You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
82 lines
2.0 KiB
82 lines
2.0 KiB
4 months ago
|
// Copyright 2020 The Pigweed Authors
|
||
|
|
//
|
||
|
|
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
|
||
|
|
// use this file except in compliance with the License. You may obtain a copy of
|
||
|
|
// the License at
|
||
|
|
//
|
||
|
|
// https://www.apache.org/licenses/LICENSE-2.0
|
||
|
|
//
|
||
|
|
// Unless required by applicable law or agreed to in writing, software
|
||
|
|
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
||
|
|
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
||
|
|
// License for the specific language governing permissions and limitations under
|
||
|
|
// the License.
|
||
|
|
|
||
|
|
#include "pw_containers/intrusive_list.h"
|
||
|
|
|
||
|
|
#include "pw_assert/assert.h"
|
||
|
|
|
||
|
|
namespace pw::intrusive_list_impl {
|
||
|
|
|
||
|
|
List::Item::~Item() { unlist(); }
|
||
|
|
|
||
|
|
void List::Item::unlist(Item* prev) {
|
||
|
|
if (prev == nullptr) {
|
||
|
|
prev = previous();
|
||
|
|
}
|
||
|
|
// Skip over this.
|
||
|
|
prev->next_ = next_;
|
||
|
|
|
||
|
|
// Retain the invariant that unlisted items are self-cycles.
|
||
|
|
next_ = this;
|
||
|
|
}
|
||
|
|
|
||
|
|
List::Item* List::Item::previous() {
|
||
|
|
// Follow the cycle around to find the previous element; O(N).
|
||
|
|
Item* prev = next_;
|
||
|
|
while (prev->next_ != this) {
|
||
|
|
prev = prev->next_;
|
||
|
|
}
|
||
|
|
return prev;
|
||
|
|
}
|
||
|
|
|
||
|
|
void List::insert_after(Item* pos, Item& item) {
|
||
|
|
PW_CHECK(
|
||
|
|
item.unlisted(),
|
||
|
|
"Cannot add an item to a pw::IntrusiveList that is already in a list");
|
||
|
|
item.next_ = pos->next_;
|
||
|
|
pos->next_ = &item;
|
||
|
|
}
|
||
|
|
|
||
|
|
void List::erase_after(Item* pos) { pos->next_->unlist(pos); }
|
||
|
|
|
||
|
|
List::Item* List::before_end() noexcept { return before_begin()->previous(); }
|
||
|
|
|
||
|
|
void List::clear() {
|
||
|
|
while (!empty()) {
|
||
|
|
erase_after(before_begin());
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
bool List::remove(const Item& item_to_remove) {
|
||
|
|
for (Item* pos = before_begin(); pos->next_ != end(); pos = pos->next_) {
|
||
|
|
if (pos->next_ == &item_to_remove) {
|
||
|
|
erase_after(pos);
|
||
|
|
return true;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
return false;
|
||
|
|
}
|
||
|
|
|
||
|
|
size_t List::size() const {
|
||
|
|
size_t total = 0;
|
||
|
|
Item* item = head_.next_;
|
||
|
|
while (item != &head_) {
|
||
|
|
item = item->next_;
|
||
|
|
total++;
|
||
|
|
}
|
||
|
|
return total;
|
||
|
|
}
|
||
|
|
|
||
|
|
} // namespace pw::intrusive_list_impl
|