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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.yolean.chain;
import java.lang.reflect.Array;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.IdentityHashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.TreeMap;
/**
* A set using identity comparison.
* Keeps track of insertion order, which is available by calling insertionOrderedList.
*
* @author Tony Vaagenes
*/
class EnumeratedIdentitySet<T> implements Set<T> {
private int counter = 0;
private final Map<T, Integer> set = new IdentityHashMap<>();
public EnumeratedIdentitySet(Collection<? extends T> collection) {
addAll(collection);
}
public EnumeratedIdentitySet() {
// empty
}
@Override
public int size() {
return set.size();
}
@Override
public boolean isEmpty() {
return set.isEmpty();
}
@Override
public boolean contains(Object o) {
return set.containsKey(o);
}
@Override
public Iterator<T> iterator() {
return set.keySet().iterator();
}
@Override
public Object[] toArray() {
return set.keySet().toArray();
}
@Override
public <T1> T1[] toArray(T1[] a) {
return set.keySet().toArray(a);
}
@Override
public boolean add(T t) {
if (set.containsKey(t)) {
return false;
} else {
set.put(t, counter++);
return true;
}
}
@Override
public boolean remove(Object o) {
return set.remove(o) != null;
}
@Override
public boolean containsAll(Collection<?> c) {
return set.keySet().containsAll(c);
}
@Override
public boolean addAll(Collection<? extends T> collection) {
boolean changed = false;
for (T t : collection) {
changed |= add(t);
}
return changed;
}
@Override
public boolean retainAll(Collection<?> collection) {
return set.keySet().retainAll(collection);
}
@Override
public boolean removeAll(Collection<?> collection) {
boolean changed = false;
for (Object o : collection) {
changed |= remove(o);
}
return changed;
}
@Override
public void clear() {
set.clear();
counter = 0;
}
public List<T> insertionOrderedList() {
if (set.isEmpty()) {
counter = 0;
return Collections.emptyList();
}
if (counter >= set.size() * 2 + 20) {
renumber();
}
return getKeysSortedByValue(set, counter);
}
private static <KEY> List<KEY> getKeysSortedByValue(Map<KEY, Integer> set, int maxValue) {
@SuppressWarnings("unchecked")
KEY[] result = (KEY[])Array.newInstance(headKey(set).getClass(), maxValue);
for (Map.Entry<KEY, Integer> entry : set.entrySet()) {
result[entry.getValue()] = entry.getKey();
}
return removeNulls(result);
}
private static <T> T headKey(Map<T, ?> map) {
return map.entrySet().iterator().next().getKey();
}
static <T> List<T> removeNulls(T[] list) {
int insertionSpot = 0;
for (int i = 0; i < list.length; i++) {
T element = list[i];
if (element != null) {
list[insertionSpot] = element;
insertionSpot++;
}
}
return Arrays.asList(list).subList(0, insertionSpot);
}
//only for testing
List<Integer> numbers() {
return new ArrayList<>(set.values());
}
private void renumber() {
SortedMap<Integer, T> invertedSet = invertedSortedMap(set);
int i = 0;
for (Map.Entry<Integer, T> entry : invertedSet.entrySet()) {
set.put(entry.getValue(), i++);
}
counter = i;
}
private static <K, V> SortedMap<V, K> invertedSortedMap(Map<K, V> map) {
SortedMap<V, K> result = new TreeMap<>();
for (Map.Entry<K, V> entry : map.entrySet()) {
result.put(entry.getValue(), entry.getKey());
}
return result;
}
}
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