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
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
use syn::{spanned::Spanned, Data, DeriveInput};
use super::{is_ignore, is_unknown, is_with, EnumType};
pub fn expand(DeriveInput { ident, data, .. }: DeriveInput) -> syn::ItemImpl {
match data {
Data::Struct(data) => {
let fields = data
.fields
.iter()
.enumerate()
.filter(|(_, field)| !is_ignore(&field.attrs))
.map(|(idx, field)| -> syn::Stmt {
let fieldpath: syn::ExprField = match field.ident.as_ref() {
Some(name) => syn::parse_quote!(self.#name),
None => {
let name = format!("{idx}");
let name = syn::LitInt::new(&name, field.span());
syn::parse_quote!(self.#name)
}
};
match is_with(&field.attrs) {
Some(with_type) => syn::parse_quote! {
cbor4ii::core::enc::Encode::encode(&#with_type(&#fieldpath), writer)?;
},
None => syn::parse_quote! {
cbor4ii::core::enc::Encode::encode(&#fieldpath, writer)?;
},
}
});
let count = data.fields.len();
let head: Option<syn::Stmt> = (count != 1).then(|| {
syn::parse_quote! {
<cbor4ii::core::types::Array<()>>::bounded(#count, writer)?;
}
});
syn::parse_quote! {
impl cbor4ii::core::enc::Encode for #ident {
#[inline]
fn encode<W: cbor4ii::core::enc::Write>(&self, writer: &mut W)
-> Result<(), cbor4ii::core::error::EncodeError<W::Error>>
{
#head
#(#fields)*;
Ok(())
}
}
}
}
Data::Enum(data) => {
let enum_type = data.variants.iter().filter(|v| !is_unknown(&v.attrs)).fold(
None,
|mut sum, next| {
let ty = match &next.fields {
syn::Fields::Named(_) => EnumType::Struct,
syn::Fields::Unnamed(fields) if fields.unnamed.len() == 1 => EnumType::One,
syn::Fields::Unit => EnumType::Unit,
syn::Fields::Unnamed(_) => {
panic!("more than 1 unnamed member field are not allowed")
}
};
match (*sum.get_or_insert(ty), ty) {
(EnumType::Struct, EnumType::Struct)
| (EnumType::Struct, EnumType::Unit)
| (EnumType::Unit, EnumType::Unit)
| (EnumType::One, EnumType::One) => (),
(EnumType::Unit, EnumType::One)
| (EnumType::One, EnumType::Unit)
| (_, EnumType::Struct) => sum = Some(EnumType::Struct),
_ => panic!("enum member types must be consistent: {:?}", (sum, ty)),
}
sum
},
);
let enum_type = enum_type.expect("enum cannot be empty");
let mut iter = data.variants.iter().peekable();
let unknown_arm: Option<syn::Arm> = iter.next_if(|variant| is_unknown(&variant.attrs))
.map(|unknown| {
let name = &unknown.ident;
assert!(
unknown.discriminant.is_none(),
"unknown member is not allowed custom discriminant"
);
assert!(
is_with(&unknown.attrs).is_none(),
"unknown member is not allowed with type"
);
match &unknown.fields {
syn::Fields::Unnamed(fields) => match fields.unnamed.len() {
1 => {
assert_eq!(enum_type, EnumType::Unit);
syn::parse_quote! {
#ident::#name(tag)
=> tag.encode(writer)?,
}
}
2 => {
assert_eq!(enum_type, EnumType::One);
syn::parse_quote! {
#ident::#name(tag, value)
=> cbor4ii::core::types::Tag((*tag).into(), &*value).encode(writer)?,
}
}
_ => panic!("unknown member must be a tag and a value"),
},
_ => panic!("named enum unsupported"),
}
});
if matches!(enum_type, EnumType::Struct) {
assert!(
unknown_arm.is_none(),
"struct enum does not allow unknown variants"
);
}
let mut discriminant: u32 = 0;
let fields = iter.map(|field| -> syn::Arm {
match field.discriminant.as_ref() {
Some((_, syn::Expr::Lit(syn::ExprLit { lit: syn::Lit::Int(lit), .. }))) => {
discriminant = lit.base10_parse::<u32>().unwrap();
},
Some(_) => panic!("unsupported discriminant type"),
None => (),
};
discriminant += 1;
let idx = discriminant;
let name = &field.ident;
assert!(
!is_unknown(&field.attrs),
"unknown member must be first: {:?}",
field.attrs.len()
);
match enum_type {
EnumType::Unit => {
assert!(
is_with(&field.attrs).is_none(),
"unit member is not allowed with type"
);
syn::parse_quote! {
#ident::#name => #idx.encode(writer)?,
}
},
EnumType::One => {
let value: syn::Expr = match is_with(&field.attrs) {
Some(ty) => syn::parse_quote! {
&#ty(&*value)
},
None => syn::parse_quote! {
&*value
},
};
syn::parse_quote! {
#ident::#name(value) => {
cbor4ii::core::types::Tag(
#idx.into(),
#value
).encode(writer)?;
},
}
},
EnumType::Struct => {
let is_named = field.fields.iter().all(|field| field.ident.is_some());
let names = field.fields.iter()
.enumerate()
.map(|(idx, field)| match field.ident.as_ref() {
Some(name) => name.clone(),
None => {
let name = format!("unit{idx}");
syn::Ident::new(&name, field.span())
}
})
.collect::<Vec<_>>();
let stmt = field.fields.iter()
.zip(names.iter())
.map(|(field, field_name)| -> syn::Stmt {
match is_with(&field.attrs) {
Some(ty) => syn::parse_quote! {
cbor4ii::core::enc::Encode::encode(&#ty(&*#field_name), writer)?;
},
None => syn::parse_quote! {
cbor4ii::core::enc::Encode::encode(&*#field_name, writer)?;
},
}
});
let count = stmt.len();
let head: syn::Expr = syn::parse_quote!{{
cbor4ii::core::types::Tag(#idx.into(), cbor4ii::core::types::Nothing).encode(writer)?;
cbor4ii::core::types::Array::bounded(#count, writer)?;
}};
if is_named {
syn::parse_quote!{
#ident::#name { #(#names),* } => {
#head;
#(#stmt)*
},
}
} else {
syn::parse_quote!{
#ident::#name ( #(#names),* ) => {
#head;
#(#stmt)*
},
}
}
}
}
});
syn::parse_quote! {
impl cbor4ii::core::enc::Encode for #ident {
#[inline]
fn encode<W: cbor4ii::core::enc::Write>(&self, writer: &mut W)
-> Result<(), cbor4ii::core::error::EncodeError<W::Error>>
{
match self {
#(#fields)*
#unknown_arm
}
Ok(())
}
}
}
}
Data::Union(_) => panic!("union unsupported"),
}
}