Class Evaluate
- java.lang.Object
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- net.sf.saxon.expr.Expression
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- net.sf.saxon.expr.FunctionCall
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- net.sf.saxon.functions.SystemFunction
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- net.sf.saxon.functions.Evaluate
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- All Implemented Interfaces:
java.io.Serializable
,javax.xml.transform.SourceLocator
,LocationProvider
,SaxonLocator
,EvaluableItem
,SequenceIterable
,InstructionInfo
,org.xml.sax.Locator
public class Evaluate extends SystemFunction
This class implements the saxon:evaluate(), saxon:expression(), and saxon:eval() extension functions, which are specially-recognized by the system because they need access to parts of the static context- See Also:
- Serialized Form
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
Evaluate.PreparedExpression
Inner class PreparedExpression represents a compiled XPath expression together with the standard variables $p1 ..
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Field Summary
Fields Modifier and Type Field Description static int
EVAL
static int
EVALUATE
static int
EVALUATE_NODE
static int
EXPRESSION
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Fields inherited from class net.sf.saxon.functions.SystemFunction
operation
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Fields inherited from class net.sf.saxon.expr.FunctionCall
argument
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Fields inherited from class net.sf.saxon.expr.Expression
EVALUATE_METHOD, ITERATE_METHOD, locationId, PROCESS_METHOD, staticProperties
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Constructor Summary
Constructors Constructor Description Evaluate()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description PathMap.PathMapNodeSet
addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap.void
checkArguments(ExpressionVisitor visitor)
Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been readItem
evaluateItem(XPathContext c)
Evaluate in a general contextint
getIntrinsicDependencies()
Determine the dependenciesprotected SequenceType
getRequiredType(int arg)
Get the required type of the nth argumentSequenceIterator
iterate(XPathContext c)
Iterate over the results of the functionExpression
preEvaluate(ExpressionVisitor visitor)
preEvaluate: for saxon:expression, if the expression is known at compile time, then it is compiled at compile time.-
Methods inherited from class net.sf.saxon.functions.SystemFunction
addContextDocumentArgument, addDocToPathMap, computeCardinality, computeSpecialProperties, copy, getDetails, getErrorCodeForTypeErrors, getItemType, makeSystemFunction, optimize, setDetails, useContextItemAsDefault
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Methods inherited from class net.sf.saxon.expr.FunctionCall
addExternalFunctionCallToPathMap, checkArgumentCount, equals, explain, getArguments, getDisplayName, getFunctionName, getNumberOfArguments, hashCode, iterateSubExpressions, promote, replaceSubExpression, setArguments, setFunctionName, simplify, simplifyArguments, toString, typeCheck
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Methods inherited from class net.sf.saxon.expr.Expression
adoptChildExpression, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, display, doPromotion, dynamicError, effectiveBooleanValue, evaluateAsString, evaluatePendingUpdates, explain, findParentOf, getCardinality, getColumnNumber, getColumnNumber, getConstructType, getContainer, getDependencies, getExecutable, getHostLanguage, getImplementationMethod, getLineNumber, getLineNumber, getLocationId, getLocationProvider, getObjectName, getProperties, getProperty, getPublicId, getSlotsUsed, getSpecialProperties, getSystemId, getSystemId, hasLoopingSubexpression, implementsStaticTypeCheck, isUpdatingExpression, iterateEvents, markTailFunctionCalls, process, resetLocalStaticProperties, setContainer, setFiltered, setFlattened, setLocationId, staticTypeCheck, suppressValidation, typeError
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Field Detail
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EVALUATE
public static final int EVALUATE
- See Also:
- Constant Field Values
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EXPRESSION
public static final int EXPRESSION
- See Also:
- Constant Field Values
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EVAL
public static final int EVAL
- See Also:
- Constant Field Values
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EVALUATE_NODE
public static final int EVALUATE_NODE
- See Also:
- Constant Field Values
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Method Detail
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getRequiredType
protected SequenceType getRequiredType(int arg)
Get the required type of the nth argument- Overrides:
getRequiredType
in classSystemFunction
- Parameters:
arg
- the number of the argument whose type is requested, zero-based- Returns:
- the required type of the argument as defined in the function signature
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checkArguments
public void checkArguments(ExpressionVisitor visitor) throws XPathException
Method supplied by each class of function to check arguments during parsing, when all the argument expressions have been read- Overrides:
checkArguments
in classSystemFunction
- Parameters:
visitor
- the expression visitor- Throws:
XPathException
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preEvaluate
public Expression preEvaluate(ExpressionVisitor visitor) throws XPathException
preEvaluate: for saxon:expression, if the expression is known at compile time, then it is compiled at compile time. In other cases this method suppresses compile-time evaluation by doing nothing (because the value of the expression depends on the runtime context).- Overrides:
preEvaluate
in classFunctionCall
- Parameters:
visitor
- an expression visitor- Returns:
- the result of the early evaluation, or the original expression, or potentially a simplified expression
- Throws:
XPathException
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addToPathMap
public PathMap.PathMapNodeSet addToPathMap(PathMap pathMap, PathMap.PathMapNodeSet pathMapNodeSet)
Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.
This particular implementation has to deal with the fact that saxon:evaluate() and related functions can navigate anywhere in the tree.
- Overrides:
addToPathMap
in classExpression
- Parameters:
pathMap
- the PathMap to which the expression should be addedpathMapNodeSet
- the PathMapNodeSet to which the paths embodied in this expression should be added- Returns:
- the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.
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evaluateItem
public Item evaluateItem(XPathContext c) throws XPathException
Evaluate in a general context- Specified by:
evaluateItem
in interfaceEvaluableItem
- Overrides:
evaluateItem
in classExpression
- Parameters:
c
- 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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iterate
public SequenceIterator iterate(XPathContext c) throws XPathException
Iterate over the results of the function- Specified by:
iterate
in interfaceSequenceIterable
- Overrides:
iterate
in classExpression
- Parameters:
c
- 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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getIntrinsicDependencies
public int getIntrinsicDependencies()
Determine the dependencies- Overrides:
getIntrinsicDependencies
in classExpression
- Returns:
- a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty
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