com.xmlmind.xml.xpath

Class ExprContextImpl

java.lang.Object

com.xmlmind.xml.xpath.OutermostExprContext

com.xmlmind.xml.xpath.ExprContextImpl

All Implemented Interfaces:

ExprContext

Direct Known Subclasses:

ScriptExprContext

public class ExprContextImpl
extends OutermostExprContext

A full-fledged OutermostExprContext supporting variables as well the id() and document() functions.

An ExprContextImpl can be reused as long as the documents explored using XPath expressions/patterns are not modified (because the IDs of these documents are cached).

It is also possible to reuse a context after invoking reset().

Field Summary

Fields

Modifier and Type	Field and Description
protected DocumentManager	documentManager
protected static HashMap<String,IdEntry>	EMPTY_ID_MAP
protected IdentityLinearHashtable<Name,Variant>	globalVariables
protected static String	ID_MAP_PROP
protected IdentityLinearHashtable<Document,Map<String,IdEntry>>	idMaps

Constructor Summary

Constructors

Constructor and Description
ExprContextImpl() Constructs an ExprContext using the global document cache as its document manager.
ExprContextImpl(DocumentManager docManager) Constructs an ExprContext using specified document manager.

Method Summary

Modifier and Type	Method and Description
protected Map<String,IdEntry>	doGetIdMap(Document doc)
XNode	findElementWithId(XNode node, String id) Returns null because this basic implementation is not schema-aware.
protected XNode	findNodeByFragment(Document doc, String fragment)
NodeIterator	getDocument(String uriRef, URL baseURL) Returns NullNodeIterator.INSTANCE because this basic implementation does not know how to load documents.
DocumentManager	getDocumentManager() Returns the document manager used by this ExprContext.
Variant	getGlobalVariable(Name name, XNode node) Returns the value of specified global variable if any; null otherwise.
protected Map<String,IdEntry>	getIdMap(XNode node)
Variant	getVariableValue(Name name, XNode node) Returns null because this basic implementation does not handle variable references.
boolean	isElementWithId(XNode node, String id) Returns false because this basic implementation is not schema aware.
void	reset() Invoke this method before reusing this context: it clears global variables and cached data (element IDs).
protected URL	resolveDocumentURL(String uriRef, URL baseURL)
void	setDocumentManager(DocumentManager docManager) Specifies the document manager used by this ExprContext.
Variant	setGlobalVariable(Name name, Variant value) Set specified global (that is, top level) variable to specified value.

Methods inherited from class com.xmlmind.xml.xpath.OutermostExprContext

getCurrent, getKeyedNodes, getLastPosition, getPosition

Methods inherited from class java.lang.Object

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

Field Detail

globalVariables

protected final IdentityLinearHashtable<Name,Variant> globalVariables

documentManager

protected DocumentManager documentManager

idMaps

protected IdentityLinearHashtable<Document,Map<String,IdEntry>> idMaps

EMPTY_ID_MAP

protected static final HashMap<String,IdEntry> EMPTY_ID_MAP

ID_MAP_PROP

protected static final String ID_MAP_PROP

See Also:

Constant Field Values

Constructor Detail

ExprContextImpl

public ExprContextImpl()

Constructs an ExprContext using the global document cache as its document manager.

See Also:

DocumentCache.getCache()

ExprContextImpl

public ExprContextImpl(DocumentManager docManager)

Constructs an ExprContext using specified document manager.

Parameters:

docManager - the document manager used by this ExprContext. May be null.

Note that without a proper document manager, the document() function always returns an empty node-set.

Method Detail

setDocumentManager

public void setDocumentManager(DocumentManager docManager)

Specifies the document manager used by this ExprContext.

Parameters:

docManager - the document manager used by this ExprContext. May be null.

Note that without a proper DocumentManager, the document() function always returns an empty node-set.

getDocumentManager

public DocumentManager getDocumentManager()

Returns the document manager used by this ExprContext. Returns null if this context has no document manager.

setGlobalVariable

public Variant setGlobalVariable(Name name,
                                 Variant value)

Set specified global (that is, top level) variable to specified value.

Parameters:

name - name of the variable

value - new value of the variable. Specify null to unset the variable.

Returns:

the previous value of specified variable if any; null otherwise.

See Also:

getGlobalVariable(com.xmlmind.xml.name.Name, com.xmlmind.xml.doc.XNode), getVariableValue(com.xmlmind.xml.name.Name, com.xmlmind.xml.doc.XNode)

getGlobalVariable

public Variant getGlobalVariable(Name name,
                                 XNode node)
                          throws EvalException

Returns the value of specified global variable if any; null otherwise.

Parameters:

name - name of the variable

Returns:

the current value of specified variable if any; null otherwise.

Throws:

EvalException

See Also:

setGlobalVariable(com.xmlmind.xml.name.Name, com.xmlmind.xml.xpath.Variant), getVariableValue(com.xmlmind.xml.name.Name, com.xmlmind.xml.doc.XNode)

getVariableValue

public Variant getVariableValue(Name name,
                                XNode node)
                         throws EvalException

Returns null because this basic implementation does not handle variable references.

Default implementation invokes getGlobalVariable(com.xmlmind.xml.name.Name, com.xmlmind.xml.doc.XNode).

Specified by:

getVariableValue in interface ExprContext

Overrides:

getVariableValue in class OutermostExprContext

node - the context node. Generally not useful.

Throws:

EvalException

See Also:

setGlobalVariable(com.xmlmind.xml.name.Name, com.xmlmind.xml.xpath.Variant)

reset

public void reset()

Invoke this method before reusing this context: it clears global variables and cached data (element IDs).

Note that this method has no effect on the document manager, if any.

findElementWithId

public XNode findElementWithId(XNode node,
                               String id)
                        throws EvalException

Description copied from class: OutermostExprContext

Returns null because this basic implementation is not schema-aware.

Specified by:

findElementWithId in interface ExprContext

Overrides:

findElementWithId in class OutermostExprContext

Parameters:

node - used to specify the document

id - searched ID value

Returns:

element in document specified by node having specified ID if any; null otherwise

Throws:

EvalException - if a problem occurs during the search

isElementWithId

public boolean isElementWithId(XNode node,
                               String id)
                        throws EvalException

Description copied from class: OutermostExprContext

Returns false because this basic implementation is not schema aware.

Specified by:

isElementWithId in interface ExprContext

Overrides:

isElementWithId in class OutermostExprContext

Parameters:

node - node possibly having an ID attribute

id - ID value to be matched against the possible ID attribute of node

Returns:

true if specified node has an ID attribute having specified value; false otherwise

Throws:

EvalException - if a problem occurs during the match

getIdMap

protected Map<String,IdEntry> getIdMap(XNode node)

doGetIdMap

protected Map<String,IdEntry> doGetIdMap(Document doc)

getDocument

public NodeIterator getDocument(String uriRef,
                                URL baseURL)
                         throws EvalException

Description copied from class: OutermostExprContext

Returns NullNodeIterator.INSTANCE because this basic implementation does not know how to load documents.

Specified by:

getDocument in interface ExprContext

Overrides:

getDocument in class OutermostExprContext

Parameters:

uriRef - specifies nodes (using a fragment) in a document

baseURL - URL possibly used to resolve relative URL in uriRef; may be null

Returns:

nodes specified by uriRef

Throws:

EvalException - if a problem occurs during the operation

See Also:

NullNodeIterator

resolveDocumentURL

protected URL resolveDocumentURL(String uriRef,
                                 URL baseURL)
                          throws EvalException

Throws:

EvalException

findNodeByFragment

protected XNode findNodeByFragment(Document doc,
                                   String fragment)
                            throws EvalException

Throws:

EvalException