Package com.saxonica.ee.bytecode

Class CompiledExpression

    • Method Detail

      • getInterpretedExpression

        public Expression getInterpretedExpression()
        Get the original (uncompiled) expression of which this is the compiled form
        Overrides:
        getInterpretedExpression in class Expression
        Returns:
        the original expression

      • setClassName

        public void setClassName​(java.lang.String cname)

      • getClassName

        public java.lang.String getClassName()

      • getExpressionName

        public java.lang.String getExpressionName()
        Description copied from class: Expression
        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 export() output displaying the expression.

      • getImplementationMethod

        public int getImplementationMethod()
        Description copied from class: Expression
        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

      • getCardinality

        public int getCardinality()
        Description copied from class: Expression
        Determine the static cardinality of the expression. This establishes how many items there will be in the result of the expression, at compile time (i.e., without actually evaluating the result.
        Overrides:
        getCardinality in class Expression
        Returns:
        one of the values Cardinality.ONE_OR_MORE, Cardinality.ZERO_OR_MORE, Cardinality.EXACTLY_ONE, Cardinality.ZERO_OR_ONE, Cardinality.EMPTY. This default implementation returns ZERO_OR_MORE (which effectively gives no information).

      • getItemType

        public ItemType getItemType()
        Description copied from class: Expression
        Determine the static item type of the expression, as precisely possible. All expression return sequences, in general; this method determines the type of the items within the sequence, assuming that (a) this is known in advance, and (b) it is the same for all items in the sequence.

        This method should always return a result, though it may be the best approximation that is available at the time.

        Specified by:
        getItemType in class Expression
        Returns:
        a value such as Type.STRING, Type.BOOLEAN, Type.NUMBER, Type.NODE, or Type.ITEM (meaning not known at compile time)

      • getDependencies

        public int getDependencies()
        Description copied from class: Expression
        Determine which aspects of the context the expression depends on. The result is a bitwise-or'ed value composed from constants such as XPathContext.VARIABLES and XPathContext.CURRENT_NODE. The default implementation combines the intrinsic dependencies of this expression with the dependencies of the subexpressions, computed recursively. This is overridden for expressions such as FilterExpression where a subexpression's dependencies are not necessarily inherited by the parent expression.
        Overrides:
        getDependencies in class Expression
        Returns:
        a set of bit-significant flags identifying the dependencies of the expression

      • process

        public void process​(Outputter output,
                    XPathContext context)
             throws XPathException
        Description copied from class: Expression
        Process the instruction, without returning any tail calls
        Overrides:
        process in class Expression
        Parameters:
        output - the destination for the result
        context - The dynamic context, giving access to the current node, the current variables, etc.
        Throws:
        XPathException - if a dynamic error occurs

      • evaluatePendingUpdates

        public void evaluatePendingUpdates​(XPathContext context,
                                   PendingUpdateList pul)
                            throws XPathException
        Description copied from class: Expression
        Evaluate an updating expression, adding the results to a Pending Update List. The default implementation of this method, which is used for non-updating expressions, throws an UnsupportedOperationException
        Overrides:
        evaluatePendingUpdates in class Expression
        Parameters:
        context - the XPath dynamic evaluation context
        pul - the pending update list to which the results should be written
        Throws:
        XPathException - if evaluation fails

      • toString

        public java.lang.String toString()
        Description copied from class: Expression

        The toString() method for an expression attempts to give a representation of the expression in an XPath-like form.

        For subclasses of Expression that represent XPath expressions, the result should always be a string that parses as an XPath 3.0 expression. The expression produced should be equivalent to the original making certain assumptions about the static context. In general the expansion will make no assumptions about namespace bindings, except that (a) the prefix "xs" is used to refer to the XML Schema namespace, and (b) the default function namespace is assumed to be the "fn" namespace.

        In the case of XSLT instructions and XQuery expressions, the toString() method gives an abstracted view of the syntax that is not designed in general to be parseable.

        Overrides:
        toString in class Expression
        Returns:
        a representation of the expression as a string

      • export

        public void export​(ExpressionPresenter out)
            throws XPathException
        Description copied from class: Expression
        Diagnostic print of expression structure. The abstract expression tree is written to the supplied output destination.
        Specified by:
        export in interface ExportAgent
        Specified by:
        export in class Expression
        Parameters:
        out - 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.

      • checkPermittedContents

        public void checkPermittedContents​(SchemaType parentType,
                                   boolean whole)
                            throws XPathException
        Description copied from class: Expression
        Check that any elements and attributes constructed or returned by this expression are acceptable in the content model of a given complex type. It's always OK to say yes, since the check will be repeated at run-time. The process of checking element and attribute constructors against the content model of a complex type also registers the type of content expected of those constructors, so the static validation can continue recursively.
        Overrides:
        checkPermittedContents in class Expression
        Parameters:
        parentType - the "given complex type": the method is checking that the nodes returned by this expression are acceptable members of the content model of this type
        whole - if true, we want to check that the value of this expression satisfies the content model as a whole; if false we want to check that the value of the expression is acceptable as one part of the content
        Throws:
        XPathException - if the value delivered by this expression cannot be part of the content model of the given type

      • computeSpecialProperties

        protected int computeSpecialProperties()
        Description copied from class: Expression
        Compute the special properties of this expression. These properties are denoted by a bit-significant integer, possible values are in class StaticProperty. The "special" properties are properties other than cardinality and dependencies, and most of them relate to properties of node sequences, for example whether the nodes are in document order.
        Overrides:
        computeSpecialProperties in class Expression
        Returns:
        the special properties, as a bit-significant integer

      • computeDependencies

        public int computeDependencies()
        Description copied from class: Expression
        Compute the dependencies of an expression, as the union of the dependencies of its subexpressions. (This is overridden for path expressions and filter expressions, where the dependencies of a subexpression are not all propogated). This method should be called only once, to compute the dependencies; after that, getDependencies should be used.
        Overrides:
        computeDependencies in class Expression
        Returns:
        the depencies, as a bit-mask

      • getIntrinsicDependencies

        public int getIntrinsicDependencies()
        Description copied from class: Expression
        Determine the intrinsic dependencies of an expression, that is, those which are not derived from the dependencies of its subexpressions. For example, position() has an intrinsic dependency on the context position, while (position()+1) does not. The default implementation of the method returns 0, indicating "no dependencies".
        Overrides:
        getIntrinsicDependencies in class Expression
        Returns:
        a set of bit-significant flags identifying the "intrinsic" dependencies. The flags are documented in class net.sf.saxon.value.StaticProperty

      • checkForUpdatingSubexpressions

        public void checkForUpdatingSubexpressions()
                                    throws XPathException
        Description copied from class: Expression
        Check to ensure that this expression does not contain any inappropriate updating subexpressions. This check is overridden for those expressions that permit updating subexpressions.
        Overrides:
        checkForUpdatingSubexpressions in class Expression
        Throws:
        XPathException - if the expression has a non-permitted updating subexpression

      • isUpdatingExpression

        public boolean isUpdatingExpression()
        Description copied from class: Expression
        Determine whether this is an updating expression as defined in the XQuery update specification
        Overrides:
        isUpdatingExpression in class Expression
        Returns:
        true if this is an updating expression

      • isVacuousExpression

        public boolean isVacuousExpression()
        Description copied from class: Expression
        Determine whether this is a vacuous expression as defined in the XQuery update specification
        Overrides:
        isVacuousExpression in class Expression
        Returns:
        true if this expression is vacuous

      • copy

        public Expression copy​(RebindingMap rebindings)
        Description copied from class: Expression
        Copy an expression. This makes a deep copy.
        Specified by:
        copy in class Expression
        Parameters:
        rebindings - a mutable list of (old binding, new binding) pairs that is used to update the bindings held in any local variable references that are copied.
        Returns:
        the copy of the original expression

      • getObjectName

        public StructuredQName getObjectName()
        Description copied from interface: Traceable
        Get a name identifying the object of the expression, for example a function name, template name, variable name, key name, element name, etc. This is used only where the name is known statically.
        Specified by:
        getObjectName in interface Traceable
        Overrides:
        getObjectName in class Expression
        Returns:
        the QName of the object declared or manipulated by this instruction or expression

      • equals

        public boolean equals​(java.lang.Object other)
        Is this expression the same as another expression?
        Overrides:
        equals in class Expression
        Parameters:
        other - the expression to be compared with this one
        Returns:
        true if the two expressions are statically equivalent

      • computeHashCode

        protected int computeHashCode()
        Hashcode supporting equals()
        Overrides:
        computeHashCode in class Expression
        Returns:
        a computed hash code

      • getProperty

        public java.lang.Object getProperty​(java.lang.String name)
        Overrides:
        getProperty in class Expression

      • getProperties

        public java.util.Iterator<java.lang.String> getProperties()
        Description copied from class: Expression
        Get an iterator over all the properties available. The values returned by the iterator will be of type String, and each string can be supplied as input to the getProperty() method to retrieve the value of the property. The iterator may return properties whose value is null.
        Overrides:
        getProperties in class Expression
        Returns:
        an iterator over the properties

      • addToPathMap

        public PathMap.PathMapNodeSet addToPathMap​(PathMap pathMap,
                                           PathMap.PathMapNodeSet pathMapNodeSet)
        Description copied from class: Expression
        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.

      • isSubtreeExpression

        public boolean isSubtreeExpression()
        Description copied from class: Expression
        Determine whether the expression can be evaluated without reference to the part of the context document outside the subtree rooted at the context node.
        Overrides:
        isSubtreeExpression in class Expression
        Returns:
        true if the expression has no dependencies on the context node, or if the only dependencies on the context node are downward selections using the self, child, descendant, attribute, and namespace axes.

      • iterate

        public SequenceIterator iterate​(XPathContext context)
                         throws XPathException
        Description copied from class: Expression
        Return an Iterator to iterate over the values of a sequence. The value of every expression can be regarded as a sequence, so this method is supported for all expressions. This default implementation handles iteration for expressions that return singleton values: for non-singleton expressions, the subclass must provide its own implementation.
        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 Item evaluateItem​(XPathContext context)
                  throws XPathException
        Description copied from class: Expression
        Evaluate an expression as a single item. This always returns either a single Item or null (denoting the empty sequence). No conversion is done. This method should not be used unless the static type of the expression is a subtype of "item" or "item?": that is, it should not be called if the expression may return a sequence. There is no guarantee that this condition will be detected.
        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

      • effectiveBooleanValue

        public boolean effectiveBooleanValue​(XPathContext context)
                              throws XPathException
        Description copied from class: Expression
        Get the effective boolean value of the expression. This returns false if the value is the empty sequence, a zero-length string, a number equal to zero, or the boolean false. Otherwise it returns true.
        Overrides:
        effectiveBooleanValue in class Expression
        Parameters:
        context - The context in which the expression is to be evaluated
        Returns:
        the effective boolean value
        Throws:
        XPathException - if any dynamic error occurs evaluating the expression