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/*
* This file is part of SpongeAPI, licensed under the MIT License (MIT).
*
* Copyright (c) SpongePowered
* Copyright (c) contributors
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.spongepowered.api.util.weighted;
import com.google.common.collect.Lists;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
/**
* A table of weighted entry, each entry is given a weight, the higher the
* weight the more likely the chance that the entry is chosen. Each roll will
* only return a single entries value.
*
* @param The entry type
*/
public class WeightedTable extends RandomObjectTable {
private double totalWeight = 0;
/**
* Creates a new {@link WeightedTable} with a default roll
* count of {@code 1}.
*/
public WeightedTable() {
super(1);
}
/**
* Creates a new {@link WeightedTable} with the provided
* number of {@code rolls}.
*
* @param rolls The rolls for variance
*/
public WeightedTable(int rolls) {
super(rolls);
}
/**
* Creates a new {@link WeightedTable} with the provided
* {@link VariableAmount} for the amount of rolls and variance.
*
* @param rolls The rolls for variance
*/
public WeightedTable(VariableAmount rolls) {
super(rolls);
}
@Override
public boolean add(TableEntry entry) {
final boolean added = super.add(entry);
if (added) {
this.recalculateWeight();
}
return added;
}
@Override
public boolean add(T object, double weight) {
final boolean added = super.add(object, weight);
if (added) {
this.recalculateWeight();
}
return added;
}
@Override
public boolean addAll(Collection> c) {
final boolean added = super.addAll(c);
if (added) {
this.recalculateWeight();
}
return added;
}
@Override
public boolean remove(Object entry) {
final boolean removed = super.remove(entry);
if (removed) {
this.recalculateWeight();
}
return removed;
}
@Override
public boolean removeObject(Object entry) {
final boolean removed = super.removeObject(entry);
if (removed) {
this.recalculateWeight();
}
return removed;
}
@Override
public boolean removeAll(Collection c) {
final boolean removed = super.removeAll(c);
if (removed) {
this.recalculateWeight();
}
return removed;
}
@Override
public boolean retainAll(Collection c) {
final boolean removed = super.retainAll(c);
if (removed) {
this.recalculateWeight();
}
return removed;
}
@Override
public void clear() {
super.clear();
this.recalculateWeight();
}
/**
* Recalculates the total weight of all entries in this table.
*/
protected void recalculateWeight() {
this.totalWeight = 0;
for (Iterator> it = this.entries.iterator(); it.hasNext();) {
final TableEntry entry = it.next();
if (entry.weight() < 0) {
// Negative weights on entries will really break this, so we
// remove them if found, this is fine as a negatively weighted
// entry should never be picked anyway
it.remove();
} else {
this.totalWeight += entry.weight();
}
}
}
@Override
public List get(Random rand) {
final List results = Lists.newArrayList();
if (this.entries.isEmpty()) {
return results;
}
final int rolls = this.rolls().flooredAmount(rand);
for (int i = 0; i < rolls; i++) {
double roll = rand.nextDouble() * this.totalWeight;
for (Iterator> it = this.entries.iterator(); it.hasNext();) {
final TableEntry next = it.next();
roll -= next.weight();
if (roll <= 0) {
if (next instanceof NestedTableEntry) {
results.addAll(((NestedTableEntry) next).get(rand));
} else if (next instanceof WeightedObject) {
results.add(((WeightedObject) next).get());
}
break;
}
}
}
return results;
}
@Override
public Iterator> iterator() {
return new Itr();
}
@Override
public boolean equals(Object o) {
if (o == this) {
return true;
}
if (!(o instanceof WeightedTable)) {
return false;
}
final WeightedTable c = (WeightedTable) o;
if (this.rolls() != c.rolls()) {
return false;
}
if (this.entries.size() != c.entries.size()) {
return false;
}
for (int i = 0; i < this.entries.size(); i++) {
if (!this.entries.get(i).equals(c.entries.get(i))) {
return false;
}
}
return true;
}
@Override
public int hashCode() {
int r = 1;
r = r * 37 + this.rolls().hashCode();
for (TableEntry entry : this.entries) {
r = r * 37 + entry.hashCode();
}
return r;
}
@Override
public String toString() {
final StringBuilder r = new StringBuilder();
r.append("WeightedTable (rolls=").append(this.rolls());
r.append(",entries=").append(this.entries.size()).append(") {\n");
for (TableEntry entry : this.entries) {
r.append("\t").append(entry.toString()).append("\n");
}
r.append("}");
return r.toString();
}
/**
* An iterator which will properly trigger a rebuild of the total weight on
* removal.
*/
private class Itr implements Iterator> {
private final Iterator> iter;
protected Itr() {
this.iter = WeightedTable.super.iterator();
}
@Override
public boolean hasNext() {
return this.iter.hasNext();
}
@Override
public TableEntry next() {
return this.iter.next();
}
@Override
public void remove() {
this.iter.remove();
WeightedTable.this.recalculateWeight();
}
}
}