    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;
    024
    025/**
    026 * This class holds inner classes for escaping/unescaping Comma Separated Values.
    027 * <p>
    028 * In general the use a high level API like <a href="https://commons.apache.org/proper/commons-csv/">Apache Commons
    029 * CSV</a> should be preferred over these low level classes.
    030 * </p>
    031 *
    032 * @see <a href="https://commons.apache.org/proper/commons-csv/apidocs/index.html">Apache Commons CSV</a>
    033 */
    034public final class CsvTranslators {
    035
    036    /**
    037     * Translator for escaping Comma Separated Values.
    038     */
    039    public static class CsvEscaper extends SinglePassTranslator {
    040
    041        /**
    042         * Construct a new instance.
    043         */
    044        public CsvEscaper() {
    045            // empty
    046        }
    047
    048        @Override
    049        void translateWhole(final CharSequence input, final Writer writer) throws IOException {
    050            final String inputSting = input.toString();
    051            if (StringUtils.containsNone(inputSting, CSV_SEARCH_CHARS)) {
    052                writer.write(inputSting);
    053            } else {
    054                // input needs quoting
    055                writer.write(CSV_QUOTE);
    056                writer.write(StringUtils.replace(inputSting, CSV_QUOTE_STR, CSV_ESCAPED_QUOTE_STR));
    057                writer.write(CSV_QUOTE);
    058            }
    059        }
    060    }
    061    /**
    062     * Translator for unescaping escaped Comma Separated Value entries.
    063     */
    064    public static class CsvUnescaper extends SinglePassTranslator {
    065
    066        /**
    067         * Construct a new instance.
    068         */
    069        public CsvUnescaper() {
    070            // empty
    071        }
    072
    073        @Override
    074        void translateWhole(final CharSequence input, final Writer writer) throws IOException {
    075            // is input not quoted?
    076            if (input.charAt(0) != CSV_QUOTE || input.charAt(input.length() - 1) != CSV_QUOTE) {
    077                writer.write(input.toString());
    078                return;
    079            }
    080
    081            // strip quotes
    082            final String quoteless = input.subSequence(1, input.length() - 1).toString();
    083
    084            if (StringUtils.containsAny(quoteless, CSV_SEARCH_CHARS)) {
    085                // deal with escaped quotes; ie) ""
    086                writer.write(StringUtils.replace(quoteless, CSV_ESCAPED_QUOTE_STR, CSV_QUOTE_STR));
    087            } else {
    088                writer.write(quoteless);
    089            }
    090        }
    091    }
    092    /** Comma character. */
    093    private static final char CSV_DELIMITER = ',';
    094    /** Quote character. */
    095    private static final char CSV_QUOTE = '"';
    096    /** Quote character converted to string. */
    097    private static final String CSV_QUOTE_STR = String.valueOf(CSV_QUOTE);
    098
    099    /** Escaped quote string. */
    100    private static final String CSV_ESCAPED_QUOTE_STR = CSV_QUOTE_STR + CSV_QUOTE_STR;
    101
    102    /** CSV key characters in an array. */
    103    private static final char[] CSV_SEARCH_CHARS = { CSV_DELIMITER, CSV_QUOTE, CharUtils.CR, CharUtils.LF };
    104
    105    /** Hidden constructor. */
    106    private CsvTranslators() {
    107        // empty
    108    }
    109}