jaxp/src/java.xml/share/classes/com/sun/org/apache/xerces/internal/dom/CharacterDataImpl.java - platform/libcore - Git at Google

 /*
  * reserved comment block
  * DO NOT REMOVE OR ALTER!
  */
 /*
  * Copyright 1999-2002,2004 The Apache Software Foundation.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package com.sun.org.apache.xerces.internal.dom;

 import org.w3c.dom.DOMException;
 import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;

 /**
  * CharacterData is an abstract Node that can carry character data as its
  * Value.  It provides shared behavior for Text, CData, and
  * possibly other node types. All offsets are 0-based.
  * <p>
  * Since ProcessingInstructionImpl inherits from this class to reuse the
  * setNodeValue method, this class isn't declared as implementing the interface
  * CharacterData. This is done by relevant subclasses (TexImpl, CommentImpl).
  * <p>
  * This class doesn't directly support mutation events, however, it notifies
  * the document when mutations are performed so that the document class do so.
  *
  * @xerces.internal
  *
  * @since  PR-DOM-Level-1-19980818.
  */
 public abstract class CharacterDataImpl
     extends ChildNode {

     //
     // Constants
     //

     /** Serialization version. */
     static final long serialVersionUID = 7931170150428474230L;

     //
     // Data
     //

     protected String data;

     /** Empty child nodes. */
     private static transient NodeList singletonNodeList = new NodeList() {
         public Node item(int index) { return null; }
         public int getLength() { return 0; }
     };

     //
     // Constructors
     //

     public CharacterDataImpl(){}

     /** Factory constructor. */
     protected CharacterDataImpl(CoreDocumentImpl ownerDocument, String data) {
         super(ownerDocument);
         this.data = data;
     }

     //
     // Node methods
     //

     /** Returns an empty node list. */
     public NodeList getChildNodes() {
         return singletonNodeList;
     }

     /*
      * returns the content of this node
      */
     public String getNodeValue() {
         if (needsSyncData()) {
             synchronizeData();
         }
         return data;
     }

    /** Convenience wrapper for calling setNodeValueInternal when
      * we are not performing a replacement operation
      */
     protected void setNodeValueInternal (String value) {
         setNodeValueInternal(value, false);
     }

     /** This function added so that we can distinguish whether
      *  setNodeValue has been called from some other DOM functions.
      *  or by the client.<p>
      *  This is important, because we do one type of Range fix-up,
      *  from the high-level functions in CharacterData, and another
      *  type if the client simply calls setNodeValue(value).
      */
     protected void setNodeValueInternal(String value, boolean replace) {

         CoreDocumentImpl ownerDocument = ownerDocument();

         if (ownerDocument.errorChecking && isReadOnly()) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
             throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
         }

         // revisit: may want to set the value in ownerDocument.
         // Default behavior, overridden in some subclasses
         if (needsSyncData()) {
             synchronizeData();
         }

         // keep old value for document notification
         String oldvalue = this.data;

         // notify document
         ownerDocument.modifyingCharacterData(this, replace);

         this.data = value;

         // notify document
         ownerDocument.modifiedCharacterData(this, oldvalue, value, replace);
     }

     /**
      * Sets the content, possibly firing related events,
      * and updating ranges (via notification to the document)
      */
     public void setNodeValue(String value) {

         setNodeValueInternal(value);

         // notify document
         ownerDocument().replacedText(this);
     }

     //
     // CharacterData methods
     //

     /**
      * Retrieve character data currently stored in this node.
      *
      * @throws DOMExcpetion(DOMSTRING_SIZE_ERR) In some implementations,
      * the stored data may exceed the permitted length of strings. If so,
      * getData() will throw this DOMException advising the user to
      * instead retrieve the data in chunks via the substring() operation.
      */
     public String getData() {
         if (needsSyncData()) {
             synchronizeData();
         }
         return data;
     }

     /**
      * Report number of characters currently stored in this node's
      * data. It may be 0, meaning that the value is an empty string.
      */
     public int getLength() {
         if (needsSyncData()) {
             synchronizeData();
         }
         return data.length();
     }

     /**
      * Concatenate additional characters onto the end of the data
      * stored in this node. Note that this, and insert(), are the paths
      * by which a DOM could wind up accumulating more data than the
      * language's strings can easily handle. (See above discussion.)
      *
      * @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
      */
     public void appendData(String data) {

         if (isReadOnly()) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
             throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
         }
         if (data == null) {
             return;
         }
         if (needsSyncData()) {
             synchronizeData();
         }

         setNodeValue(this.data + data);

     } // appendData(String)

     /**
      * Remove a range of characters from the node's value. Throws a
      * DOMException if the offset is beyond the end of the
      * string. However, a deletion _count_ that exceeds the available
      * data is accepted as a delete-to-end request.
      *
      * @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
      * greater than length, or if count is negative.
      *
      * @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is
      * readonly.
      */
     public void deleteData(int offset, int count)
         throws DOMException {

         internalDeleteData(offset, count, false);
     } // deleteData(int,int)


     /** NON-DOM INTERNAL: Within DOM actions, we sometimes need to be able
      * to control which mutation events are spawned. This version of the
      * deleteData operation allows us to do so. It is not intended
      * for use by application programs.
      */
     void internalDeleteData (int offset, int count, boolean replace)
     throws DOMException {

         CoreDocumentImpl ownerDocument = ownerDocument();
         if (ownerDocument.errorChecking) {
             if (isReadOnly()) {
                 String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
                 throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
             }

             if (count < 0) {
                 String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
                 throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
             }
         }

         if (needsSyncData()) {
             synchronizeData();
         }
         int tailLength = Math.max(data.length() - count - offset, 0);
         try {
             String value = data.substring(0, offset) +
             (tailLength > 0 ? data.substring(offset + count, offset + count + tailLength) : "");

             setNodeValueInternal(value, replace);

             // notify document
             ownerDocument.deletedText(this, offset, count);
         }
         catch (StringIndexOutOfBoundsException e) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
             throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
         }

     } // internalDeleteData(int,int,boolean)

     /**
      * Insert additional characters into the data stored in this node,
      * at the offset specified.
      *
      * @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
      * greater than length.
      *
      * @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
      */
     public void insertData(int offset, String data)
         throws DOMException {

         internalInsertData(offset, data, false);

     } // insertData(int,int)


     /** NON-DOM INTERNAL: Within DOM actions, we sometimes need to be able
      * to control which mutation events are spawned. This version of the
      * insertData operation allows us to do so. It is not intended
      * for use by application programs.
      */
     void internalInsertData (int offset, String data, boolean replace)
     throws DOMException {

         CoreDocumentImpl ownerDocument = ownerDocument();

         if (ownerDocument.errorChecking && isReadOnly()) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
             throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
         }

         if (needsSyncData()) {
             synchronizeData();
         }
         try {
             String value =
                 new StringBuffer(this.data).insert(offset, data).toString();


             setNodeValueInternal(value, replace);

             // notify document
             ownerDocument.insertedText(this, offset, data.length());
         }
         catch (StringIndexOutOfBoundsException e) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
             throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
         }

     } // internalInsertData(int,String,boolean)


     /**
      * Replace a series of characters at the specified (zero-based)
      * offset with a new string, NOT necessarily of the same
      * length. Convenience method, equivalent to a delete followed by an
      * insert. Throws a DOMException if the specified offset is beyond
      * the end of the existing data.
      *
      * @param offset       The offset at which to begin replacing.
      *
      * @param count        The number of characters to remove,
      * interpreted as in the delete() method.
      *
      * @param data         The new string to be inserted at offset in place of
      * the removed data. Note that the entire string will
      * be inserted -- the count parameter does not affect
      * insertion, and the new data may be longer or shorter
      * than the substring it replaces.
      *
      * @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
      * greater than length, or if count is negative.
      *
      * @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is
      * readonly.
      */
     public void replaceData(int offset, int count, String data)
     throws DOMException {

         CoreDocumentImpl ownerDocument = ownerDocument();

         // The read-only check is done by deleteData()
         // ***** This could be more efficient w/r/t Mutation Events,
         // specifically by aggregating DOMAttrModified and
         // DOMSubtreeModified. But mutation events are
         // underspecified; I don't feel compelled
         // to deal with it right now.
         if (ownerDocument.errorChecking && isReadOnly()) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
             throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
         }

         if (needsSyncData()) {
             synchronizeData();
         }

         //notify document
         ownerDocument.replacingData(this);

         // keep old value for document notification
         String oldvalue = this.data;

         internalDeleteData(offset, count, true);
         internalInsertData(offset, data, true);

         ownerDocument.replacedCharacterData(this, oldvalue, this.data);

     } // replaceData(int,int,String)

     /**
      * Store character data into this node.
      *
      * @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
      */
     public void setData(String value)
         throws DOMException {
         setNodeValue(value);
     }

     /**
      * Substring is more than a convenience function. In some
      * implementations of the DOM, where the stored data may exceed the
      * length that can be returned in a single string, the only way to
      * read it all is to extract it in chunks via this method.
      *
      * @param offset        Zero-based offset of first character to retrieve.
      * @param count Number of characters to retrieve.
      *
      * If the sum of offset and count exceeds the length, all characters
      * to end of data are returned.
      *
      * @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
      * greater than length, or if count is negative.
      *
      * @throws DOMException(WSTRING_SIZE_ERR) In some implementations,
      * count may exceed the permitted length of strings. If so,
      * substring() will throw this DOMException advising the user to
      * instead retrieve the data in smaller chunks.
      */
     public String substringData(int offset, int count)
         throws DOMException {

         if (needsSyncData()) {
             synchronizeData();
         }

         int length = data.length();
         if (count < 0 || offset < 0 || offset > length - 1) {
             String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
             throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
         }

         int tailIndex = Math.min(offset + count, length);

         return data.substring(offset, tailIndex);

     } // substringData(int,int):String

 } // class CharacterDataImpl
	/*
	* reserved comment block
	* DO NOT REMOVE OR ALTER!
	*/
	/*
	* Copyright 1999-2002,2004 The Apache Software Foundation.
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package com.sun.org.apache.xerces.internal.dom;

	import org.w3c.dom.DOMException;
	import org.w3c.dom.Node;
	import org.w3c.dom.NodeList;

	/**
	* CharacterData is an abstract Node that can carry character data as its
	* Value. It provides shared behavior for Text, CData, and
	* possibly other node types. All offsets are 0-based.
	* <p>
	* Since ProcessingInstructionImpl inherits from this class to reuse the
	* setNodeValue method, this class isn't declared as implementing the interface
	* CharacterData. This is done by relevant subclasses (TexImpl, CommentImpl).
	* <p>
	* This class doesn't directly support mutation events, however, it notifies
	* the document when mutations are performed so that the document class do so.
	*
	* @xerces.internal
	*
	* @since PR-DOM-Level-1-19980818.
	*/
	public abstract class CharacterDataImpl
	extends ChildNode {

	//
	// Constants
	//

	/** Serialization version. */
	static final long serialVersionUID = 7931170150428474230L;

	//
	// Data
	//

	protected String data;

	/** Empty child nodes. */
	private static transient NodeList singletonNodeList = new NodeList() {
	public Node item(int index) { return null; }
	public int getLength() { return 0; }
	};

	//
	// Constructors
	//

	public CharacterDataImpl(){}

	/** Factory constructor. */
	protected CharacterDataImpl(CoreDocumentImpl ownerDocument, String data) {
	super(ownerDocument);
	this.data = data;
	}

	//
	// Node methods
	//

	/** Returns an empty node list. */
	public NodeList getChildNodes() {
	return singletonNodeList;
	}

	/*
	* returns the content of this node
	*/
	public String getNodeValue() {
	if (needsSyncData()) {
	synchronizeData();
	}
	return data;
	}

	/** Convenience wrapper for calling setNodeValueInternal when
	* we are not performing a replacement operation
	*/
	protected void setNodeValueInternal (String value) {
	setNodeValueInternal(value, false);
	}

	/** This function added so that we can distinguish whether
	* setNodeValue has been called from some other DOM functions.
	* or by the client.<p>
	* This is important, because we do one type of Range fix-up,
	* from the high-level functions in CharacterData, and another
	* type if the client simply calls setNodeValue(value).
	*/
	protected void setNodeValueInternal(String value, boolean replace) {

	CoreDocumentImpl ownerDocument = ownerDocument();

	if (ownerDocument.errorChecking && isReadOnly()) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
	throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
	}

	// revisit: may want to set the value in ownerDocument.
	// Default behavior, overridden in some subclasses
	if (needsSyncData()) {
	synchronizeData();
	}

	// keep old value for document notification
	String oldvalue = this.data;

	// notify document
	ownerDocument.modifyingCharacterData(this, replace);

	this.data = value;

	// notify document
	ownerDocument.modifiedCharacterData(this, oldvalue, value, replace);
	}

	/**
	* Sets the content, possibly firing related events,
	* and updating ranges (via notification to the document)
	*/
	public void setNodeValue(String value) {

	setNodeValueInternal(value);

	// notify document
	ownerDocument().replacedText(this);
	}

	//
	// CharacterData methods
	//

	/**
	* Retrieve character data currently stored in this node.
	*
	* @throws DOMExcpetion(DOMSTRING_SIZE_ERR) In some implementations,
	* the stored data may exceed the permitted length of strings. If so,
	* getData() will throw this DOMException advising the user to
	* instead retrieve the data in chunks via the substring() operation.
	*/
	public String getData() {
	if (needsSyncData()) {
	synchronizeData();
	}
	return data;
	}

	/**
	* Report number of characters currently stored in this node's
	* data. It may be 0, meaning that the value is an empty string.
	*/
	public int getLength() {
	if (needsSyncData()) {
	synchronizeData();
	}
	return data.length();
	}

	/**
	* Concatenate additional characters onto the end of the data
	* stored in this node. Note that this, and insert(), are the paths
	* by which a DOM could wind up accumulating more data than the
	* language's strings can easily handle. (See above discussion.)
	*
	* @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
	*/
	public void appendData(String data) {

	if (isReadOnly()) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
	throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
	}
	if (data == null) {
	return;
	}
	if (needsSyncData()) {
	synchronizeData();
	}

	setNodeValue(this.data + data);

	} // appendData(String)

	/**
	* Remove a range of characters from the node's value. Throws a
	* DOMException if the offset is beyond the end of the
	* string. However, a deletion _count_ that exceeds the available
	* data is accepted as a delete-to-end request.
	*
	* @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
	* greater than length, or if count is negative.
	*
	* @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is
	* readonly.
	*/
	public void deleteData(int offset, int count)
	throws DOMException {

	internalDeleteData(offset, count, false);
	} // deleteData(int,int)


	/** NON-DOM INTERNAL: Within DOM actions, we sometimes need to be able
	* to control which mutation events are spawned. This version of the
	* deleteData operation allows us to do so. It is not intended
	* for use by application programs.
	*/
	void internalDeleteData (int offset, int count, boolean replace)
	throws DOMException {

	CoreDocumentImpl ownerDocument = ownerDocument();
	if (ownerDocument.errorChecking) {
	if (isReadOnly()) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
	throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
	}

	if (count < 0) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
	throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
	}
	}

	if (needsSyncData()) {
	synchronizeData();
	}
	int tailLength = Math.max(data.length() - count - offset, 0);
	try {
	String value = data.substring(0, offset) +
	(tailLength > 0 ? data.substring(offset + count, offset + count + tailLength) : "");

	setNodeValueInternal(value, replace);

	// notify document
	ownerDocument.deletedText(this, offset, count);
	}
	catch (StringIndexOutOfBoundsException e) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
	throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
	}

	} // internalDeleteData(int,int,boolean)

	/**
	* Insert additional characters into the data stored in this node,
	* at the offset specified.
	*
	* @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
	* greater than length.
	*
	* @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
	*/
	public void insertData(int offset, String data)
	throws DOMException {

	internalInsertData(offset, data, false);

	} // insertData(int,int)



	/** NON-DOM INTERNAL: Within DOM actions, we sometimes need to be able
	* to control which mutation events are spawned. This version of the
	* insertData operation allows us to do so. It is not intended
	* for use by application programs.
	*/
	void internalInsertData (int offset, String data, boolean replace)
	throws DOMException {

	CoreDocumentImpl ownerDocument = ownerDocument();

	if (ownerDocument.errorChecking && isReadOnly()) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
	throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
	}

	if (needsSyncData()) {
	synchronizeData();
	}
	try {
	String value =
	new StringBuffer(this.data).insert(offset, data).toString();


	setNodeValueInternal(value, replace);

	// notify document
	ownerDocument.insertedText(this, offset, data.length());
	}
	catch (StringIndexOutOfBoundsException e) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
	throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
	}

	} // internalInsertData(int,String,boolean)



	/**
	* Replace a series of characters at the specified (zero-based)
	* offset with a new string, NOT necessarily of the same
	* length. Convenience method, equivalent to a delete followed by an
	* insert. Throws a DOMException if the specified offset is beyond
	* the end of the existing data.
	*
	* @param offset The offset at which to begin replacing.
	*
	* @param count The number of characters to remove,
	* interpreted as in the delete() method.
	*
	* @param data The new string to be inserted at offset in place of
	* the removed data. Note that the entire string will
	* be inserted -- the count parameter does not affect
	* insertion, and the new data may be longer or shorter
	* than the substring it replaces.
	*
	* @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
	* greater than length, or if count is negative.
	*
	* @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is
	* readonly.
	*/
	public void replaceData(int offset, int count, String data)
	throws DOMException {

	CoreDocumentImpl ownerDocument = ownerDocument();

	// The read-only check is done by deleteData()
	// ***** This could be more efficient w/r/t Mutation Events,
	// specifically by aggregating DOMAttrModified and
	// DOMSubtreeModified. But mutation events are
	// underspecified; I don't feel compelled
	// to deal with it right now.
	if (ownerDocument.errorChecking && isReadOnly()) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "NO_MODIFICATION_ALLOWED_ERR", null);
	throw new DOMException(DOMException.NO_MODIFICATION_ALLOWED_ERR, msg);
	}

	if (needsSyncData()) {
	synchronizeData();
	}

	//notify document
	ownerDocument.replacingData(this);

	// keep old value for document notification
	String oldvalue = this.data;

	internalDeleteData(offset, count, true);
	internalInsertData(offset, data, true);

	ownerDocument.replacedCharacterData(this, oldvalue, this.data);

	} // replaceData(int,int,String)

	/**
	* Store character data into this node.
	*
	* @throws DOMException(NO_MODIFICATION_ALLOWED_ERR) if node is readonly.
	*/
	public void setData(String value)
	throws DOMException {
	setNodeValue(value);
	}

	/**
	* Substring is more than a convenience function. In some
	* implementations of the DOM, where the stored data may exceed the
	* length that can be returned in a single string, the only way to
	* read it all is to extract it in chunks via this method.
	*
	* @param offset Zero-based offset of first character to retrieve.
	* @param count Number of characters to retrieve.
	*
	* If the sum of offset and count exceeds the length, all characters
	* to end of data are returned.
	*
	* @throws DOMException(INDEX_SIZE_ERR) if offset is negative or
	* greater than length, or if count is negative.
	*
	* @throws DOMException(WSTRING_SIZE_ERR) In some implementations,
	* count may exceed the permitted length of strings. If so,
	* substring() will throw this DOMException advising the user to
	* instead retrieve the data in smaller chunks.
	*/
	public String substringData(int offset, int count)
	throws DOMException {

	if (needsSyncData()) {
	synchronizeData();
	}

	int length = data.length();
	if (count < 0 \|\| offset < 0 \|\| offset > length - 1) {
	String msg = DOMMessageFormatter.formatMessage(DOMMessageFormatter.DOM_DOMAIN, "INDEX_SIZE_ERR", null);
	throw new DOMException(DOMException.INDEX_SIZE_ERR, msg);
	}

	int tailIndex = Math.min(offset + count, length);

	return data.substring(offset, tailIndex);

	} // substringData(int,int):String

	} // class CharacterDataImpl