Package net.sf.saxon.expr

Class BooleanExpression

java.lang.Object
net.sf.saxon.expr.Expression
net.sf.saxon.expr.BinaryExpression
net.sf.saxon.expr.BooleanExpression
All Implemented Interfaces:
Serializable, SourceLocator, LocationProvider, SaxonLocator, EvaluableItem, Negatable, SequenceIterable, InstructionInfo, Locator
public class BooleanExpression extends BinaryExpression implements Negatable
Boolean expression: two truth values combined using AND or OR.
See Also:

  • Constructor Details

    • BooleanExpression

      public BooleanExpression(Expression p1, int operator, Expression p2)
      Construct a boolean expression
      Parameters:
      p1 - the first operand
      operator - one of Token.AND or Token.OR
      p2 - the second operand

  • Method Details

    • typeCheck

      public Expression typeCheck(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
      Description copied from class: BinaryExpression
      Type-check the expression. Default implementation for binary operators that accept any kind of operand
      Overrides:
      typeCheck in class BinaryExpression
      Parameters:
      visitor - an expression visitor
      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 - if an error is discovered during this phase (typically a type error)

    • computeCardinality

      public int computeCardinality()
      Determine the static cardinality. Returns [1..1]
      Overrides:
      computeCardinality in class BinaryExpression
      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

    • optimize

      public Expression optimize(ExpressionVisitor visitor, ItemType contextItemType) throws XPathException
      Perform optimisation of an expression and its subexpressions.

      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 BinaryExpression
      Parameters:
      visitor - an expression visitor
      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 if appropriate to optimize execution
      Throws:
      XPathException - if an error is discovered during this phase (typically a type error)

    • copy

      public Expression copy()
      Copy an expression. This makes a deep copy.
      Specified by:
      copy in class Expression
      Returns:
      the copy of the original expression

    • isNegatable

      public boolean isNegatable(ExpressionVisitor visitor)
      Check whether this specific instance of the expression is negatable
      Specified by:
      isNegatable in interface Negatable
      Returns:
      true if it is

    • negate

      public Expression negate()
      Return the negation of this boolean expression, that is, an expression that returns true when this expression returns false, and vice versa
      Specified by:
      negate in interface Negatable
      Returns:
      the negation of this expression

    • evaluateItem

      public Item evaluateItem(XPathContext context) throws XPathException
      Evaluate the expression
      Specified by:
      evaluateItem in interface EvaluableItem
      Overrides:
      evaluateItem in class Expression
      Parameters:
      context - The context in which the expression is to be evaluated
      Returns:
      the node or atomic value that results from evaluating the expression; or null to indicate that the result is an empty sequence
      Throws:
      XPathException - if any dynamic error occurs evaluating the expression

    • effectiveBooleanValue

      public boolean effectiveBooleanValue(XPathContext c) throws XPathException
      Evaluate as a boolean.
      Overrides:
      effectiveBooleanValue in class Expression
      Parameters:
      c - 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

    • getItemType

      public ItemType getItemType(TypeHierarchy th)
      Determine the data type of the expression
      Specified by:
      getItemType in class Expression
      Parameters:
      th - the type hierarchy cache
      Returns:
      BuiltInAtomicType.BOOLEAN

    • listAndComponents

      public static void listAndComponents(Expression exp, List list)
      Construct a list containing the "anded" subexpressions of an expression: if the expression is (A and B and C), this returns (A, B, C).
      Parameters:
      exp - the expression to be decomposed
      list - the list to which the subexpressions are to be added.