    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 *      http://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
    022/**
    023 * Translates codepoints to their Unicode escaped value.
    024 *
    025 * @since 1.0
    026 */
    027public class UnicodeEscaper extends CodePointTranslator {
    028
    029    /** int value representing the lowest codepoint boundary. */
    030    private final int below;
    031    /** int value representing the highest codepoint boundary. */
    032    private final int above;
    033    /** whether to escape between the boundaries or outside them. */
    034    private final boolean between;
    035
    036    /**
    037     * <p>Constructs a <code>UnicodeEscaper</code> for all characters.
    038     * </p>
    039     */
    040    public UnicodeEscaper() {
    041        this(0, Integer.MAX_VALUE, true);
    042    }
    043
    044    /**
    045     * <p>Constructs a <code>UnicodeEscaper</code> for the specified range. This is
    046     * the underlying method for the other constructors/builders. The <code>below</code>
    047     * and <code>above</code> boundaries are inclusive when <code>between</code> is
    048     * <code>true</code> and exclusive when it is <code>false</code>. </p>
    049     *
    050     * @param below int value representing the lowest codepoint boundary
    051     * @param above int value representing the highest codepoint boundary
    052     * @param between whether to escape between the boundaries or outside them
    053     */
    054    protected UnicodeEscaper(final int below, final int above, final boolean between) {
    055        this.below = below;
    056        this.above = above;
    057        this.between = between;
    058    }
    059
    060    /**
    061     * <p>Constructs a <code>UnicodeEscaper</code> below the specified value (exclusive). </p>
    062     *
    063     * @param codepoint below which to escape
    064     * @return the newly created {@code UnicodeEscaper} instance
    065     */
    066    public static UnicodeEscaper below(final int codepoint) {
    067        return outsideOf(codepoint, Integer.MAX_VALUE);
    068    }
    069
    070    /**
    071     * <p>Constructs a <code>UnicodeEscaper</code> above the specified value (exclusive). </p>
    072     *
    073     * @param codepoint above which to escape
    074     * @return the newly created {@code UnicodeEscaper} instance
    075     */
    076    public static UnicodeEscaper above(final int codepoint) {
    077        return outsideOf(0, codepoint);
    078    }
    079
    080    /**
    081     * <p>Constructs a <code>UnicodeEscaper</code> outside of the specified values (exclusive). </p>
    082     *
    083     * @param codepointLow below which to escape
    084     * @param codepointHigh above which to escape
    085     * @return the newly created {@code UnicodeEscaper} instance
    086     */
    087    public static UnicodeEscaper outsideOf(final int codepointLow, final int codepointHigh) {
    088        return new UnicodeEscaper(codepointLow, codepointHigh, false);
    089    }
    090
    091    /**
    092     * <p>Constructs a <code>UnicodeEscaper</code> between the specified values (inclusive). </p>
    093     *
    094     * @param codepointLow above which to escape
    095     * @param codepointHigh below which to escape
    096     * @return the newly created {@code UnicodeEscaper} instance
    097     */
    098    public static UnicodeEscaper between(final int codepointLow, final int codepointHigh) {
    099        return new UnicodeEscaper(codepointLow, codepointHigh, true);
    100    }
    101
    102    /**
    103     * {@inheritDoc}
    104     */
    105    @Override
    106    public boolean translate(final int codepoint, final Writer out) throws IOException {
    107        if (between) {
    108            if (codepoint < below || codepoint > above) {
    109                return false;
    110            }
    111        } else {
    112            if (codepoint >= below && codepoint <= above) {
    113                return false;
    114            }
    115        }
    116
    117        if (codepoint > 0xffff) {
    118            out.write(toUtf16Escape(codepoint));
    119        } else {
    120          out.write("\\u");
    121          out.write(HEX_DIGITS[(codepoint >> 12) & 15]);
    122          out.write(HEX_DIGITS[(codepoint >> 8) & 15]);
    123          out.write(HEX_DIGITS[(codepoint >> 4) & 15]);
    124          out.write(HEX_DIGITS[(codepoint) & 15]);
    125        }
    126        return true;
    127    }
    128
    129    /**
    130     * Converts the given codepoint to a hex string of the form {@code "\\uXXXX"}.
    131     *
    132     * @param codepoint
    133     *            a Unicode code point
    134     * @return the hex string for the given codepoint
    135     *
    136     */
    137    protected String toUtf16Escape(final int codepoint) {
    138        return "\\u" + hex(codepoint);
    139    }
    140}