Package net.sf.saxon.expr

Class AtomicSequenceConverter

    • Constructor Detail

      • AtomicSequenceConverter

        public AtomicSequenceConverter​(Expression sequence,
                               PlainType requiredItemType)
        Constructor
        Parameters:
        sequence - this must be a sequence of atomic values. This is not checked; a ClassCastException will occur if the precondition is not satisfied.
        requiredItemType - the item type to which all items in the sequence should be converted,

    • Method Detail

      • allocateConverterStatically

        public void allocateConverterStatically​(Configuration config,
                                        boolean allowNull)

      • getRequiredItemType

        public PlainType getRequiredItemType()
        Get the required item type (the target type of the conversion
        Returns:
        the required item type

      • getConverter

        public Converter getConverter()
        Get the converter used to convert the items in the sequence
        Returns:
        the converter. Note that a converter is always allocated during the typeCheck() phase, even if the source type is not known.

      • setConverter

        public void setConverter​(Converter converter)

      • setRoleDiagnostic

        public void setRoleDiagnostic​(RoleDiagnostic role)
        Set a RoleDiagnostic, used to give more precise error information if the conversion fails
        Parameters:
        role - the RoleDiagnostic, which gives more precise error information

      • getRoleDiagnostic

        public RoleDiagnostic getRoleDiagnostic()
        Get the RoleDiagnostic, used to give more precise error information if the conversion fails
        Returns:
        the RoleDiagnostic, or null if none has been set

      • simplify

        public Expression simplify()
                    throws XPathException
        Simplify an expression
        Overrides:
        simplify in class Expression
        Returns:
        the simplified expression (or the original if unchanged, or if modified in-situ)
        Throws:
        XPathException - if an error is discovered during expression rewriting

      • typeCheck

        public Expression typeCheck​(ExpressionVisitor visitor,
                            ContextItemStaticInfo contextInfo)
                     throws XPathException
        Type-check the expression
        Overrides:
        typeCheck in class UnaryExpression
        Parameters:
        visitor - an expression visitor
        contextInfo - Information available statically about the context item: whether it is (possibly) absent; its static type; its streaming posture.
        Returns:
        the original expression, rewritten to perform necessary run-time type checks, and to perform other type-related optimizations
        Throws:
        XPathException - if an error is discovered during this phase (typically a type error)

      • optimize

        public Expression optimize​(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextInfo)
                    throws XPathException
        Perform optimisation of an expression and its subexpressions.
        Overrides:
        optimize in class UnaryExpression
        Parameters:
        visitor - an expression visitor
        contextInfo - 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:
        XPathException - if an error is discovered during this phase (typically a type error)

      • 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 directly. The other methods will always be available indirectly, using an implementation that relies on one of the other methods.
        Specified by:
        getImplementationMethod in class Expression
        Returns:
        the implementation method, for example Expression.ITERATE_METHOD or Expression.EVALUATE_METHOD or Expression.PROCESS_METHOD

      • getStreamerName

        public java.lang.String getStreamerName()
        Description copied from class: Expression
        Get the (partial) name of a class that supports streaming of this kind of expression
        Overrides:
        getStreamerName in class Expression
        Returns:
        the partial name of a class that can be instantiated to provide streaming support in Saxon-EE, or null if there is no such class

      • copy

        public Expression copy​(RebindingMap rebindings)
        Copy an expression. This makes a deep copy.
        Specified by:
        copy in class Expression
        Parameters:
        rebindings - variables that need to be re-bound
        Returns:
        the copy of the original expression

      • iterate

        public SequenceIterator iterate​(XPathContext context)
                         throws XPathException
        Iterate over the sequence of values
        Overrides:
        iterate in class Expression
        Parameters:
        context - supplies the context for evaluation
        Returns:
        a SequenceIterator that can be used to iterate over the result of the expression
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression

      • evaluateItem

        public AtomicValue evaluateItem​(XPathContext context)
                         throws XPathException
        Evaluate as an Item. This should only be called if the AtomicSequenceConverter has cardinality zero-or-one
        Overrides:
        evaluateItem in class Expression
        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()
        Determine the data type of the items returned by the expression, if possible
        Overrides:
        getItemType in class UnaryExpression
        Returns:
        a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known in advance)

      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class UnaryExpression
        Parameters:
        other - the other operand; the result is false if this is not an Expression
        Returns:
        true if the other operand is an expression and if it can be determined that the two expressions are equivalent, in the sense that they will always return the same result.

      • computeHashCode

        protected int computeHashCode()
        get HashCode for comparing two expressions. Note that this hashcode gives the same result for (A op B) and for (B op A), whether or not the operator is commutative.
        Overrides:
        computeHashCode in class UnaryExpression
        Returns:
        a computed hash code

      • getExpressionName

        public java.lang.String getExpressionName()
        Get a name identifying the kind of expression, in terms meaningful to a user.
        Overrides:
        getExpressionName in class Expression
        Returns:
        a name identifying the kind of expression, in terms meaningful to a user. The name will always be in the form of a lexical XML QName, and should match the name used in explain() output displaying the expression.

      • displayOperator

        protected java.lang.String displayOperator​(Configuration config)
        Description copied from class: UnaryExpression
        Give a string representation of the operator for use in diagnostics
        Overrides:
        displayOperator in class UnaryExpression
        Parameters:
        config - the Saxon configuration
        Returns:
        the operator, as a string

      • toString

        public java.lang.String toString()
        Description copied from class: UnaryExpression
        The toString() method for an expression attempts to give a representation of the expression in an XPath-like form, but there is no guarantee that the syntax will actually be true XPath. In the case of XSLT instructions, the toString() method gives an abstracted view of the syntax
        Overrides:
        toString in class UnaryExpression
        Returns:
        a representation of the expression as a string

      • export

        public void export​(ExpressionPresenter destination)
            throws XPathException
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Specified by:
        export in interface ExportAgent
        Overrides:
        export in class UnaryExpression
        Parameters:
        destination - the expression presenter used to display the structure
        Throws:
        XPathException - if the export fails, for example if an expression is found that won't work in the target environment.