Package net.sf.saxon.expr.instruct

Class Copy

    • Constructor Detail

      • Copy

        public Copy​(boolean copyNamespaces,
            boolean inheritNamespaces,
            SchemaType schemaType,
            int validation)
        Create a shallow copy instruction

        param select selects the node (or other item) to be copied. Never null. param selectSpecified true if the select attribute of xsl:copy was specified explicitly (in which case the context for evaluating the body will change)

        Parameters:
        copyNamespaces - true if namespace nodes are to be copied when copying an element
        inheritNamespaces - true if child elements are to inherit the namespace nodes of their parent
        schemaType - the Schema type against which the content is to be validated
        validation - the schema validation mode

    • Method Detail

      • setCopyNamespaces

        public void setCopyNamespaces​(boolean copy)
        Say whether namespace nodes are to be copied (in the case of an element)
        Parameters:
        copy - set to true if namespace nodes are to be copied

      • isCopyNamespaces

        public boolean isCopyNamespaces()
        Ask whether namespace nodes are to be copied (in the case of an element)
        Returns:
        true if all in-scope namespaces are to be copied

      • simplify

        public Expression simplify()
                    throws XPathException
        Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
        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
        Description copied from class: Expression
        Perform type checking of an expression and its subexpressions. This is the second phase of static optimization.

        This checks statically that the operands of the expression have the correct type; if necessary it generates code to do run-time type checking or type conversion. A static type error is reported only if execution cannot possibly succeed, that is, if a run-time type error is inevitable. The call may return a modified form of the expression.

        This method is called after all references to functions and variables have been resolved to the declaration of the function or variable. However, the types of such functions and variables may not be accurately known if they have not been explicitly declared.

        Overrides:
        typeCheck in class ParentNodeConstructor
        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)

      • copy

        public Expression copy​(RebindingMap rebindings)
        Copy this expression (don't be confused by the method name). 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

      • setSelectItemType

        public void setSelectItemType​(ItemType type)
        Set the item type of the input
        Parameters:
        type - the item type

      • getIntrinsicDependencies

        public int getIntrinsicDependencies()
        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:
        getIntrinsicDependencies in class Expression
        Returns:
        a set of bit-significant flags identifying the dependencies of the expression

      • getInstructionNameCode

        public int getInstructionNameCode()
        Get the name of this instruction for diagnostic and tracing purposes
        Overrides:
        getInstructionNameCode in class Instruction
        Returns:
        a code identifying the instruction: typically but not always the fingerprint of a name in the XSLT namespace

      • operands

        public java.lang.Iterable<Operand> operands()
        Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression. Default implementation returns a zero-length array, appropriate for an expression that has no sub-expressions.
        Specified by:
        operands in class Instruction
        Returns:
        an iterator containing the sub-expressions of this expression

      • getItemType

        public ItemType getItemType()
        Get the item type of the result of this instruction.
        Overrides:
        getItemType in class ElementCreator
        Returns:
        The context item type.

      • optimize

        public Expression optimize​(ExpressionVisitor visitor,
                           ContextItemStaticInfo contextItemType)
                    throws XPathException
        Description copied from class: Expression
        Perform optimisation of an expression and its subexpressions. This is the third and final phase of static optimization.

        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 ParentNodeConstructor
        Parameters:
        visitor - an expression visitor
        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:
        XPathException - if an error is discovered during this phase (typically a type error)

      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                  throws XPathException
        Evaluate as an item
        Overrides:
        evaluateItem in class Instruction
        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

      • getStreamerName

        public java.lang.String getStreamerName()
        Get the (partial) name of a class that supports streaming of this kind of expression
        Overrides:
        getStreamerName in class ElementCreator
        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

      • export

        public void export​(ExpressionPresenter out)
            throws XPathException
        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.