net.sf.saxon.expr

Class ItemChecker

public final class ItemChecker extends UnaryExpression implements MappingExpression

A ItemChecker implements the item type checking of "treat as": that is, it returns the supplied sequence, checking that all its items are of the correct type

Constructor Summary
	ItemChecker(Expression sequence, ItemType itemType, RoleLocator role) Constructor

Method Summary
Expression	copy() Copy an expression.
boolean	equals(Object other) Is this expression the same as another expression?
Item	evaluateItem(XPathContext context) Evaluate as an Item.
void	explain(ExpressionPresenter out) Diagnostic print of expression structure.
int	getImplementationMethod() An implementation of Expression must provide at least one of the methods evaluateItem(), iterate(), or process().
ItemType	getItemType(TypeHierarchy th) Determine the data type of the items returned by the expression
SequenceIterator	getMappingIterator(SequenceIterator base, XPathContext context)
ItemType	getRequiredType() Get the required type
RoleLocator	getRoleLocator() Get the RoleLocator (used to construct error messages)
SequenceIterator	iterate(XPathContext context) Iterate over the sequence of values
void	process(XPathContext context) Process the instruction, without returning any tail calls
Expression	simplify(ExpressionVisitor visitor) Simplify an expression
Expression	typeCheck(ExpressionVisitor visitor, ItemType contextItemType) Type-check the expression

Constructor Detail

ItemChecker

public ItemChecker(Expression sequence, ItemType itemType, RoleLocator role)

Constructor

Parameters: sequence the expression whose value we are checking itemType the required type of the items in the sequence role information used in constructing an error message

Method Detail

copy

public Expression copy()

Copy an expression. This makes a deep copy.

Returns: the copy of the original expression

equals

public boolean equals(Object other)

Is this expression the same as another expression?

evaluateItem

public Item evaluateItem(XPathContext context)

Evaluate as an Item.

explain

public void explain(ExpressionPresenter out)

Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.

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. This implementation provides both iterate() and process() methods natively.