Class VennPattern

java.lang.Object
net.sf.saxon.pattern.Pattern
net.sf.saxon.pattern.VennPattern
All Implemented Interfaces:
Serializable, SourceLocator, Container, PatternFinder
Direct Known Subclasses:
ExceptPattern, IntersectPattern, UnionPattern

public abstract class VennPattern extends Pattern
A pattern formed as the union, intersection, or difference of two other patterns
See Also:
  • Field Details

  • Constructor Details

    • VennPattern

      public VennPattern(Pattern p1, Pattern p2)
      Constructor
      Parameters:
      p1 - the left-hand operand
      p2 - the right-hand operand
  • Method Details

    • setExecutable

      public void setExecutable(Executable executable)
      Set the executable containing this pattern
      Overrides:
      setExecutable in class Pattern
      Parameters:
      executable - the executable
    • simplify

      public Pattern simplify(ExpressionVisitor visitor) throws XPathException
      Simplify the pattern: perform any context-independent optimisations
      Overrides:
      simplify in class Pattern
      Parameters:
      visitor - an expression visitor
      Returns:
      the optimised Pattern
      Throws:
      XPathException - if a static error is discovered
    • analyze

      public Pattern analyze(ExpressionVisitor visitor, ExpressionVisitor.ContextItemType contextItemType) throws XPathException
      Type-check the pattern. 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
    • resolveCurrent

      public void resolveCurrent(LetExpression let, PromotionOffer offer, boolean topLevel) 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
      Overrides:
      resolveCurrent in class Pattern
      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
      topLevel -
      Throws:
      XPathException
    • 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
    • setOriginalText

      public void setOriginalText(String pattern)
      Set the original text
      Overrides:
      setOriginalText in class Pattern
      Parameters:
      pattern - the original text of the pattern
    • 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 -
      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
    • setVariableBindingExpression

      public void setVariableBindingExpression(Expression exp)
      Set an expression used to bind the variable that represents the value of the current() function
      Overrides:
      setVariableBindingExpression in class Pattern
      Parameters:
      exp - the expression that binds the variable
    • getVariableBindingExpression

      public Expression getVariableBindingExpression()
    • gatherComponentPatterns

      public void gatherComponentPatterns(Set set)
      Gather the component (non-Venn) patterns of this Venn pattern
      Parameters:
      set - the set into which the components will be added
    • 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
    • getItemType

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

      protected void bindVariable(Item item, XPathContext context) throws XPathException
      Throws:
      XPathException
    • getLHS

      public Pattern getLHS()
      Get the LHS of the union
      Returns:
      the first operand of the union
    • getRHS

      public Pattern getRHS()
      Get the RHS of the union
      Returns:
      the second operand of the union
    • setSystemId

      public void setSystemId(String systemId)
      Override method to set the system ID, so it's set on both halves
      Overrides:
      setSystemId in class Pattern
      Parameters:
      systemId - the URI of the module containing the pattern
    • setLineNumber

      public void setLineNumber(int lineNumber)
      Override method to set the system ID, so it's set on both halves
      Overrides:
      setLineNumber in class Pattern
      Parameters:
      lineNumber - the line number of the pattern in the source module
    • 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