runtime-macros-derive 0.8.0

Simulate expansion of procedural macros at run time
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

use std::panic::AssertUnwindSafe;

use proc_macro2::TokenStream;
use quote::ToTokens;
use syn::parse::{Parse, ParseStream};
use syn::visit::Visit;
use syn::Attribute;

struct MacroAttrs {
    tokens: TokenStream,
}

impl Parse for MacroAttrs {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        Ok(MacroAttrs {
            tokens: input.parse()?,
        })
    }
}

pub struct AttributeMacroVisitor<F> {
    macro_path: syn::Path,
    macro_fn: AssertUnwindSafe<F>,
}

impl<F> AttributeMacroVisitor<F> {
    pub fn new(macro_path: syn::Path, macro_fn: AssertUnwindSafe<F>) -> Self {
        Self {
            macro_path,
            macro_fn,
        }
    }

    fn expand_item(&self, attrs: &[Attribute], item: &impl ToTokens)
    where
        F: Fn(TokenStream, TokenStream) -> TokenStream,
    {
        attrs
            .iter()
            .filter(|attr| *attr.path() == self.macro_path)
            .for_each(|attr| {
                if let Ok(attr) = attr.parse_args::<MacroAttrs>() {
                    // processing attribute macro with argument(s) in parentheses
                    (*self.macro_fn)(attr.tokens, item.to_token_stream())
                } else {
                    // processing attribute macro without parentheses (and arguments)
                    (*self.macro_fn)(TokenStream::new(), item.to_token_stream())
                };
            })
    }
}

impl<'ast, F> Visit<'ast> for AttributeMacroVisitor<F>
where
    F: Fn(TokenStream, TokenStream) -> TokenStream,
{
    fn visit_item_const(&mut self, i: &'ast syn::ItemConst) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_const(self, i);
    }

    fn visit_item_enum(&mut self, i: &'ast syn::ItemEnum) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_enum(self, i);
    }

    fn visit_item_extern_crate(&mut self, i: &'ast syn::ItemExternCrate) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_extern_crate(self, i);
    }

    fn visit_item_fn(&mut self, i: &'ast syn::ItemFn) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_fn(self, i);
    }

    fn visit_item_foreign_mod(&mut self, i: &'ast syn::ItemForeignMod) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_foreign_mod(self, i);
    }

    fn visit_item_impl(&mut self, i: &'ast syn::ItemImpl) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_impl(self, i);
    }

    fn visit_item_macro(&mut self, i: &'ast syn::ItemMacro) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_macro(self, i);
    }

    fn visit_item_mod(&mut self, i: &'ast syn::ItemMod) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_mod(self, i);
    }

    fn visit_item_static(&mut self, i: &'ast syn::ItemStatic) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_static(self, i);
    }

    fn visit_item_struct(&mut self, i: &'ast syn::ItemStruct) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_struct(self, i);
    }

    fn visit_item_trait(&mut self, i: &'ast syn::ItemTrait) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_trait(self, i);
    }

    fn visit_item_trait_alias(&mut self, i: &'ast syn::ItemTraitAlias) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_trait_alias(self, i);
    }

    fn visit_item_type(&mut self, i: &'ast syn::ItemType) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_type(self, i);
    }

    fn visit_item_union(&mut self, i: &'ast syn::ItemUnion) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_union(self, i);
    }

    fn visit_item_use(&mut self, i: &'ast syn::ItemUse) {
        self.expand_item(&i.attrs, i);
        syn::visit::visit_item_use(self, i);
    }
}