (last == nullptr) m_head = p->next;
else last = p->next;
m_delete(p);
return true;
}
else {
last = p;
p = p->next;
}
}
return false;
};
if (!loop()) {
// last points to the tail now
auto old_tail = last;
m_head = nullptr; // fetch_new_data assumes cached list to be empty
if (fetch_new_data()) {
last = nullptr;
p = m_head; // let p point to the first newly fetched element
loop();
// restore cached list
if (head) {
old_tail->next = m_head;
m_head = head;
}
}
else m_head = head;
}
}
inline bool fetch_new_data() {
return fetch_new_data(stack_empty_dummy());
}
inline void clear() {
if (!closed()) {
clear_cached_elements();
if (fetch_new_data()) clear_cached_elements();
}
}
// closes this queue deletes all remaining elements
inline void close() {
clear_cached_elements();
if (fetch_new_data(nullptr)) clear_cached_elements();
}
