com.google.common.base.Predicates Maven / Gradle / Ivy
/*
* Copyright (C) 2007 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.common.base;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.regex.Pattern;
import javax.annotation.Nullable;
/**
* Contains static factory methods for creating {@code Predicate} instances.
*
* All methods returns serializable predicates as long as they're given
* serializable parameters.
*
* @author Kevin Bourrillion
* @since 2 (imported from Google Collections Library)
*/
@GwtCompatible
public final class Predicates {
private Predicates() {}
// TODO: considering having these implement a VisitablePredicate interface
// which specifies an accept(PredicateVisitor) method.
/**
* Returns a predicate that always evaluates to {@code true}.
*/
@GwtCompatible(serializable = true)
@SuppressWarnings("unchecked")
public static Predicate alwaysTrue() {
return (Predicate) AlwaysTruePredicate.INSTANCE;
}
/**
* Returns a predicate that always evaluates to {@code false}.
*/
@GwtCompatible(serializable = true)
@SuppressWarnings("unchecked")
public static Predicate alwaysFalse() {
return (Predicate) AlwaysFalsePredicate.INSTANCE;
}
/**
* Returns a predicate that evaluates to {@code true} if the object reference
* being tested is null.
*/
@SuppressWarnings("unchecked")
public static Predicate isNull() {
return (Predicate) IsNullPredicate.INSTANCE;
}
/**
* Returns a predicate that evaluates to {@code true} if the object reference
* being tested is not null.
*/
@SuppressWarnings("unchecked")
public static Predicate notNull() {
return (Predicate) NotNullPredicate.INSTANCE;
}
/**
* Returns a predicate that evaluates to {@code true} if the given predicate
* evaluates to {@code false}.
*/
public static Predicate not(Predicate predicate) {
return new NotPredicate(predicate);
}
/**
* Returns a predicate that evaluates to {@code true} if each of its
* components evaluates to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a false
* predicate is found. It defensively copies the iterable passed in, so future
* changes to it won't alter the behavior of this predicate. If {@code
* components} is empty, the returned predicate will always evaluate to {@code
* true}.
*/
public static Predicate and(
Iterable> components) {
return new AndPredicate(defensiveCopy(components));
}
/**
* Returns a predicate that evaluates to {@code true} if each of its
* components evaluates to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a false
* predicate is found. It defensively copies the array passed in, so future
* changes to it won't alter the behavior of this predicate. If {@code
* components} is empty, the returned predicate will always evaluate to {@code
* true}.
*/
public static Predicate and(Predicate... components) {
return new AndPredicate(defensiveCopy(components));
}
/**
* Returns a predicate that evaluates to {@code true} if both of its
* components evaluate to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a false
* predicate is found.
*/
public static Predicate and(Predicate first,
Predicate second) {
return new AndPredicate(Predicates.asList(
checkNotNull(first), checkNotNull(second)));
}
/**
* Returns a predicate that evaluates to {@code true} if any one of its
* components evaluates to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a
* true predicate is found. It defensively copies the iterable passed in, so
* future changes to it won't alter the behavior of this predicate. If {@code
* components} is empty, the returned predicate will always evaluate to {@code
* false}.
*/
public static Predicate or(
Iterable> components) {
return new OrPredicate(defensiveCopy(components));
}
/**
* Returns a predicate that evaluates to {@code true} if any one of its
* components evaluates to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a
* true predicate is found. It defensively copies the array passed in, so
* future changes to it won't alter the behavior of this predicate. If {@code
* components} is empty, the returned predicate will always evaluate to {@code
* false}.
*/
public static Predicate or(Predicate... components) {
return new OrPredicate(defensiveCopy(components));
}
/**
* Returns a predicate that evaluates to {@code true} if either of its
* components evaluates to {@code true}. The components are evaluated in
* order, and evaluation will be "short-circuited" as soon as a
* true predicate is found.
*/
public static Predicate or(
Predicate first, Predicate second) {
return new OrPredicate(Predicates.asList(
checkNotNull(first), checkNotNull(second)));
}
/**
* Returns a predicate that evaluates to {@code true} if the object being
* tested {@code equals()} the given target or both are null.
*/
public static Predicate equalTo(@Nullable T target) {
return (target == null)
? Predicates.isNull()
: new IsEqualToPredicate(target);
}
/**
* Returns a predicate that evaluates to {@code true} if the object being
* tested is an instance of the given class. If the object being tested
* is {@code null} this predicate evaluates to {@code false}.
*
* If you want to filter an {@code Iterable} to narrow its type, consider
* using {@link com.google.common.collect.Iterables#filter(Iterable, Class)}
* in preference.
*/
@GwtIncompatible("Class.isInstance")
public static Predicate