smol-attributes 0.1.3

Proc macro for smol runtime.
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
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144

#![forbid(unsafe_code, future_incompatible, rust_2018_idioms)]
#![deny(missing_debug_implementations, nonstandard_style)]
#![recursion_limit = "512"]

use proc_macro::TokenStream;
use quote::{quote, quote_spanned};
use syn::spanned::Spanned;

/// Enables an async main function.
///
/// # Examples
///
/// ```ignore
/// #[smol::main]
/// async fn main() -> std::io::Result<()> {
///     Ok(())
/// }
/// ```
#[cfg(not(test))] // NOTE: exporting main breaks tests, we should file an issue.
#[proc_macro_attribute]
pub fn main(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = syn::parse_macro_input!(item as syn::ItemFn);

    let ret = &input.sig.output;
    let inputs = &input.sig.inputs;
    let name = &input.sig.ident;
    let body = &input.block;
    let attrs = &input.attrs;

    if name != "main" {
        return TokenStream::from(quote_spanned! { name.span() =>
            compile_error!("only the main function can be tagged with #[smol::main]"),
        });
    }

    if input.sig.asyncness.is_none() {
        return TokenStream::from(quote_spanned! { input.span() =>
            compile_error!("the async keyword is missing from the function declaration"),
        });
    }

    let result = quote! {
        fn main() #ret {
            #(#attrs)*
            async fn main(#inputs) #ret {
                #body
            }

            smol::run(async {
                main().await
            })
        }

    };

    result.into()
}

/// Enables an async test function.
///
/// # Examples
///
/// ```ignore
/// #[smol::test]
/// async fn my_test() -> std::io::Result<()> {
///     assert_eq!(2 * 2, 4);
///     Ok(())
/// }
/// ```
#[proc_macro_attribute]
pub fn test(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = syn::parse_macro_input!(item as syn::ItemFn);

    let ret = &input.sig.output;
    let name = &input.sig.ident;
    let body = &input.block;
    let attrs = &input.attrs;

    if input.sig.asyncness.is_none() {
        return TokenStream::from(quote_spanned! { input.span() =>
            compile_error!("the async keyword is missing from the function declaration"),
        });
    }

    let result = quote! {
        #[test]
        #(#attrs)*
        fn #name() #ret {
            smol::run(async { #body })
        }
    };

    result.into()
}

/// Enables an async benchmark function.
///
/// # Examples
///
/// ```ignore
/// #![feature(test)]
/// extern crate test;
///
/// #[smol::bench]
/// async fn bench() {
///     println!("hello world");
/// }
/// ```
#[proc_macro_attribute]
pub fn bench(_attr: TokenStream, item: TokenStream) -> TokenStream {
    let input = syn::parse_macro_input!(item as syn::ItemFn);

    let ret = &input.sig.output;
    let args = &input.sig.inputs;
    let name = &input.sig.ident;
    let body = &input.block;
    let attrs = &input.attrs;

    if input.sig.asyncness.is_none() {
        return TokenStream::from(quote_spanned! { input.span() =>
            compile_error!("the async keyword is missing from the function declaration"),
        });
    }

    if !args.is_empty() {
        return TokenStream::from(quote_spanned! { args.span() =>
            compile_error!("async benchmarks don't take any arguments"),
        });
    }

    let result = quote! {
        #[bench]
        #(#attrs)*
        fn #name(b: &mut test::Bencher) #ret {
            let _ = b.iter(|| {
                smol::block_on(async {
                    #body
                })
            });
        }
    };

    result.into()
}