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:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,org.xml.sax.Locator
- Direct Known Subclasses:
AdjacentTextNodeMerger
,AtomicSequenceConverter
,Atomizer
,CardinalityChecker
,CastingExpression
,DocumentSorter
,EmptyTextNodeRemover
,HomogeneityChecker
,InstanceOfExpression
,ItemChecker
,NegateExpression
,SingleItemFilter
,SingletonAtomizer
,TailCallLoop
public abstract class UnaryExpression extends Expression
Unary Expression: an expression taking a single operand expression- See Also:
- Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected Expression
operand
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Fields inherited from class net.sf.saxon.expr.Expression
EFFECTIVE_BOOLEAN_VALUE, EVALUATE_METHOD, EVENT_FEED_METHOD, ITEM_FEED_METHOD, ITERATE_METHOD, locationId, MAX_SEQUENCE_LENGTH, MAX_STRING_LENGTH, PROCESS_METHOD, PUSH_SELECTION, staticProperties, UNBOUNDED_LOWER, UNBOUNDED_UPPER, WATCH_METHOD
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Constructor Summary
Constructors Constructor Description UnaryExpression()
UnaryExpression(Expression p0)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
computeCardinality()
Determine the static cardinality.int
computeSpecialProperties()
Get the static properties of this expression (other than its type).protected java.lang.String
displayOperator(Configuration config)
Give a string representation of the operator for use in diagnosticsboolean
equals(java.lang.Object other)
Is this expression the same as another expression?void
explain(ExpressionPresenter out)
Diagnostic print of expression structure.Expression
getBaseExpression()
ItemType
getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible.int
hashCode()
get HashCode for comparing two expressions.java.util.Iterator<Expression>
iterateSubExpressions()
Get the immediate subexpressions of this expressionExpression
optimize(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Perform optimisation of an expression and its subexpressions.Expression
promote(PromotionOffer offer, Expression parent)
Promote this expression if possibleboolean
replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpressionExpression
simplify(ExpressionVisitor visitor)
Simplify an expressionjava.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.Expression
typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType)
Type-check the expression.-
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, copy, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, 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, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterate, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Field Detail
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operand
protected Expression operand
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Constructor Detail
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UnaryExpression
public UnaryExpression()
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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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simplify
public Expression simplify(ExpressionVisitor visitor) throws XPathException
Simplify an expression- Overrides:
simplify
in classExpression
- Parameters:
visitor
- an expression visitor- Returns:
- the simplified expression
- Throws:
XPathException
- if an error is discovered during expression rewriting
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
Type-check the expression. Default implementation for unary operators that accept any kind of operand- Overrides:
typeCheck
in classExpression
- Parameters:
visitor
- an expression visitorcontextItemType
- 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 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, 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 classExpression
- Parameters:
visitor
- an expression visitorcontextItemType
- 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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promote
public Expression promote(PromotionOffer offer, Expression parent) throws XPathException
Promote this expression if possible- Overrides:
promote
in classExpression
- Parameters:
offer
- details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expressionparent
- the containing expression in the expression tree- Returns:
- if the offer is not accepted, return this expression unchanged. Otherwise return the result of rewriting the expression to promote this subexpression
- Throws:
XPathException
- if any error is detected
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iterateSubExpressions
public java.util.Iterator<Expression> iterateSubExpressions()
Get the immediate subexpressions of this expression- Overrides:
iterateSubExpressions
in classExpression
- Returns:
- an iterator containing the sub-expressions of this expression
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replaceSubExpression
public boolean replaceSubExpression(Expression original, Expression replacement)
Replace one subexpression by a replacement subexpression- Overrides:
replaceSubExpression
in classExpression
- Parameters:
original
- the original subexpressionreplacement
- the replacement subexpression- Returns:
- true if the original subexpression is found
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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:
computeSpecialProperties
in 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:
computeCardinality
in 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
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getItemType
public ItemType getItemType(TypeHierarchy th)
Determine the data type of the expression, if possible. The default implementation for unary expressions returns the item type of the operand- Specified by:
getItemType
in classExpression
- Parameters:
th
- the type hierarchy cache- 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:
equals
in classjava.lang.Object
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hashCode
public int hashCode()
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:
hashCode
in classjava.lang.Object
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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:
toString
in classExpression
- Returns:
- a representation of the expression as a string
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explain
public void explain(ExpressionPresenter out)
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
explain
in classExpression
- Parameters:
out
- the expression presenter used to display the structure
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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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