gradle-master/subprojects/file-collections/src/main/java/org/gradle/api/internal/file/UnionFileTree.java
/*
 * Copyright 2009 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 com.google.common.collect.Sets;
import org.gradle.api.file.FileCollection;
import org.gradle.api.file.FileTree;
import org.gradle.api.internal.tasks.TaskDependencyFactory;
import org.gradle.internal.Cast;

import java.util.Arrays;
import java.util.Collection;
import java.util.Set;
import java.util.function.Consumer;

public class UnionFileTree extends CompositeFileTree {
    private final Set<FileTreeInternal> sourceTrees;
    private final String displayName;

    public UnionFileTree(TaskDependencyFactory taskDependencyFactory, FileTreeInternal... sourceTrees) {
        this(taskDependencyFactory, "file tree", Arrays.asList(sourceTrees));
    }

    public UnionFileTree(TaskDependencyFactory taskDependencyFactory, String displayName, FileTreeInternal... sourceTrees) {
        this(taskDependencyFactory, displayName, Arrays.asList(sourceTrees));
    }

    public UnionFileTree(TaskDependencyFactory taskDependencyFactory, String displayName, Collection<? extends FileTreeInternal> sourceTrees) {
        super(taskDependencyFactory);
        this.displayName = displayName;
        this.sourceTrees = Sets.newLinkedHashSet(sourceTrees);
    }

    @Override
    public String getDisplayName() {
        return displayName;
    }

    @Override
    protected void visitChildren(Consumer<FileCollectionInternal> visitor) {
        for (FileTreeInternal sourceTree : sourceTrees) {
            visitor.accept(sourceTree);
        }
    }

    public void addToUnion(FileCollection source) {
        if (!(source instanceof FileTree)) {
            throw new UnsupportedOperationException(String.format("Can only add FileTree instances to %s.", getDisplayName()));
        }

        sourceTrees.add(Cast.cast(FileTreeInternal.class, source));
    }
}
