org.xipki.common.util.FileBigIntegerIterator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of common Show documentation
The newest version!
/*
 *
 * Copyright (c) 2013 - 2017 Lijun Liao
 *
 * 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.xipki.common.util;

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.math.BigInteger;
import java.util.Iterator;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;
import java.util.concurrent.ConcurrentLinkedQueue;

/**
 * @author Lijun Liao
 * @since 2.1.0
 */

public class FileBigIntegerIterator implements Iterator {

    private final boolean hex;

    private final boolean loop;

    private final String fileName;

    private BufferedReader reader;

    private ConcurrentLinkedQueue nextNumbers = new ConcurrentLinkedQueue<>();

    private BigInteger currentNumber;

    public FileBigIntegerIterator(String fileName, boolean hex, boolean loop)
            throws IOException {
        this.fileName = ParamUtil.requireNonBlank("fileName", fileName);
        this.hex = hex;
        this.loop = loop;
        this.reader = new BufferedReader(new FileReader(fileName));
        this.currentNumber = readNextNumber();
    }

    @Override
    public synchronized boolean hasNext() {
        return currentNumber != null;
    }

    @Override
    public synchronized BigInteger next() {
        if (currentNumber == null) {
            return null;
        }

        BigInteger ret = currentNumber;
        this.currentNumber = readNextNumber();
        return ret;
    }

    private BigInteger readNextNumber() {
        BigInteger number = nextNumbers.poll();
        if (number != null) {
            return number;
        }

        String line;
        try {
            line = reader.readLine();
            if (loop && line == null) {
                reader.close();
                reader = new BufferedReader(new FileReader(fileName));
                line = reader.readLine();
            }

            if (line == null) {
                reader.close();
                return null;
            }
        } catch (IOException ex) {
            throw new NoSuchElementException("could not read next number from file " + fileName);
        }

        if (line.indexOf(',') == -1) {
            nextNumbers.add(new BigInteger(line.trim(), hex ? 16 : 10));
        } else {
            StringTokenizer st = new StringTokenizer(line.trim(), ", ");
            while (st.hasMoreTokens()) {
                nextNumbers.add(new BigInteger(st.nextToken(), hex ? 16 : 10));
            }
        }

        return nextNumbers.poll();
    }

    public void close() {
        try {
            reader.close();
        } catch (Throwable th) {
            // STYLECHECK: SKIPTEST
        }
    }

}