com.xmlmind.xml.xpath

Interface ExprContext

All Known Implementing Classes:

DelegateExprContext, ExprContextImpl, OutermostExprContext, ScriptExprContext

public interface ExprContext

Specifies what must be implemented by an expression context. (that is, the evaluation context or the evaluation environment as defined in the XPath spec).

See OutermostExprContext for a trivial implementation which can be used to evaluate outermost expressions (that is, an expression that is not part of another expression).

Method Summary

Modifier and Type	Method and Description
XNode	findElementWithId(XNode node, String id) Used to implement the id() function in an expression.
XNode	getCurrent(XNode contextNode) Used to implement the current() function.
NodeIterator	getDocument(String uriRef, URL baseURL) Used to implement the document() function.
NodeIterator	getKeyedNodes(Name keyName, String keyValue, XNode node) Used to implement the key() function.
int	getLastPosition() Returns a number equal to the context position from this expression evaluation context.
int	getPosition() Returns a number equal to the context size from this expression evaluation context.
Variant	getVariableValue(Name name, XNode node) Returns the value of variable with specified name if any; null otherwise
boolean	isElementWithId(XNode node, String id) Used to implement the id() function in a pattern.

Method Detail

getPosition

int getPosition()
         throws EvalException

Returns a number equal to the context size from this expression evaluation context.

Throws:

EvalException

getLastPosition

int getLastPosition()
             throws EvalException

Returns a number equal to the context position from this expression evaluation context.

Throws:

EvalException

getVariableValue

Variant getVariableValue(Name name,
                         XNode node)
                  throws EvalException

Returns the value of variable with specified name if any; null otherwise

Parameters:

node - the context node. Generally not useful.

Throws:

EvalException

getCurrent

XNode getCurrent(XNode contextNode)

Used to implement the current() function.

In practice, the single only useful implementation of this method is in private class WithCurrentExpr.

Parameters:

contextNode - the context node. For an outermost expression (an expression not occurring within another expression), the current node is always the same as the context node.

Returns:

the current node

findElementWithId

XNode findElementWithId(XNode node,
                        String id)
                 throws EvalException

Used to implement the id() function in an expression.

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

boolean isElementWithId(XNode node,
                        String id)
                 throws EvalException

Used to implement the id() function in a pattern.

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

getDocument

NodeIterator getDocument(String uriRef,
                         URL baseURL)
                  throws EvalException

Used to implement the document() function.

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

getKeyedNodes

NodeIterator getKeyedNodes(Name keyName,
                           String keyValue,
                           XNode node)
                    throws EvalException

Used to implement the key() function.

Parameters:

keyName - name of the key

keyValue - searched value

node - the context node.

Returns:

nodes belonging to the same document as node having specified key with specified value.

The returned nodes don't need to be sorted by document order.

Throws:

EvalException - if a problem occurs during the operation