org.exolab.adaptx.xpath

Class XPathContext

java.lang.Object

org.exolab.adaptx.xpath.XPathContext

Direct Known Subclasses:

ProcessorState

public class XPathContext
extends java.lang.Object

Base implementation of an XPath context. An XPath context provides a way to manage a stack of node-sets, resolve variable and function names, and return the size and position of the context. This implementation is not thread-safe, care must be taken not to use the same context when evaluating expressions concurrently.

Impelementations may wish to extend this class and provide additional facilities for locating the document order of a node, or providing a function library.

Version:

$Revision: 3633 $

Author:

Keith Visco, Assaf Arkin

Constructor Summary

Constructors

Constructor and Description
XPathContext(VariableSet variables, NodeSet nodeSet, int position) Constructs a new XPath context.
XPathContext(XPathNode node) Constructs a new XPath context using the given node as the context node.
XPathContext(XPathNode node, VariableSet variables) Constructs a new XPath context using the given node as as the context node.

Method Summary

Modifier and Type	Method and Description
void	addNamespaceBinding(java.lang.String prefix, java.lang.String namespace) Creates a binding within this XPathContext between a given prefix and a namespace URI.
int[]	getDocumentOrder(XPathNode node) Returns the document order of the given node.
XPathNode	getElementById(XPathNode root, java.lang.String id) Returns the element associated with the given identifier.
XPathFunction	getFunction(java.lang.String uri, java.lang.String name) Returns the XPath function by the given name, or null if no such function is defined.
java.lang.String	getNamespaceURI(java.lang.String prefix) Returns the namespace associated with the given prefix as defined in this context.
XPathNode	getNode() Returns the context node of this XPathContext
NodeSet	getNodeSet() Returns the current context node-set.
int	getPosition() Returns the position of the context node.
int	getSize() Returns the size of the context.
XPathResult	getVariable(java.lang.String name) Returns the XPath result bound to the given variable name.
XPathContext	newContext(NodeSet nodeSet, int position) Creates a new XPathContext with this XPathContext as it's parent.
XPathContext	newContext(XPathNode node) Creates a new XPathContext with this XPathContext as it's parent.
NodeSet	newNodeSet() Constructs and returns a new empty node-set.
NodeSet	newNodeSet(int size) Constructs and returns a new node-set with the specified size.
NodeSet	newNodeSet(XPathNode node) Constructs and returns a new node-set with one node.
void	setNodeSet(NodeSet nodeSet, int position) Sets the given node-set as the context node-set for this XPathContext
void	setPosition(int position) Sets the position of the context node within the context node-set

Methods inherited from class java.lang.Object

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

Constructor Detail

XPathContext

public XPathContext(XPathNode node)

Constructs a new XPath context using the given node as the context node. The size is set to 1 and position is set to 0 and no variable bindings are provided.

Parameters:

node - the context XPathNode.

XPathContext

public XPathContext(XPathNode node,
                    VariableSet variables)

Constructs a new XPath context using the given node as as the context node. The size is set to 1 and position is set to 0. Variables bindings may be optionally provided.

Parameters:

node - the context XPathNode.

variable - Variable bindings, or null

XPathContext

public XPathContext(VariableSet variables,
                    NodeSet nodeSet,
                    int position)

Constructs a new XPath context. Variables bindings may be optionally provided, size and position are required.

Parameters:

variable - Variable bindings, or null

nodeSet - the context node-set for this XPathContext

position - The position of the context node (zero base)

Method Detail

addNamespaceBinding

public void addNamespaceBinding(java.lang.String prefix,
                                java.lang.String namespace)

Creates a binding within this XPathContext between a given prefix and a namespace URI. This namespace binding will be override any binding for the given prefix within a parent context, and will be available to all sub-contexts unless they also override the namespace binding with one of their own.

Parameters:

prefix - the prefix to associate with the namespace

namespace - the namespace URI.

getNode

public XPathNode getNode()

Returns the context node of this XPathContext

Returns:

the context node

getPosition

public int getPosition()

Returns the position of the context node. The position is a value between zero and the context size minus one. One must be added in order to obtain a value XPath position.

Returns:

The position of the context node

See Also:

getSize()

getSize

public int getSize()

Returns the size of the context.

Returns:

The size of the context

newContext

public XPathContext newContext(XPathNode node)

Creates a new XPathContext with this XPathContext as it's parent.

Returns:

the new XPathContext

newContext

public XPathContext newContext(NodeSet nodeSet,
                               int position)

Creates a new XPathContext with this XPathContext as it's parent.

Returns:

the new XPathContext

newNodeSet

public NodeSet newNodeSet(int size)

Constructs and returns a new node-set with the specified size.

Parameters:

size - The size of the node-set

Returns:

A new node-set with that size

newNodeSet

public NodeSet newNodeSet(XPathNode node)

Constructs and returns a new node-set with one node.

Parameters:

node - The node to include in the node-set

Returns:

A new node-set

newNodeSet

public NodeSet newNodeSet()

Constructs and returns a new empty node-set.

Returns:

A new empty node-set

getNodeSet

public NodeSet getNodeSet()

Returns the current context node-set.

Returns:

The current context node-set

setNodeSet

public void setNodeSet(NodeSet nodeSet,
                       int position)

Sets the given node-set as the context node-set for this XPathContext

Parameters:

nodeSet - the node-set to use as the context node-set.

position - the position of the context node

getDocumentOrder

public int[] getDocumentOrder(XPathNode node)

Returns the document order of the given node.

Returns:

The document order of the given node

getElementById

public XPathNode getElementById(XPathNode root,
                                java.lang.String id)

Returns the element associated with the given identifier. Locates the element underneath the specified root node.

Parameters:

root - The root node

id - The element's identifier

Returns:

The first element in document order with the given identifier, or null if no such element was found

getVariable

public XPathResult getVariable(java.lang.String name)

Returns the XPath result bound to the given variable name. Returns null if the variable was not set.

Parameters:

name - The variable name

Returns:

The variable's value

getFunction

public XPathFunction getFunction(java.lang.String uri,
                                 java.lang.String name)

Returns the XPath function by the given name, or null if no such function is defined.

Parameters:

uri - The function's namespace URI

name - The function's name within that URI

Returns:

The XPath function by the given name, or null if no such function is defined

getNamespaceURI

public java.lang.String getNamespaceURI(java.lang.String prefix)

Returns the namespace associated with the given prefix as defined in this context. Null is returned if no namespace has been defined.

Parameters:

prefix - the namespace prefix

Returns:

the namespace uri or null.

setPosition

public void setPosition(int position)

Sets the position of the context node within the context node-set

Parameters:

the - position of the context node within the context node-set

Throws:

java.lang.IndexOutOfBoundsException - when the position is not within the bounds of the context node-set.