com.facebook.presto.jdbc.internal.guava.base.Functions Maven / Gradle / Ivy
/*
* Copyright (C) 2007 The Guava Authors
*
* 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.facebook.presto.jdbc.internal.guava.base;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkArgument;
import static com.facebook.presto.jdbc.internal.guava.base.Preconditions.checkNotNull;
import com.facebook.presto.jdbc.internal.guava.annotations.GwtCompatible;
import java.io.Serializable;
import java.util.Map;
import org.checkerframework.checker.nullness.qual.Nullable;
/**
* Static utility methods pertaining to {@code com.facebook.presto.jdbc.internal.guava.base.Function} instances; see that
* class for information about migrating to {@code java.util.function}.
*
* All methods return serializable functions as long as they're given serializable parameters.
*
*
See the Guava User Guide article on the use of {@code Function}.
*
* @author Mike Bostock
* @author Jared Levy
* @since 2.0
*/
@GwtCompatible
public final class Functions {
private Functions() {}
/**
* A function equivalent to the method reference {@code Object::toString}, for users not yet using
* Java 8. The function simply invokes {@code toString} on its argument and returns the result. It
* throws a {@link NullPointerException} on null input.
*
*
Warning: The returned function may not be consistent with equals (as
* documented at {@link Function#apply}). For example, this function yields different results for
* the two equal instances {@code ImmutableSet.of(1, 2)} and {@code ImmutableSet.of(2, 1)}.
*
*
Warning: as with all function types in this package, avoid depending on the specific
* {@code equals}, {@code hashCode} or {@code toString} behavior of the returned function. A
* future migration to {@code java.util.function} will not preserve this behavior.
*
*
For Java 8 users: use the method reference {@code Object::toString} instead. In the
* future, when this class requires Java 8, this method will be deprecated. See {@link Function}
* for more important information about the Java 8 transition.
*/
public static Function