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/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 468654 2006-10-28 07:09:23Z minchau $
*/
package org.apache.xml.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;
}
}
