/*
* Copyright 2017 the original author or 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 org.gradle.api.provider;
import org.gradle.api.Incubating;
import org.gradle.api.tasks.Internal;
/**
* A container object which provides a value of a specific type. The value can be retrieved by the method {@code get()} or {@code getOrNull()}.
* <p>
* <b>Note:</b> This interface is not intended for implementation by build script or plugin authors. An instance of this class can be created
* through the factory methods {@link org.gradle.api.Project#provider(java.util.concurrent.Callable)} or
* {@link org.gradle.api.provider.ProviderFactory#provider(java.util.concurrent.Callable)}.
*
* @param <T> Type of value represented by provider
* @since 4.0
*/
@Incubating
public interface Provider<T> {
/**
* If a value is present in this provider, returns the value, otherwise throws {@code java.lang.IllegalStateException}.
*
* @return Value
* @throws IllegalStateException if there is no value present
*/
T get();
/**
* Returns the value if present in this provider. Returns null if value is not available.
*
* @return Value
*/
@Internal
T getOrNull();
/**
* Returns {@code true} if there is a value present, otherwise {@code false}.
*
* @return {@code true} if there is a value present, otherwise {@code false}
*/
@Internal
boolean isPresent();
}