Package net.sf.saxon.expr.instruct

Class NumberInstruction

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.instruct.NumberInstruction
All Implemented Interfaces:
ExportAgent, Locatable, IdentityComparable, Traceable
public class NumberInstruction extends Expression
This instruction performs the node-counting function of the xsl:number instruction. It delivers as its result a sequence of integers. The parent expression is typically a NumberSequenceFormatter which takes this sequence of integers and performs the necessary formatting.

  • Field Details

  • Constructor Details

    • NumberInstruction

      public NumberInstruction(Expression select, int level, Pattern count, Pattern from)
      Construct a NumberInstruction
      Parameters:
      select - the expression supplied in the select attribute
      level - one of "single", "level", "multi"
      count - the pattern supplied in the count attribute
      from - the pattern supplied in the from attribute

  • Method Details

    • isInstruction

      public boolean isInstruction()
      Ask whether this expression is an instruction. In XSLT streamability analysis this is used to distinguish constructs corresponding to XSLT instructions from other constructs, typically XPath expressions.
      Overrides:
      isInstruction in class Expression
      Returns:
      true -- this construct originates as an XSLT instruction

    • 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 Expression
      Returns:
      an iterator containing the sub-expressions of this expression

    • getLevel

      public int getLevel()
      Get the level attribute
      Returns:
      the coded value of the level attribute

    • getCount

      public Pattern getCount()
      Get the count pattern, if specified
      Returns:
      the count pattern if there is one, otherwise null

    • getFrom

      public Pattern getFrom()
      Get the from pattern, if specified
      Returns:
      the from pattern if there is one, otherwise null

    • getSelect

      public Expression getSelect()
      Get the select expression
      Returns:
      the select expression (which defaults to a ContextItemExpression)

    • 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()
      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)

    • computeCardinality

      protected int computeCardinality()
      Description copied from class: Expression
      Compute the static cardinality of this expression
      Specified by:
      computeCardinality in class Expression
      Returns:
      the computed cardinality, as one of the values StaticProperty.ALLOWS_ZERO_OR_ONE, StaticProperty.EXACTLY_ONE, StaticProperty.ALLOWS_ONE_OR_MORE, StaticProperty.ALLOWS_ZERO_OR_MORE. May also return StaticProperty.ALLOWS_ZERO if the result is known to be an empty sequence, or StaticProperty.ALLOWS_MANY if if is known to return a sequence of length two or more.

    • 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 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

    • optimize

      public Expression optimize(ExpressionVisitor visitor, ContextItemStaticInfo contextInfo) throws XPathException
      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 Expression
      Parameters:
      visitor - an expression visitor
      contextInfo - 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)

    • iterate

      public SequenceIterator iterate(XPathContext context) throws XPathException
      Compute the required node number as a sequence of integers
      Overrides:
      iterate in class Expression
      Parameters:
      context - supplies the context for evaluation
      Returns:
      a SequenceIterator of IntegerValue values
      Throws:
      XPathException - if a failure occurs

    • getExpressionName

      public 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.

    • 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:
      an appropriate Elaborator