add Conditional and Predicative helpers
Vladimir Bauer
3 years ago
| 0 | 0 | package decor |
| 1 | 1 | |
| 2 | // OnPredicate returns decorator if predicate evaluates to true. | |
| 2 | // OnCondition applies decorator only if a condition is true. | |
| 3 | // | |
| 4 | // `decorator` Decorator | |
| 5 | // | |
| 6 | // `cond` bool | |
| 7 | // | |
| 8 | func OnCondition(decorator Decorator, cond bool) Decorator { | |
| 9 | return Conditional(cond, decorator, nil) | |
| 10 | } | |
| 11 | ||
| 12 | // OnPredicate applies decorator only if a predicate evaluates to true. | |
| 3 | 13 | // |
| 4 | 14 | // `decorator` Decorator |
| 5 | 15 | // |
| 6 | 16 | // `predicate` func() bool |
| 7 | 17 | // |
| 8 | 18 | func OnPredicate(decorator Decorator, predicate func() bool) Decorator { |
| 9 | if predicate() { | |
| 10 | return decorator | |
| 11 | } | |
| 12 | return nil | |
| 19 | return Predicative(predicate, decorator, nil) | |
| 13 | 20 | } |
| 14 | 21 | |
| 15 | // OnCondition returns decorator if condition is true. | |
| 16 | // | |
| 17 | // `decorator` Decorator | |
| 22 | // Conditional returns decorator `a` if condition is true, otherwise | |
| 23 | // decorator `b`. | |
| 18 | 24 | // |
| 19 | 25 | // `cond` bool |
| 20 | 26 | // |
| 21 | func OnCondition(decorator Decorator, cond bool) Decorator { | |
| 27 | // `a` Decorator | |
| 28 | // | |
| 29 | // `b` Decorator | |
| 30 | // | |
| 31 | func Conditional(cond bool, a, b Decorator) Decorator { | |
| 22 | 32 | if cond { |
| 23 | return decorator | |
| 33 | return a | |
| 34 | } else { | |
| 35 | return b | |
| 24 | 36 | } |
| 25 | return nil | |
| 26 | 37 | } |
| 38 | ||
| 39 | // Predicative returns decorator `a` if predicate evaluates to true, | |
| 40 | // otherwise decorator `b`. | |
| 41 | // | |
| 42 | // `predicate` func() bool | |
| 43 | // | |
| 44 | // `a` Decorator | |
| 45 | // | |
| 46 | // `b` Decorator | |
| 47 | // | |
| 48 | func Predicative(predicate func() bool, a, b Decorator) Decorator { | |
| 49 | if predicate() { | |
| 50 | return a | |
| 51 | } else { | |
| 52 | return b | |
| 53 | } | |
| 54 | } |