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Styled XML parser is used by iText modules to parse HTML and XML

There is a newer version: 9.0.0

/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2023 Apryse Group NV
    Authors: Apryse Software.

    This program is offered under a commercial and under the AGPL license.
    For commercial licensing, contact us at https://itextpdf.com/sales.  For AGPL licensing, see below.

    AGPL licensing:
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU Affero General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU Affero General Public License for more details.

    You should have received a copy of the GNU Affero General Public License
    along with this program.  If not, see .
 */
package com.itextpdf.styledxmlparser.util;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Utility class for white-space handling methods that are used both in pdfHTML and the iText-core SVG module
 */
public class WhiteSpaceUtil {

    private static final Set EM_SPACES;

    static {
        // HashSet is required in order to autoport correctly in .Net
        HashSet tempSet = new HashSet<>();
        tempSet.add((char) 0x2002);
        tempSet.add((char) 0x2003);
        tempSet.add((char) 0x2009);
        EM_SPACES = Collections.unmodifiableSet(tempSet);
    }

    /**
     * Collapse all consecutive spaces of the passed String into single spaces
     * @param s String to collapse
     * @return a String containing the contents of the input, with consecutive spaces collapsed
     */
    public static String collapseConsecutiveSpaces(String s) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < s.length(); i++) {
            if (isNonEmSpace(s.charAt(i))) {
                if (sb.length() == 0 || !isNonEmSpace(sb.charAt(sb.length() - 1))) {
                    sb.append(" ");
                }
            } else {
                sb.append(s.charAt(i));
            }
        }
        return sb.toString();
    }

    /**
     * Checks if a character is white space value that is not em, en or similar special whitespace character.
     *
     * @param ch the character
     * @return true, if the character is a white space character, but no em, en or similar
     */
    public static boolean isNonEmSpace(char ch) {
        return Character.isWhitespace(ch) && !EM_SPACES.contains(ch);
    }
}