com.streamsets.pipeline.lib.csv.CsvParser.java Source code

Introduction

Here is the source code for com.streamsets.pipeline.lib.csv.CsvParser.java

Source

/**
 * Copyright 2015 StreamSets Inc.
 *
 * Licensed under 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 com.streamsets.pipeline.lib.csv;

import com.streamsets.pipeline.api.impl.Utils;
import com.streamsets.pipeline.lib.io.CountingReader;
import com.streamsets.pipeline.lib.io.ObjectLengthException;
import com.streamsets.pipeline.lib.util.ExceptionUtils;
import org.apache.commons.csv.CSVFormat;
import org.apache.commons.csv.CSVParser;
import org.apache.commons.csv.CSVRecord;
import org.apache.commons.io.IOUtils;

import java.io.Closeable;
import java.io.IOException;
import java.io.Reader;
import java.util.Iterator;

public class CsvParser implements Closeable, AutoCloseable {
    private long currentPos;
    private long skipLinesPosCorrection;
    private final CSVParser parser;
    private final CountingReader reader;
    private final int maxObjectLen;
    private Iterator<CSVRecord> iterator;
    private CSVRecord nextRecord;
    private final String[] headers;
    private boolean closed;

    public CsvParser(Reader reader, CSVFormat format, int maxObjectLen) throws IOException {
        this(new CountingReader(reader), format, maxObjectLen, 0, 0);
    }

    @SuppressWarnings("unchecked")
    public CsvParser(CountingReader reader, CSVFormat format, int maxObjectLen, long initialPosition,
            int skipStartLines) throws IOException {
        Utils.checkNotNull(reader, "reader");
        Utils.checkNotNull(reader.getPos() == 0,
                "reader must be in position zero, the CsvParser will fast-forward to the initialPosition");
        Utils.checkNotNull(format, "format");
        Utils.checkArgument(initialPosition >= 0, "initialPosition must be greater or equal than zero");
        Utils.checkArgument(skipStartLines >= 0, "skipStartLines must be greater or equal than zero");
        this.reader = reader;
        currentPos = initialPosition;
        this.maxObjectLen = maxObjectLen;
        if (initialPosition == 0) {
            if (skipStartLines > 0) {
                skipLinesPosCorrection = skipLines(reader, skipStartLines);
                currentPos = skipLinesPosCorrection;
            }
            if (format.getSkipHeaderRecord()) {
                format = format.withSkipHeaderRecord(false);
                parser = new CSVParser(reader, format, 0, 0);
                headers = read();
            } else {
                parser = new CSVParser(reader, format, 0, 0);
                headers = null;
            }
        } else {
            if (format.getSkipHeaderRecord()) {
                format = format.withSkipHeaderRecord(false);
                parser = new CSVParser(reader, format, 0, 0);
                headers = read();
                while (getReaderPosition() < initialPosition && read() != null) {
                }
                if (getReaderPosition() != initialPosition) {
                    throw new IOException(
                            Utils.format("Could not position reader at position '{}', got '{}' instead",
                                    initialPosition, getReaderPosition()));
                }
            } else {
                IOUtils.skipFully(reader, initialPosition);
                parser = new CSVParser(reader, format, initialPosition, 0);
                headers = null;
            }
        }
    }

    private long skipLines(Reader reader, int lines) throws IOException {
        int count = 0;
        int skipped = 0;
        while (skipped < lines) {
            int c = reader.read();
            if (c == -1) {
                throw new IOException(Utils.format("Could not skip '{}' lines, reached EOF", lines));
            }
            // this is enough to handle \n and \r\n EOL files
            if (c == '\n') {
                skipped++;
            }
            count++;
        }
        return count;
    }

    protected Reader getReader() {
        return reader;
    }

    protected CSVRecord nextRecord() throws IOException {
        return (iterator.hasNext()) ? iterator.next() : null;
    }

    public String[] getHeaders() throws IOException {
        return headers;
    }

    public long getReaderPosition() {
        return currentPos;
    }

    public String[] read() throws IOException {
        if (closed) {
            throw new IOException("Parser has been closed");
        }
        if (iterator == null) {
            iterator = parser.iterator();
            nextRecord = nextRecord();
        }
        CSVRecord record = nextRecord;
        if (nextRecord != null) {
            nextRecord = nextRecord();
        }
        long prevPos = currentPos;
        currentPos = (nextRecord != null) ? nextRecord.getCharacterPosition() + skipLinesPosCorrection
                : reader.getPos();
        if (maxObjectLen > -1) {
            if (currentPos - prevPos > maxObjectLen) {
                ExceptionUtils.throwUndeclared(new ObjectLengthException(
                        Utils.format("CSV Object at offset '{}' exceeds max length '{}'", prevPos, maxObjectLen),
                        prevPos));
            }
        }
        return toArray(record);
    }

    private String[] toArray(CSVRecord record) {
        String[] array = (record == null) ? null : new String[record.size()];
        if (array != null) {
            for (int i = 0; i < record.size(); i++) {
                array[i] = record.get(i);
            }
        }
        return array;
    }

    @Override
    public void close() {
        try {
            closed = true;
            parser.close();
        } catch (IOException ex) {
            //NOP
        }
    }
}