num_enum_derive/
variant_attributes.rs

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1use syn::{
2    parse::{Parse, ParseStream},
3    Expr, Result,
4};
5
6mod kw {
7    syn::custom_keyword!(default);
8    syn::custom_keyword!(catch_all);
9    syn::custom_keyword!(alternatives);
10}
11
12pub(crate) struct NumEnumVariantAttributes {
13    pub(crate) items: syn::punctuated::Punctuated<NumEnumVariantAttributeItem, syn::Token![,]>,
14}
15
16impl Parse for NumEnumVariantAttributes {
17    fn parse(input: ParseStream<'_>) -> Result<Self> {
18        Ok(Self {
19            items: input.parse_terminated(NumEnumVariantAttributeItem::parse, syn::Token![,])?,
20        })
21    }
22}
23
24pub(crate) enum NumEnumVariantAttributeItem {
25    Default(VariantDefaultAttribute),
26    CatchAll(VariantCatchAllAttribute),
27    Alternatives(VariantAlternativesAttribute),
28}
29
30impl Parse for NumEnumVariantAttributeItem {
31    fn parse(input: ParseStream<'_>) -> Result<Self> {
32        let lookahead = input.lookahead1();
33        if lookahead.peek(kw::default) {
34            input.parse().map(Self::Default)
35        } else if lookahead.peek(kw::catch_all) {
36            input.parse().map(Self::CatchAll)
37        } else if lookahead.peek(kw::alternatives) {
38            input.parse().map(Self::Alternatives)
39        } else {
40            Err(lookahead.error())
41        }
42    }
43}
44
45pub(crate) struct VariantDefaultAttribute {
46    pub(crate) keyword: kw::default,
47}
48
49impl Parse for VariantDefaultAttribute {
50    fn parse(input: ParseStream) -> Result<Self> {
51        Ok(Self {
52            keyword: input.parse()?,
53        })
54    }
55}
56
57pub(crate) struct VariantCatchAllAttribute {
58    pub(crate) keyword: kw::catch_all,
59}
60
61impl Parse for VariantCatchAllAttribute {
62    fn parse(input: ParseStream) -> Result<Self> {
63        Ok(Self {
64            keyword: input.parse()?,
65        })
66    }
67}
68
69pub(crate) struct VariantAlternativesAttribute {
70    _keyword: kw::alternatives,
71    _eq_token: syn::Token![=],
72    _bracket_token: syn::token::Bracket,
73    pub(crate) expressions: syn::punctuated::Punctuated<Expr, syn::Token![,]>,
74}
75
76impl Parse for VariantAlternativesAttribute {
77    fn parse(input: ParseStream) -> Result<Self> {
78        let content;
79        let keyword = input.parse()?;
80        let _eq_token = input.parse()?;
81        let _bracket_token = syn::bracketed!(content in input);
82        let expressions = content.parse_terminated(Expr::parse, syn::Token![,])?;
83        Ok(Self {
84            _keyword: keyword,
85            _eq_token,
86            _bracket_token,
87            expressions,
88        })
89    }
90}
num_enum_derive/variant_attributes.rs

num_enum_derive/
variant_attributes.rs
