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
#![recursion_limit = "128"]
extern crate proc_macro;
extern crate syn;
#[macro_use]
extern crate quote;
extern crate struct_diff;
use proc_macro::TokenStream;
#[proc_macro_derive(Diff)]
pub fn generate_diff_impl(input: TokenStream) -> TokenStream {
let s = input.to_string();
let ast = syn::parse_derive_input(&s).unwrap();
let gen = impl_diff(&ast);
gen.parse().unwrap()
}
fn impl_diff(ast: &syn::DeriveInput) -> quote::Tokens {
let name = &ast.ident;
match ast.body {
syn::Body::Struct(ref vdata) => impl_diff_struct(name, &vdata),
syn::Body::Enum(ref variants) => impl_diff_enum(name, &variants),
}
}
struct StructGenerator<'a> {
fields: &'a [syn::Field]
}
impl<'a> quote::ToTokens for StructGenerator<'a> {
fn to_tokens(&self, tokens: &mut quote::Tokens) {
for field in self.fields.iter() {
if let Some(ref field_name) = field.ident {
let field_name_s = field_name.to_string();
tokens.append(
quote!{
if let Some(inner_diffs) = self.#field_name.diff(&other.#field_name) {
for diff in inner_diffs {
let mut path = String::from(#field_name_s);
if !diff.field.is_empty() {
path.push_str(&".");
}
path.push_str(&diff.field);
diffs.push(::struct_diff::Difference {
field: path,
left: diff.left,
right: diff.right,
})
}
}
}
)
}
}
}
}
struct FieldGenerator<'a> {
name: &'a syn::Ident,
fields: &'a [syn::Field],
}
impl<'a> quote::ToTokens for FieldGenerator<'a> {
fn to_tokens(&self, tokens: &mut quote::Tokens) {
for (i, field) in self.fields.iter().enumerate() {
let field_name = field.ident.clone().unwrap_or(syn::Ident::from(i));
let field_name_s = field_name.to_string();
let left = {
let mut new_name = String::from("left_");
new_name.push_str(&field_name.to_string());
syn::Ident::from(new_name)
};
let right = {
let mut new_name = String::from("right_");
new_name.push_str(&field_name.to_string());
syn::Ident::from(new_name)
};
let name = self.name.to_string();
tokens.append(
quote!{
if let Some(inner_diffs) = #left.diff(&#right) {
for diff in inner_diffs {
let mut path = String::from(#name);
path.push_str(".");
path.push_str(&#field_name_s);
if !diff.field.is_empty() {
path.push_str(&".");
}
path.push_str(&diff.field);
diffs.push(::struct_diff::Difference {
field: path,
left: #left,
right: #right,
})
}
}
}
)
}
}
}
struct StructPatField<'a> {
name: &'a syn::Ident,
prefix: &'static str,
}
impl<'a> quote::ToTokens for StructPatField<'a> {
fn to_tokens(&self, tokens: &mut quote::Tokens) {
let ident = self.name;
let prefixed_ident = {
let mut new_name = String::from(self.prefix);
new_name.push_str("_");
new_name.push_str(&ident.to_string());
syn::Ident::from(new_name)
};
tokens.append(quote! {
#ident: ref #prefixed_ident
})
}
}
fn impl_diff_enum(name: &syn::Ident, variants: &[syn::Variant]) -> quote::Tokens {
let mut differs = Vec::new();
for variant in variants {
let var_name = &variant.ident;
let var_data = &variant.data;
let diff = match var_data {
&syn::VariantData::Tuple(ref fields) => {
let gen = FieldGenerator { name: var_name, fields };
let names: Vec<syn::Ident> = fields.iter()
.enumerate()
.map(|(id, field)| field.ident.clone().unwrap_or(syn::Ident::from(id)))
.collect();
let left = names.iter().map(|ident| {
let mut new_name = String::from("left_");
new_name.push_str(&ident.to_string());
syn::Ident::from(new_name)
}).collect::<Vec<_>>();
let right = names.iter().map(|ident| {
let mut new_name = String::from("right_");
new_name.push_str(&ident.to_string());
syn::Ident::from(new_name)
}).collect::<Vec<_>>();
quote! {
(&#name::#var_name(#(ref #left),*), &#name::#var_name(#(ref #right),*)) => {
#gen
}
}
},
&syn::VariantData::Struct(ref fields) => {
let gen = FieldGenerator { name: var_name, fields };
let names: Vec<syn::Ident> = fields.iter()
.enumerate()
.map(|(id, field)| field.ident.clone().unwrap_or(syn::Ident::from(id)))
.collect();
let left = names.iter().map(|ident| {
StructPatField{ name: ident, prefix: "left"}
}).collect::<Vec<_>>();
let right = names.iter().map(|ident| {
StructPatField{ name: ident, prefix: "right"}
}).collect::<Vec<_>>();
quote! {
(&#name::#var_name{ #(#left),* }, &#name::#var_name{ #(#right),* }) => {
#gen
}
}
},
&syn::VariantData::Unit => {
quote! {
(&#name::#var_name, &#name::#var_name) => {
return None;
}
}
},
};
differs.push(diff);
}
return quote! {
impl Diff for #name {
fn diff<'a>(&'a self, other: &'a #name) -> Option<Vec<Difference<'a>>> {
let mut diffs = Vec::new();
match (self, other) {
#(#differs),*
_ => {
return Some(vec![Difference { field: "self".into(), left: self, right: other }]);
}
}
if diffs.len() > 0 {
return Some(diffs);
}
None
}
}
}
}
fn impl_diff_struct(name: &syn::Ident, struct_: &syn::VariantData) -> quote::Tokens {
match struct_ {
&syn::VariantData::Struct(ref fields) | &syn::VariantData::Tuple(ref fields) => {
let gen = StructGenerator { fields };
return quote! {
impl Diff for #name {
fn diff<'a>(&'a self, other: &'a #name) -> Option<Vec<Difference<'a>>> {
let mut diffs = Vec::new();
#gen
if diffs.len() > 0 {
return Some(diffs);
}
return None;
}
}
}
},
v@_ => {
panic!("Support for {:?} not implemented", v);
}
}
}