Package groovy.contracts

Annotation Interface Decreases

@Documented @Retention(RUNTIME) @Target(TYPE) @Incubating public @interface Decreases
Specifies a termination measure for a loop. The closure must return a Comparable value that strictly decreases on every iteration and remains non-negative (i.e., >= 0 for numeric types).

At runtime, the expression is evaluated at the start and end of each iteration. A LoopVariantViolation is thrown if:

  • the value did not decrease, or
  • the value became negative.

Example: 

 int n = 10
 @Decreases({ n })
 while (n > 0) {
     n--
 }
Since:
6.0.0
See Also:

  • Required Element Summary

    Required Elements
    Modifier and Type
    Required Element
    Description
    Class
    value
     

  • Element Details