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/*
* Licensed to GraphHopper GmbH under one or more contributor
* license agreements. See the NOTICE file distributed with this work for
* additional information regarding copyright ownership.
*
* GraphHopper GmbH 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.
*/
package com.onthegomap.planetiler.collection;
import java.util.function.IntBinaryOperator;
/**
* API for min-heaps that keeps track of {@code int} keys in a range from {@code [0, size)} ordered by {@code long}
* values.
*
* Ported from GraphHopper
* and modified to extract a common interface for subclass implementations.
*/
public interface LongMinHeap {
/**
* Returns a new min-heap where each element has 4 children backed by elements in an array.
*
* This is slightly faster than a traditional binary min heap due to a shallower, more cache-friendly memory layout.
*/
static LongMinHeap newArrayHeap(int elements, IntBinaryOperator tieBreaker) {
return new ArrayLongMinHeap(elements, tieBreaker);
}
int size();
boolean isEmpty();
/**
* Adds an element to the heap, the given id must not exceed the size specified in the constructor. Its illegal to
* push the same id twice (unless it was polled/removed before). To update the value of an id contained in the heap
* use the {@link #update} method.
*/
void push(int id, long value);
/**
* @return true if the heap contains an element with the given id
*/
boolean contains(int id);
/**
* Updates the element with the given id. The complexity of this method is O(log(N)), just like push/poll. Its illegal
* to update elements that are not contained in the heap. Use {@link #contains} to check the existence of an id.
*/
void update(int id, long value);
/**
* Updates the weight of the head element in the heap, pushing it down and bubbling up the new min element if
* necessary.
*/
void updateHead(long value);
/**
* @return the id of the next element to be polled, i.e. the same as calling poll() without removing the element
*/
int peekId();
long peekValue();
/**
* Extracts the element with minimum value from the heap
*/
int poll();
void clear();
}