Package net.sf.saxon.expr

Class CastingExpression

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.UnaryExpression

net.sf.saxon.expr.CastingExpression

All Implemented Interfaces:

ExportAgent, Locatable, IdentityComparable, Traceable

Direct Known Subclasses:

CastableExpression, CastExpression

public abstract class CastingExpression
extends UnaryExpression

Casting Expression: abstract superclass for "cast as X" and "castable as X", which share a good deal of logic

Field Summary

Fields

Modifier and Type	Field	Description
protected Converter	converter

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

EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, MAX_COST, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, UPDATE_METHOD, WATCH_METHOD

Constructor Summary

Constructors

Constructor	Description
CastingExpression(Expression source, AtomicType target, boolean allowEmpty)	Create a cast expression

Method Summary

Modifier and Type	Method	Description
boolean	allowsEmpty()	Ask whether the expression accepts an empty sequence as input (producing an empty sequence as output)
protected int	computeSpecialProperties()	Determine the special properties of this expression
protected void	export(ExpressionPresenter out, java.lang.String elemName)	Export expression structure to SEF file.
Converter	getConverter()	Get the Converter allocated to implement this cast expression, if any
int	getIntrinsicDependencies()	Get the expression's dependencies.
NamespaceResolver	getNamespaceResolver()	Get the namespace resolver, if any
protected OperandRole	getOperandRole()	Get the usage (in terms of streamability analysis) of the single operand
AtomicType	getTargetPrimitiveType()	Get the primitive base type of the target type of the cast
AtomicType	getTargetType()	Get the target type (the result type)
boolean	isOperandIsStringLiteral()	Ask whether the operand to the cast expression was supplied in the form of a string literal.
void	setAllowEmpty(boolean allow)	Say whether the expression accepts an empty sequence as input (producing an empty sequence as output)
void	setOperandIsStringLiteral(boolean option)	Say whether the operand to the cast expression was supplied in the form of a string literal.
void	setTargetType(AtomicType type)	Set the target type
Expression	simplify()	Simplify the expression

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

computeCardinality, computeHashCode, displayOperator, emitExtraAttributes, equals, export, getBaseExpression, getItemType, getOperand, operands, optimize, setBaseExpression, toShortString, toString, typeCheck

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

addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, dispatchTailCall, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, getCardinality, getConfiguration, getCost, getDependencies, getElaborator, getEvaluationMethod, getExpressionName, getExtraProperty, getImplementationMethod, getIntegerBounds, getLocalRetainedStaticContext, getLocation, getNetCost, getObjectName, getPackageData, getParentExpression, getProperties, getProperty, getRetainedStaticContext, getScopingExpression, getSlotsUsed, getSpecialProperties, getStaticBaseURI, getStaticBaseURIString, getStaticType, getStaticUType, getStreamerName, getTracingTag, hasCompatibleStaticContext, hashCode, hasSpecialProperty, hasVariableBinding, identityHashCode, implementsStaticTypeCheck, isCallOn, isEqual, isIdentical, isInstruction, isLiftable, isMultiThreaded, isStaticPropertiesKnown, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, makeElaborator, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers, withLocation

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.sf.saxon.trace.Traceable

gatherProperties

Field Detail

converter

protected Converter converter

Constructor Detail

CastingExpression

public CastingExpression(Expression source,
                         AtomicType target,
                         boolean allowEmpty)

Create a cast expression

Parameters:

source - expression giving the value to be converted

target - the type to which the value is to be converted

allowEmpty - true if the expression allows an empty sequence as input, producing an empty sequence as output. If false, an empty sequence is a type error.

Method Detail

getTargetPrimitiveType

public AtomicType getTargetPrimitiveType()

Get the primitive base type of the target type of the cast

Returns:

the primitive type of the target type

setTargetType

public void setTargetType(AtomicType type)

Set the target type

Parameters:

type - the target type for the cast

getTargetType

public AtomicType getTargetType()

Get the target type (the result type)

Returns:

the target type

getOperandRole

protected OperandRole getOperandRole()

Description copied from class: UnaryExpression

Get the usage (in terms of streamability analysis) of the single operand

Specified by:

getOperandRole in class UnaryExpression

Returns:

the operand usage

setAllowEmpty

public void setAllowEmpty(boolean allow)

Say whether the expression accepts an empty sequence as input (producing an empty sequence as output)

Parameters:

allow - true if an empty sequence is accepted

allowsEmpty

public boolean allowsEmpty()

Ask whether the expression accepts an empty sequence as input (producing an empty sequence as output)

Returns:

true if an empty sequence is accepted

setOperandIsStringLiteral

public void setOperandIsStringLiteral(boolean option)

Say whether the operand to the cast expression was supplied in the form of a string literal. This is relevant only for XPath 2.0 / XQuery 1.0, and then only when the target type is a QName or NOTATION.

Parameters:

option - true if the operand was supplied as a string literal

isOperandIsStringLiteral

public boolean isOperandIsStringLiteral()

Ask whether the operand to the cast expression was supplied in the form of a string literal. This is relevant only for XPath 2.0 / XQuery 1.0, and then only when the target type is a QName or NOTATION.

Returns:

true if the operand was supplied as a string literal

getConverter

public Converter getConverter()

Get the Converter allocated to implement this cast expression, if any

Returns:

the Converter if one has been statically allocated, or null if not

getNamespaceResolver

public NamespaceResolver getNamespaceResolver()

Get the namespace resolver, if any

Returns:

the namespace resolver that was statically allocated if the target type is namespace-sensitive

getIntrinsicDependencies

public int getIntrinsicDependencies()

Get the expression's dependencies. If the target type is namespace-sensitive, then the expression has a dependency on the namespace bindings in the static context

Overrides:

getIntrinsicDependencies in class Expression

Returns:

the expression's dependencies.

simplify

public Expression simplify()
                    throws XPathException

Simplify the expression

Overrides:

simplify in class Expression

Returns:

the simplified expression (or the original if unchanged, or if modified in-situ)

Throws:

XPathException - if an error is discovered during expression rewriting

computeSpecialProperties

protected int computeSpecialProperties()

Determine the special properties of this expression

Overrides:

computeSpecialProperties in class UnaryExpression

Returns:

StaticProperty.NO_NODES_NEWLY_CREATED.

export

protected void export(ExpressionPresenter out,
                      java.lang.String elemName)
               throws XPathException

Export expression structure to SEF file. The abstract expression tree is written to the supplied output destination. Helper method for subclasses.

Parameters:

out - the destination of the output

elemName - the element name to be used in the SEF file

Throws:

XPathException - if output fails