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