Package net.sf.saxon.expr
Class NegateExpression
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.UnaryExpression
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- net.sf.saxon.expr.NegateExpression
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- All Implemented Interfaces:
ExportAgent,Locatable,IdentityComparable,Traceable
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.
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Field Summary
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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
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Constructor Summary
Constructors Constructor Description NegateExpression(Expression base)Create a NegateExpression
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description intcomputeCardinality()Determine the static cardinality.Expressioncopy(RebindingMap rebindings)Copy an expression.protected java.lang.StringdisplayOperator(Configuration config)Give a string representation of the operator for use in diagnosticsNumericValueevaluateItem(XPathContext context)Evaluate the expression.voidexport(ExpressionPresenter out)Diagnostic print of expression structure.java.lang.StringgetExpressionName()Get a name identifying the kind of expression, in terms meaningful to a user.intgetImplementationMethod()An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().ItemTypegetItemType()Determine the data type of the expression, if this is known staticallyprotected OperandRolegetOperandRole()Get the usage (in terms of streamability analysis) of the single operandbooleanisBackwardsCompatible()Ask whether the expression is to be evaluated in XPath 1.0 compatibility modevoidsetBackwardsCompatible(boolean compatible)Set whether the expression is to be evaluated in XPath 1.0 compatibility modeExpressiontypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.UnaryExpression
computeHashCode, computeSpecialProperties, emitExtraAttributes, equals, getBaseExpression, getOperand, operands, optimize, setBaseExpression, toShortString, toString
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Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExtraProperty, getIntegerBounds, getInterpretedExpression, getIntrinsicDependencies, 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, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, suppressValidation, toPattern, typeCheckChildren, typeError, unordered, verifyParentPointers
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Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
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Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Detail
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NegateExpression
public NegateExpression(Expression base)
Create a NegateExpression- Parameters:
base- the expression that computes the value whose sign is to be reversed
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Method Detail
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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
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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
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getOperandRole
protected OperandRole getOperandRole()
Description copied from class:UnaryExpressionGet the usage (in terms of streamability analysis) of the single operand- Specified by:
getOperandRolein classUnaryExpression- Returns:
- the operand usage
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Description copied from class:UnaryExpressionType-check the expression. Default implementation for unary operators that accept any kind of operand- Overrides:
typeCheckin classUnaryExpression- Parameters:
visitor- an expression visitorcontextInfo- Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.- 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)
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getItemType
public ItemType getItemType()
Determine the data type of the expression, if this is known statically- Overrides:
getItemTypein classUnaryExpression- Returns:
- the item type of the items in the result sequence, insofar as this is known statically.
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computeCardinality
public int computeCardinality()
Description copied from class:UnaryExpressionDetermine the static cardinality. Default implementation returns the cardinality of the operand- Overrides:
computeCardinalityin classUnaryExpression- 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. May also returnStaticProperty.ALLOWS_ZEROif the result is known to be an empty sequence, orStaticProperty.ALLOWS_MANYif if is known to return a sequence of length two or more.
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getImplementationMethod
public int getImplementationMethod()
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process(). This method indicates which of these methods is provided directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.- Specified by:
getImplementationMethodin classExpression- Returns:
- the implementation method, for example
Expression.ITERATE_METHODorExpression.EVALUATE_METHODorExpression.PROCESS_METHOD
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evaluateItem
public NumericValue evaluateItem(XPathContext context) throws XPathException
Evaluate the expression.- Overrides:
evaluateItemin classExpression- 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
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copy
public Expression copy(RebindingMap rebindings)
Copy an expression. This makes a deep copy.- Specified by:
copyin classExpression- Parameters:
rebindings-- Returns:
- the copy of the original expression
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displayOperator
protected java.lang.String displayOperator(Configuration config)
Description copied from class:UnaryExpressionGive a string representation of the operator for use in diagnostics- Overrides:
displayOperatorin classUnaryExpression- Parameters:
config- the Saxon configuration- Returns:
- the operator, as a string
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getExpressionName
public java.lang.String getExpressionName()
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionNamein classExpression- 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.
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export
public void export(ExpressionPresenter out) throws XPathException
Description copied from class:UnaryExpressionDiagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
exportin interfaceExportAgent- Overrides:
exportin classUnaryExpression- Parameters:
out- the expression presenter used to display the structure- Throws:
XPathException- if the export fails, for example if an expression is found that won't work in the target environment.
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