net.sf.saxon.expr

Class InstanceOfExpression

public final class InstanceOfExpression extends UnaryExpression

InstanceOf Expression: implements "Expr instance of data-type"
Field Summary
inttargetCardinality
ItemTypetargetType
Constructor Summary
InstanceOfExpression(Expression source, SequenceType target)
Method Summary
intcomputeCardinality()
Determine the cardinality
voiddisplay(int level, NamePool pool, PrintStream out)
Diagnostic print of expression structure
protected StringdisplayOperator(NamePool pool)
Give a string representation of the operator for use in diagnostics
booleaneffectiveBooleanValue(XPathContext context)
Evaluate the expression as a boolean
booleanequals(Object other)
Is this expression the same as another expression?
ItemevaluateItem(XPathContext context)
Evaluate the expression
ItemTypegetItemType(TypeHierarchy th)
Determine the data type of the result of the InstanceOf expression
Expressionoptimize(Optimizer opt, StaticContext env, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
ExpressiontypeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression

Field Detail

targetCardinality

int targetCardinality

targetType

ItemType targetType

Constructor Detail

InstanceOfExpression

public InstanceOfExpression(Expression source, SequenceType target)

Method Detail

computeCardinality

public int computeCardinality()
Determine the cardinality

display

public void display(int level, NamePool pool, PrintStream out)
Diagnostic print of expression structure

displayOperator

protected String displayOperator(NamePool pool)
Give a string representation of the operator for use in diagnostics

Returns: the operator, as a string

effectiveBooleanValue

public boolean effectiveBooleanValue(XPathContext context)
Evaluate the expression as a boolean

equals

public boolean equals(Object other)
Is this expression the same as another expression?

evaluateItem

public Item evaluateItem(XPathContext context)
Evaluate the expression

getItemType

public ItemType getItemType(TypeHierarchy th)
Determine the data type of the result of the InstanceOf expression

Parameters: th

optimize

public Expression optimize(Optimizer opt, StaticContext env, ItemType contextItemType)
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 allows different optimization strategies to be used in different circumstances. env the static context of the expression 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 to ITEM_TYPE

Returns: 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)

typeCheck

public Expression typeCheck(StaticContext env, ItemType contextItemType)
Type-check the expression

Returns: the checked expression