net.sf.saxon.expr
Interface Negatable

All Known Implementing Classes:

BooleanExpression, BooleanFn, Existence, ValueComparison

public interface Negatable

This interface is implemented by expressions that returns a boolean value, and returns an expression whose result is the negated boolean value

Method Summary

boolean	isNegatable(ExpressionVisitor visitor) Check whether this specific instance of the expression is negatable
Expression	negate() Create an expression that returns the negation of this expression

Method Detail

isNegatable

boolean isNegatable(ExpressionVisitor visitor)

Check whether this specific instance of the expression is negatable

Returns:

true if it is

negate

Expression negate()

Create an expression that returns the negation of this expression

Returns:

the negated expression

Throws:

IllegalOperationException - if isNegatable() returns false