net.sf.saxon.expr

Class CastableToUnion

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.UnaryExpression

net.sf.saxon.expr.CastableToUnion

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class CastableToUnion
extends UnaryExpression

Expression class for a cast to a union type

See Also:

Serialized Form

Field Summary

Fields inherited from class net.sf.saxon.expr.UnaryExpression

operand

Fields inherited from class net.sf.saxon.expr.Expression

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, INHERITED_CONTEXT, INSPECTION_CONTEXT, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, NAVIGATION_CONTEXT, NODE_VALUE_CONTEXT, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, W3C_CONSUMING, W3C_FREE_RANGING, W3C_GROUP_CONSUMING, W3C_MOTIONLESS, WATCH_METHOD

Constructor Summary

Constructors

Constructor and Description
CastableToUnion(Expression source, UnionType targetType, boolean allowEmpty)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	allowsEmpty()
int	computeCardinality() Get the static cardinality of the expression
int	computeSpecialProperties() Determine the special properties of this expression
Expression	copy() Copy an expression.
boolean	effectiveBooleanValue(XPathContext context) Get the effective boolean value of the expression.
boolean	equals(Object other) Is this expression the same as another expression?
BooleanValue	evaluateItem(XPathContext context) Evaluate the expression
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
CastableToUnionCompiler	getExpressionCompiler() Return the compiler of the CastableToUnion expression
ItemType	getItemType(TypeHierarchy th) Get the static type of the expression
NamespaceResolver	getNamespaceResolver()
UnionType	getTargetType()
int	hashCode() get HashCode for comparing two expressions.
boolean	isAllowEmpty()
Expression	optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Perform optimisation of an expression and its subexpressions.
Expression	simplify(ExpressionVisitor visitor) Simplify the expression
String	toString() The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath.
Expression	typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the expression

Methods inherited from class net.sf.saxon.expr.UnaryExpression

displayOperator, getBaseExpression, iterateSubExpressions, promote, replaceSubExpression

Methods inherited from class net.sf.saxon.expr.Expression

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, getExpressionName, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getStreamability, getStreamingAdjunct, getSystemId, getSystemId, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSubExpressionInfo, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, toPattern, toStreamingPattern, typeError

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CastableToUnion

public CastableToUnion(Expression source,
               UnionType targetType,
               boolean allowEmpty)

Method Detail

isAllowEmpty

public boolean isAllowEmpty()

getTargetType

public UnionType getTargetType()

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

simplify

public Expression simplify(ExpressionVisitor visitor)
                    throws XPathException

Simplify the expression

Overrides:

simplify in class UnaryExpression

Parameters:

visitor - an expression visitor

Returns:

the simplified expression

Throws:

XPathException - if an error is discovered during expression rewriting

typeCheck

public Expression typeCheck(ExpressionVisitor visitor,
                   ExpressionVisitor.ContextItemType contextItemType)
                     throws XPathException

Type-check the expression

Overrides:

typeCheck in class UnaryExpression

Parameters:

visitor - an expression visitor

contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

optimize

public Expression optimize(ExpressionVisitor visitor,
                  ExpressionVisitor.ContextItemType contextItemType)
                    throws XPathException

Perform optimisation of an expression and its subexpressions.

This method is called after all references to functions and variables have been resolved to the declaration of the function or variable, and after all type checking has been done.

Overrides:

optimize in class UnaryExpression

Parameters:

visitor - an expression visitor

contextItemType - the static type of "." at the point where this expression is invoked. The parameter is set to null if it is known statically that the context item will be undefined. If the type of the context item is not known statically, the argument is set to Type.ITEM_TYPE

Returns:

the original expression, rewritten if appropriate to optimize execution

Throws:

XPathException - if an error is discovered during this phase (typically a type error)

computeCardinality

public int computeCardinality()

Get the static cardinality of the expression

Overrides:

computeCardinality in class UnaryExpression

Returns:

the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE

getItemType

public ItemType getItemType(TypeHierarchy th)

Get the static type of the expression

Overrides:

getItemType in class UnaryExpression

Parameters:

th - the type hierarchy cache

Returns:

the item type of the items in the result sequence, insofar as this is known statically.

computeSpecialProperties

public int computeSpecialProperties()

Determine the special properties of this expression

Overrides:

computeSpecialProperties in class UnaryExpression

Returns:

StaticProperty.NON_CREATIVE.

allowsEmpty

public boolean allowsEmpty()

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Specified by:

copy in class Expression

Returns:

the copy of the original expression

evaluateItem

public BooleanValue evaluateItem(XPathContext context)
                          throws XPathException

Evaluate the expression

Overrides:

evaluateItem in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence

Throws:

XPathException - if any dynamic error occurs evaluating the expression

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
                              throws XPathException

Description copied from class: Expression

Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.

Overrides:

effectiveBooleanValue in class Expression

Parameters:

context - The context in which the expression is to be evaluated

Returns:

the effective boolean value

Throws:

XPathException - if any dynamic error occurs evaluating the expression

equals

public boolean equals(Object other)

Is this expression the same as another expression?

Overrides:

equals in class UnaryExpression

hashCode

public int hashCode()

get HashCode for comparing two expressions.

Overrides:

hashCode in class UnaryExpression

getExpressionCompiler

public CastableToUnionCompiler getExpressionCompiler()

Return the compiler of the CastableToUnion expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

toString

public String toString()

The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax

Overrides:

toString in class UnaryExpression

Returns:

a representation of the expression as a string

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

Overrides:

explain in class UnaryExpression

Parameters:

out - the expression presenter used to display the structure