gradle-master/subprojects/file-collections/src/main/java/org/gradle/api/internal/file/FileCollectionFactory.java
/*
 * Copyright 2016 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.internal.file;

import org.gradle.api.Action;
import org.gradle.api.Buildable;
import org.gradle.api.file.ConfigurableFileCollection;
import org.gradle.api.file.ConfigurableFileTree;
import org.gradle.api.file.FileCollection;
import org.gradle.api.internal.file.collections.FileCollectionObservationListener;
import org.gradle.api.internal.file.collections.MinimalFileSet;
import org.gradle.api.internal.file.collections.MinimalFileTree;
import org.gradle.api.internal.provider.PropertyHost;
import org.gradle.api.internal.tasks.TaskDependencyFactory;
import org.gradle.api.internal.tasks.TaskDependencyResolveContext;
import org.gradle.api.tasks.TaskDependency;
import org.gradle.internal.Factory;
import org.gradle.internal.file.PathToFileResolver;
import org.gradle.internal.service.scopes.Scope;
import org.gradle.internal.service.scopes.ServiceScope;

import java.io.File;
import java.io.OutputStream;
import java.util.Collection;
import java.util.List;
import java.util.function.Consumer;

@ServiceScope(Scope.Global.class)
public interface FileCollectionFactory {
    /**
     * Creates a copy of this factory that uses the given resolver to convert various types to File instances.
     */
    FileCollectionFactory withResolver(PathToFileResolver fileResolver);

    FileCollectionFactory forChildScope(FileCollectionObservationListener listener);

    FileCollectionFactory forChildScope(PathToFileResolver fileResolver, TaskDependencyFactory taskDependencyFactory, PropertyHost propertyHost);

    /**
     * Creates a {@link FileCollection} with the given contents.
     *
     * The collection is live, so that the contents are queried as required on query of the collection.
     */
    FileCollectionInternal create(MinimalFileSet contents);

    /**
     * Creates a {@link FileCollection} with the given contents, and built by the given tasks.
     *
     * The collection is live, so that the contents are queried as required on query of the collection.
     */
    FileCollectionInternal create(TaskDependency builtBy, MinimalFileSet contents);

    /**
     * Creates a {@link FileCollection} with the given contents, and visiting its task dependencies (the tasks that it is built by) in the specified way.
     * <p>
     * The collection is live, so that the contents are queried as required on query of the collection.
     *
     * @param contents The file set contents for the constructed file collection
     * @param visitTaskDependencies The implementation of visiting dependencies for the constructed file collection's {@link Buildable#getBuildDependencies()}
     * @see org.gradle.api.internal.tasks.TaskDependencyFactory#visitingDependencies(Consumer)
     */
    FileCollectionInternal create(MinimalFileSet contents, Consumer<? super TaskDependencyResolveContext> visitTaskDependencies);

    /**
     * Creates an empty {@link FileCollection}
     */
    static FileCollectionInternal empty(String displayName) {
        if (FileCollectionInternal.DEFAULT_COLLECTION_DISPLAY_NAME.equals(displayName)) {
            return empty();
        } else {
            return new EmptyFileCollection(displayName);
        }
    }

    /**
     * Creates an empty {@link FileCollection}
     */
    static FileCollectionInternal empty() {
        return EmptyFileCollection.INSTANCE;
    }

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is not live. The provided array is queried on construction and discarded.
     */
    FileCollectionInternal fixed(File... files);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is not live. The provided {@link Collection} is queried on construction and discarded.
     */
    FileCollectionInternal fixed(Collection<File> files);

    /**
     * Creates a {@link FileCollection} with the given files as content. The result is not live and does not reflect changes to the array.
     *
     * <p>The collection is not live. The provided array is queried on construction and discarded.
     */
    FileCollectionInternal fixed(String displayName, File... files);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is not live. The provided {@link Collection} is queried on construction and discarded.
     */
    FileCollectionInternal fixed(String displayName, Collection<File> files);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is live and resolves the files on each query.
     *
     * <p>The collection fails to resolve if it contains providers which are not present.
     */
    FileCollectionInternal resolving(String displayName, Object sources);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is live and resolves the files on each query.
     *
     * <p>The collection ignores providers which are not present.
     */
    FileCollectionInternal resolvingLeniently(String displayName, Object sources);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is live and resolves the files on each query.
     *
     * <p>The collection fails to resolve if it contains providers which are not present.
     */
    FileCollectionInternal resolving(Object sources);

    /**
     * Creates a {@link FileCollection} with the given files as content.
     *
     * <p>The collection is live and resolves the files on each query.
     *
     * <p>The collection ignores providers which are not present.
     */
    FileCollectionInternal resolvingLeniently(Object sources);

    /**
     * Creates an empty {@link ConfigurableFileCollection} instance.
     */
    ConfigurableFileCollection configurableFiles(String displayName);

    /**
     * Creates an empty {@link ConfigurableFileCollection} instance.
     */
    ConfigurableFileCollection configurableFiles();

    /**
     * Creates a {@link ConfigurableFileTree} instance with no base dir specified.
     */
    ConfigurableFileTree fileTree();

    /**
     * Creates a file tree containing the given generated file.
     */
    FileTreeInternal generated(Factory<File> tmpDir, String fileName, Action<File> fileGenerationListener, Action<OutputStream> contentGenerator);

    /**
     * Creates a file tree made up of the union of the given trees.
     *
     * <p>The tree is not live. The provided list is queried on construction and discarded.
     */
    FileTreeInternal treeOf(List<? extends FileTreeInternal> fileTrees);

    FileTreeInternal treeOf(MinimalFileTree tree);

    static FileTreeInternal emptyTree() {
        return EmptyFileTree.INSTANCE;
    }

    static FileTreeInternal emptyTree(String displayName) {
        if (FileTreeInternal.DEFAULT_TREE_DISPLAY_NAME.equals(displayName)) {
            return emptyTree();
        } else {
            return new EmptyFileTree(displayName);
        }
    }
}
