norbert.mynemo.dataimport.scraping.input.CkRatingFile.java Source code

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Here is the source code for norbert.mynemo.dataimport.scraping.input.CkRatingFile.java

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/*
 * Copyright 2015 Norbert
 *
 * 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 norbert.mynemo.dataimport.scraping.input;

import static com.google.common.base.Preconditions.checkArgument;

import java.io.File;
import java.io.IOException;
import java.util.Iterator;

import norbert.mynemo.dataimport.scraping.CkRating;

import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;

import com.google.common.collect.UnmodifiableIterator;

/**
 * This class represents a file containing ratings of CK web site. The format of this file is
 * defined in the {@link CkRating} class.
 */
public class CkRatingFile implements Iterable<CkRating> {

    private final class RatingIterator extends UnmodifiableIterator<CkRating> {

        private Iterator<CSVRecord> iterator = parser.iterator();

        @Override
        public boolean hasNext() {
            boolean result = iterator.hasNext();

            if (!result) {
                try {
                    parser.close();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return result;
        }

        @Override
        public CkRating next() {
            return CkRating.createRating(iterator.next());
        }
    }

    /**
     * Returns <code>true</code> if the given file can be parsed, <code>false</code> otherwise.
     */
    public static boolean canParse(String filepath) throws IOException {
        checkArgument(new File(filepath).exists(), "The file must exists.");

        try (CSVParser parser = CkRating.createParser(filepath)) {
            for (CSVRecord record : parser) {
                return CkRating.isValid(record);
            }
        }

        // everything seems right
        return true;
    }

    private final CSVParser parser;

    public CkRatingFile(String filepath) throws IOException {
        checkArgument(filepath != null, "The rating filepath must be not null.");
        checkArgument(new File(filepath).exists(), "The file must exist.");

        parser = CkRating.createParser(filepath);
    }

    @Override
    public Iterator<CkRating> iterator() {
        return new RatingIterator();
    }
}