Package net.sf.saxon.expr
Class HomogeneityChecker
java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.UnaryExpression
net.sf.saxon.expr.HomogeneityChecker
- All Implemented Interfaces:
ExportAgent
,Locatable
,IdentityComparable
,Traceable
This class is an expression that does a run-time check of the result of a "/" expression
to ensure that (a) the results consists entirely of atomic values and function items, or entirely of nodes,
and (b) if the results are nodes, then they are deduplicated and sorted into document order.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic class
Elaborator for a homogeneity checker, which checks that the items in a sequence are either all nodes, or all non-nodes. -
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 TypeMethodDescriptioncopy
(RebindingMap rebindings) Copy an expression.Make an elaborator for this expressionGet a name identifying the kind of expression, in terms meaningful to a user.int
An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().protected OperandRole
Get the usage (in terms of streamability analysis) of the single operanditerate
(XPathContext context) Iterate the path-expression in a given contextoptimize
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Perform optimisation of an expression and its subexpressions.toPattern
(Configuration config) Convert this expression to an equivalent XSLT patterntypeCheck
(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) Type-check the expression.Methods inherited from class net.sf.saxon.expr.UnaryExpression
computeCardinality, computeHashCode, computeSpecialProperties, displayOperator, emitExtraAttributes, equals, export, getBaseExpression, getItemType, getOperand, operands, setBaseExpression, toShortString, toString
Methods inherited from class net.sf.saxon.expr.Expression
addToPathMap, adoptChildExpression, allowExtractingCommonSubexpressions, checkedOperands, checkForUpdatingSubexpressions, checkPermittedContents, computeDependencies, computeStaticProperties, dispatchTailCall, dynamicError, effectiveBooleanValue, evaluateAsString, evaluateItem, explain, getCardinality, getConfiguration, getCost, getDependencies, getEvaluationMethod, 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, isUpdatingExpression, isVacuousExpression, makeElaborator, markTailFunctionCalls, operandList, operandSparseList, optimizeChildren, prepareForStreaming, process, resetLocalStaticProperties, restoreParentPointers, setEvaluationMethod, setExtraProperty, setFiltered, setFlattened, setLocation, setParentExpression, setRetainedStaticContext, setRetainedStaticContextLocally, setRetainedStaticContextThoroughly, setStaticProperty, simplify, simplifyChildren, staticTypeCheck, supportsLazyEvaluation, suppressValidation, 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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HomogeneityChecker
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Method Details
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getOperandRole
Description copied from class:UnaryExpression
Get the usage (in terms of streamability analysis) of the single operand- Specified by:
getOperandRole
in classUnaryExpression
- Returns:
- the operand usage
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typeCheck
public Expression typeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Type-check the expression. Default implementation for unary operators that accept any kind of operand- Overrides:
typeCheck
in 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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toPattern
Convert this expression to an equivalent XSLT pattern- Overrides:
toPattern
in classExpression
- Parameters:
config
- the Saxon configuration- Returns:
- the equivalent pattern
- Throws:
XPathException
- if conversion is not possible
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optimize
public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException Description copied from class:UnaryExpression
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 classUnaryExpression
- Parameters:
visitor
- an expression visitorcontextInfo
- 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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copy
Copy an expression. This makes a deep copy.- Specified by:
copy
in classExpression
- Parameters:
rebindings
- variables that must 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:
getImplementationMethod
in classExpression
- Returns:
- the implementation method, for example
Expression.ITERATE_METHOD
orExpression.EVALUATE_METHOD
orExpression.PROCESS_METHOD
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iterate
Iterate the path-expression in a given context- Overrides:
iterate
in classExpression
- Parameters:
context
- the evaluation context- 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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getExpressionName
Get a name identifying the kind of expression, in terms meaningful to a user.- Overrides:
getExpressionName
in 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 explain() output displaying the expression.
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getElaborator
Make an elaborator for this expression- Overrides:
getElaborator
in classExpression
- Returns:
- a suitable elaborator
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