Class NodeSetPattern

java.lang.Object
net.sf.saxon.pattern.Pattern
net.sf.saxon.pattern.NodeSetPattern
All Implemented Interfaces:
Serializable, SourceLocator, Container, PatternFinder
public class NodeSetPattern extends Pattern
A NodeSetPattern is a pattern based on an expression that is evaluated to return a set of nodes; a node matches the pattern if it is a member of this node-set.

In XSLT 2.0 there are two forms of NodeSetPattern allowed, represented by calls on the id() and key() functions. In XSLT 3.0, additional forms are allowed, for example a variable reference, and a call to the doc() function. This class provides the general capability to use any expression at the head of a pattern. This is used also to support streaming, where streaming XPath expressions are mapped to patterns.

See Also:

  • Field Details

  • Constructor Details

    • NodeSetPattern

      public NodeSetPattern(Expression exp, Configuration config)
      Create a node-set pattern.
      Parameters:
      exp - an expression that can be evaluated to return a node-set; a node matches the pattern if it is present in this node-set. The expression must not depend on the focus, though it can depend on other aspects of the dynamic context such as local or global variables.

  • Method Details

    • analyze

      public Pattern analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
      Type-check the pattern. Default implementation does nothing. This is only needed for patterns that contain variable references or function calls.
      Overrides:
      analyze in class Pattern
      Parameters:
      visitor - the expression visitor
      contextItemType - the type of the context item at the point where the pattern is defined. Set to null if it is known that the context item is undefined.
      Returns:
      the optimised Pattern
      Throws:
      XPathException - if a static error is discovered

    • getDependencies

      public int getDependencies()
      Get the dependencies of the pattern. The only possible dependency for a pattern is on local variables. This is analyzed in those patterns where local variables may appear.
      Overrides:
      getDependencies in class Pattern
      Returns:
      the dependencies, as a bit-significant mask

    • iterateSubExpressions

      public Iterator iterateSubExpressions()
      Iterate over the subexpressions within this pattern
      Overrides:
      iterateSubExpressions in class Pattern
      Returns:
      an iterator over the subexpressions. Default implementation returns an empty sequence

    • promote

      public void promote(PromotionOffer offer, Expression parent) throws XPathException
      Offer promotion for subexpressions within this pattern. The offer will be accepted if the subexpression is not dependent on the factors (e.g. the context item) identified in the PromotionOffer. By default the offer is not accepted - this is appropriate in the case of simple expressions such as constant values and variable references where promotion would give no performance advantage. This method is always called at compile time.

      Unlike the corresponding method on Expression, this method does not return anything: it can make internal changes to the pattern, but cannot return a different pattern. Only certain kinds of promotion are applicable within a pattern: specifically, promotions affecting local variable references within the pattern.

      Overrides:
      promote in class Pattern
      Parameters:
      offer - details of the offer, for example the offer to move expressions that don't depend on the context to an outer level in the containing expression
      parent -
      Throws:
      XPathException - if any error is detected

    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Replace a subexpression by a replacement subexpression
      Overrides:
      replaceSubExpression in class Pattern
      Parameters:
      original - the expression to be replaced
      replacement - the new expression to be inserted in its place
      Returns:
      true if the replacement was carried out

    • allocateSlots

      public int allocateSlots(StaticContext env, SlotManager slotManager, int nextFree)
      Allocate slots to any variables used within the pattern
      Overrides:
      allocateSlots in class Pattern
      Parameters:
      env - the static context in the XSLT stylesheet
      slotManager - the slot manager representing the stack frame for local variables
      nextFree - the next slot that is free to be allocated @return the next slot that is free to be allocated
      Returns:
      the next slot that is free to be allocated

    • matches

      public boolean matches(Item item, XPathContext context) throws XPathException
      Determine whether this Pattern matches the given Node
      Specified by:
      matches in class Pattern
      Parameters:
      item - The NodeInfo representing the Element or other node to be tested against the Pattern
      context - The dynamic context. Only relevant if the pattern uses variables, or contains calls on functions such as document() or key().
      Returns:
      true if the node matches the Pattern, false otherwise
      Throws:
      XPathException - if a dynamic error occurs during pattern matching

    • getNodeKind

      public int getNodeKind()
      Determine the type of nodes to which this pattern applies.
      Overrides:
      getNodeKind in class Pattern
      Returns:
      Type.NODE (may be overridden in subclasses)

    • getItemType

      public ItemType getItemType()
      Get a NodeTest that all the nodes matching this pattern must satisfy
      Specified by:
      getItemType in class Pattern
      Returns:
      an ItemType, as specific as possible, which all the matching items satisfy

    • equals

      public boolean equals(Object other)
      Determine whether this pattern is the same as another pattern
      Overrides:
      equals in class Object
      Parameters:
      other - the other object

    • hashCode

      public int hashCode()
      Hashcode supporting equals()
      Overrides:
      hashCode in class Object