Package net.sf.saxon.expr
Class AtomicSequenceConverter
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.AtomicSequenceConverter
- All Implemented Interfaces:
Serializable
,SourceLocator
,LocationProvider
,SaxonLocator
,InstructionInfo
,Locator
An AtomicSequenceConverter is an expression that performs a cast on each member of
a supplied sequence
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
Mapping function wrapped around a converterstatic class
Mapping function that converts every item in a sequence to a stringstatic class
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Field Summary
FieldsModifier and TypeFieldDescriptionFields 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, 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
ConstructorsConstructorDescriptionAtomicSequenceConverter
(Expression sequence, PlainType requiredItemType, boolean allConverted) Constructor -
Method Summary
Modifier and TypeMethodDescriptionvoid
allocateConverter
(Configuration config) int
Determine the static cardinality of the expressionint
Determine the special properties of this expressioncopy()
Copy an expression.boolean
Is this expression the same as another expression?evaluateItem
(XPathContext context) Evaluate as an Item.void
explain
(ExpressionPresenter destination) Diagnostic print of expression structure.Get the converter used to convert the items in the sequenceDetermine the data type of the items returned by the expression, if possibleint
hashCode()
get HashCode for comparing two expressions.boolean
Ask if all items in the input are converted to the target typeiterate
(XPathContext context) Iterate over the sequence of valuesstatic AtomicSequenceConverter
makeUntypedSequenceConverter
(Configuration config, Expression operand, PlainType requiredItemType) Create an AtomicSequenceConverter that converts all untypedAtomic values in the input sequence to a specified target type, while leaving items other than untypedAtomic unchangedstatic AtomicSequenceConverter
makeUntypedSequenceRejector
(Configuration config, Expression operand, PlainType requiredItemType) optimize
(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Perform optimisation of an expression and its subexpressions.void
setConverter
(Converter converter) simplify
(ExpressionVisitor visitor) Simplify an expressiontypeCheck
(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) Type-check the expressionMethods inherited from class net.sf.saxon.expr.UnaryExpression
displayOperator, getBaseExpression, iterateSubExpressions, promote, replaceSubExpression, 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, getExpressionName, getHostLanguage, getImplementationMethod, getIntegerBounds, getIntrinsicDependencies, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, hasVariableBinding, implementsStaticTypeCheck, isSubtreeExpression, isUpdatingExpression, isVacuousExpression, iterateEvents, iterateSameFocusSubExpressions, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setEvaluationMethod, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Field Details
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TO_STRING_MAPPER
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Constructor Details
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AtomicSequenceConverter
public AtomicSequenceConverter(Expression sequence, PlainType requiredItemType, boolean allConverted) Constructor- Parameters:
sequence
- this must be a sequence of atomic values. This is not checked; a ClassCastException will occur if the precondition is not satisfied.requiredItemType
- the item type to which all items in the sequence should be converted, using the rules for "cast as".
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Method Details
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makeUntypedSequenceConverter
public static AtomicSequenceConverter makeUntypedSequenceConverter(Configuration config, Expression operand, PlainType requiredItemType) throws XPathException Create an AtomicSequenceConverter that converts all untypedAtomic values in the input sequence to a specified target type, while leaving items other than untypedAtomic unchanged- Parameters:
config
- the Saxon configurationoperand
- the expression that delivers the input sequencerequiredItemType
- the type to which untypedAtomic values should be cast, which must either be an atomic type or a "plain" union type- Returns:
- an AtomicSequenceConverter that performs the required conversion
- Throws:
XPathException
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makeUntypedSequenceRejector
public static AtomicSequenceConverter makeUntypedSequenceRejector(Configuration config, Expression operand, PlainType requiredItemType) -
allocateConverter
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getConverter
Get the converter used to convert the items in the sequence- Returns:
- the converter. Note that a converter is always allocated during the typeCheck() phase, even if the source type is not known.
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setConverter
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isAllItemsConverted
public boolean isAllItemsConverted()Ask if all items in the input are converted to the target type -
simplify
Simplify an expression- Overrides:
simplify
in classUnaryExpression
- 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- Overrides:
typeCheck
in classUnaryExpression
- 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.- Overrides:
optimize
in classUnaryExpression
- 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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computeSpecialProperties
public int computeSpecialProperties()Determine the special properties of this expression- Overrides:
computeSpecialProperties
in classUnaryExpression
- Returns:
StaticProperty.NON_CREATIVE
.
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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Returns:
- the copy of the original expression
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iterate
Iterate over the sequence of values- Overrides:
iterate
in classExpression
- Parameters:
context
- supplies the context for evaluation- Returns:
- a SequenceIterator that can be used to iterate over the result of the expression
- Throws:
XPathException
- if any dynamic error occurs evaluating the expression
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evaluateItem
Evaluate as an Item. This should only be called if the AtomicSequenceConverter has cardinality zero-or-one- Overrides:
evaluateItem
in 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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getItemType
Determine the data type of the items returned by the expression, if possible- Overrides:
getItemType
in classUnaryExpression
- Parameters:
th
- the type hierarchy cache- Returns:
- a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)
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computeCardinality
public int computeCardinality()Determine the static cardinality of the expression- Overrides:
computeCardinality
in 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
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equals
Is this expression the same as another expression?- Overrides:
equals
in classUnaryExpression
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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 classUnaryExpression
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explain
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Overrides:
explain
in classUnaryExpression
- Parameters:
destination
- the expression presenter used to display the structure
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