~ubuntu-branches/ubuntu/precise/xom/precise

/* Copyright 2002-2005 Elliotte Rusty Harold
   
   This library is free software; you can redistribute it and/or modify
   it under the terms of version 2.1 of the GNU Lesser General Public 
   License as published by the Free Software Foundation.
   
   This library 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 Lesser General Public License for more details.
   
   You should have received a copy of the GNU Lesser General Public
   License along with this library; if not, write to the 
   Free Software Foundation, Inc., 59 Temple Place, Suite 330, 
   Boston, MA 02111-1307  USA
   
   You can contact Elliotte Rusty Harold by sending e-mail to
   elharo@metalab.unc.edu. Please include the word "XOM" in the
   subject line. The XOM home page is located at http://www.xom.nu/
*/

package nu.xom;

/**
 * <p>
 * This class represents an attribute such as 
 * <code>type="empty"</code> or 
 * <code>xlink:href="http://www.example.com"</code>.
 * </p>
 * 
 * <p>
 * Attributes that declare namespaces such as
 * <code>xmlns="http://www.w3.org/TR/1999/xhtml"</code>
 * or <code>xmlns:xlink="http://www.w3.org/TR/1999/xlink"</code>
 * are stored separately on the elements where they
 * appear. They are never represented as <code>Attribute</code>
 * objects.
 * </p>
 * 
 * @author Elliotte Rusty Harold
 * @version 1.1b5
 * 
 */
public class Attribute extends Node {
    
    private String localName;
    private String prefix;
    private String URI;
    private String value = "";
    private Type   type;

    
    /**
     * <p>
     * Creates a new attribute in no namespace with the
     * specified name and value and undeclared type.
     * </p>
     * 
     * @param localName the unprefixed attribute name
     * @param value the attribute value
     * 
     * @throws IllegalNameException if the local name is not 
     *     a namespace well-formed, non-colonized name
     * @throws IllegalDataException if the value contains characters  
     *     which are not legal in XML such as vertical tab or a null.
     *     Characters such as " and &amp; are legal, but will be  
     *     automatically escaped when the attribute is serialized.
     */
    public Attribute(String localName, String value) {
        this(localName, "", value, Type.UNDECLARED);
    }

    
    /**
     * <p>
     * Creates a new attribute in no namespace with the
     * specified name, value, and type.
     * </p>
     * 
     * @param localName the unprefixed attribute name
     * @param value the attribute value
     * @param type the attribute type
     * 
     * @throws IllegalNameException if the local name is 
     *     not a namespace well-formed non-colonized name
     * @throws IllegalDataException if the value contains 
     *     characters which are not legal in
     *     XML such as vertical tab or a null. Note that 
     *     characters such as " and &amp; are legal,
     *     but will be automatically escaped when the 
     *     attribute is serialized.
     */
    public Attribute(String localName, String value, Type type) {
        this(localName, "", value, type);
    }

    
    /**
     * <p>
     * Creates a new attribute in the specified namespace with the
     * specified name and value and undeclared type.
     * </p>
     * 
     * @param name the prefixed attribute name
     * @param URI the namespace URI
     * @param value the attribute value
     * 
     * @throws IllegalNameException  if the name is not a namespace 
     *     well-formed name
     * @throws IllegalDataException if the value contains characters 
     *     which are not legal in XML such as vertical tab or a null. 
     *     Note that characters such as " and &amp; are legal, but will
     *     be automatically escaped when the attribute is serialized.
     * @throws MalformedURIException if <code>URI</code> is not 
     *     an RFC 3986 URI reference
     * @throws NamespaceConflictException if there's no prefix,
     *     but the URI is not the empty string, or the prefix is 
     *     <code>xml</code> and the URI is not 
     *     http://www.w3.org/XML/1998/namespace
     */
    public Attribute(String name, String URI, String value) {
        this(name, URI, value, Type.UNDECLARED);
    }

    
    /**
     * <p>
     * Creates a new attribute in the specified namespace with the
     * specified name, value, and type.
     * </p>
     * 
     * @param name  the prefixed attribute name
     * @param URI the namespace URI
     * @param value the attribute value
     * @param type the attribute type
     * 
     * @throws IllegalNameException if the name is not a namespace 
     *     well-formed prefixed name
     * @throws IllegalDataException if the value contains 
     *     characters which are not legal in XML such as 
     *     vertical tab or a null. Note that characters such as 
     *     " and &amp; are legal, but will be automatically escaped 
     *     when the attribute is serialized.
     * @throws MalformedURIException if <code>URI</code> is not 
     *     an RFC 3986 absolute URI reference
     */
    public Attribute(
      String name, String URI, String value, Type type) {

        prefix = "";
        String localName = name;
        // ???? Warning: do not cache the value returned by indexOf here
        // and in build
        // without profiling. My current tests show doing this slows 
        // down the parse by about 7%. I can't explain it.
        if (name.indexOf(':') > 0) {
            prefix = name.substring(0, name.indexOf(':'));   
            localName = name.substring(name.indexOf(':') + 1);
        }

        try {
            _setLocalName(localName);
        }
        catch (IllegalNameException ex) {
            ex.setData(name);
            throw ex;
        }
        _setNamespace(prefix, URI);
        _setValue(value);
        if ("xml".equals(this.prefix) && "id".equals(this.localName)) {
            _setType(Attribute.Type.ID);
        }   
        else {
            _setType(type);
        }
        
    }

    
    /**
     * <p>
     * Creates a copy of the specified attribute.
     * </p>
     * 
     * @param attribute the attribute to copy
     * 
     */
    public Attribute(Attribute attribute) {
        
        // These are all immutable types
        this.localName = attribute.localName;
        this.prefix    = attribute.prefix;
        this.URI       = attribute.URI;
        this.value     = attribute.value;
        this.type      = attribute.type;
        
    }

    
    private Attribute() {}
    
    static Attribute build(
      String qualifiedName, String URI, String value, Type type, String localName) {
        
        Attribute result = new Attribute();
    
        String prefix = "";
        if (qualifiedName.indexOf(':') >= 0) {
            prefix = qualifiedName.substring(0, qualifiedName.indexOf(':'));
            if ("xml:id".equals(qualifiedName)) {
                type = Attribute.Type.ID;
                value = normalize(value);
                // ???? should I only do this if validating?
                // Verifier.checkNCName(value);
            }
        }        
        
        result.localName = localName;
        result.prefix = prefix;
        result.type = type;
        result.URI = URI;
        result.value = value;
        
        return result;
        
    }


    private static String normalize(String s) {

        int length = s.length();
        int pos = 0;
        while (pos < length && s.charAt(pos) == ' ') pos++;
        s = s.substring(pos);
        int end = s.length()-1;
        while (end > 0 && s.charAt(end) == ' ') end--;
        s = s.substring(0, end+1);
        
        length = s.length();
        StringBuffer sb = new StringBuffer(length);
        boolean wasSpace = false;
        for (int i = 0; i < length; i++) {
            char c = s.charAt(i);
            if (c == ' ') {
                if (wasSpace) continue;
                sb.append(' ');
                wasSpace = true;
            }
            else {
                sb.append(c);
                wasSpace = false;
            }
        }
        return sb.toString();
        
    }


    /**
     * <p>
     * Returns the DTD type of this attribute. 
     * If this attribute does not have a type, then
     * <code>Type.UNDECLARED</code> is returned.
     * </p>
     * 
     * @return the DTD type of this attribute
     */
    public final Type getType() {
        return type;
    }

    
    /**
     * <p>
     * Sets the type of this attribute to one of the ten
     * DTD types or <code>Type.UNDECLARED</code>. 
     * </p>
     * 
     * @param type the DTD type of this attribute
     */
    public void setType(Type type) {
        
        if (isXMLID() && ! Type.ID.equals(type)) {
            throw new IllegalDataException(
              "Can't change type of xml:id attribute to " + type);
        }
        _setType(type);
        
    }
    
    
    private boolean isXMLID() {
        return "xml".equals(this.prefix) && "id".equals(this.localName);
    }

    
    private void _setType(Type type) {
        this.type = type;
    }


    /**
     * <p>
     * Returns the attribute value. If the attribute was
     * originally created by a parser, it will have been
     * normalized according to its type.
     * However, attributes created in memory are not normalized.
     * </p>
     * 
     * @return the value of the attribute
     * 
     */
    public final String getValue() {
        return value;
    }

    
    /**
     * <p>
     * Sets the attribute's value to the specified string,
     * replacing any previous value. The value is not normalized
     * automatically.
     * </p>
     * 
     * @param value the value assigned to the attribute
     * @throws IllegalDataException if the value contains characters 
     *     which are not legal in XML such as vertical tab or a null. 
     *     Characters such as " and &amp; are legal, but will be 
     *     automatically escaped when the attribute is serialized.
     * @throws MalformedURIException if this is an 
     *     <code>xml:base</code> attribute, and the value is not a
     *     legal IRI
     */
    public void setValue(String value) {
        _setValue(value);
    }

    
    private void _setValue(String value) {
        
        if ("xml".equals(this.prefix) && "id".equals(this.localName)) {
            // ???? do I really want to do this. XML ID test case
            // suggests not
            Verifier.checkNCName(value);
        }
        else {
            Verifier.checkPCDATA(value);
        }
        this.value = value;
        
    }


    /**
     * <p>
     * Returns the local name of this attribute,
     * not including the prefix.
     * </p>
     * 
     * @return the attribute's local name
     */
    public final String getLocalName() {
        return localName;
    }

    
    /**
     * <p>
     * Sets the local name of the attribute.
     * </p>
     * 
     * @param localName the new local name
     * 
     * @throws IllegalNameException if <code>localName</code>
     *      is not a namespace well-formed, non-colonized name
     * 
     */
    public void setLocalName(String localName) {
        
        if ("id".equals(localName) &&
          "http://www.w3.org/XML/1998/namespace".equals(this.URI)) {
            Verifier.checkNCName(this.value);
        }
        _setLocalName(localName);
        if (isXMLID()) {
            this.setType(Attribute.Type.ID);
        }
        
    }   
    
    
    private void _setLocalName(String localName) {
        Verifier.checkNCName(localName);
        if (localName.equals("xmlns")) {
            throw new IllegalNameException("The Attribute class is not"
              + " used for namespace declaration attributes.");
        }
        this.localName = localName;
    }


    /**
     * <p>
     * Returns the qualified name of this attribute,
     * including the prefix if this attribute is in a namespace.
     * </p>
     * 
     * @return the attribute's qualified name
     */
    public final String getQualifiedName() {
        if (prefix.length() == 0) return localName;
        else return prefix + ":" + localName;
    }
    
    
    /**
     * <p>
     * Returns the namespace URI of this attribute, or the empty string
     * if this attribute is not in a namespace.
     * </p>
     * 
     * @return the attribute's namespace URI
     */ 
    public final String getNamespaceURI() {
        return URI;
    }

    
    /**
     * <p>
     * Returns the prefix of this attribute,
     * or the empty string if this attribute 
     * is not in a namespace.
     * </p>
     * 
     * @return the attribute's prefix
     */
    public final String getNamespacePrefix() {
        return prefix;
    }

    
    /**
     * <p>
     * Sets the attribute's namespace prefix and URI.
     * Because attributes must be prefixed in order to have a  
     * namespace URI (and vice versa) this must be done 
     * simultaneously.
     * </p>
     * 
     * @param prefix the new namespace prefix
     * @param URI the new namespace URI
     * 
     * @throws MalformedURIException if <code>URI</code> is 
     *     not an RFC 3986 URI reference
     * @throws IllegalNameException if
     *  <ul>
     *      <li>The prefix is <code>xmlns</code>.</li>
     *      <li>The prefix is null or the empty string.</li>
     *      <li>The URI is null or the empty string.</li>
     * </ul>
     * @throws NamespaceConflictException if
     *  <ul>
     *      <li>The prefix is <code>xml</code> and the namespace URI is
     *          not <code>http://www.w3.org/XML/1998/namespace</code>.</li>
     *      <li>The prefix conflicts with an existing declaration
     *          on the attribute's parent element.</li>
     * </ul>
     */
    public void setNamespace(String prefix, String URI) {
        
        if ("xml".equals(prefix) && "id".equals(this.localName)) {
            Verifier.checkNCName(this.value);
            this.setType(Attribute.Type.ID);
        }
        
        _setNamespace(prefix, URI);
        
    }

    
    private void _setNamespace(String prefix, String URI) {
        
        if (URI == null) URI = "";
        if (prefix == null) prefix = "";
        
        // ???? use == to compare?
        if (prefix.equals("xmlns")) {
            throw new IllegalNameException(
              "Attribute objects are not used to represent "
              + " namespace declarations"); 
        }
        else if (prefix.equals("xml") 
          && !(URI.equals("http://www.w3.org/XML/1998/namespace"))) {
            throw new NamespaceConflictException(
              "Wrong namespace URI for xml prefix: " + URI); 
        }
        else if (URI.equals("http://www.w3.org/XML/1998/namespace")
          && !prefix.equals("xml")) {
            throw new NamespaceConflictException(
              "Wrong prefix for the XML namespace: " + prefix); 
        }
        else if (prefix.length() == 0) {
            if (URI.length() == 0) {
                this.prefix = "";
                this.URI = "";
                return; 
            }
            else {
                throw new NamespaceConflictException(
                  "Unprefixed attribute " + this.localName 
                  + " cannot be in default namespace " + URI);
            }
        }
        else if (URI.length() == 0) {
            throw new NamespaceConflictException(
             "Attribute prefixes must be declared.");
        }
        
        ParentNode parent = this.getParent();
        if (parent != null) {
           // test for namespace conflicts 
           Element element = (Element) parent;
           String  currentURI = element.getLocalNamespaceURI(prefix);
           if (currentURI != null && !currentURI.equals(URI)) {
                throw new NamespaceConflictException(
                  "New prefix " + prefix 
                  + "conflicts with existing namespace declaration"
                );
           } 
        }
        
        
        Verifier.checkAbsoluteURIReference(URI);
        Verifier.checkNCName(prefix);
        
        this.URI = URI;
        this.prefix = prefix;
        
    }
    
    
    /**
     * <p>
     *  Throws <code>IndexOutOfBoundsException</code>
     *  because attributes do not have children.
     * </p>
     *
     * @param position the child to return
     *
     * @return nothing. This method always throws an exception.
     *
     * @throws IndexOutOfBoundsException because attributes do 
     *     not have children
     */
    public final Node getChild(int position) {
        throw new IndexOutOfBoundsException(
          "Attributes do not have children"
        );        
    }

    
    /**
     * <p>
     * Returns 0 because attributes do not have children.
     * </p>
     * 
     * @return zero
     */
    public final int getChildCount() {
        return 0;   
    }

    
    /**
     * <p>
     * Creates a deep copy of this attribute that   
     * is not attached to an element.
     * </p>
     * 
     * @return a copy of this attribute
     * 
     */ 
    public Node copy() {
        return new Attribute(this);
    }

    
    /**
     * <p>
     * Returns a string representation of the attribute 
     * that is a well-formed XML attribute. 
     * </p>
     * 
     * @return a string containing the XML form of this attribute
     */
    public final String toXML() {
        // It's a common belief that methods like this one should be
        // implemented using StringBuffers rather than String 
        // concatenation for maximum performance. However, 
        // disassembling the code shows that today's compilers are 
        // smart enough to figure this out for themselves. The compiled
        // version of this class only uses a single StringBuffer. No 
        // benefit would be gained by making the code more opaque here. 
        return getQualifiedName() + "=\"" + escapeText(value) + "\"";    
    }

    
    /**
     * <p>
     * Returns a string representation of the attribute suitable for 
     * debugging and diagnosis. However, this is not necessarily 
     * a well-formed XML attribute.
     * </p>
     * 
     *  @return a non-XML string representation of this attribute
     *
     * @see java.lang.Object#toString()
     */
    public final String toString() {
        return "[" + getClass().getName() + ": " 
         + getQualifiedName() + "=\"" 
         + Text.escapeLineBreaksAndTruncate(getValue()) + "\"]";
    }

    
    private static String escapeText(String s) {
        
        int length = s.length();
        // Give the string buffer enough room for a couple of escaped characters 
        StringBuffer result = new StringBuffer(length+12);
        for (int i = 0; i < length; i++) {
            char c = s.charAt(i);
            switch (c) {
                case '\t':
                    result.append("&#x09;");
                    break;
                case '\n':
                    result.append("&#x0A;");
                    break;
                case 11:
                    // impossible
                    break;
                case 12:
                    // impossible
                    break;
                case '\r':
                    result.append("&#x0D;");
                    break;
                case 14:
                    // impossible
                    break;
                case 15:
                    // impossible
                    break;
                case 16:
                    // impossible
                    break;
                case 17:
                    // impossible
                    break;
                case 18:
                    // impossible
                    break;
                case 19:
                    // impossible
                    break;
                case 20:
                    // impossible
                    break;
                case 21:
                    // impossible
                    break;
                case 22:
                    // impossible
                    break;
                case 23:
                    // impossible
                    break;
                case 24:
                    // impossible
                    break;
                case 25:
                    // impossible
                    break;
                case 26:
                    // impossible
                    break;
                case 27:
                    // impossible
                    break;
                case 28:
                    // impossible
                    break;
                case 29:
                    // impossible
                    break;
                case 30:
                    // impossible
                    break;
                case 31:
                    // impossible
                    break;
                case ' ':
                    result.append(' ');
                    break;
                case '!':
                    result.append('!');
                    break;
                case '"':
                    result.append("&quot;");
                    break;
                case '#':
                    result.append('#');
                    break;
                case '$':
                    result.append('$');
                    break;
                case '%':
                    result.append('%');
                    break;
                case '&':
                    result.append("&amp;");
                    break;
                case '\'':
                    result.append('\'');
                    break;
                case '(':
                    result.append('(');
                    break;
                case ')':
                    result.append(')');
                    break;
                case '*':
                    result.append('*');
                    break;
                case '+':
                    result.append('+');
                    break;
                case ',':
                    result.append(',');
                    break;
                case '-':
                    result.append('-');
                    break;
                case '.':
                    result.append('.');
                    break;
                case '/':
                    result.append('/');
                    break;
                case '0':
                    result.append('0');
                    break;
                case '1':
                    result.append('1');
                    break;
                case '2':
                    result.append('2');
                    break;
                case '3':
                    result.append('3');
                    break;
                case '4':
                    result.append('4');
                    break;
                case '5':
                    result.append('5');
                    break;
                case '6':
                    result.append('6');
                    break;
                case '7':
                    result.append('7');
                    break;
                case '8':
                    result.append('8');
                    break;
                case '9':
                    result.append('9');
                    break;
                case ':':
                    result.append(':');
                    break;
                case ';':
                    result.append(';');
                    break;
                case '<':
                    result.append("&lt;");
                    break;
                case '=':
                    result.append('=');
                    break;
                case '>':
                    result.append("&gt;");
                    break;
                default: 
                    result.append(c);
            }
        }
        return result.toString();
        
    }

    
    boolean isAttribute() {
        return true;   
    } 
    
    
    /**
     * <p>
     * Uses the type-safe enumeration 
     * design pattern to represent attribute types,
     * as specified by XML DTDs. 
     * </p>
     * 
     * <p>
     *   XOM enforces well-formedness, but it does not enforce 
     *   validity. Thus it is possible for a single element to have 
     *   multiple ID type attributes, or ID type attributes 
     *   on different elements to have the same value, 
     *   or NMTOKEN type attributes that don't contain legal 
     *   XML name tokens, and so forth.
     * </p>
     * 
     * @author Elliotte Rusty Harold
     * @version 1.0
     *
     */
    public static final class Type {

        /**
         * <p>
         *   The type of attributes declared to have type CDATA
         *   in the DTD. The most general attribute type.
         *   All well-formed attribute values are valid for 
         *   attributes of type CDATA.
         * </p>
         */
        public static final Type CDATA = new Type(1);

        /**
         * <p>
         *   The type of attributes declared to have type ID
         *   in the DTD. In order to be valid, an ID type attribute
         *   must contain an XML name which is unique among other 
         *   ID type attributes in the document.
         *   Furthermore, each element may contain no more than one
         *   ID type attribute. However, XOM does not enforce
         *   such validity constraints.
         * </p>
         */
        public static final Type ID = new Type(2);
        
        /**
         * <p>
         *   The type of attributes declared to have type IDREF
         *   in the DTD. In order to be valid, an IDREF type attribute
         *   must contain an XML name which is also the value of  
         *   ID type attribute of some element in the document. 
         *   However, XOM does not enforce such validity constraints.
         * </p>
         *
         */
        public static final Type IDREF = new Type(3);

        /**
         * <p>
         *   The type of attributes declared to have type IDREFS
         *   in the DTD. In order to be valid, an IDREFS type attribute
         *   must contain a white space separated list of
         *   XML names, each of which is also the value of  
         *   ID type attribute of some element in the document. 
         *   However, XOM does not enforce such validity constraints.
         * </p>
         *
         */
        public static final Type IDREFS = new Type(4);

        /**
         * <p>
         *   The type of attributes declared to have type NMTOKEN
         *   in the DTD. In order to be valid, a NMTOKEN type 
         *   attribute must contain a single XML name token. However, 
         *   XOM does not enforce such validity constraints.
         * </p>
         *
         */
        public static final Type NMTOKEN = new Type(5);

        /**
         * <p>
         *   The type of attributes declared to have type NMTOKENS
         *   in the DTD. In order to be valid, a NMTOKENS type attribute
         *   must contain a white space separated list of XML name  
         *   tokens. However, XOM does not enforce such validity 
         *   constraints.
         * </p>
         *
         */
        public static final Type NMTOKENS = new Type(6);


        /**
         * <p>
         *   The type of attributes declared to have type NOTATION
         *   in the DTD. In order to be valid, a NOTATION type 
         *   attribute must contain the name of a notation declared  
         *   in the DTD. However, XOM does not enforce such 
         *   validity constraints.
         * </p>
          *
         */
        public static final Type NOTATION = new Type(7);

        /**
         * <p>
         *   The type of attributes declared to have type ENTITY
         *   in the DTD. In order to be valid, a  ENTITY type attribute
         *   must contain the name of an unparsed entity declared in  
         *   the DTD. However, XOM does not enforce such 
         *   validity constraints.
         * </p>
         *
         */
        public static final Type ENTITY = new Type(8);

        /**
         * <p>
         *   The type of attributes declared to have type ENTITIES
         *   in the DTD. In order to be valid, an ENTITIES type 
         *   attribute must contain a white space separated list of 
         *   names of unparsed entities declared in the DTD.  
         *   However, XOM does not enforce such validity constraints.
         * </p>
         *
         */
        public static final Type ENTITIES = new Type(9);

        /**
         * <p>
         *   The type of attributes declared by an enumeration
         *   in the DTD. In order to be valid, a enumeration type 
         *   attribute must contain exactly one of the names given  
         *   in the enumeration in the DTD. However, XOM does not 
         *   enforce such validity constraints.
         * </p>
         * 
         * <p>
         *   Most parsers report attributes of type enumeration as 
         *   having type NMTOKEN. In this case, XOM will not  
         *   distinguish NMTOKEN and enumerated attributes.
         * </p>
         *
         */
        public static final Type ENUMERATION = new Type(10);
        
        /**
         * <p>
         *   The type of attributes not declared in the DTD.
         *   This type only appears in invalid documents.
         *   This is the default type for all attributes in
         *   documents without DTDs.
         * </p>
         * 
         * <p>
         *   Most parsers report attributes of undeclared 
         *   type as having type CDATA. In this case, XOM 
         *   will not distinguish CDATA and undeclared attributes.
         * </p>
         */
        public static final Type UNDECLARED = new Type(0);

        
        /**
         * <p>
         * Returns the string name of this type as might 
         * be used in a DTD; for example, "ID", "CDATA", etc. 
         * </p>
         * 
         *  @return an XML string representation of this type
         */
        public String getName() {  
            
            switch (type) {
              case 0:
                return "UNDECLARED";   
              case 1:
                return "CDATA";  
              case 2:
                return "ID";  
              case 3:
                return "IDREF";   
              case 4:
                return "IDREFS";   
              case 5:
                return "NMTOKEN";  
              case 6:
                return "NMTOKENS";   
              case 7:
                return "NOTATION";   
              case 8:
                return "ENTITY";   
              case 9:
                return "ENTITIES";  
              case 10:
                return "ENUMERATION"; 
              default: 
                throw new RuntimeException(
                  "Bug in XOM: unexpected attribute type: " + type); 
            }
            
        }   


        private final int type;

        private Type(int type) {
          this.type = type;
        }
        
        
        /**
         * <p>
         * Returns a unique identifier for this type.
         * </p>
         * 
         * @return a unique identifier for this type
         * 
         * @see java.lang.Object#hashCode()
         */
        public int hashCode() {
            return this.type;   
        }
        
        
        /**
         * <p>
         * Tests for type equality. This is only necessary,
         * to handle the case where two <code>Type</code> objects
         * are loaded by different class loaders. 
         * </p>
         * 
         * @param o the object compared for equality to this type
         * 
         * @return true if and only if <code>o</code> represents 
         *      the same type
         * 
         * @see java.lang.Object#equals(Object)
         */
        public boolean equals(Object o) {
            
            if (o == this) return true; 
            if (o == null) return false;      
            if (this.hashCode() != o.hashCode()) return false;           
            if (!o.getClass().getName().equals("nu.xom.Attribute.Type")) {
                return false;
            }
            return true;   
            
        }          
        
        
        /**
         * <p>
         * Returns a string representation of the type  
         * suitable for debugging and diagnosis. 
         * </p>
         * 
         * @return a non-XML string representation of this type
         *
         * @see java.lang.Object#toString()
         */
         public String toString() {    
             
            StringBuffer result 
              = new StringBuffer("[Attribute.Type: ");
            result.append(getName()); 
            result.append("]");
            return result.toString();    
            
        }         

         
    }

    
}