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/*
* Copyright (c) 2013, 2014 Eike Stepper (Berlin, Germany) and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Eike Stepper - initial API and implementation
*/
package org.eclipse.net4j.util;
import java.util.HashSet;
import java.util.Set;
/**
* @author Eike Stepper
* @since 3.3
*/
public final class Predicates
{
private Predicates()
{
}
/**
* @since 3.4
*/
public static <T> Predicate<T> included(Set<T> inclusions)
{
return new IncludedPredicate<T>(inclusions);
}
/**
* @since 3.4
*/
public static <T> Predicate<T> excluded(Set<T> exclusions)
{
return new ExcludedPredicate<T>(exclusions);
}
/**
* @since 3.4
*/
public static <T> Predicate<T> unique()
{
return new UniquePredicate<T>();
}
@SuppressWarnings("unchecked")
public static <T> Predicate<T> alwaysFalse()
{
return (Predicate<T>)FalsePredicate.INSTANCE;
}
@SuppressWarnings("unchecked")
public static <T> Predicate<T> alwaysTrue()
{
return (Predicate<T>)TruePredicate.INSTANCE;
}
/**
* @author Eike Stepper
* @since 3.4
*/
public static final class IncludedPredicate<T> implements Predicate<T>
{
private final Set<T> inclusions;
public IncludedPredicate(Set<T> inclusions)
{
this.inclusions = inclusions;
}
public boolean apply(T element)
{
return inclusions.contains(element);
}
}
/**
* @author Eike Stepper
* @since 3.4
*/
public static final class ExcludedPredicate<T> implements Predicate<T>
{
private final Set<T> exclusions;
public ExcludedPredicate(Set<T> exclusions)
{
this.exclusions = exclusions;
}
public boolean apply(T element)
{
return !exclusions.contains(element);
}
}
/**
* @author Eike Stepper
* @since 3.4
*/
public static final class UniquePredicate<T> implements Predicate<T>
{
private final Set<T> applied = new HashSet<T>();
public boolean apply(T element)
{
return applied.add(element);
}
}
/**
* @author Eike Stepper
*/
private static final class FalsePredicate implements Predicate<Object>
{
private static final Predicate<Object> INSTANCE = new FalsePredicate();
public boolean apply(Object element)
{
return false;
}
}
/**
* @author Eike Stepper
*/
private static final class TruePredicate implements Predicate<Object>
{
private static final Predicate<Object> INSTANCE = new TruePredicate();
public boolean apply(Object element)
{
return true;
}
}
}
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