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


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