    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      https://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017package org.apache.commons.text.translate;
    018
    019import java.io.IOException;
    020import java.io.Writer;
    021
    022import org.apache.commons.lang3.CharUtils;
    023import org.apache.commons.lang3.StringUtils;
    024import org.apache.commons.lang3.Strings;
    025
    026/**
    027 * Holds inner classes for escaping/unescaping Comma Separated Values.
    028 * <p>
    029 * In general the use a high level API like <a href="https://commons.apache.org/proper/commons-csv/">Apache Commons
    030 * CSV</a> should be preferred over these low level classes.
    031 * </p>
    032 *
    033 * @see <a href="https://commons.apache.org/proper/commons-csv/apidocs/index.html">Apache Commons CSV</a>
    034 */
    035public final class CsvTranslators {
    036
    037    /**
    038     * Translator for escaping Comma Separated Values.
    039     */
    040    public static class CsvEscaper extends SinglePassTranslator {
    041
    042        /**
    043         * Construct a new instance.
    044         */
    045        public CsvEscaper() {
    046            // empty
    047        }
    048
    049        @Override
    050        void translateWhole(final CharSequence input, final Writer writer) throws IOException {
    051            final String inputString = input.toString();
    052            if (StringUtils.containsNone(inputString, CSV_SEARCH_CHARS)) {
    053                writer.write(inputString);
    054            } else {
    055                // input needs quoting
    056                writer.write(CSV_QUOTE);
    057                writer.write(Strings.CS.replace(inputString, CSV_QUOTE_STR, CSV_ESCAPED_QUOTE_STR));
    058                writer.write(CSV_QUOTE);
    059            }
    060        }
    061    }
    062    /**
    063     * Translator for unescaping escaped Comma Separated Value entries.
    064     */
    065    public static class CsvUnescaper extends SinglePassTranslator {
    066
    067        /**
    068         * Construct a new instance.
    069         */
    070        public CsvUnescaper() {
    071            // empty
    072        }
    073
    074        @Override
    075        void translateWhole(final CharSequence input, final Writer writer) throws IOException {
    076            // is input not quoted?
    077            if (input.charAt(0) != CSV_QUOTE || input.charAt(input.length() - 1) != CSV_QUOTE) {
    078                writer.write(input.toString());
    079                return;
    080            }
    081
    082            // strip quotes
    083            final String quoteless = input.subSequence(1, input.length() - 1).toString();
    084
    085            if (StringUtils.containsAny(quoteless, CSV_SEARCH_CHARS)) {
    086                // deal with escaped quotes; ie) ""
    087                writer.write(Strings.CS.replace(quoteless, CSV_ESCAPED_QUOTE_STR, CSV_QUOTE_STR));
    088            } else {
    089                writer.write(quoteless);
    090            }
    091        }
    092    }
    093    /** Comma character. */
    094    private static final char CSV_DELIMITER = ',';
    095    /** Quote character. */
    096    private static final char CSV_QUOTE = '"';
    097    /** Quote character converted to string. */
    098    private static final String CSV_QUOTE_STR = String.valueOf(CSV_QUOTE);
    099
    100    /** Escaped quote string. */
    101    private static final String CSV_ESCAPED_QUOTE_STR = CSV_QUOTE_STR + CSV_QUOTE_STR;
    102
    103    /** CSV key characters in an array. */
    104    private static final char[] CSV_SEARCH_CHARS = { CSV_DELIMITER, CSV_QUOTE, CharUtils.CR, CharUtils.LF };
    105
    106    /** Hidden constructor. */
    107    private CsvTranslators() {
    108        // empty
    109    }
    110}