Package net.sf.saxon.expr.instruct

Class ComputedElement

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.instruct.Instruction
net.sf.saxon.expr.instruct.ParentNodeConstructor
net.sf.saxon.expr.instruct.ElementCreator
net.sf.saxon.expr.instruct.ComputedElement
All Implemented Interfaces:
ExportAgent, InstructionWithComplexContent, ValidatingInstruction, Locatable, IdentityComparable, Traceable
public class ComputedElement extends ElementCreator
An instruction representing an xsl:element element in an XSLT stylesheet, or a computed element constructor in XQuery. (In both cases, if the element name is expressed as a compile-time expression, then a FixedElement instruction is used instead.)
See Also:

  • Constructor Details

    • ComputedElement

      public ComputedElement(Expression elementName, Expression namespace, SchemaType schemaType, int validation, boolean inheritNamespaces, boolean allowQName)
      Create an instruction that creates a new element node
      Parameters:
      elementName - Expression that evaluates to produce the name of the element node as a lexical QName
      namespace - Expression that evaluates to produce the namespace URI of the element node. Set to null if the namespace is to be deduced from the prefix of the elementName.
      schemaType - The required schema type for the content
      validation - Required validation mode (e.g. STRICT, LAX, SKIP)
      inheritNamespaces - true if child elements automatically inherit the namespaces of their parent
      allowQName - True if the elementName expression is allowed to return a QNameValue; false if

  • Method Details

    • getNameExp

      public Expression getNameExp()
      Get the expression used to compute the element name
      Returns:
      the expression used to compute the element name

    • getNamespaceExp

      public Expression getNamespaceExp()
      Get the expression used to compute the namespace URI
      Returns:
      the expression used to compute the namespace URI

    • setNameExp

      protected void setNameExp(Expression elementName)

    • setNamespaceExp

      protected void setNamespaceExp(Expression namespace)

    • operands

      public Iterable<Operand> operands()
      Description copied from class: Expression
      Get the immediate sub-expressions of this expression, with information about the relationship of each expression to its parent expression.

      If the expression is a Callable, then it is required that the order of the operands returned by this function is the same as the order of arguments supplied to the corresponding call() method.

      Specified by:
      operands in class Instruction
      Returns:
      an iterator containing the sub-expressions of this expression

    • getNamespaceResolver

      public NamespaceResolver getNamespaceResolver()
      Get the namespace resolver that provides the namespace bindings defined in the static context
      Returns:
      the namespace resolver

    • simplify

      public Expression simplify() throws XPathException
      Description copied from class: Expression
      Simplify an expression. This performs any static optimization (by rewriting the expression as a different expression). The default implementation simplifies its operands.
      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 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

    • getItemType

      public ItemType getItemType()
      Get the item type of the value returned by this instruction
      Overrides:
      getItemType in class ElementCreator
      Returns:
      the item type

    • checkPermittedContents

      public void checkPermittedContents(SchemaType parentType, boolean whole) throws XPathException
      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

    • getElementName

      public NodeName getElementName(XPathContext context) throws XPathException
      Callback from the superclass ElementCreator to get the nameCode for the element name
      Parameters:
      context - The evaluation context (not used)
      Returns:
      the name code for the element name
      Throws:
      XPathException

    • isAllowNameAsQName

      public boolean isAllowNameAsQName()
      Ask whether the name can be supplied as a QName. In practice this is true for XQuery, false for XSLT
      Returns:
      true if the name can be supplied as a QName

    • makeElementCreationDetails

      public ElementCreator.ElementCreationDetails makeElementCreationDetails()
      Overrides:
      makeElementCreationDetails in class ElementCreator

    • outputNamespaceNodes

      public void outputNamespaceNodes(Outputter out, NodeName nodeName, ElementCreator.ElementCreationDetails details) throws XPathException
      Callback to output namespace nodes for the new element.
      Specified by:
      outputNamespaceNodes in class ElementCreator
      Parameters:
      out - the Outputter where the namespace nodes are to be written
      nodeName - The name of the element node being output
      details - Where this is a copied node, the node being copied
      Throws:
      XPathException - if a dynamic error occurs

    • 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

    • 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.

    • getElaborator

      public Elaborator getElaborator()
      Make an elaborator for this expression
      Overrides:
      getElaborator in class Expression
      Returns:
      a suitable elaborator