Package net.sf.saxon.expr
Class UnaryExpression
- 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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- All Implemented Interfaces:
ExportAgent,Locatable,IdentityComparable,Traceable
- Direct Known Subclasses:
AdjacentTextNodeMerger,AtomicSequenceConverter,Atomizer,ByteCodeCandidate,CardinalityChecker,CastingExpression,CompareToConstant,ConsumingOperand,DocumentSorter,EmptyTextNodeRemover,FunctionSequenceCoercer,HomogeneityChecker,InstanceOfExpression,ItemChecker,LookupAllExpression,NegateExpression,OnEmptyExpr,OnNonEmptyExpr,SequenceInstr,SingleItemFilter,SingletonAtomizer,TailCallLoop,TailExpression,WherePopulated
public abstract class UnaryExpression extends Expression
Unary Expression: an expression taking a single operand expression
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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 UnaryExpression(Expression p0)
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description intcomputeCardinality()Determine the static cardinality.intcomputeHashCode()get HashCode for comparing two expressions.intcomputeSpecialProperties()Get the static properties of this expression (other than its type).protected java.lang.StringdisplayOperator(Configuration config)Give a string representation of the operator for use in diagnosticsprotected voidemitExtraAttributes(ExpressionPresenter out)booleanequals(java.lang.Object other)Is this expression the same as another expression?voidexport(ExpressionPresenter out)Diagnostic print of expression structure.ExpressiongetBaseExpression()ItemTypegetItemType()Determine the data type of the expression, if possible.OperandgetOperand()protected abstract OperandRolegetOperandRole()Get the usage (in terms of streamability analysis) of the single operandjava.lang.Iterable<Operand>operands()Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.Expressionoptimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Perform optimisation of an expression and its subexpressions.voidsetBaseExpression(Expression child)java.lang.StringtoShortString()Produce a short string identifying the expression for use in error messagesjava.lang.StringtoString()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.ExpressiontypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, evaluatePendingUpdates, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExpressionName, getExtraProperty, getImplementationMethod, 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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UnaryExpression
public UnaryExpression(Expression p0)
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Method Detail
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getBaseExpression
public Expression getBaseExpression()
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setBaseExpression
public void setBaseExpression(Expression child)
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getOperand
public Operand getOperand()
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operands
public java.lang.Iterable<Operand> operands()
Description copied from class:ExpressionGet the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation works off the results of iterateSubExpressions()If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.
- Overrides:
operandsin classExpression- Returns:
- an iterator containing the sub-expressions of this expression
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getOperandRole
protected abstract OperandRole getOperandRole()
Get the usage (in terms of streamability analysis) of the single operand- Returns:
- the operand usage
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Type-check the expression. Default implementation for unary operators that accept any kind of operand- Overrides:
typeCheckin classExpression- 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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optimize
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) 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:
optimizein classExpression- Parameters:
visitor- an expression visitorcontextInfo- 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 toType.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)
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computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.- Overrides:
computeSpecialPropertiesin classExpression- Returns:
- the special properties, as a bit-significant integer
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computeCardinality
public int computeCardinality()
Determine the static cardinality. Default implementation returns the cardinality of the operand- Specified by:
computeCardinalityin classExpression- 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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getItemType
public ItemType getItemType()
Determine the data type of the expression, if possible. The default implementation for unary expressions returns the item type of the operand- Specified by:
getItemTypein classExpression- Returns:
- the item type of the items in the result sequence, insofar as this is known statically.
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equals
public boolean equals(java.lang.Object other)
Is this expression the same as another expression?- Overrides:
equalsin classExpression- Parameters:
other- the other operand; the result is false if this is not an Expression- Returns:
- true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.
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computeHashCode
public int computeHashCode()
get HashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.- Overrides:
computeHashCodein classExpression- Returns:
- a computed hash code
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toString
public java.lang.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:
toStringin classExpression- Returns:
- a representation of the expression as a string
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toShortString
public java.lang.String toShortString()
Description copied from class:ExpressionProduce a short string identifying the expression for use in error messages- Overrides:
toShortStringin classExpression- Returns:
- a short string, sufficient to identify the expression
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export
public void export(ExpressionPresenter out) throws XPathException
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
exportin interfaceExportAgent- Specified by:
exportin classExpression- 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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emitExtraAttributes
protected void emitExtraAttributes(ExpressionPresenter out)
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displayOperator
protected java.lang.String displayOperator(Configuration config)
Give a string representation of the operator for use in diagnostics- Parameters:
config- the Saxon configuration- Returns:
- the operator, as a string
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