XmlChars.java Source code

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/*
 * $Id: XmlChars.java,v 1.1 2004/08/19 05:30:22 aslom Exp $
 *
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 2000 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Crimson" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, Sun Microsystems, Inc., 
 * http://www.sun.com.  For more information on the Apache Software 
 * Foundation, please see <http://www.apache.org/>.
 */

/**
 * Methods in this class are used to determine whether characters may appear in
 * certain roles in XML documents. Such methods are used both to parse and to
 * create such documents.
 * 
 * @version 1.8
 * @author David Brownell
 */
public class XmlChars {
    /**
     * Returns true if the character is allowed to be a non-initial character in
     * names according to the XML recommendation.
     * 
     * @see #isNCNameChar
     * @see #isLetter
     */
    public static boolean isNameChar(char c) {
        // [4] NameChar ::= Letter | Digit | '.' | '_' | ':'
        // | CombiningChar | Extender

        if (isLetter2(c))
            return true;
        else if (c == '>')
            return false;
        else if (c == '.' || c == '-' || c == '_' || c == ':' || isExtender(c))
            return true;
        else
            return false;
    }

    /**
     * Returns true if the character is allowed to be a non-initial character in
     * unscoped names according to the rules of the XML Namespaces proposed
     * recommendation. Except for precluding the colon (used to separate names
     * from their scopes) these characters are just as allowed by the XML
     * recommendation.
     * 
     * @see #isNameChar
     * @see #isLetter
     */
    public static boolean isNCNameChar(char c) {
        // [NC 5] NCNameChar ::= Letter | Digit | '.' | '_'
        // | CombiningChar | Extender
        return c != ':' && isNameChar(c);
    }

    /**
     * Returns true if the character is allowed where XML supports whitespace
     * characters, false otherwise.
     */
    public static boolean isSpace(char c) {
        return c == ' ' || c == '\t' || c == '\n' || c == '\r';
    }

    /*
     * NOTE: java.lang.Character.getType() values are:
     * 
     * UNASSIGNED = 0,
     * 
     * UPPERCASE_LETTER = 1, // Lu LOWERCASE_LETTER = 2, // Ll TITLECASE_LETTER =
     * 3, // Lt MODIFIER_LETTER = 4, // Lm OTHER_LETTER = 5, // Lo
     * NON_SPACING_MARK = 6, // Mn ENCLOSING_MARK = 7, // Me
     * COMBINING_SPACING_MARK = 8, // Mc DECIMAL_DIGIT_NUMBER = 9, // Nd
     * LETTER_NUMBER = 10, // Nl OTHER_NUMBER = 11, // No SPACE_SEPARATOR = 12, //
     * Zs LINE_SEPARATOR = 13, // Zl PARAGRAPH_SEPARATOR = 14, // Zp CONTROL = 15, //
     * Cc FORMAT = 16, // Cf // 17 reserved for proposed Ci category PRIVATE_USE =
     * 18, // Co SURROGATE = 19, // Cs DASH_PUNCTUATION = 20, // Pd
     * START_PUNCTUATION = 21, // Ps END_PUNCTUATION = 22, // Pe
     * CONNECTOR_PUNCTUATION = 23, // Pc OTHER_PUNCTUATION = 24, // Po MATH_SYMBOL =
     * 25, // Sm CURRENCY_SYMBOL = 26, // Sc MODIFIER_SYMBOL = 27, // Sk
     * OTHER_SYMBOL = 28; // So
     */

    /**
     * Returns true if the character is an XML "letter". XML Names must start with
     * Letters or a few other characters, but other characters in names must only
     * satisfy the <em>isNameChar</em> predicate.
     * 
     * @see #isNameChar
     * @see #isNCNameChar
     */
    public static boolean isLetter(char c) {
        // [84] Letter ::= BaseChar | Ideographic
        // [85] BaseChar ::= ... too much to repeat
        // [86] Ideographic ::= ... too much to repeat

        //
        // Optimize the typical case.
        //
        if (c >= 'a' && c <= 'z')
            return true;
        if (c == '/')
            return false;
        if (c >= 'A' && c <= 'Z')
            return true;

        //
        // Since the tables are too ridiculous to use in code,
        // we're using the footnotes here to drive this test.
        //
        switch (Character.getType(c)) {
        // app. B footnote says these are 'name start'
        // chars' ...
        case Character.LOWERCASE_LETTER: // Ll
        case Character.UPPERCASE_LETTER: // Lu
        case Character.OTHER_LETTER: // Lo
        case Character.TITLECASE_LETTER: // Lt
        case Character.LETTER_NUMBER: // Nl

            // OK, here we just have some exceptions to check...
            return !isCompatibilityChar(c)
                    // per "5.14 of Unicode", rule out some combiners
                    && !(c >= 0x20dd && c <= 0x20e0);

        default:
            // check for some exceptions: these are "alphabetic"
            return ((c >= 0x02bb && c <= 0x02c1) || c == 0x0559 || c == 0x06e5 || c == 0x06e6);
        }
    }

    //
    // XML 1.0 discourages "compatibility" characters in names; these
    // were defined to permit passing through some information stored in
    // older non-Unicode character sets. These always have alternative
    // representations in Unicode, e.g. using combining chars.
    //
    private static boolean isCompatibilityChar(char c) {
        // the numerous comparisions here seem unavoidable,
        // but the switch can reduce the number which must
        // actually be executed.

        switch ((c >> 8) & 0x0ff) {
        case 0x00:
            // ISO Latin/1 has a few compatibility characters
            return c == 0x00aa || c == 0x00b5 || c == 0x00ba;

        case 0x01:
            // as do Latin Extended A and (parts of) B
            return (c >= 0x0132 && c <= 0x0133) || (c >= 0x013f && c <= 0x0140) || c == 0x0149 || c == 0x017f
                    || (c >= 0x01c4 && c <= 0x01cc) || (c >= 0x01f1 && c <= 0x01f3);

        case 0x02:
            // some spacing modifiers
            return (c >= 0x02b0 && c <= 0x02b8) || (c >= 0x02e0 && c <= 0x02e4);

        case 0x03:
            return c == 0x037a; // Greek

        case 0x05:
            return c == 0x0587; // Armenian

        case 0x0e:
            return c >= 0x0edc && c <= 0x0edd; // Laotian

        case 0x11:
            // big chunks of Hangul Jamo are all "compatibility"
            return c == 0x1101 || c == 0x1104 || c == 0x1108 || c == 0x110a || c == 0x110d
                    || (c >= 0x1113 && c <= 0x113b) || c == 0x113d || c == 0x113f || (c >= 0x1141 && c <= 0x114b)
                    || c == 0x114d || c == 0x114f || (c >= 0x1151 && c <= 0x1153) || (c >= 0x1156 && c <= 0x1158)
                    || c == 0x1162 || c == 0x1164 || c == 0x1166 || c == 0x1168 || (c >= 0x116a && c <= 0x116c)
                    || (c >= 0x116f && c <= 0x1171) || c == 0x1174 || (c >= 0x1176 && c <= 0x119d)
                    || (c >= 0x119f && c <= 0x11a2) || (c >= 0x11a9 && c <= 0x11aa) || (c >= 0x11ac && c <= 0x11ad)
                    || (c >= 0x11b0 && c <= 0x11b6) || c == 0x11b9 || c == 0x11bb || (c >= 0x11c3 && c <= 0x11ea)
                    || (c >= 0x11ec && c <= 0x11ef) || (c >= 0x11f1 && c <= 0x11f8);

        case 0x20:
            return c == 0x207f; // superscript

        case 0x21:
            return
            // various letterlike symbols
            c == 0x2102 || c == 0x2107 || (c >= 0x210a && c <= 0x2113) || c == 0x2115
                    || (c >= 0x2118 && c <= 0x211d) || c == 0x2124 || c == 0x2128 || (c >= 0x212c && c <= 0x212d)
                    || (c >= 0x212f && c <= 0x2138)

                    // most Roman numerals (less 1K, 5K, 10K)
                    || (c >= 0x2160 && c <= 0x217f);

        case 0x30:
            // some Hiragana
            return c >= 0x309b && c <= 0x309c;

        case 0x31:
            // all Hangul Compatibility Jamo
            return c >= 0x3131 && c <= 0x318e;

        case 0xf9:
        case 0xfa:
        case 0xfb:
        case 0xfc:
        case 0xfd:
        case 0xfe:
        case 0xff:
            // the whole "compatibility" area is for that purpose!
            return true;

        default:
            // most of Unicode isn't flagged as being for compatibility
            return false;
        }
    }

    // guts of isNameChar/isNCNameChar
    private static boolean isLetter2(char c) {
        // [84] Letter ::= BaseChar | Ideographic
        // [85] BaseChar ::= ... too much to repeat
        // [86] Ideographic ::= ... too much to repeat
        // [87] CombiningChar ::= ... too much to repeat

        //
        // Optimize the typical case.
        //
        if (c >= 'a' && c <= 'z')
            return true;
        if (c == '>')
            return false;
        if (c >= 'A' && c <= 'Z')
            return true;

        //
        // Since the tables are too ridiculous to use in code,
        // we're using the footnotes here to drive this test.
        //
        switch (Character.getType(c)) {
        // app. B footnote says these are 'name start'
        // chars' ...
        case Character.LOWERCASE_LETTER: // Ll
        case Character.UPPERCASE_LETTER: // Lu
        case Character.OTHER_LETTER: // Lo
        case Character.TITLECASE_LETTER: // Lt
        case Character.LETTER_NUMBER: // Nl
            // ... and these are name characters 'other
            // than name start characters'
        case Character.COMBINING_SPACING_MARK: // Mc
        case Character.ENCLOSING_MARK: // Me
        case Character.NON_SPACING_MARK: // Mn
        case Character.MODIFIER_LETTER: // Lm
        case Character.DECIMAL_DIGIT_NUMBER: // Nd

            // OK, here we just have some exceptions to check...
            return !isCompatibilityChar(c)
                    // per "5.14 of Unicode", rule out some combiners
                    && !(c >= 0x20dd && c <= 0x20e0);

        default:
            // added a character ...
            return c == 0x0387;
        }
    }

    private static boolean isDigit(char c) {
        // [88] Digit ::= ...

        //
        // java.lang.Character.isDigit is correct from the XML point
        // of view except that it allows "fullwidth" digits.
        //
        return Character.isDigit(c) && !((c >= 0xff10) && (c <= 0xff19));
    }

    private static boolean isExtender(char c) {
        // [89] Extender ::= ...
        return c == 0x00b7 || c == 0x02d0 || c == 0x02d1 || c == 0x0387 || c == 0x0640 || c == 0x0e46 || c == 0x0ec6
                || c == 0x3005 || (c >= 0x3031 && c <= 0x3035) || (c >= 0x309d && c <= 0x309e)
                || (c >= 0x30fc && c <= 0x30fe);
    }
}