public final class EmptySequence extends Value
EMPTY_CLASS_ARRAY
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
EMPTY_VALUE_ARRAY
Modifier and Type | Method and Description |
---|---|
void |
display(int level,
NamePool pool,
PrintStream out)
Diagnostic print of expression structure
|
boolean |
effectiveBooleanValue(XPathContext context)
Get the effective boolean value - always false
|
boolean |
equals(Object other)
Is this expression the same as another expression?
|
int |
getCardinality()
Determine the static cardinality
|
int |
getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
|
static EmptySequence |
getInstance()
Get the implicit instance of this class
|
ItemType |
getItemType(TypeHierarchy th)
Determine the item type
|
int |
getLength()
Get the length of the sequence
|
int |
getSpecialProperties()
Get the static properties of this expression (other than its type).
|
int |
hashCode()
Return a hash code to support the equals() function
|
SequenceIterator |
iterate(XPathContext context)
Return an iteration over the sequence
|
asItem, asIterator, asValue, checkPermittedContents, collapseWhitespace, convert, convertJavaObjectToXPath, convertToJava, evaluateAsString, evaluateItem, getDependencies, getIterator, getParentExpression, getStringValue, itemAt, iterateSubExpressions, makeQNameValue, normalizeWhitespace, optimize, process, promote, reduce, schemaEquals, simplify, stringToNumber, toString, trimWhitespace, typeCheck
public static EmptySequence getInstance()
public int getImplementationMethod()
public SequenceIterator iterate(XPathContext context)
context
- supplies the context for evaluationpublic ItemType getItemType(TypeHierarchy th)
getItemType
in interface Expression
getItemType
in class Value
th
- public int getCardinality()
getCardinality
in interface Expression
getCardinality
in class Value
StaticProperty.ALLOWS_ONE
,
StaticProperty.ALLOWS_ZERO_OR_MORE
, StaticProperty.ALLOWS_ZERO_OR_ONE
,
StaticProperty.ALLOWS_ONE_OR_MORE
, StaticProperty.EMPTY
. This default
implementation returns ZERO_OR_MORE (which effectively gives no
information).public int getSpecialProperties()
getSpecialProperties
in interface Expression
getSpecialProperties
in class Value
StaticProperty.NON_CREATIVE
public final int getLength()
public boolean equals(Object other)
equals
in class Value
ClassCastException
- if the values are not comparablepublic int hashCode()
Value
public boolean effectiveBooleanValue(XPathContext context)
effectiveBooleanValue
in interface Expression
effectiveBooleanValue
in class Value
context
- The context in which the expression is to be evaluatedpublic void display(int level, NamePool pool, PrintStream out)
display
in interface Expression
display
in class Value
level
- indentation level for this expressionpool
- NamePool used to expand any names appearing in the expressionout
- Output destination