net.sf.saxon.functions
Class Subsequence
- EvaluableItem, InstructionInfoProvider, SequenceIterable, Serializable, SourceLocator
Implements the XPath 2.0 subsequence() function
addContextDocumentArgument , addDocToPathMap , checkArguments , computeCardinality , computeSpecialProperties , copy , getDetails , getErrorCodeForTypeErrors , getItemType , getRequiredType , makeSystemFunction , optimize , setDetails , useContextItemAsDefault |
addExternalFunctionCallToPathMap , checkArgumentCount , checkArguments , equals , explain , getArguments , getDisplayName , getFunctionName , getNumberOfArguments , hashCode , iterateSubExpressions , optimize , preEvaluate , promote , replaceSubExpression , setArguments , setFunctionName , simplify , simplifyArguments , toString , typeCheck |
addToPathMap , adoptChildExpression , checkPermittedContents , computeCardinality , computeDependencies , computeSpecialProperties , computeStaticProperties , copy , display , doPromotion , dynamicError , effectiveBooleanValue , evaluateAsString , evaluateItem , explain , explain , findParentOf , getCardinality , getColumnNumber , getConstructType , getContainer , getDependencies , getExecutable , getHostLanguage , getImplementationMethod , getInstructionInfo , getIntrinsicDependencies , getItemType , getLineNumber , getLocationId , getLocationProvider , getPublicId , getSlotsUsed , getSpecialProperties , getSystemId , hasLoopingSubexpression , implementsStaticTypeCheck , iterate , iterateEvents , iterateSubExpressions , markTailFunctionCalls , optimize , process , promote , replaceSubExpression , resetLocalStaticProperties , setContainer , setFiltered , setFlattened , setLocationId , simplify , staticTypeCheck , suppressValidation , toString , typeCheck , typeError |
computeSpecialProperties
public int computeSpecialProperties()
Get the static properties of this expression (other than its type). The result is
bit-significant. These properties are used for optimizations. In general, if
property bit is set, it is true, but if it is unset, the value is unknown.
- computeSpecialProperties in interface SystemFunction
optimize
public Expression optimize(ExpressionVisitor visitor,
ItemType contextItemType)
throws XPathException
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.
- optimize in interface SystemFunction
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 to
Type.ITEM_TYPE
- the original expression, rewritten if appropriate to optimize execution
XPathException
- if an error is discovered during this phase
(typically a type error)