net.sourceforge.htmlunit.xpath.xml.dtm.ref

Class DTMManagerDefault

java.lang.Object

net.sourceforge.htmlunit.xpath.xml.dtm.DTMManager

net.sourceforge.htmlunit.xpath.xml.dtm.ref.DTMManagerDefault

public class DTMManagerDefault
extends DTMManager

The default implementation for the DTMManager.

%REVIEW% There is currently a reentrancy issue, since the finalizer for XRTreeFrag (which runs in the GC thread) wants to call DTMManager.release(), and may do so at the same time that the main transformation thread is accessing the manager. Our current solution is to make most of the manager's methods synchronized. Early tests suggest that doing so is not causing a significant performance hit in Xalan. However, it should be noted that there is a possible alternative solution: rewrite release() so it merely posts a request for release onto a threadsafe queue, and explicitly process that queue on an infrequent basis during main-thread activity (eg, when getDTM() is invoked). The downside of that solution would be a greater delay before the DTM's storage is actually released for reuse.

Field Summary

Fields

Modifier and Type	Field and Description
protected DTM[]	m_dtms Map from DTM identifier numbers to DTM objects that this manager manages.

Fields inherited from class net.sourceforge.htmlunit.xpath.xml.dtm.DTMManager

IDENT_DTM_DEFAULT, IDENT_DTM_NODE_BITS, IDENT_MAX_DTMS, IDENT_NODE_DEFAULT

Constructor Summary

Constructors

Constructor and Description
DTMManagerDefault() Constructor DTMManagerDefault

Method Summary

Modifier and Type	Method and Description
void	addDTM(DTM dtm, int id, int offset) Add a DTM to the DTM table.
DTMIterator	createDTMIterator(int whatToShow, DTMFilter filter, boolean entityReferenceExpansion) Create a new DTMIterator based only on a whatToShow and a DTMFilter.
DTMIterator	createDTMIterator(Object xpathCompiler, int pos) Create a new DTMIterator based on an XPath LocationPath or a UnionExpr.
DTMIterator	createDTMIterator(String xpathString, PrefixResolver presolver) Create a new DTMIterator based on an XPath LocationPath or a UnionExpr.
DTM	getDTM(int nodeHandle) Get the instance of DTM that "owns" a node handle.
DTM	getDTM(Source source, boolean unique, boolean incremental, boolean doIndexing) Get an instance of a DTM, loaded with the content from the specified source.
int	getDTMHandleFromNode(Node node) Given a W3C DOM node, try and return a DTM handle.
ExpandedNameTable	getExpandedNameTable()
int	getFirstFreeDTMID()

Methods inherited from class net.sourceforge.htmlunit.xpath.xml.dtm.DTMManager

newInstance

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

m_dtms

protected DTM[] m_dtms

Map from DTM identifier numbers to DTM objects that this manager manages. One DTM may have several prefix numbers, if extended node indexing is in use; in that case, m_dtm_offsets[] will used to control which prefix maps to which section of the DTM.

This array grows as necessary; see addDTM().

This array grows as necessary; see addDTM(). Growth is uncommon... but access needs to be blindingly fast since it's used in node addressing.

Constructor Detail

DTMManagerDefault

public DTMManagerDefault()

Constructor DTMManagerDefault

Method Detail

addDTM

public void addDTM(DTM dtm,
                   int id,
                   int offset)

Add a DTM to the DTM table.

Parameters:

dtm - Should be a valid reference to a DTM.

id - Integer DTM ID to be bound to this DTM.

offset - Integer addressing offset. The internal DTM Node ID is obtained by adding this offset to the node-number field of the public DTM Handle. For the first DTM ID accessing each DTM, this is 0; for overflow addressing it will be a multiple of 1<<IDENT_DTM_NODE_BITS.

getFirstFreeDTMID

public int getFirstFreeDTMID()

Returns:

the first free DTM ID available. %OPT% Linear search is inefficient!

getDTM

public DTM getDTM(Source source,
                  boolean unique,
                  boolean incremental,
                  boolean doIndexing)

Description copied from class: DTMManager

Get an instance of a DTM, loaded with the content from the specified source. If the unique flag is true, a new instance will always be returned. Otherwise it is up to the DTMManager to return a new instance or an instance that it already created and may be being used by someone else.

(More parameters may eventually need to be added for error handling and entity resolution, and to better control selection of implementations.)

Specified by:

getDTM in class DTMManager

Parameters:

source - the specification of the source object, which may be null, in which case it is assumed that node construction will take by some other means.

unique - true if the returned DTM must be unique, probably because it is going to be mutated.

incremental - true if the DTM should be built incrementally, if possible.

doIndexing - true if the caller considers it worth it to use indexing schemes.

Returns:

a non-null DTM reference.

getDTMHandleFromNode

public int getDTMHandleFromNode(Node node)

Given a W3C DOM node, try and return a DTM handle. Note: calling this may be non-optimal.

Specified by:

getDTMHandleFromNode in class DTMManager

Parameters:

node - Non-null reference to a DOM node.

Returns:

a valid DTM handle.

getDTM

public DTM getDTM(int nodeHandle)

Get the instance of DTM that "owns" a node handle.

Specified by:

getDTM in class DTMManager

Parameters:

nodeHandle - the nodeHandle.

Returns:

a non-null DTM reference.

createDTMIterator

public DTMIterator createDTMIterator(int whatToShow,
                                     DTMFilter filter,
                                     boolean entityReferenceExpansion)

Create a new DTMIterator based only on a whatToShow and a DTMFilter. The traversal semantics are defined as the descendant access.

Note that DTMIterators may not be an exact match to DOM NodeIterators. They are initialized and used in much the same way as a NodeIterator, but their response to document mutation is not currently defined.

Specified by:

createDTMIterator in class DTMManager

Parameters:

whatToShow - This flag specifies which node types may appear in the logical view of the tree presented by the iterator. See the description of NodeFilter for the set of possible SHOW_ values.These flags can be combined using OR .

filter - The NodeFilter to be used with this DTMFilter, or null to indicate no filter.

entityReferenceExpansion - The value of this flag determines whether entity reference nodes are expanded.

Returns:

The newly created DTMIterator.

createDTMIterator

public DTMIterator createDTMIterator(String xpathString,
                                     PrefixResolver presolver)

Create a new DTMIterator based on an XPath LocationPath or a UnionExpr.

Specified by:

createDTMIterator in class DTMManager

Parameters:

xpathString - Must be a valid string expressing a LocationPath or a UnionExpr.

presolver - An object that can resolve prefixes to namespace URLs.

Returns:

The newly created DTMIterator.

createDTMIterator

public DTMIterator createDTMIterator(Object xpathCompiler,
                                     int pos)

Create a new DTMIterator based on an XPath LocationPath or a UnionExpr.

Specified by:

createDTMIterator in class DTMManager

Parameters:

xpathCompiler - ??? Somehow we need to pass in a subpart of the expression. I hate to do this with strings, since the larger expression has already been parsed.

pos - The position in the expression.

Returns:

The newly created DTMIterator.

getExpandedNameTable

public ExpandedNameTable getExpandedNameTable()

Returns:

the expanded name table.

NEEDSDOC @param dtm

NEEDSDOC ($objectName$) @return