reluxscript 0.1.4

Write AST transformations once. Compile to Babel, SWC, and beyond.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63

/**
 * Test: Null-Coalescing Assignment (??=)
 *
 * C# developers write:
 *   name ??= "default";
 *
 * Instead of:
 *   if name.is_none() { name = Some("default"); }
 */
plugin NullCoalescingAssign {

    struct State {
        result: Str,
        cached: Option<Str>,
    }

    fn init() -> State {
        State {
            result: "",
            cached: None,
        }
    }

    pub fn visit_identifier(node: &Identifier) {
        // Basic null coalescing assignment
        self.state.cached ??= "default";

        // With computed value
        self.state.cached ??= compute_value();

        // Local variable
        let mut name: Option<Str> = None;
        name ??= "anonymous";

        // Chained assignment
        let mut a: Option<Str> = None;
        let mut b: Option<Str> = None;
        a ??= "first";
        b ??= a ?? "second";

        // In a loop pattern
        let mut cache: Option<Str> = None;
        for item in items {
            cache ??= expensive_compute(item);
        }

        // With struct field
        let mut config = Config { name: None };
        config.name ??= "default_config";
    }

    fn compute_value() -> Str {
        "computed"
    }

    fn expensive_compute(item: &Item) -> Str {
        item.name.clone()
    }

    fn finish() -> Str {
        self.state.result
    }
}