Package net.sf.saxon.expr

## Interface Negatable

- All Known Implementing Classes:
    `AndExpression`, `BooleanExpression`, `OrExpression`, `SystemFunctionCall`, `SystemFunctionCall.Optimized`, `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

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method | Description
    --- | --- | ---
    `boolean` | `isNegatable​(TypeHierarchy th)` | 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​(TypeHierarchy th)

      Check whether this specific instance of the expression is negatable
      Parameters:
        `th` - the type hierarchy cache
      Returns:
        true if it is

    - #### negate

          Expression negate()

      Create an expression that returns the negation of this expression
      Returns:
        the negated expression