Class CardinalityChecker

  • All Implemented Interfaces:
    java.io.Serializable, javax.xml.transform.SourceLocator, Container, Expression, InstructionInfoProvider

    public final class CardinalityChecker
    extends UnaryExpression
    A CardinalityChecker implements the cardinality checking of "treat as": that is, it returns the supplied sequence, checking that its cardinality is correct
    See Also:
    Serialized Form
    • Method Detail

      • makeCardinalityChecker

        public static ComputedExpression makeCardinalityChecker​(Expression sequence,
                                                                int cardinality,
                                                                RoleLocator role)
        Factory method to construct a CardinalityChecker. The method may create an expression that combines the cardinality checking with the functionality of the underlying expression class
        Parameters:
        sequence -
        cardinality -
        role -
        Returns:
        a new Expression that does the CardinalityChecking (not necessarily a CardinalityChecker)
      • getRequiredCardinality

        public int getRequiredCardinality()
        Get the required cardinality
      • typeCheck

        public Expression typeCheck​(StaticContext env,
                                    ItemType contextItemType)
                             throws XPathException
        Type-check the expression
        Specified by:
        typeCheck in interface Expression
        Overrides:
        typeCheck in class UnaryExpression
        Parameters:
        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 Type.ITEM_TYPE
        Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
        Throws:
        StaticError - if an error is discovered during this phase (typically a type error)
        XPathException
      • optimize

        public Expression optimize​(Optimizer opt,
                                   StaticContext env,
                                   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.

        Specified by:
        optimize in interface Expression
        Overrides:
        optimize in class UnaryExpression
        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 Type.ITEM_TYPE
        Returns:
        the original expression, rewritten if appropriate to optimize execution
        Throws:
        StaticError - if an error is discovered during this phase (typically a type error)
        XPathException
      • setErrorCode

        public void setErrorCode​(java.lang.String code)
        Set the error code to be returned (this is used when evaluating the functions such as exactly-one() which have their own error codes)
      • 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. This implementation provides both iterate() and process() methods natively.
        Specified by:
        getImplementationMethod in interface Expression
        Overrides:
        getImplementationMethod in class ComputedExpression
      • depictSequenceStart

        public java.lang.String depictSequenceStart​(SequenceIterator seq,
                                                    int max)
        Show the first couple of items in a sequence in an error message
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate as an Item.
        Specified by:
        evaluateItem in interface Expression
        Overrides:
        evaluateItem in class ComputedExpression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression
      • getItemType

        public ItemType getItemType​(TypeHierarchy th)
        Determine the data type of the items returned by the expression, if possible
        Specified by:
        getItemType in interface Expression
        Overrides:
        getItemType in class UnaryExpression
        Parameters:
        th -
        Returns:
        a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)
      • computeSpecialProperties

        public int computeSpecialProperties()
        Get the static properties of this expression (other than its type). The result is bit-signficant. 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.
        Overrides:
        computeSpecialProperties in class UnaryExpression
      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class UnaryExpression
      • displayOperator

        public java.lang.String displayOperator​(Configuration config)
        Diagnostic print of expression structure
        Specified by:
        displayOperator in class UnaryExpression
        Parameters:
        config -
        Returns:
        the operator, as a string