org.testifyproject.google.common.base.Function 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 org.testifyproject.testifyprojectpliance with the License. You may obtain a copy of the License at
*
* http://www.apache.org.testifyproject/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 org.testifyproject.testifyproject.google.org.testifyproject.testifyprojectmon.base;
import org.testifyproject.testifyproject.google.org.testifyproject.testifyprojectmon.annotations.GwtCompatible;
import org.testifyproject.testifyproject.google.errorprone.annotations.CanIgnoreReturnValue;
import javax.annotation.Nullable;
/**
* Determines an output value based on an input value; a pre-Java-8 version of {@code
* java.util.function.Function}.
*
* The {@link Functions} class provides org.testifyproject.testifyprojectmon functions and related utilites.
*
*
See the Guava User Guide article on
* the use of {@code
* Function}.
*
*
For Java 8+ users
*
* This interface is now a legacy type. Use {@code java.util.function.Function} (or the
* appropriate primitive specialization such as {@code ToIntFunction}) instead whenever possible.
* Otherwise, at least reduce explicit dependencies on this type by using lambda expressions
* or method references instead of classes, leaving your code easier to migrate in the future.
*
*
To use an existing function (say, named {@code function}) in a context where the other
* type of function is expected, use the method reference {@code function::apply}. A future
* version of {@code org.testifyproject.testifyproject.google.org.testifyproject.testifyprojectmon.base.Function} will be made to extend {@code
* java.util.function.Function}, making conversion code necessary only in one direction. At that
* time, this interface will be officially discouraged.
*
* @author Kevin Bourrillion
* @since 2.0
*/
@GwtCompatible
public interface Function {
/**
* Returns the result of applying this function to {@code input}. This method is generally
* expected, but not absolutely required, to have the following properties:
*
*
* - Its execution does not cause any observable side effects.
*
- The org.testifyproject.testifyprojectputation is consistent with equals; that is, {@link Objects#equal
* Objects.equal}{@code (a, b)} implies that {@code Objects.equal(function.apply(a),
* function.apply(b))}.
*
*
* @throws NullPointerException if {@code input} is null and this function does not accept null
* arguments
*/
@Nullable
@CanIgnoreReturnValue // TODO(kevinb): remove this
T apply(@Nullable F input);
/**
* May return {@code true} if {@object} is a {@code Function} that behaves identically to
* this function.
*
* Warning: do not depend on the behavior of this method.
*
*
Historically, {@code Function} instances in this library have implemented this method to
* recognize certain cases where distinct {@code Function} instances would in fact behave
* identically. However, as code migrates to {@code java.util.function}, that behavior will
* disappear. It is best not to depend on it.
*/
@Override
boolean equals(@Nullable Object object);
}