/* * reserved comment block * DO NOT REMOVE OR ALTER! */ /* * Copyright 2003-2004 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. */ /* * $Id: AttributesImplSerializer.java,v 1.2.4.1 2005/09/15 08:15:14 suresh_emailid Exp $ */ package com.sun.org.apache.xml.internal.serializer; import java.util.Hashtable; import org.xml.sax.Attributes; import org.xml.sax.helpers.AttributesImpl; /** * This class extends org.xml.sax.helpers.AttributesImpl which implements org. * xml.sax.Attributes. But for optimization this class adds a Hashtable for * faster lookup of an index by qName, which is commonly done in the stream * serializer. * * @see org.xml.sax.Attributes * * @xsl.usage internal */ public final class AttributesImplSerializer extends AttributesImpl { /** * Hash table of qName/index values to quickly lookup the index * of an attributes qName. qNames are in uppercase in the hash table * to make the search case insensitive. * * The keys to the hashtable to find the index are either * "prefix:localName" or "{uri}localName". */ private final Hashtable m_indexFromQName = new Hashtable(); private final StringBuffer m_buff = new StringBuffer(); /** * This is the number of attributes before switching to the hash table, * and can be tuned, but 12 seems good for now - Brian M. */ private static final int MAX = 12; /** * One less than the number of attributes before switching to * the Hashtable. */ private static final int MAXMinus1 = MAX - 1; /** * This method gets the index of an attribute given its qName. * @param qname the qualified name of the attribute, e.g. "prefix1:locName1" * @return the integer index of the attribute. * @see org.xml.sax.Attributes#getIndex(String) */ public final int getIndex(String qname) { int index; if (super.getLength() < MAX) { // if we haven't got too many attributes let the // super class look it up index = super.getIndex(qname); return index; } // we have too many attributes and the super class is slow // so find it quickly using our Hashtable. Integer i = (Integer)m_indexFromQName.get(qname); if (i == null) index = -1; else index = i.intValue(); return index; } /** * This method adds the attribute, but also records its qName/index pair in * the hashtable for fast lookup by getIndex(qName). * @param uri the URI of the attribute * @param local the local name of the attribute * @param qname the qualified name of the attribute * @param type the type of the attribute * @param val the value of the attribute * * @see org.xml.sax.helpers.AttributesImpl#addAttribute(String, String, String, String, String) * @see #getIndex(String) */ public final void addAttribute( String uri, String local, String qname, String type, String val) { int index = super.getLength(); super.addAttribute(uri, local, qname, type, val); // (index + 1) is now the number of attributes // so either compare (index+1) to MAX, or compare index to (MAX-1) if (index < MAXMinus1) { return; } else if (index == MAXMinus1) { switchOverToHash(MAX); } else { /* add the key with the format of "prefix:localName" */ /* we have just added the attibute, its index is the old length */ Integer i = new Integer(index); m_indexFromQName.put(qname, i); /* now add with key of the format "{uri}localName" */ m_buff.setLength(0); m_buff.append('{').append(uri).append('}').append(local); String key = m_buff.toString(); m_indexFromQName.put(key, i); } return; } /** * We are switching over to having a hash table for quick look * up of attributes, but up until now we haven't kept any * information in the Hashtable, so we now update the Hashtable. * Future additional attributes will update the Hashtable as * they are added. * @param numAtts */ private void switchOverToHash(int numAtts) { for (int index = 0; index < numAtts; index++) { String qName = super.getQName(index); Integer i = new Integer(index); m_indexFromQName.put(qName, i); // Add quick look-up to find with uri/local name pair String uri = super.getURI(index); String local = super.getLocalName(index); m_buff.setLength(0); m_buff.append('{').append(uri).append('}').append(local); String key = m_buff.toString(); m_indexFromQName.put(key, i); } } /** * This method clears the accumulated attributes. * * @see org.xml.sax.helpers.AttributesImpl#clear() */ public final void clear() { int len = super.getLength(); super.clear(); if (MAX <= len) { // if we have had enough attributes and are // using the Hashtable, then clear the Hashtable too. m_indexFromQName.clear(); } } /** * This method sets the attributes, previous attributes are cleared, * it also keeps the hashtable up to date for quick lookup via * getIndex(qName). * @param atts the attributes to copy into these attributes. * @see org.xml.sax.helpers.AttributesImpl#setAttributes(Attributes) * @see #getIndex(String) */ public final void setAttributes(Attributes atts) { super.setAttributes(atts); // we've let the super class add the attributes, but // we need to keep the hash table up to date ourselves for the // potentially new qName/index pairs for quick lookup. int numAtts = atts.getLength(); if (MAX <= numAtts) switchOverToHash(numAtts); } /** * This method gets the index of an attribute given its uri and locanName. * @param uri the URI of the attribute name. * @param localName the local namer (after the ':' ) of the attribute name. * @return the integer index of the attribute. * @see org.xml.sax.Attributes#getIndex(String) */ public final int getIndex(String uri, String localName) { int index; if (super.getLength() < MAX) { // if we haven't got too many attributes let the // super class look it up index = super.getIndex(uri,localName); return index; } // we have too many attributes and the super class is slow // so find it quickly using our Hashtable. // Form the key of format "{uri}localName" m_buff.setLength(0); m_buff.append('{').append(uri).append('}').append(localName); String key = m_buff.toString(); Integer i = (Integer)m_indexFromQName.get(key); if (i == null) index = -1; else index = i.intValue(); return index; } }