| java.lang.Object
 net.sf.saxon.expr.ComputedExpression
net.sf.saxon.expr.SingleNodeExpression
All known Subclasses: net.sf.saxon.expr.ParentNodeExpression, net.sf.saxon.expr.RootExpression,
| SingleNodeExpression | | abstract public class SingleNodeExpression extends ComputedExpression (Code) | | A node set expression that will always return zero or one nodes
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| computeCardinality | | public int computeCardinality()(Code) | | Specify that the expression returns a singleton
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| computeSpecialProperties | | public int computeSpecialProperties()(Code) | | |
| getIntrinsicDependencies | | public int getIntrinsicDependencies()(Code) | | Determine which aspects of the context the expression depends on. The result is
a bitwise-or'ed value composed from constants such as StaticProperty.VARIABLES and
StaticProperty.CURRENT_NODE
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| getItemType | | public ItemType getItemType(TypeHierarchy th)(Code) | | Determine the data type of the items returned by this expression
Type.NODE
Parameters:
th - |
| optimize | | public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType) throws XPathException(Code) | | 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.
Parameters:
opt - the optimizer in use. This provides access to supporting functions; it also allowsdifferent optimization strategies to be used in different circumstances.
Parameters:
env - the static context of the expression
Parameters:
contextItemType - 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 tonet.sf.saxon.type.Type.ITEM_TYPE the original expression, rewritten if appropriate to optimize execution
throws:
net.sf.saxon.trans.StaticError - if an error is discovered during this phase(typically a type error) |
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