Class DocumentInstr

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

    public class DocumentInstr
    extends ParentNodeConstructor
    An instruction to create a document node. This corresponds to the xsl:document-node instruction in XSLT. It is also used to support the document node constructor expression in XQuery, and is generated implicitly within an xsl:variable that constructs a temporary tree.

    Conceptually it represents an XSLT instruction xsl:document-node, with no attributes, whose content is a complex content constructor for the children of the document node.

    See Also:
    Serialized Form
    • Constructor Detail

      • DocumentInstr

        public DocumentInstr​(boolean textOnly,
                             java.lang.String constantText,
                             java.lang.String baseURI)
    • Method Detail

      • 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 prefered. For instructions this is the process() method.
        Specified by:
        getImplementationMethod in interface Expression
        Overrides:
        getImplementationMethod in class Instruction
      • setValidationAction

        public void setValidationAction​(int action)
        Set the validation action
      • isTextOnly

        public boolean isTextOnly()
        Determine whether this is a "text only" document: essentially, an XSLT xsl:variable that contains a single text node or xsl:value-of instruction.
      • simplify

        public Expression simplify​(StaticContext env)
                            throws XPathException
        Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation does nothing.
        Specified by:
        simplify in interface Expression
        Overrides:
        simplify in class ParentNodeConstructor
        Parameters:
        env - the static context
        Returns:
        the simplified expression
        Throws:
        XPathException - if an error is discovered during expression rewriting
      • typeCheck

        public Expression typeCheck​(StaticContext env,
                                    ItemType contextItemType)
                             throws XPathException
        Description copied from interface: 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.

        If the implementation returns a value other than "this", then it is required to ensure that the parent pointer and location information in the returned expression have been set up correctly. It should not rely on the caller to do this, although for historical reasons many callers do so.

        Specified by:
        typeCheck in interface Expression
        Overrides:
        typeCheck in class ParentNodeConstructor
        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
      • getStringValueExpression

        public Expression getStringValueExpression​(StaticContext env)
        In the case of a text-only instruction (xsl:variable containing a text node or one or more xsl:value-of instructions, return an expression that evaluates to the textual content
        Returns:
        an expression that evaluates to the textual content
      • processLeavingTail

        public TailCall processLeavingTail​(XPathContext context)
                                    throws XPathException
        Description copied from class: Instruction
        ProcessLeavingTail: called to do the real work of this instruction. This method must be implemented in each subclass. The results of the instruction are written to the current Receiver, which can be obtained via the Controller.
        Specified by:
        processLeavingTail in interface TailCallReturner
        Specified by:
        processLeavingTail in class Instruction
        Parameters:
        context - The dynamic context of the transformation, giving access to the current node, the current variables, etc.
        Returns:
        null if the instruction has completed execution; or a TailCall indicating a function call or template call that is delegated to the caller, to be made after the stack has been unwound so as to save stack space.
        Throws:
        XPathException
      • evaluateItem

        public Item evaluateItem​(XPathContext context)
                          throws XPathException
        Evaluate as an expression.
        Specified by:
        evaluateItem in interface Expression
        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
      • getInstructionNameCode

        public int getInstructionNameCode()
        Get the name of this instruction for diagnostic and tracing purposes (the string "document-constructor")
        Overrides:
        getInstructionNameCode in class Instruction
      • display

        public void display​(int level,
                            java.io.PrintStream out,
                            Configuration config)
        Display this instruction as an expression, for diagnostics
        Parameters:
        level - indentation level for this expression
        out - Output destination