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
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
use super::{generate_fn::FnParent, FnBuilder, Parent, StreamBuilder};
use crate::{
parse::{GenericConstraints, Generics},
prelude::{Delimiter, Result},
};
#[must_use]
/// A helper struct for implementing a trait for a given struct or enum.
pub struct ImplFor<'a, P: Parent> {
generator: &'a mut P,
trait_name: String,
lifetimes: Option<Vec<String>>,
consts: Vec<StreamBuilder>,
custom_generic_constraints: Option<GenericConstraints>,
impl_types: Vec<StreamBuilder>,
fns: Vec<(StreamBuilder, StreamBuilder)>,
}
impl<'a, P: Parent> ImplFor<'a, P> {
pub(super) fn new(generator: &'a mut P, trait_name: impl Into<String>) -> Self {
Self {
generator,
trait_name: trait_name.into(),
lifetimes: None,
consts: Vec::new(),
custom_generic_constraints: None,
impl_types: Vec::new(),
fns: Vec::new(),
}
}
pub(super) fn new_with_lifetimes<ITER, T>(
generator: &'a mut P,
trait_name: T,
lifetimes: ITER,
) -> Self
where
ITER: IntoIterator,
ITER::Item: Into<String>,
T: Into<String>,
{
Self {
generator,
trait_name: trait_name.into(),
lifetimes: Some(lifetimes.into_iter().map(Into::into).collect()),
consts: Vec::new(),
custom_generic_constraints: None,
impl_types: Vec::new(),
fns: Vec::new(),
}
}
/// Add a const to the trait implementation
/// ```no_run
/// # use virtue::prelude::Generator;
/// # let mut generator: Generator = unsafe { std::mem::zeroed() };
/// generator.impl_for("Foo")
/// .generate_const("BAR", "u8")
/// .with_value(|b| {
/// b.push_parsed("5")?;
/// Ok(())
/// })?;
/// # Ok::<_, virtue::Error>(())
/// ```
///
/// Generates:
/// ```ignore
/// impl Foo for <struct or enum> {
/// const BAR: u8 = 5;
/// }
pub fn generate_const<'s>(
&'s mut self,
name: impl Into<String>,
ty: impl Into<String>,
) -> GenConst<'s, 'a, P> {
GenConst {
parent: self,
name: name.into(),
ty: ty.into(),
}
}
/// Add a function to the trait implementation.
///
/// `generator.impl_for("Foo").generate_fn("bar")` results in code like:
///
/// ```ignore
/// impl Foo for <struct or enum> {
/// fn bar() {}
/// }
/// ```
///
/// See [`FnBuilder`] for more options, as well as information on how to fill the function body.
pub fn generate_fn(&mut self, name: impl Into<String>) -> FnBuilder<ImplFor<'a, P>> {
FnBuilder::new(self, name)
}
/// Add a type to the impl
///
/// `generator.impl_for("Foo").impl_type("Bar", "u8")` results in code like:
///
/// ```ignore
/// impl Foo for <struct or enum> {
/// type Bar = u8;
/// }
/// ```
pub fn impl_type(&mut self, name: impl AsRef<str>, value: impl AsRef<str>) -> Result {
let mut builder = StreamBuilder::new();
builder
.ident_str("type")
.push_parsed(name)?
.punct('=')
.push_parsed(value)?
.punct(';');
self.impl_types.push(builder);
Ok(())
}
///
/// Modify the generic constraints of a type.
/// This can be used to add additional type constraints to your implementation.
///
/// ```ignore
/// // Your derive:
/// #[derive(YourTrait)]
/// pub struct Foo<B> {
/// ...
/// }
///
/// // With this code:
/// generator
/// .impl_for("YourTrait")
/// .modify_generic_constraints(|generics, constraints| {
/// for g in generics.iter_generics() {
/// constraints.push_generic(g, "YourTrait");
/// }
/// })
///
/// // will generate:
/// impl<B> YourTrait for Foo<B>
/// where B: YourTrait // <-
/// {
/// }
/// ```
///
pub fn modify_generic_constraints<CB>(&mut self, cb: CB) -> Result<&mut Self>
where
CB: FnOnce(&Generics, &mut GenericConstraints) -> Result,
{
if let Some(generics) = self.generator.generics() {
let mut constraints = self
.generator
.generic_constraints()
.cloned()
.unwrap_or_default();
cb(generics, &mut constraints)?;
self.custom_generic_constraints = Some(constraints)
}
Ok(self)
}
}
impl<'a, P: Parent> FnParent for ImplFor<'a, P> {
fn append(&mut self, fn_definition: StreamBuilder, fn_body: StreamBuilder) -> Result {
self.fns.push((fn_definition, fn_body));
Ok(())
}
}
impl<P: Parent> Drop for ImplFor<'_, P> {
fn drop(&mut self) {
if std::thread::panicking() {
return;
}
let mut builder = StreamBuilder::new();
self.generate_fn_definition(&mut builder);
builder
.group(Delimiter::Brace, |builder| {
for ty in std::mem::take(&mut self.impl_types) {
builder.append(ty);
}
for r#const in std::mem::take(&mut self.consts) {
builder.append(r#const);
}
for (fn_def, fn_body) in std::mem::take(&mut self.fns) {
builder.append(fn_def);
builder
.group(Delimiter::Brace, |body| {
*body = fn_body;
Ok(())
})
.unwrap();
}
Ok(())
})
.unwrap();
self.generator.append(builder);
}
}
impl<P: Parent> ImplFor<'_, P> {
fn generate_fn_definition(&mut self, builder: &mut StreamBuilder) {
builder.ident_str("impl");
if let Some(lifetimes) = &self.lifetimes {
if let Some(generics) = self.generator.generics() {
builder.append(generics.impl_generics_with_additional_lifetimes(lifetimes));
} else {
append_lifetimes(builder, lifetimes);
}
} else if let Some(generics) = self.generator.generics() {
builder.append(generics.impl_generics());
}
builder.push_parsed(&self.trait_name).unwrap();
if let Some(lifetimes) = &self.lifetimes {
append_lifetimes(builder, lifetimes);
}
builder.ident_str("for");
builder.ident(self.generator.name().clone());
if let Some(generics) = &self.generator.generics() {
builder.append(generics.type_generics());
}
if let Some(generic_constraints) = self.custom_generic_constraints.take() {
builder.append(generic_constraints.where_clause());
} else if let Some(generic_constraints) = &self.generator.generic_constraints() {
builder.append(generic_constraints.where_clause());
}
}
}
fn append_lifetimes(builder: &mut StreamBuilder, lifetimes: &[String]) {
for (idx, lt) in lifetimes.iter().enumerate() {
builder.punct(if idx == 0 { '<' } else { ',' });
builder.lifetime_str(lt);
}
builder.punct('>');
}
/// A builder for constants.
pub struct GenConst<'a, 'b, P: Parent> {
parent: &'a mut ImplFor<'b, P>,
name: String,
ty: String,
}
impl<'a, 'b, P: Parent> GenConst<'a, 'b, P> {
/// Complete the constant definition. This function takes a callback that will form the value of the constant.
///
/// ```no_run
/// # use virtue::prelude::Generator;
/// # let mut generator: Generator = unsafe { std::mem::zeroed() };
/// generator.impl_for("Foo")
/// .generate_const("BAR", "u8")
/// .with_value(|b| {
/// b.push_parsed("5")?;
/// Ok(())
/// })?;
/// # Ok::<_, virtue::Error>(())
/// ```
///
/// Generates:
/// ```ignore
/// impl Foo for <struct or enum> {
/// const BAR: u8 = 5;
/// }
/// ```
pub fn with_value<F>(self, f: F) -> Result
where
F: FnOnce(&mut StreamBuilder) -> Result,
{
let mut builder = StreamBuilder::new();
builder
.ident_str("const")
.push_parsed(self.name)?
.punct(':')
.push_parsed(self.ty)?
.punct('=');
f(&mut builder)?;
builder.punct(';');
self.parent.consts.push(builder);
Ok(())
}
}