comparison: src/metaprogramming.rs
src/metaprogramming.rs
- changeset 94
- 1f19c6bbf07b
- parent 75
- e9f4550cfa18
equal
deleted
inserted
replaced
| 93:123f7f38e161 | 94:1f19c6bbf07b |
|---|---|
| 7 /// | 7 /// |
| 8 /// ```ignore | 8 /// ```ignore |
| 9 /// maybe_ref!(ref, V) // ➡ &V | 9 /// maybe_ref!(ref, V) // ➡ &V |
| 10 /// maybe_ref!(noref, V) // ➡ V | 10 /// maybe_ref!(noref, V) // ➡ V |
| 11 /// ``` | 11 /// ``` |
| 12 #[macro_export] | |
| 13 macro_rules! maybe_ref { | 12 macro_rules! maybe_ref { |
| 14 (ref, $x:expr) => { &$x }; | 13 (ref, $x:expr) => { |
| 15 (noref, $x:expr) => { $x }; | 14 &$x |
| 16 (ref, $x:ty) => { &$x }; | 15 }; |
| 17 (noref, $x:ty) => { $x }; | 16 (noref, $x:expr) => { |
| 17 $x | |
| 18 }; | |
| 19 (ref, $x:ty) => { | |
| 20 &$x | |
| 21 }; | |
| 22 (noref, $x:ty) => { | |
| 23 $x | |
| 24 }; | |
| 18 } | 25 } |
| 19 | 26 |
| 20 /// Choose `a` if first argument is the literal `ref`, otherwise `b`. | 27 /// Choose `a` if first argument is the literal `ref`, otherwise `b`. |
| 21 #[macro_export] | 28 // macro_rules! ifref { |
| 22 macro_rules! ifref { | 29 // (noref, $a:expr, $b:expr) => { |
| 23 (noref, $a:expr, $b:expr) => { $b }; | 30 // $b |
| 24 (ref, $a:expr, $b:expr) => { $a }; | 31 // }; |
| 25 } | 32 // (ref, $a:expr, $b:expr) => { |
| 26 | 33 // $a |
| 34 // }; | |
| 35 // } | |
| 27 | 36 |
| 28 /// Annotate `x` with a lifetime if the first parameter | 37 /// Annotate `x` with a lifetime if the first parameter |
| 29 /// Typically to be used from another macro. | 38 /// Typically to be used from another macro. |
| 30 /// | 39 /// |
| 31 /// ```ignore | 40 /// ```ignore |
| 32 /// maybe_ref!(ref, &'a V) // ➡ &'a V | 41 /// maybe_ref!(ref, &'a V) // ➡ &'a V |
| 33 /// maybe_ref!(noref, &'a V) // ➡ V | 42 /// maybe_ref!(noref, &'a V) // ➡ V |
| 34 /// ``` | 43 /// ``` |
| 35 #[macro_export] | |
| 36 macro_rules! maybe_lifetime { | 44 macro_rules! maybe_lifetime { |
| 37 (ref, $x:ty) => { $x }; | 45 (ref, $x:ty) => { |
| 38 (noref, &$lt:lifetime $x:ty) => { $x }; | 46 $x |
| 39 (noref, &$x:ty) => { $x }; | 47 }; |
| 48 (noref, &$lt:lifetime $x:ty) => { | |
| 49 $x | |
| 50 }; | |
| 51 (noref, &$x:ty) => { | |
| 52 $x | |
| 53 }; | |
| 40 } | 54 } |
| 41 |
