Package com.saxonica.ee.update
Class BasicUpdatingExpression
java.lang.Object
net.sf.saxon.expr.Expression
com.saxonica.ee.update.BasicUpdatingExpression
- All Implemented Interfaces:
ExportAgent
,Locatable
,IdentityComparable
,Traceable
- Direct Known Subclasses:
DeleteExpression
,InsertExpression
,RenameExpression
,ReplaceNodeExpression
,ReplaceValueExpression
A basic updating expression: insert, replace, delete, rename (but not copy)
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Field Summary
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 -
Method Summary
Modifier and TypeMethodDescriptionprotected int
Determine the static cardinality of the expression.evaluateItem
(XPathContext context) Evaluate an expression as a single item.Make an elaborator for this expressionint
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().Determine the data type of the expression, if possible.final boolean
Determine whether this is an updating expression as defined in the XQuery update specificationiterate
(XPathContext context) Return an Iterator to iterate over the values of a sequence.void
process
(Outputter output, XPathContext context) Process the instruction, without returning any tail callsMethods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeHashCode, computeSpecialProperties, computeStaticProperties, copy, dispatchTailCall, dynamicError, effectiveBooleanValue, equals, evaluateAsString, explain, export, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, getExpressionName, getExtraProperty, getIntegerBounds, 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, isVacuousExpression, makeElaborator, markTailFunctionCalls, operandList, operands, operandSparseList, optimize, optimizeChildren, prepareForStreaming, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, toPattern, toShortString, toString, typeCheck, typeCheckChildren, typeError, unordered, verifyParentPointers, withLocation
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface net.sf.saxon.trace.Traceable
gatherProperties
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Constructor Details
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BasicUpdatingExpression
public BasicUpdatingExpression()
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Method Details
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isUpdatingExpression
public final boolean isUpdatingExpression()Determine whether this is an updating expression as defined in the XQuery update specification- Overrides:
isUpdatingExpression
in classExpression
- Returns:
- true if this is an updating expression (which it is)
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computeCardinality
protected int computeCardinality()Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.- Specified by:
computeCardinality
in classExpression
- Returns:
- one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).
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getItemType
Determine the data type of the expression, if possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.This method should always return a result, though it may be the best approximation that is available at the time.
- Specified by:
getItemType
in classExpression
- Returns:
- a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)
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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:
getImplementationMethod
in classExpression
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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evaluateItem
Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.- 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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iterate
Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.- 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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process
Process the instruction, without returning any tail calls- Overrides:
process
in classExpression
- Parameters:
output
- the destination for the resultcontext
- The dynamic context, giving access to the current node,- Throws:
XPathException
- if a dynamic error occurs
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getElaborator
Make an elaborator for this expression- Overrides:
getElaborator
in classExpression
- Returns:
- an appropriate
Elaborator
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