org.apache.xpath.objects
Class XObject

java.lang.Object
  |
  +--org.apache.xpath.Expression
        |
        +--org.apache.xpath.objects.XObject
Direct Known Subclasses:
NodeSequence, XBoolean, XNumber, XRTreeFrag, XString, XUnresolvedVariable, XUnresolvedVariableSimple

public class XObject
extends Expression
implements java.io.Serializable, java.lang.Cloneable

This class represents an XPath object, and is capable of converting the object to various types, such as a string. This class acts as the base class to other XPath type objects, such as XString, and provides polymorphic casting capabilities.

See Also:
Serialized Form
Usage:

Field Summary
static int CLASS_BOOLEAN
          Constant for BOOLEAN object type
static int CLASS_NODESET
          Constant for NODESET object type
static int CLASS_NULL
          Constant for NULL object type
static int CLASS_NUMBER
          Constant for NUMBER object type
static int CLASS_RTREEFRAG
          Constant for RESULT TREE FRAGMENT object type
static int CLASS_STRING
          Constant for STRING object type
static int CLASS_UNKNOWN
          Constant for UNKNOWN object type
static int CLASS_UNRESOLVEDVARIABLE
          Represents an unresolved variable type as an integer.
 
Constructor Summary
XObject()
          Create an XObject.
XObject(java.lang.Object obj)
          Create an XObject.
 
Method Summary
 void allowDetachToRelease(boolean allowRelease)
          Specify if it's OK for detach to release the iterator for reuse.
 void appendToFsb(FastStringBuffer fsb)
          Cast result object to a string.
 boolean bool()
          Cast result object to a boolean.
 boolean boolWithSideEffects()
          Cast result object to a boolean, but allow side effects, such as the incrementing of an iterator.
 void callVisitors(ExpressionOwner owner, XPathVisitor visitor)
           
 java.lang.Object castToType(int t, XPathContext support)
          Cast object to type t.
static XObject create(java.lang.Object val)
          Create the right XObject based on the type of the object passed.
static XObject create(java.lang.Object val, XPathContext xctxt)
          Create the right XObject based on the type of the object passed.
 boolean deepEquals(Expression expr)
           
 void destruct()
          Forces the object to release it's resources.
 void detach()
          Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state.
 void dispatchCharactersEvents(ContentHandler ch)
          Directly call the characters method on the passed ContentHandler for the string-value.
 boolean equals(XObject obj2)
          Tell if two objects are functionally equal.
 XObject execute(XPathContext xctxt)
          For support of literal objects in xpaths.
 void fixupVariables(java.util.Vector vars, int globalsSize)
          XObjects should not normally need to fix up variables.
 XObject getFresh()
          Get a fresh copy of the object.
 int getType()
          Tell what kind of class this is.
 java.lang.String getTypeString()
          Given a request type, return the equivalent string.
 boolean greaterThan(XObject obj2)
          Tell if one object is greater than the other.
 boolean greaterThanOrEqual(XObject obj2)
          Tell if one object is greater than or equal to the other.
 DTMIterator iter()
          Cast result object to a nodelist.
 boolean lessThan(XObject obj2)
          Tell if one object is less than the other.
 boolean lessThanOrEqual(XObject obj2)
          Tell if one object is less than or equal to the other.
 NodeSetDTM mutableNodeset()
          Cast result object to a nodelist.
 NodeList nodelist()
          Cast result object to a nodelist.
 NodeIterator nodeset()
          Cast result object to a nodelist.
 boolean notEquals(XObject obj2)
          Tell if two objects are functionally not equal.
 double num()
          Cast result object to a number.
 double numWithSideEffects()
          Cast result object to a number, but allow side effects, such as the incrementing of an iterator.
 java.lang.Object object()
          Return a java object that's closest to the representation that should be handed to an extension.
 void reset()
          Reset for fresh reuse.
 int rtf()
          For functions to override.
 int rtf(XPathContext support)
          Cast result object to a result tree fragment.
 DocumentFragment rtree()
          For functions to override.
 DocumentFragment rtree(XPathContext support)
          Cast result object to a result tree fragment.
 java.lang.String str()
          Cast result object to a string.
 java.lang.String toString()
          Return the string representation of the object
 XMLString xstr()
          Cast result object to a string.
 
Methods inherited from class org.apache.xpath.Expression
asIterator, asIteratorRaw, asNode, assertion, bool, canTraverseOutsideSubtree, error, execute, execute, execute, executeCharsToContentHandler, exprAddChild, exprGetChild, exprGetNumChildren, exprGetParent, exprSetParent, getColumnNumber, getExpressionOwner, getLineNumber, getPublicId, getSystemId, isNodesetExpr, isStableNumber, num, warn, xstr
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Field Detail

CLASS_NULL

public static final int CLASS_NULL
Constant for NULL object type

CLASS_UNKNOWN

public static final int CLASS_UNKNOWN
Constant for UNKNOWN object type

CLASS_BOOLEAN

public static final int CLASS_BOOLEAN
Constant for BOOLEAN object type

CLASS_NUMBER

public static final int CLASS_NUMBER
Constant for NUMBER object type

CLASS_STRING

public static final int CLASS_STRING
Constant for STRING object type

CLASS_NODESET

public static final int CLASS_NODESET
Constant for NODESET object type

CLASS_RTREEFRAG

public static final int CLASS_RTREEFRAG
Constant for RESULT TREE FRAGMENT object type

CLASS_UNRESOLVEDVARIABLE

public static final int CLASS_UNRESOLVEDVARIABLE
Represents an unresolved variable type as an integer.
Constructor Detail

XObject

public XObject()
Create an XObject.

XObject

public XObject(java.lang.Object obj)
Create an XObject.
Parameters:
obj - Can be any object, should be a specific type for derived classes, or null.
Method Detail

execute

public XObject execute(XPathContext xctxt)
                throws TransformerException
For support of literal objects in xpaths.
Parameters:
xctxt - The XPath execution context.
Returns:
This object.
Throws:
TransformerException -  
Overrides:
execute in class Expression

allowDetachToRelease

public void allowDetachToRelease(boolean allowRelease)
Specify if it's OK for detach to release the iterator for reuse. This function should be called with a value of false for objects that are stored in variables. Calling this with a value of false on a XNodeSet will cause the nodeset to be cached.
Parameters:
allowRelease - true if it is OK for detach to release this iterator for pooling.

detach

public void detach()
Detaches the DTMIterator from the set which it iterated over, releasing any computational resources and placing the iterator in the INVALID state. After detach has been invoked, calls to nextNode or previousNode will raise a runtime exception.

destruct

public void destruct()
Forces the object to release it's resources. This is more harsh than detach().

reset

public void reset()
Reset for fresh reuse.

dispatchCharactersEvents

public void dispatchCharactersEvents(ContentHandler ch)
                              throws SAXException
Directly call the characters method on the passed ContentHandler for the string-value. Multiple calls to the ContentHandler's characters methods may well occur for a single call to this method.
Parameters:
ch - A non-null reference to a ContentHandler.
Throws:
SAXException -  

create

public static XObject create(java.lang.Object val)
Create the right XObject based on the type of the object passed. This function can not make an XObject that exposes DOM Nodes, NodeLists, and NodeIterators to the XSLT stylesheet as node-sets.
Parameters:
val - The java object which this object will wrap.
Returns:
the right XObject based on the type of the object passed.

create

public static XObject create(java.lang.Object val,
                             XPathContext xctxt)
Create the right XObject based on the type of the object passed. This function can make an XObject that exposes DOM Nodes, NodeLists, and NodeIterators to the XSLT stylesheet as node-sets.
Parameters:
val - The java object which this object will wrap.
xctxt - The XPath context.
Returns:
the right XObject based on the type of the object passed.

getType

public int getType()
Tell what kind of class this is.
Returns:
CLASS_UNKNOWN

getTypeString

public java.lang.String getTypeString()
Given a request type, return the equivalent string. For diagnostic purposes.
Returns:
type string "#UNKNOWN" + object class name

num

public double num()
           throws TransformerException
Cast result object to a number. Always issues an error.
Returns:
0.0
Throws:
TransformerException -  

numWithSideEffects

public double numWithSideEffects()
                          throws TransformerException
Cast result object to a number, but allow side effects, such as the incrementing of an iterator.
Returns:
numeric value of the string conversion from the next node in the NodeSetDTM, or NAN if no node was found

bool

public boolean bool()
             throws TransformerException
Cast result object to a boolean. Always issues an error.
Returns:
false
Throws:
TransformerException -  

boolWithSideEffects

public boolean boolWithSideEffects()
                            throws TransformerException
Cast result object to a boolean, but allow side effects, such as the incrementing of an iterator.
Returns:
True if there is a next node in the nodeset

xstr

public XMLString xstr()
Cast result object to a string.
Returns:
The string this wraps or the empty string if null

str

public java.lang.String str()
Cast result object to a string.
Returns:
The object as a string

toString

public java.lang.String toString()
Return the string representation of the object
Returns:
the string representation of the object
Overrides:
toString in class java.lang.Object

rtf

public int rtf(XPathContext support)
Cast result object to a result tree fragment.
Parameters:
support - XPath context to use for the conversion
Returns:
the objec as a result tree fragment.

rtree

public DocumentFragment rtree(XPathContext support)
Cast result object to a result tree fragment.
Parameters:
support - XPath context to use for the conversion
Returns:
the objec as a result tree fragment.

rtree

public DocumentFragment rtree()
For functions to override.
Returns:
null

rtf

public int rtf()
For functions to override.
Returns:
null

object

public java.lang.Object object()
Return a java object that's closest to the representation that should be handed to an extension.
Returns:
The object that this class wraps

iter

public DTMIterator iter()
                 throws TransformerException
Cast result object to a nodelist. Always issues an error.
Returns:
null
Throws:
TransformerException -  

getFresh

public XObject getFresh()
Get a fresh copy of the object. For use with variables.
Returns:
This object, unless overridden by subclass.

nodeset

public NodeIterator nodeset()
                     throws TransformerException
Cast result object to a nodelist. Always issues an error.
Returns:
null
Throws:
TransformerException -  

nodelist

public NodeList nodelist()
                  throws TransformerException
Cast result object to a nodelist. Always issues an error.
Returns:
null
Throws:
TransformerException -  

mutableNodeset

public NodeSetDTM mutableNodeset()
                          throws TransformerException
Cast result object to a nodelist. Always issues an error.
Returns:
The object as a NodeSetDTM.
Throws:
TransformerException -  

castToType

public java.lang.Object castToType(int t,
                                   XPathContext support)
                            throws TransformerException
Cast object to type t.
Parameters:
t - Type of object to cast this to
support - XPath context to use for the conversion
Returns:
This object as the given type t
Throws:
TransformerException -  

lessThan

public boolean lessThan(XObject obj2)
                 throws TransformerException
Tell if one object is less than the other.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is less than the given object
Throws:
TransformerException -  

lessThanOrEqual

public boolean lessThanOrEqual(XObject obj2)
                        throws TransformerException
Tell if one object is less than or equal to the other.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is less than or equal to the given object
Throws:
TransformerException -  

greaterThan

public boolean greaterThan(XObject obj2)
                    throws TransformerException
Tell if one object is greater than the other.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is greater than the given object
Throws:
TransformerException -  

greaterThanOrEqual

public boolean greaterThanOrEqual(XObject obj2)
                           throws TransformerException
Tell if one object is greater than or equal to the other.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is greater than or equal to the given object
Throws:
TransformerException -  

equals

public boolean equals(XObject obj2)
Tell if two objects are functionally equal.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is equal to the given object
Throws:
TransformerException -  

notEquals

public boolean notEquals(XObject obj2)
                  throws TransformerException
Tell if two objects are functionally not equal.
Parameters:
obj2 - Object to compare this to
Returns:
True if this object is not equal to the given object
Throws:
TransformerException -  

fixupVariables

public void fixupVariables(java.util.Vector vars,
                           int globalsSize)
XObjects should not normally need to fix up variables.
Overrides:
fixupVariables in class Expression

appendToFsb

public void appendToFsb(FastStringBuffer fsb)
Cast result object to a string. NEEDSDOC @param fsb
Returns:
The string this wraps or the empty string if null

callVisitors

public void callVisitors(ExpressionOwner owner,
                         XPathVisitor visitor)
See Also:
XPathVisitable.callVisitors(ExpressionOwner, XPathVisitor)

deepEquals

public boolean deepEquals(Expression expr)
Overrides:
deepEquals in class Expression
See Also:
Expression.deepEquals(Expression)


Copyright 2006 Apache XML Project. All Rights Reserved.