Package net.sf.saxon.expr

Class Atomizer

    • Field Detail

      • STRING_KINDS

        public static final UType STRING_KINDS
        Node kinds whose typed value is always a string

      • UNTYPED_KINDS

        public static final UType UNTYPED_KINDS
        Node kinds whose typed value is always untypedAtomic

      • UNTYPED_IF_UNTYPED_KINDS

        public static final UType UNTYPED_IF_UNTYPED_KINDS
        Node kinds whose typed value is untypedAtomic if the configuration is untyped

    • Constructor Detail

      • Atomizer

        public Atomizer​(Expression sequence,
                RoleDiagnostic role)
        Constructor
        Parameters:
        sequence - the sequence to be atomized
        role - (may be null) additional information for use in diagnostics

    • Method Detail

      • makeAtomizer

        public static Expression makeAtomizer​(Expression sequence,
                                      RoleDiagnostic role)
        Make an atomizer with a given operand
        Parameters:
        sequence - the operand
        role - (may be null) additional information for diagnostics
        Returns:
        an Atomizer that atomizes the given operand, or another expression that returns the same result

      • 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

      • getOperandItemType

        public ItemType getOperandItemType()

      • setRoleDiagnostic

        public void setRoleDiagnostic​(RoleDiagnostic role)

      • 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.

        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.

        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)

      • isUntyped

        public boolean isUntyped()
        Ask whether it is known that any nodes in the input will always be untyped
        Returns:
        true if it is known that all nodes in the input will be untyped

      • resetLocalStaticProperties

        public void resetLocalStaticProperties()
        Reset the static properties of the expression to -1, so that they have to be recomputed next time they are used.
        Overrides:
        resetLocalStaticProperties in class Expression

      • 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 rebound
        Returns:
        the copy of the original expression

      • 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

      • 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 Atomizer has cardinality zero-or-one, which will only be the case if the underlying expression 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. For this class, the result is always an atomic type, but it might be more specific.

      • getStaticUType

        public UType getStaticUType​(UType contextItemType)
        Description copied from class: Expression
        Get the static type of the expression as a UType, following precisely the type inference rules defined in the XSLT 3.0 specification.
        Overrides:
        getStaticUType in class Expression
        Parameters:
        contextItemType - the static type of the context item
        Returns:
        the static item type of the expression according to the XSLT 3.0 defined rules

      • getAtomizedItemType

        public static ItemType getAtomizedItemType​(Expression operand,
                                           boolean alwaysUntyped,
                                           TypeHierarchy th)
        Compute the type that will result from atomizing the result of a given expression
        Parameters:
        operand - the given expression
        alwaysUntyped - true if it is known that nodes will always be untyped
        th - the type hierarchy cache
        Returns:
        the item type of the result of evaluating the operand expression, after atomization, or xs:error if it is known that atomization will return an error

      • addToPathMap

        public PathMap.PathMapNodeSet addToPathMap​(PathMap pathMap,
                                           PathMap.PathMapNodeSet pathMapNodeSet)
        Add a representation of this expression to a PathMap. The PathMap captures a map of the nodes visited by an expression in a source tree.

        The default implementation of this method assumes that an expression does no navigation other than the navigation done by evaluating its subexpressions, and that the subexpressions are evaluated in the same context as the containing expression. The method must be overridden for any expression where these assumptions do not hold. For example, implementations exist for AxisExpression, ParentExpression, and RootExpression (because they perform navigation), and for the doc(), document(), and collection() functions because they create a new navigation root. Implementations also exist for PathExpression and FilterExpression because they have subexpressions that are evaluated in a different context from the calling expression.

        Overrides:
        addToPathMap in class Expression
        Parameters:
        pathMap - the PathMap to which the expression should be added
        pathMapNodeSet - the PathMapNodeSet to which the paths embodied in this expression should be added
        Returns:
        the pathMapNodeSet representing the points in the source document that are both reachable by this expression, and that represent possible results of this expression. For an expression that does navigation, it represents the end of the arc in the path map that describes the navigation route. For other expressions, it is the same as the input pathMapNode.

      • getAtomizingIterator

        public static SequenceIterator getAtomizingIterator​(SequenceIterator base,
                                                    boolean oneToOne)
                                             throws XPathException
        Get an iterator that returns the result of atomizing the sequence delivered by the supplied iterator
        Parameters:
        base - the supplied iterator, the input to atomization
        oneToOne - this can safely be set to true if it is known that all nodes in the base sequence will be untyped and that there will be no arrays in the base sequence; but it is always OK to set it to false.
        Returns:
        an iterator that returns atomic values, the result of the atomization
        Throws:
        XPathException - if a dynamic evaluation error occurs

      • getExpressionName

        public java.lang.String getExpressionName()
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        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 export() output displaying the expression.

      • toString

        public java.lang.String toString()
        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

      • toShortString

        public java.lang.String toShortString()
        Description copied from class: Expression
        Produce a short string identifying the expression for use in error messages
        Overrides:
        toShortString in class UnaryExpression
        Returns:
        a short string, sufficient to identify the expression