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/**
* Copyright (C) 2019 Adrien Hopkins
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package org.unitConverter.math;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
/**
* A "wrapper" for an existing map that treats a zero value as equivalent to null.
*
* @author Adrien Hopkins
* @since 2019-10-16
* @param <T>
* type of key
*/
public final class ZeroIsNullMap<T> extends AbstractMap<T, Integer> {
/**
* Create a ZeroIsNullMap. This method always creates a new map.
*
* @param <T>
* type of key
* @param map
* map to input
* @return map that treats zero as null
* @throws NullPointerException
* if map is null
* @since 2019-10-16
*/
public static <T> Map<T, Integer> create(final Map<T, Integer> map) {
return new ZeroIsNullMap<>(Objects.requireNonNull(map, "map must not be null."));
}
private final Map<T, Integer> map;
/**
* Creates the {@code ObjectProductMap}.
*
* @param map
* @since 2019-10-16
*/
private ZeroIsNullMap(final Map<T, Integer> map) {
this.map = map;
}
@Override
public void clear() {
this.map.clear();
}
@Override
public boolean containsKey(final Object key) {
return this.map.containsKey(key) && this.map.get(key) != 0;
}
@Override
public boolean containsValue(final Object value) {
return this.values().contains(value);
}
@Override
public Set<Entry<T, Integer>> entrySet() {
final Set<Entry<T, Integer>> entrySet = new HashSet<>(this.map.entrySet());
entrySet.removeIf(e -> e.getValue() == 0);
return entrySet;
}
@Override
public Integer get(final Object key) {
final Integer i = this.map.get(key);
if (Objects.equals(i, 0))
return null;
else
return i;
}
@Override
public Set<T> keySet() {
final Set<T> keySet = new HashSet<>(this.map.keySet());
keySet.removeIf(k -> this.map.get(k) == 0);
return keySet;
}
@Override
public Integer put(final T key, final Integer value) {
if (value != 0)
return this.map.put(key, value);
else
return null;
}
@Override
public void putAll(final Map<? extends T, ? extends Integer> m) {
for (final T key : m.keySet()) {
this.put(key, m.get(key));
}
}
@Override
public Integer remove(final Object key) {
return this.map.remove(key);
}
@Override
public Collection<Integer> values() {
final List<Integer> values = new ArrayList<>(this.map.values());
values.removeIf(i -> i == 0);
return values;
}
}
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