/*
* 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: ElemContext.java,v 1.2 2004/02/17 04:18:19 minchau Exp $
*/
package com.sun.org.apache.xml.internal.serializer;
/**
* This class is a stack frame that consists of
* information about the element currently being processed
* by a serializer. Consider this example:
* <pre>
* <A>
* <B1>
* </B1>
* <B2>
* </B2>
* <A>
* </pre>
*
* A stack frame will be pushed for "A" at depth 1,
* then another one for "B1" at depth 2.
* Then "B1" stackframe is popped. When the stack frame for "B2" is
* pushed, this implementation re-uses the old stack fram object used
* by "B1" to be efficient at not creating too many of these object.
*
* This is by no means a public class, and neither are its fields or methods,
* they are all helper fields for a serializer.
*
* The purpose of this class is to be more consistent with pushing information
* when a new element is being serialized and more quickly restoring the old
* information about the parent element with a simple pop() when the
* child element is done. Previously there was some redundant and error-prone
* calculations going on to retore information.
*
*/
class ElemContext
{
// Fields that form the context of the element
/**
* The nesting depth of the element inside other elements.
*/
final int m_currentElemDepth;
/** HTML field, the element description of the HTML element */
ElemDesc m_elementDesc = null;
/**
* The local name of the element.
*/
String m_elementLocalName = null;
/**
* The fully qualified name of the element (with prefix, if any).
*/
String m_elementName = null;
/**
* The URI of the element.
*/
String m_elementURI = null;
/** If the element is in the cdata-section-names list
* then the value is true. If it is true the text children of the element
* should be output in CDATA section blocks.
*/
boolean m_isCdataSection;
/** True if the current element has output escaping disabled.
* This is true for SCRIPT and STYLE elements.
*/
boolean m_isRaw = false;
/** The next element "stack frame". This value will only be
* set once as deeper stack frames are not deleted when popped off,
* but are rather re-used when a push is required.
*
* This makes for very fast pushing and popping of stack frames
* because very few stack frame objects are ever created, they are
* mostly re-used. This re-use saves object creation but it also means
* that connections between the frames via m_next and m_prev
* never changes either. Just the contents of the frames change
* as they are re-used. Only the reference to the current stack frame, which
* is held by the serializer is changed via a quick pop() or push().
*/
private ElemContext m_next;
/** The previous element "stack frame". */
final ElemContext m_prev;
/**
* Set to true when a start tag is started, or open, but not all the
* attributes or namespace information is yet collected.
*/
boolean m_startTagOpen = false;
/**
* Constructor to create the root of the element contexts.
*
*/
ElemContext()
{
// this assignment means can never pop this context off
m_prev = this;
// depth 0 because it doesn't correspond to any element
m_currentElemDepth = 0;
}
/**
* Constructor to create the "stack frame" for a given element depth.
*
* This implementation will re-use the context at each depth. If
* a documents deepest element depth is N then there will be (N+1)
* such objects created, no more than that.
*
* @param previous The "stack frame" corresponding to the new
* elements parent element.
*/
private ElemContext(final ElemContext previous)
{
m_prev = previous;
m_currentElemDepth = previous.m_currentElemDepth + 1;
}
/**
* Pop the current "stack frame".
* @return Returns the parent "stack frame" of the one popped.
*/
final ElemContext pop()
{
/* a very simple pop. No clean up is done of the deeper
* stack frame. All deeper stack frames are still attached
* but dormant, just waiting to be re-used.
*/
return this.m_prev;
}
/**
* This method pushes an element "stack frame"
* but with no initialization of values in that frame.
* This method is used for optimization purposes, like when pushing
* a stack frame for an HTML "IMG" tag which has no children and
* the stack frame will almost immediately be popped.
*/
final ElemContext push()
{
ElemContext frame = this.m_next;
if (frame == null)
{
/* We have never been at this depth yet, and there is no
* stack frame to re-use, so we now make a new one.
*/
frame = new ElemContext(this);
this.m_next = frame;
}
/*
* We shouldn't need to set this true because we should just
* be pushing a dummy stack frame that will be instantly popped.
* Yet we need to be ready in case this element does have
* unexpected children.
*/
frame.m_startTagOpen = true;
return frame;
}
/**
* Push an element context on the stack. This context keeps track of
* information gathered about the element.
* @param uri The URI for the namespace for the element name,
* can be null if it is not yet known.
* @param localName The local name of the element (no prefix),
* can be null.
* @param qName The qualified name (with prefix, if any)
* of the element, this parameter is required.
*/
final ElemContext push(
final String uri,
final String localName,
final String qName)
{
ElemContext frame = this.m_next;
if (frame == null)
{
/* We have never been at this depth yet, and there is no
* stack frame to re-use, so we now make a new one.
*/
frame = new ElemContext(this);
this.m_next = frame;
}
// Initialize, or reset values in the new or re-used stack frame.
frame.m_elementName = qName;
frame.m_elementLocalName = localName;
frame.m_elementURI = uri;
frame.m_isCdataSection = false;
frame.m_startTagOpen = true;
// is_Raw is already set in the HTML startElement() method
// frame.m_isRaw = false;
return frame;
}
}
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