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

#[doc(hidden)]
#[macro_export]
macro_rules! private_parse_expr {
    // Entry point. Dup tokens.
    {
        $caller:tt
        input = [{ $($input:tt)* }]
    } => {
        $crate::private_parse_expr! {
            $caller
            tokens = [{ $($input)* }]
            _tokens = [{ $($input)* }]
        }
    };

    // TODO: our own expression parser for better error recovery
    // TODO: support non-empty `rest`
    {
        $caller:tt
        tokens = [{ $e:expr }]
        _tokens = [{ $($tokens:tt)* }]
    } => {
        $crate::tt_return! {
            $caller
            expr = [{ $($tokens)* }]
            rest = [{ }]
        }
    };

    // Unexpected: input does not match $:expr.
    {
        $caller:tt
        tokens = [{ $($unexpected:tt)+ }]
        _tokens = [{ $($dup:tt)* }]
    } => {
        $crate::error_unexpected! {
            $($unexpected)*
        }
    };
}