SimplePathVisitor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.commons.io.file;

import java.io.IOException;
import java.nio.file.FileVisitResult;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.util.Objects;

import org.apache.commons.io.build.AbstractSupplier;
import org.apache.commons.io.function.IOBiFunction;

/**
 * A {@link SimpleFileVisitor} typed to a {@link Path}.
 *
 * @since 2.7
 */
public abstract class SimplePathVisitor extends SimpleFileVisitor<Path> implements PathVisitor {

    /**
     * Abstracts builder for subclasses.
     *
     * @param <T> The SimplePathVisitor type.
     * @param <B> The builder type.
     * @since 2.19.0
     */
    protected abstract static class AbstractBuilder<T, B extends AbstractSupplier<T, B>> extends AbstractSupplier<T, B> {

        private IOBiFunction<Path, IOException, FileVisitResult> visitFileFailedFunction;

        /**
         * Constructs a new builder for subclasses.
         */
        public AbstractBuilder() {
            // empty.
        }

        IOBiFunction<Path, IOException, FileVisitResult> getVisitFileFailedFunction() {
            return visitFileFailedFunction;
        }

        /**
         * Sets the function to call on {@link #visitFileFailed(Path, IOException)}.
         * <p>
         * Defaults to {@link SimpleFileVisitor#visitFileFailed(Object, IOException)} on construction.
         * </p>
         *
         * @param visitFileFailedFunction the function to call on {@link #visitFileFailed(Path, IOException)}.
         * @return this instance.
         */
        public B setVisitFileFailedFunction(final IOBiFunction<Path, IOException, FileVisitResult> visitFileFailedFunction) {
            this.visitFileFailedFunction = visitFileFailedFunction;
            return asThis();
        }

    }

    private final IOBiFunction<Path, IOException, FileVisitResult> visitFileFailedFunction;

    /**
     * Constructs a new instance.
     */
    protected SimplePathVisitor() {
        this.visitFileFailedFunction = super::visitFileFailed;
    }

    /**
     * Constructs a new instance.
     *
     * @param builder The builder provided by a subclass.
     */
    SimplePathVisitor(final AbstractBuilder<?, ?> builder) {
        this.visitFileFailedFunction = builder.visitFileFailedFunction != null ? builder.visitFileFailedFunction : super::visitFileFailed;
    }

    /**
     * Constructs a new instance.
     *
     * @param visitFileFailedFunction Called on {@link #visitFileFailed(Path, IOException)}.
     */
    protected SimplePathVisitor(final IOBiFunction<Path, IOException, FileVisitResult> visitFileFailedFunction) {
        this.visitFileFailedFunction = Objects.requireNonNull(visitFileFailedFunction, "visitFileFailedFunction");
    }

    @Override
    public FileVisitResult visitFileFailed(final Path file, final IOException exc) throws IOException {
        return visitFileFailedFunction.apply(file, exc);
    }
}