net.sf.saxon.expr

Class NegateExpression

java.lang.Object

net.sf.saxon.expr.Expression

net.sf.saxon.expr.UnaryExpression

net.sf.saxon.expr.NegateExpression

All Implemented Interfaces:

Serializable, SourceLocator, LocationProvider, SaxonLocator, InstructionInfo, Locator

public class NegateExpression
extends UnaryExpression

Negate Expression: implements the unary minus operator. This expression is initially created as an ArithmeticExpression (or in backwards compatibility mode, an ArithmeticExpression10) to take advantage of the type checking code. So we don't need to worry about type checking or argument conversion.

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
NegateExpression(Expression base) Create a NegateExpression

Method Summary

Methods

Modifier and Type	Method and Description
Expression	copy() Copy an expression.
protected String	displayOperator(Configuration config) Give a string representation of the operator for use in diagnostics
NumericValue	evaluateItem(XPathContext context) Evaluate the expression.
ExpressionCompiler	getExpressionCompiler() Return the compiler of the Negate expression
String	getExpressionName() Get a name identifying the kind of expression, in terms meaningful to a user.
ItemType	getItemType(TypeHierarchy th) Determine the data type of the expression, if this is known statically
boolean	isBackwardsCompatible() Ask whether the expression is to be evaluated in XPath 1.0 compatibility mode
void	setBackwardsCompatible(boolean compatible) Set whether the expression is to be evaluated in XPath 1.0 compatibility mode
Expression	typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the expression.

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

computeCardinality, computeSpecialProperties, equals, explain, getBaseExpression, hashCode, iterateSubExpressions, optimize, promote, replaceSubExpression, simplify, toString

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

addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getEvaluationMethod, getExecutable, 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

NegateExpression

public NegateExpression(Expression base)

Create a NegateExpression

Parameters:

base - the expression that computes the value whose sign is to be reversed

Method Detail

setBackwardsCompatible

public void setBackwardsCompatible(boolean compatible)

Set whether the expression is to be evaluated in XPath 1.0 compatibility mode

Parameters:

compatible - true if XPath 1.0 compatibility mode is enabled

isBackwardsCompatible

public boolean isBackwardsCompatible()

Ask whether the expression is to be evaluated in XPath 1.0 compatibility mode

Returns:

true if XPath 1.0 compatibility mode is enabled

typeCheck

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

Description copied from class: UnaryExpression

Type-check the expression. Default implementation for unary operators that accept any kind of operand

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)

getItemType

public ItemType getItemType(TypeHierarchy th)

Determine the data type of the expression, if this is known statically

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.

evaluateItem

public NumericValue 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

getExpressionCompiler

public ExpressionCompiler getExpressionCompiler()

Return the compiler of the Negate expression

Overrides:

getExpressionCompiler in class Expression

Returns:

the relevant ExpressionCompiler

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

displayOperator

protected String displayOperator(Configuration config)

Description copied from class: UnaryExpression

Give a string representation of the operator for use in diagnostics

Overrides:

displayOperator in class UnaryExpression

Parameters:

config - the Saxon configuration

Returns:

the operator, as a string

getExpressionName

public String getExpressionName()

Get a name identifying the kind of expression, in terms meaningful to a user.

Overrides:

getExpressionName in class Expression

Returns:

a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.