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
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
use proc_macro::TokenStream;
use quote::quote;
use syn::{
Attribute, Data, DeriveInput, Error, Fields, Ident, LitStr, Result, Variant, parse_macro_input,
};
pub fn derive_enum_tag(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
match derive_enum_tag_impl(input) {
Ok(tokens) => tokens.into(),
Err(err) => err.to_compile_error().into(),
}
}
/// Implementation of the `EnumTag` derive macro
fn derive_enum_tag_impl(input: DeriveInput) -> Result<proc_macro2::TokenStream> {
let enum_name = &input.ident;
let generics = &input.generics;
// Extract enum data
let data = match input.data {
Data::Enum(data_enum) => data_enum,
Data::Struct(_) => {
return Err(Error::new_spanned(
enum_name,
"EnumTag can only be derived for enums, not structs",
));
}
Data::Union(_) => {
return Err(Error::new_spanned(
enum_name,
"EnumTag can only be derived for enums, not unions",
));
}
};
// Process each variant
let mut variant_info = Vec::new();
let mut match_arms = Vec::new();
let mut build_match_arms = Vec::new();
for variant in data.variants {
process_variant(
&variant,
enum_name,
&mut variant_info,
&mut match_arms,
&mut build_match_arms,
)?;
}
// Generate the implementation
let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
let expanded = quote! {
impl #impl_generics ::mingling::EnumTag for #enum_name #ty_generics #where_clause {
fn enum_info(&self) -> (&'static str, &'static str) {
match self {
#(#match_arms)*
}
}
fn build_enum(name: String) -> Option<Self>
where
Self: Sized
{
match name.as_str() {
#(#build_match_arms)*
_ => None,
}
}
fn enums() -> &'static [(&'static str, &'static str)] {
&[#(#variant_info),*]
}
}
};
Ok(expanded)
}
/// Process a single enum variant
fn process_variant(
variant: &Variant,
enum_name: &Ident,
variant_info: &mut Vec<proc_macro2::TokenStream>,
match_arms: &mut Vec<proc_macro2::TokenStream>,
build_match_arms: &mut Vec<proc_macro2::TokenStream>,
) -> Result<()> {
let variant_name = variant.ident.clone();
// Check if variant has fields
match &variant.fields {
Fields::Unit => {
// Good, unit variant
}
Fields::Named(_) | Fields::Unnamed(_) => {
return Err(Error::new_spanned(
variant,
format!(
"EnumTag cannot be derived for enum variant `{variant_name}` with fields. Only unit variants are supported."
),
));
}
}
// Extract description from #[enum_desc] attribute
let description = extract_description(&variant.attrs)?;
// Extract rename from #[enum_rename] attribute
let rename = extract_rename(&variant.attrs)?;
// Generate tokens for this variant
let variant_name_str = variant_name.to_string();
let display_name = rename.unwrap_or_else(|| variant_name_str.clone());
let description_str = description.unwrap_or_default();
variant_info.push(quote! {
(#display_name, #description_str)
});
match_arms.push(quote! {
#enum_name::#variant_name => (#display_name, #description_str),
});
build_match_arms.push(quote! {
#display_name => Some(#enum_name::#variant_name),
});
Ok(())
}
/// Extract description from #[`enum_desc`] attribute
fn extract_description(attrs: &[Attribute]) -> Result<Option<String>> {
for attr in attrs {
if attr.path().is_ident("enum_desc") {
return match attr.parse_args::<LitStr>() {
Ok(lit_str) => Ok(Some(lit_str.value())),
Err(_) => Err(Error::new_spanned(
attr,
"#[enum_desc] attribute must be in the form `#[enum_desc(\"description\")]`",
)),
};
}
}
// If no #[enum_desc] attribute, return None
Ok(None)
}
/// Extract rename from #[`enum_rename`] attribute
fn extract_rename(attrs: &[Attribute]) -> Result<Option<String>> {
for attr in attrs {
if attr.path().is_ident("enum_rename") {
return match attr.parse_args::<LitStr>() {
Ok(lit_str) => Ok(Some(lit_str.value())),
Err(_) => Err(Error::new_spanned(
attr,
"#[enum_rename] attribute must be in the form `#[enum_rename(\"new_name\")]`",
)),
};
}
}
// If no #[enum_rename] attribute, return None
Ok(None)
}
|
