Class VennExpression

All Implemented Interfaces:
Serializable, SourceLocator, Container, Expression, InstructionInfoProvider

public class VennExpression extends BinaryExpression
An expression representing a nodeset that is a union, difference, or intersection of two other NodeSets
See Also:
  • Constructor Details

    • VennExpression

      public VennExpression(Expression p1, int op, Expression p2)
      Constructor
      Parameters:
      p1 - the left-hand operand
      op - the operator (union, intersection, or difference)
      p2 - the right-hand operand
  • Method Details

    • getItemType

      public final ItemType getItemType(TypeHierarchy th)
      Determine the data type of the items returned by this expression
      Parameters:
      th -
      Returns:
      the data type
    • computeCardinality

      public final int computeCardinality()
      Determine the static cardinality of the expression
      Overrides:
      computeCardinality in class BinaryExpression
    • computeSpecialProperties

      public 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 BinaryExpression
      Returns:
      StaticProperty.NON_CREATIVE. This is overridden for some subclasses.
    • simplify

      public Expression simplify(StaticContext env) throws XPathException
      Simplify the expression
      Specified by:
      simplify in interface Expression
      Overrides:
      simplify in class BinaryExpression
      Parameters:
      env - the static context
      Returns:
      the simplified expression
      Throws:
      XPathException - if an error is discovered during expression rewriting
    • typeCheck

      public Expression typeCheck(StaticContext env, ItemType contextItemType) throws XPathException
      Type-check the expression
      Specified by:
      typeCheck in interface Expression
      Overrides:
      typeCheck in class BinaryExpression
      Parameters:
      env - the static context of the expression
      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 to perform necessary run-time type checks, and to perform other type-related optimizations
      Throws:
      XPathException
    • hashCode

      public int hashCode()
      Is this expression the same as another expression?
      Overrides:
      hashCode in class BinaryExpression
    • iterate

      public SequenceIterator iterate(XPathContext c) throws XPathException
      Iterate over the value of the expression. The result will always be sorted in document order, with duplicates eliminated
      Specified by:
      iterate in interface Expression
      Overrides:
      iterate in class ComputedExpression
      Parameters:
      c - The context for evaluation
      Returns:
      a SequenceIterator representing the union of the two operands
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression
    • effectiveBooleanValue

      public boolean effectiveBooleanValue(XPathContext context) throws XPathException
      Get the effective boolean value. In the case of a union expression, this is reduced to an OR expression, for efficiency
      Specified by:
      effectiveBooleanValue in interface Expression
      Overrides:
      effectiveBooleanValue in class ComputedExpression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the effective boolean value
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression