Package net.sf.saxon.expr.instruct

Class ComputedAttribute

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.instruct.Instruction
net.sf.saxon.expr.instruct.SimpleNodeConstructor
net.sf.saxon.expr.instruct.AttributeCreator
net.sf.saxon.expr.instruct.ComputedAttribute
All Implemented Interfaces:
ExportAgent, ValidatingInstruction, Locatable, IdentityComparable, Traceable
public final class ComputedAttribute extends AttributeCreator
An instruction derived from an xsl:attribute element in stylesheet, or from an attribute constructor in XQuery, in cases where the attribute name is not known statically

  • Constructor Details

    • ComputedAttribute

      public ComputedAttribute(Expression attributeName, Expression namespace, int validationAction, SimpleType schemaType, boolean allowNameAsQName)
      Construct an Attribute instruction
      Parameters:
      attributeName - An expression to calculate the attribute name
      namespace - An expression to calculate the attribute namespace
      validationAction - e.g. validation=strict, lax, strip, preserve
      schemaType - Type against which the attribute must be validated. This must not be a namespace-sensitive type; it is the caller's responsibility to check this.
      allowNameAsQName - true if the attributeName expression is allowed to evaluate to a value of type xs:QName (true in XQuery, false in XSLT)

  • Method Details

    • setRejectDuplicates

      public void setRejectDuplicates()
      Indicate that two attributes with the same name are not acceptable. (This option is set in XQuery, but not in XSLT)
      Overrides:
      setRejectDuplicates in class AttributeCreator

    • getInstructionNameCode

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

    • getNameExp

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

    • getNamespaceExp

      public Expression getNamespaceExp()
      Get the expression used to compute the namespace part of the name of the attribute
      Returns:
      the expression used to compute the namespace part of the name of the attribute

    • setNameExp

      public void setNameExp(Expression attributeName)

    • setNamespace

      public void setNamespace(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.

      Overrides:
      operands in class SimpleNodeConstructor
      Returns:
      an iterator containing the sub-expressions of this expression

    • getNamespaceResolver

      public NamespaceResolver getNamespaceResolver()
      Get the namespace resolver used to resolve any prefix in the name of the attribute
      Returns:
      the namespace resolver if one has been saved; or null otherwise

    • getItemType

      public ItemType getItemType()
      Get the static type of this expression
      Overrides:
      getItemType in class AttributeCreator
      Returns:
      the static type of the item returned by this expression

    • getCardinality

      public int getCardinality()
      Get the static cardinality of this expression
      Overrides:
      getCardinality in class Expression
      Returns:
      the static cardinality (exactly one)

    • isAllowNameAsQName

      public boolean isAllowNameAsQName()
      Ask whether it is allowed for the name to be evaluted as an xs:QName instance (true in XQuery)
      Returns:
      the boolean if name is allowed as a QName

    • computeSpecialProperties

      protected int computeSpecialProperties()
      Get the static properties of this expression (other than its type). The result is bit-signficant. These properties are used for optimizations. In general, if property bit is set, it is true, but if it is unset, the value is unknown.
      Overrides:
      computeSpecialProperties in class AttributeCreator
      Returns:
      a set of flags indicating static properties of this expression

    • localTypeCheck

      public void localTypeCheck(ExpressionVisitor visitor, ContextItemStaticInfo contextItemType) throws XPathException
      Description copied from class: SimpleNodeConstructor
      Method to perform type-checking specific to the kind of instruction
      Specified by:
      localTypeCheck in class SimpleNodeConstructor
      Parameters:
      visitor - an expression visitor
      contextItemType - the static type of the context item
      Throws:
      XPathException - if a type error is detected

    • 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 SimpleNodeConstructor
      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)

    • 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

    • 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

    • evaluateNodeName

      public NodeName evaluateNodeName(XPathContext context) throws XPathException
      Determine the name to be used for the attribute, as an integer name code
      Overrides:
      evaluateNodeName in class SimpleNodeConstructor
      Parameters:
      context - Dynamic evaluation context
      Returns:
      the integer name code for the attribute name
      Throws:
      XPathException - if a dynamic error occurs (for example, if the attribute name is invalid)

    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Description copied from class: SimpleNodeConstructor
      Evaluate as an expression.
      Overrides:
      evaluateItem in class SimpleNodeConstructor
      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

    • 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()
      Description copied from class: Expression
      Make an elaborator for this expression
      Overrides:
      getElaborator in class Expression
      Returns:
      an appropriate Elaborator