Class LocationPathPattern

java.lang.Object
net.sf.saxon.pattern.Pattern
net.sf.saxon.pattern.LocationPathPattern
All Implemented Interfaces:
Serializable, SourceLocator, Container

public final class LocationPathPattern extends Pattern
A LocationPathPattern represents a path, for example of the form A/B/C... The components are represented as a linked list, each component pointing to its predecessor
See Also:
  • Field Details

    • parentPattern

      public Pattern parentPattern
    • ancestorPattern

      public Pattern ancestorPattern
    • nodeTest

      public NodeTest nodeTest
    • filters

      protected Expression[] filters
    • numberOfFilters

      protected int numberOfFilters
    • equivalentExpr

      protected Expression equivalentExpr
    • firstElementPattern

      protected boolean firstElementPattern
    • lastElementPattern

      protected boolean lastElementPattern
    • specialFilter

      protected boolean specialFilter
  • Constructor Details

    • LocationPathPattern

      public LocationPathPattern()
  • Method Details

    • addFilter

      public void addFilter(Expression filter)
      Add a filter to the pattern (while under construction)
      Parameters:
      filter - The predicate (a boolean expression or numeric expression) to be added
    • simplify

      public Pattern simplify(StaticContext env) throws XPathException
      Simplify the pattern: perform any context-independent optimisations
      Overrides:
      simplify in class Pattern
      Returns:
      the optimised Pattern
      Throws:
      XPathException
    • analyze

      public Pattern analyze(StaticContext env, ItemType contextItemType) throws XPathException
      Type-check the pattern, performing any type-dependent optimizations.
      Overrides:
      analyze in class Pattern
      Returns:
      the optimised Pattern
      Throws:
      XPathException
    • 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
    • iterateSubExpressions

      public Iterator iterateSubExpressions()
      Iterate over the subexpressions within this pattern
      Overrides:
      iterateSubExpressions in class Pattern
    • replaceSubExpression

      public boolean replaceSubExpression(Expression original, Expression replacement)
      Replace one subexpression by a replacement subexpression
      Specified by:
      replaceSubExpression in interface Container
      Overrides:
      replaceSubExpression in class Pattern
      Parameters:
      original - the original subexpression
      replacement - the replacement subexpression
      Returns:
      true if the original subexpression is found
    • promote

      public void promote(PromotionOffer offer) 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
      Throws:
      XPathException - if any error is detected
    • matches

      public boolean matches(NodeInfo node, XPathContext context) throws XPathException
      Determine whether the pattern matches a given node.
      Specified by:
      matches in class Pattern
      Parameters:
      node - the node to be tested
      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 pattern matches, else false
      Throws:
      XPathException
    • internalMatches

      protected boolean internalMatches(NodeInfo node, XPathContext context) throws XPathException
      Test whether the pattern matches, but without changing the current() node
      Overrides:
      internalMatches in class Pattern
      Parameters:
      node - 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
    • getNodeKind

      public int getNodeKind()
      Determine the types of nodes to which this pattern applies. Used for optimisation. For patterns that match nodes of several types, return Node.NODE
      Overrides:
      getNodeKind in class Pattern
      Returns:
      the type of node matched by this pattern. e.g. Node.ELEMENT or Node.TEXT
    • getFingerprint

      public int getFingerprint()
      Determine the fingerprint of nodes to which this pattern applies. Used for optimisation.
      Overrides:
      getFingerprint in class Pattern
      Returns:
      the fingerprint of nodes matched by this pattern.
    • getNodeTest

      public NodeTest getNodeTest()
      Get a NodeTest that all the nodes matching this pattern must satisfy
      Specified by:
      getNodeTest in class Pattern
    • resolveCurrent

      public void resolveCurrent(LetExpression let, PromotionOffer offer) throws XPathException
      If the pattern contains any calls on current(), this method is called to modify such calls to become variable references to a variable declared in a specially-allocated local variable
      Parameters:
      let - the expression that assigns the local variable. This returns a dummy result, and is executed just before evaluating the pattern, to get the value of the context item into the variable.
      offer - A PromotionOffer used to process the expressions and change the call on current() into a variable reference
      Throws:
      XPathException