org.apache.commons.jxpath.ri.model

Class NodePointer

Implemented Interfaces:
Cloneable, Comparable, Pointer, Serializable
Known Direct Subclasses:
CollectionPointer, ContainerPointer, DOMAttributePointer, DOMNodePointer, JDOMAttributePointer, JDOMNamespacePointer, JDOMNodePointer, LangAttributePointer, NamespacePointer, PropertyOwnerPointer, PropertyPointer, VariablePointer

public abstract class NodePointer
extends java.lang.Object
implements Pointer

Common superclass for Pointers of all kinds. A NodePointer maps to a deterministic XPath that represents the location of a node in an object graph. This XPath uses only simple axes: child, namespace and attribute and only simple, context-independent predicates.
Version:
$Revision: 1.25 $ $Date: 2004/04/01 02:55:32 $
Author:
Dmitri Plotnikov

Field Summary

static String
UNKNOWN_NAMESPACE
static int
WHOLE_COLLECTION
protected int
index
protected Locale
locale
protected NodePointer
parent

Constructor Summary

NodePointer(NodePointer parent)
NodePointer(NodePointer parent, Locale locale)

Method Summary

String
asPath()
Returns an XPath that maps to this Pointer.
NodeIterator
attributeIterator(QName qname)
Returns a NodeIterator that iterates over all attributes of the current node matching the supplied node name (could have a wildcard).
NodeIterator
childIterator(NodeTest test, boolean reverse, NodePointer startWith)
Returns a NodeIterator that iterates over all children or all children that match the given NodeTest, starting with the specified one.
Object
clone()
Pointers are cloneable
abstract int
compareChildNodePointers(NodePointer pointer1, NodePointer pointer2)
Compares two child NodePointers and returns a positive number, zero or a positive number according to the order of the pointers.
int
compareTo(Object object)
NodePointer
createAttribute(JXPathContext context, QName name)
Called to create a non-existing attribute
NodePointer
createChild(JXPathContext context, QName name, int index)
Called by a child pointer when it needs to create a parent object for a non-existent collection element.
NodePointer
createChild(JXPathContext context, QName name, int index, Object value)
Called by a child pointer if that child needs to assign the value supplied in the createPath(context, value) call to a non-existent node.
NodePointer
createPath(JXPathContext context)
Called by a child pointer when it needs to create a parent object.
NodePointer
createPath(JXPathContext context, Object value)
Called directly by JXPathContext.
abstract Object
getBaseValue()
Returns the value represented by the pointer before indexing.
protected String
getDefaultNamespaceURI()
abstract Object
getImmediateNode()
Returns the object the pointer points to; does not convert it to a "canonical" type.
NodePointer
getImmediateParentPointer()
NodePointer
getImmediateValuePointer()
int
getIndex()
If the pointer represents a collection, the index identifies an element of that collection.
abstract int
getLength()
If the pointer represents a collection (or collection element), returns the length of the collection.
Locale
getLocale()
If the Pointer has a parent, returns the parent's locale; otherwise returns the locale specified when this Pointer was created.
abstract QName
getName()
Returns the name of this node.
NamespaceResolver
getNamespaceResolver()
String
getNamespaceURI()
Returns the namespace URI associated with this Pointer.
String
getNamespaceURI(String prefix)
Decodes a namespace prefix to the corresponding URI.
Object
getNode()
Returns the object the pointer points to; does not convert it to a "canonical" type.
Object
getNodeValue()
Deprecated. 1.1 Please use getNode()
NodePointer
getParent()
Pointer
getPointerByID(JXPathContext context, String id)
Locates a node by ID.
Pointer
getPointerByKey(JXPathContext context, String key, String value)
Locates a node by key and value.
Object
getRootNode()
Returns the node this pointer is based on.
Object
getValue()
By default, returns getNode(), can be overridden to return a "canonical" value, like for instance a DOM element should return its string value.
NodePointer
getValuePointer()
If this pointer manages a transparent container, like a variable, this method returns the pointer to the contents.
boolean
isActual()
An actual pointer points to an existing part of an object graph, even if it is null.
boolean
isAttribute()
Returns true if the pointer represents the "attribute::" axis.
abstract boolean
isCollection()
Returns true if the value of the pointer is an array or a Collection.
boolean
isContainer()
If true, this node is axiliary and can only be used as an intermediate in the chain of pointers.
protected boolean
isDefaultNamespace(String prefix)
Returns true if the supplied prefix represents the default namespace in the context of the current node.
boolean
isLanguage(String lang)
Returns true if the selected locale name starts with the specified prefix lang, case-insensitive.
abstract boolean
isLeaf()
If true, this node does not have children
boolean
isNode()
Deprecated. Please use !isContainer()
boolean
isRoot()
Returns true if this Pointer has no parent.
NodeIterator
namespaceIterator()
Returns a NodeIterator that iterates over all namespaces of the value currently pointed at.
NodePointer
namespacePointer(String namespace)
Returns a NodePointer for the specified namespace.
static NodePointer
newChildNodePointer(NodePointer parent, QName name, Object bean)
Allocates an new child NodePointer by iterating through all installed NodePointerFactories until it finds one that can create a pointer.
static NodePointer
newNodePointer(QName name, Object bean, Locale locale)
Allocates an entirely new NodePointer by iterating through all installed NodePointerFactories until it finds one that can create a pointer.
void
printPointerChain()
Print internal structure of a pointer for debugging
void
remove()
Remove the node of the object graph this pointer points to.
void
setAttribute(boolean attribute)
Set to true if the pointer represents the "attribute::" axis.
void
setIndex(int index)
void
setNamespaceResolver(NamespaceResolver namespaceResolver)
abstract void
setValue(Object value)
Converts the value to the required type and changes the corresponding object to that value.
boolean
testNode(NodeTest test)
Checks if this Pointer matches the supplied NodeTest.
String
toString()

Field Details

UNKNOWN_NAMESPACE

public static final String UNKNOWN_NAMESPACE

WHOLE_COLLECTION

public static final int WHOLE_COLLECTION

index

protected int index

locale

protected Locale locale

parent

protected NodePointer parent

Constructor Details

NodePointer

protected NodePointer(NodePointer parent)

NodePointer

protected NodePointer(NodePointer parent,
                      Locale locale)

Method Details

asPath

public String asPath()
Returns an XPath that maps to this Pointer.
Specified by:
asPath in interface Pointer

attributeIterator

public NodeIterator attributeIterator(QName qname)
Returns a NodeIterator that iterates over all attributes of the current node matching the supplied node name (could have a wildcard). May return null if the object does not support the attributes.

childIterator

public NodeIterator childIterator(NodeTest test,
                                  boolean reverse,
                                  NodePointer startWith)
Returns a NodeIterator that iterates over all children or all children that match the given NodeTest, starting with the specified one.

clone

public Object clone()
Pointers are cloneable
Specified by:
clone in interface Pointer

compareChildNodePointers

public abstract int compareChildNodePointers(NodePointer pointer1,
                                             NodePointer pointer2)
Compares two child NodePointers and returns a positive number, zero or a positive number according to the order of the pointers.

compareTo

public int compareTo(Object object)

createAttribute

public NodePointer createAttribute(JXPathContext context,
                                   QName name)
Called to create a non-existing attribute

createChild

public NodePointer createChild(JXPathContext context,
                               QName name,
                               int index)
Called by a child pointer when it needs to create a parent object for a non-existent collection element. It may have to expand the collection, then create an element object and return a new pointer describing the newly created element.

createChild

public NodePointer createChild(JXPathContext context,
                               QName name,
                               int index,
                               Object value)
Called by a child pointer if that child needs to assign the value supplied in the createPath(context, value) call to a non-existent node. This method may have to expand the collection in order to assign the element.

createPath

public NodePointer createPath(JXPathContext context)
Called by a child pointer when it needs to create a parent object. Must create an object described by this pointer and return a new pointer that properly describes the new object.

createPath

public NodePointer createPath(JXPathContext context,
                              Object value)
Called directly by JXPathContext. Must create path and set value.

getBaseValue

public abstract Object getBaseValue()
Returns the value represented by the pointer before indexing. So, if the node represents an element of a collection, this method returns the collection itself.

getDefaultNamespaceURI

protected String getDefaultNamespaceURI()

getImmediateNode

public abstract Object getImmediateNode()
Returns the object the pointer points to; does not convert it to a "canonical" type.

getImmediateParentPointer

public NodePointer getImmediateParentPointer()

getImmediateValuePointer

public NodePointer getImmediateValuePointer()
Returns:
NodePointer is either this or a pointer for the immediately contained value.

getIndex

public int getIndex()
If the pointer represents a collection, the index identifies an element of that collection. The default value of index is WHOLE_COLLECTION, which just means that the pointer is not indexed at all. Note: the index on NodePointer starts with 0, not 1.

getLength

public abstract int getLength()
If the pointer represents a collection (or collection element), returns the length of the collection. Otherwise returns 1 (even if the value is null).

getLocale

public Locale getLocale()
If the Pointer has a parent, returns the parent's locale; otherwise returns the locale specified when this Pointer was created.

getName

public abstract QName getName()
Returns the name of this node. Can be null.

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

getNamespaceURI

public String getNamespaceURI()
Returns the namespace URI associated with this Pointer.

getNamespaceURI

public String getNamespaceURI(String prefix)
Decodes a namespace prefix to the corresponding URI.

getNode

public Object getNode()
Returns the object the pointer points to; does not convert it to a "canonical" type. Opens containers, properties etc and returns the ultimate contents.
Specified by:
getNode in interface Pointer

getNodeValue

public Object getNodeValue()

Deprecated. 1.1 Please use getNode()

Returns the object the pointer points to; does not convert it to a "canonical" type.

getParent

public NodePointer getParent()

getPointerByID

public Pointer getPointerByID(JXPathContext context,
                              String id)
Locates a node by ID.

getPointerByKey

public Pointer getPointerByKey(JXPathContext context,
                               String key,
                               String value)
Locates a node by key and value.

getRootNode

public Object getRootNode()
Returns the node this pointer is based on.
Specified by:
getRootNode in interface Pointer

getValue

public Object getValue()
By default, returns getNode(), can be overridden to return a "canonical" value, like for instance a DOM element should return its string value.
Specified by:
getValue in interface Pointer

getValuePointer

public NodePointer getValuePointer()
If this pointer manages a transparent container, like a variable, this method returns the pointer to the contents. Only an auxiliary (non-node) pointer can (and should) return a value pointer other than itself. Note that you probably don't want to override getValuePointer() directly. Override the getImmediateValuePointer() method instead. The getValuePointer() method is calls getImmediateValuePointer() and, if the result is not this, invokes getValuePointer() recursively. The idea here is to open all nested containers. Let's say we have a container within a container within a container. The getValuePointer() method should then open all those containers and return the pointer to the ultimate contents. It does so with the above recursion.

isActual

public boolean isActual()
An actual pointer points to an existing part of an object graph, even if it is null. A non-actual pointer represents a part that does not exist at all. For instance consider the pointer "/address/street". If both address and street are not null, the pointer is actual. If address is not null, but street is null, the pointer is still actual. If address is null, the pointer is not actual. (In JavaBeans) if address is not a property of the root bean, a Pointer for this path cannot be obtained at all - actual or otherwise.

isAttribute

public boolean isAttribute()
Returns true if the pointer represents the "attribute::" axis.

isCollection

public abstract boolean isCollection()
Returns true if the value of the pointer is an array or a Collection.

isContainer

public boolean isContainer()
If true, this node is axiliary and can only be used as an intermediate in the chain of pointers.

isDefaultNamespace

protected boolean isDefaultNamespace(String prefix)
Returns true if the supplied prefix represents the default namespace in the context of the current node.

isLanguage

public boolean isLanguage(String lang)
Returns true if the selected locale name starts with the specified prefix lang, case-insensitive.

isLeaf

public abstract boolean isLeaf()
If true, this node does not have children

isNode

public boolean isNode()

Deprecated. Please use !isContainer()


isRoot

public boolean isRoot()
Returns true if this Pointer has no parent.

namespaceIterator

public NodeIterator namespaceIterator()
Returns a NodeIterator that iterates over all namespaces of the value currently pointed at. May return null if the object does not support the namespaces.

namespacePointer

public NodePointer namespacePointer(String namespace)
Returns a NodePointer for the specified namespace. Will return null if namespaces are not supported. Will return UNKNOWN_NAMESPACE if there is no such namespace.

newChildNodePointer

public static NodePointer newChildNodePointer(NodePointer parent,
                                              QName name,
                                              Object bean)
Allocates an new child NodePointer by iterating through all installed NodePointerFactories until it finds one that can create a pointer.

newNodePointer

public static NodePointer newNodePointer(QName name,
                                         Object bean,
                                         Locale locale)
Allocates an entirely new NodePointer by iterating through all installed NodePointerFactories until it finds one that can create a pointer.

printPointerChain

public void printPointerChain()
Print internal structure of a pointer for debugging

remove

public void remove()
Remove the node of the object graph this pointer points to.

setAttribute

public void setAttribute(boolean attribute)
Set to true if the pointer represents the "attribute::" axis.

setIndex

public void setIndex(int index)

setNamespaceResolver

public void setNamespaceResolver(NamespaceResolver namespaceResolver)

setValue

public abstract void setValue(Object value)
Converts the value to the required type and changes the corresponding object to that value.
Specified by:
setValue in interface Pointer

testNode

public boolean testNode(NodeTest test)
Checks if this Pointer matches the supplied NodeTest.

toString

public String toString()