net.sf.saxon.expr
public class BooleanExpression extends BinaryExpression implements Negatable
Constructor Summary | |
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BooleanExpression(Expression p1, int operator, Expression p2)
Construct a boolean expression |
Method Summary | |
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int | computeCardinality()
Determine the static cardinality. |
Expression | copy()
Copy an expression. |
boolean | effectiveBooleanValue(XPathContext c)
Evaluate as a boolean. |
Item | evaluateItem(XPathContext context)
Evaluate the expression |
ItemType | getItemType(TypeHierarchy th)
Determine the data type of the expression |
boolean | isNegatable(ExpressionVisitor visitor)
Check whether this specific instance of the expression is negatable
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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). |
Expression | negate()
Return the negation of this boolean expression, that is, an expression that returns true
when this expression returns false, and vice versa
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Expression | optimize(ExpressionVisitor visitor, ItemType contextItemType)
Perform optimisation of an expression and its subexpressions.
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Expression | typeCheck(ExpressionVisitor visitor, ItemType contextItemType) |
Parameters: p1 the first operand operator one of AND or OR p2 the second operand
Returns: the copy of the original expression
Parameters: th the type hierarchy cache
Returns: BuiltInAtomicType.BOOLEAN
Returns: true if it is
Parameters: exp the expression to be decomposed list the list to which the subexpressions are to be added.
Returns: the negation of this expression
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.
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 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)