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/*******************************************************************************
* Copyright (c) 2010-2018, Gabor Bergmann, IncQuery Labs Ltd.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.matchers.util;
import java.util.Collections;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.Set;
/**
* An immutable memory view that consists of a single non-null element with multiplicity 1.
* @author Gabor Bergmann
* @since 2.0
*/
public final class SingletonMemoryView<Value> implements IMemoryView<Value> {
private Value wrapped;
private static final int ONE_HASH = Integer.valueOf(1).hashCode();
public SingletonMemoryView(Value value) {
this.wrapped = value;
}
@Override
public Iterator<Value> iterator() {
return new Iterator<Value>() {
boolean hasNext = true;
@Override
public boolean hasNext() {
return hasNext;
}
@Override
public Value next() {
if (hasNext) {
hasNext = false;
return wrapped;
} else throw new NoSuchElementException();
}
};
}
@Override
public int getCount(Value value) {
return wrapped.equals(value) ? 1 : 0;
}
@Override
public int getCountUnsafe(Object value) {
return wrapped.equals(value) ? 1 : 0;
}
@Override
public boolean containsNonZero(Value value) {
return wrapped.equals(value);
}
@Override
public boolean containsNonZeroUnsafe(Object value) {
return wrapped.equals(value);
}
@Override
public int size() {
return 1;
}
@Override
public boolean isEmpty() {
return false;
}
@Override
public Set<Value> distinctValues() {
return Collections.singleton(wrapped);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof IMemoryView<?>) {
IMemoryView<?> other = (IMemoryView<?>) obj;
if (1 != other.size()) return false;
if (1 != other.getCountUnsafe(wrapped)) return false;
return true;
}
return false;
}
@Override
public int hashCode() {
return wrapped.hashCode() ^ ONE_HASH;
}
@Override
public String toString() {
return "{" + wrapped + "}";
}
}
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