java.io.Serializable
, Expression
, ValueRepresentation
public final class EmptySequence extends Value
EVALUATE_METHOD, ITERATE_METHOD, PROCESS_METHOD
EMPTY_CLASS_ARRAY
EMPTY_VALUE_ARRAY
Modifier and Type | Method | Description |
---|---|---|
void |
display(int level,
java.io.PrintStream out,
Configuration config) |
Diagnostic print of expression structure
|
boolean |
effectiveBooleanValue(XPathContext context) |
Get the effective boolean value - always false
|
boolean |
equals(java.lang.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
|
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
asItem, asIterator, asValue, checkPermittedContents, convert, convertJavaObjectToXPath, convertToJava, evaluateAsString, evaluateItem, getDependencies, getIterator, getParentExpression, getStringValue, getStringValueCS, itemAt, iterateSubExpressions, makeQNameValue, optimize, process, promote, reduce, simplify, stringToNumber, toString, typeCheck
public static EmptySequence getInstance()
public int getImplementationMethod()
public SequenceIterator iterate(XPathContext context)
context
- The context in which the expression is to be evaluated. Note that this
context must contain a stackframe with sufficient slots to allow evaluation of any
variables contained in the expression (including variables allocated internally
by the optimizer)public 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(java.lang.Object other)
public 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, java.io.PrintStream out, Configuration config)
display
in interface Expression
display
in class Value
level
- indentation level for this expressionout
- Output destination