Package net.sf.saxon.functions.hof
Class FunctionSequenceCoercer
- 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.functions.hof.FunctionSequenceCoercer
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- All Implemented Interfaces:
ExportAgent,Locatable,IdentityComparable,Traceable
public final class FunctionSequenceCoercer extends UnaryExpression
An FunctionSequenceCoercer is an expression that performs function coercion on a sequence of function items: it takes a sequence of supplied items as input, and wraps each one in a CoercedFunction value, which dynamically converts the supplied arguments to the required type, and converts the result in the opposite direction, or throws a type error if conversion is not possible.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static classFunctionSequenceCoercer.Coercer
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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 FunctionSequenceCoercer(Expression sequence, SpecificFunctionType requiredItemType, RoleDiagnostic role)Constructor
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description intcomputeCardinality()Determine the static cardinality of the expressionintcomputeHashCode()get HashCode for comparing two expressions.intcomputeSpecialProperties()Determine the special properties of this expressionExpressioncopy(RebindingMap rebindings)Copy an expression.booleanequals(java.lang.Object other)Is this expression the same as another expression?FunctionevaluateItem(XPathContext context)Evaluate as an Item.voidexport(ExpressionPresenter destination)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().SpecificFunctionTypegetItemType()Determine the data type of the items returned by the expression, if possibleprotected OperandRolegetOperandRole()Get the usage (in terms of streamability analysis) of the single operandRoleDiagnosticgetRole()SequenceIteratoriterate(XPathContext context)Iterate over the sequence of functions, wrapping each one in a CoercedFunction objectExpressionsimplify()Simplify an expressionExpressiontypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo)Type-check the expression-
Methods inherited from class net.sf.saxon.expr.UnaryExpression
displayOperator, emitExtraAttributes, 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, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, 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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FunctionSequenceCoercer
public FunctionSequenceCoercer(Expression sequence, SpecificFunctionType requiredItemType, RoleDiagnostic role)
Constructor- Parameters:
sequence- this must be a sequence of function item values. This is not checked; a ClassCastException will occur if the precondition is not satisfied.requiredItemType- the function item type to which all items in the sequence should be converted,
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Method Detail
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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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simplify
public Expression simplify() throws XPathException
Simplify an expression- Overrides:
simplifyin classExpression- Returns:
- the simplified expression (or the original if unchanged, or if modified in-situ)
- Throws:
XPathException- if an error is discovered during expression rewriting
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
Type-check the expression- 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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computeSpecialProperties
public int computeSpecialProperties()
Determine the special properties of this expression- Overrides:
computeSpecialPropertiesin classUnaryExpression- Returns:
StaticProperty.NO_NODES_NEWLY_CREATED.
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copy
public Expression copy(RebindingMap rebindings)
Copy an expression. This makes a deep copy.- Specified by:
copyin classExpression- Parameters:
rebindings- variables that need to be re-bound- Returns:
- the copy of the original expression
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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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iterate
public SequenceIterator iterate(XPathContext context) throws XPathException
Iterate over the sequence of functions, wrapping each one in a CoercedFunction object- Overrides:
iteratein 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
public Function evaluateItem(XPathContext context) throws XPathException
Evaluate as an Item. This should only be called if the FunctionSequenceCoercer has cardinality zero-or-one- 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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getItemType
public SpecificFunctionType getItemType()
Determine the data type of the items returned by the expression, if possible- Overrides:
getItemTypein classUnaryExpression- 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:
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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getRole
public RoleDiagnostic getRole()
- Returns:
- the role locator
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equals
public boolean equals(java.lang.Object other)
Is this expression the same as another expression?- Overrides:
equalsin classUnaryExpression- 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()
Description copied from class:UnaryExpressionget 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 classUnaryExpression- Returns:
- a computed hash code
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getExpressionName
public java.lang.String getExpressionName()
Description copied from class:ExpressionGet 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 export() output displaying the expression.
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export
public void export(ExpressionPresenter destination) throws XPathException
Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.- Specified by:
exportin interfaceExportAgent- Overrides:
exportin classUnaryExpression- Parameters:
destination- 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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