| /* Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 |
| * |
| * http://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. |
| */ |
| |
| parcel Lucy; |
| |
| /** |
| * Heap sort / priority queue. |
| * |
| * PriorityQueue implements a textbook heap sort / priority queue algorithm. |
| * |
| * Subclasses must define the abstract method Less_Than. |
| */ |
| |
| class Lucy::Util::PriorityQueue cnick PriQ |
| inherits Lucy::Object::Obj { |
| uint32_t size; |
| uint32_t max_size; |
| |
| /* This particular priority queue variant leaves slot 0 open in order to |
| * keep the relationship between node rank and index clear in the up_heap |
| * and down_heap routines. |
| */ |
| Obj **heap; |
| |
| /** |
| * @param max_size Max elements the queue can hold. |
| */ |
| inert PriorityQueue* |
| init(PriorityQueue *self, uint32_t max_size); |
| |
| /** Compare queue elements. |
| */ |
| abstract bool_t |
| Less_Than(PriorityQueue *self, Obj *a, Obj *b); |
| |
| /** Possibly insert an element. Add to the Queue if either... |
| * a) the queue isn't full, or |
| * b) the element belongs in the queue and should displace another. |
| */ |
| bool_t |
| Insert(PriorityQueue *self, decremented Obj *element); |
| |
| /** Equivalent to Insert(), except for the return value. If the Queue has |
| * room, the element is inserted and Jostle() returns NULL. If not, then |
| * the item which falls out of the bottom of the Queue is returned. |
| */ |
| incremented nullable Obj* |
| Jostle(PriorityQueue *self, decremented Obj *element); |
| |
| /** Pop the *least* item off of the priority queue. |
| */ |
| incremented nullable Obj* |
| Pop(PriorityQueue *self); |
| |
| /** Empty out the PriorityQueue into a sorted array. |
| */ |
| incremented VArray* |
| Pop_All(PriorityQueue *self); |
| |
| /** Return the least item in the queue, but don't remove it. |
| */ |
| nullable Obj* |
| Peek(PriorityQueue *self); |
| |
| /** Accessor for "size" member. |
| */ |
| uint32_t |
| Get_Size(PriorityQueue *self); |
| |
| public void |
| Destroy(PriorityQueue *self); |
| } |
| |
| |