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
|
/**
* Originally from Intertrait by CodeChain
*
* https://github.com/CodeChain-io/intertrait
* https://crates.io/crates/intertrait/0.2.2
*
* Licensed under either of
*
* Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
* at your option.
*/
use std::any::{Any, TypeId};
use std::collections::HashMap;
use std::rc::Rc;
use std::sync::Arc;
use once_cell::sync::Lazy;
extern crate linkme;
mod hasher;
use hasher::BuildFastHasher;
pub mod cast_box;
pub mod cast_rc;
pub type BoxedCaster = Box<dyn Any + Send + Sync>;
#[linkme::distributed_slice]
pub static CASTERS: [fn() -> (TypeId, BoxedCaster)] = [..];
static CASTER_MAP: Lazy<HashMap<(TypeId, TypeId), BoxedCaster, BuildFastHasher>> =
Lazy::new(|| {
CASTERS
.iter()
.map(|f| {
let (type_id, caster) = f();
((type_id, (*caster).type_id()), caster)
})
.collect()
});
pub struct Caster<T: ?Sized + 'static>
{
/// Casts an immutable reference to a trait object for `Any` to a reference
/// to a trait object for trait `T`.
pub cast_ref: fn(from: &dyn Any) -> &T,
/// Casts a mutable reference to a trait object for `Any` to a mutable reference
/// to a trait object for trait `T`.
pub cast_mut: fn(from: &mut dyn Any) -> &mut T,
/// Casts a `Box` holding a trait object for `Any` to another `Box` holding a trait object
/// for trait `T`.
pub cast_box: fn(from: Box<dyn Any>) -> Box<T>,
/// Casts an `Rc` holding a trait object for `Any` to another `Rc` holding a trait object
/// for trait `T`.
pub cast_rc: fn(from: Rc<dyn Any>) -> Rc<T>,
}
impl<T: ?Sized + 'static> Caster<T>
{
pub fn new(
cast_ref: fn(from: &dyn Any) -> &T,
cast_mut: fn(from: &mut dyn Any) -> &mut T,
cast_box: fn(from: Box<dyn Any>) -> Box<T>,
cast_rc: fn(from: Rc<dyn Any>) -> Rc<T>,
) -> Caster<T>
{
Caster::<T> {
cast_ref,
cast_mut,
cast_box,
cast_rc,
}
}
pub fn new_sync(
cast_ref: fn(from: &dyn Any) -> &T,
cast_mut: fn(from: &mut dyn Any) -> &mut T,
cast_box: fn(from: Box<dyn Any>) -> Box<T>,
cast_rc: fn(from: Rc<dyn Any>) -> Rc<T>,
) -> Caster<T>
{
Caster::<T> {
cast_ref,
cast_mut,
cast_box,
cast_rc,
}
}
}
/// Returns a `Caster<S, T>` from a concrete type `S` to a trait `T` implemented by it.
fn caster<T: ?Sized + 'static>(type_id: TypeId) -> Option<&'static Caster<T>>
{
CASTER_MAP
.get(&(type_id, TypeId::of::<Caster<T>>()))
.and_then(|caster| caster.downcast_ref::<Caster<T>>())
}
/// `CastFrom` must be extended by a trait that wants to allow for casting into another trait.
///
/// It is used for obtaining a trait object for [`Any`] from a trait object for its sub-trait,
/// and blanket implemented for all `Sized + Any + 'static` types.
///
/// # Examples
/// ```ignore
/// trait Source: CastFrom {
/// ...
/// }
/// ```
pub trait CastFrom: Any + 'static
{
/// Returns a immutable reference to `Any`, which is backed by the type implementing this trait.
fn ref_any(&self) -> &dyn Any;
/// Returns a mutable reference to `Any`, which is backed by the type implementing this trait.
fn mut_any(&mut self) -> &mut dyn Any;
/// Returns a `Box` of `Any`, which is backed by the type implementing this trait.
fn box_any(self: Box<Self>) -> Box<dyn Any>;
/// Returns an `Rc` of `Any`, which is backed by the type implementing this trait.
fn rc_any(self: Rc<Self>) -> Rc<dyn Any>;
}
pub trait CastFromSync: CastFrom + Sync + Send + 'static
{
fn arc_any(self: Arc<Self>) -> Arc<dyn Any + Sync + Send + 'static>;
}
impl<T: Sized + Any + 'static> CastFrom for T
{
fn ref_any(&self) -> &dyn Any
{
self
}
fn mut_any(&mut self) -> &mut dyn Any
{
self
}
fn box_any(self: Box<Self>) -> Box<dyn Any>
{
self
}
fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
{
self
}
}
impl CastFrom for dyn Any + 'static
{
fn ref_any(&self) -> &dyn Any
{
self
}
fn mut_any(&mut self) -> &mut dyn Any
{
self
}
fn box_any(self: Box<Self>) -> Box<dyn Any>
{
self
}
fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
{
self
}
}
impl<T: Sized + Sync + Send + 'static> CastFromSync for T
{
fn arc_any(self: Arc<Self>) -> Arc<dyn Any + Sync + Send + 'static>
{
self
}
}
impl CastFrom for dyn Any + Sync + Send + 'static
{
fn ref_any(&self) -> &dyn Any
{
self
}
fn mut_any(&mut self) -> &mut dyn Any
{
self
}
fn box_any(self: Box<Self>) -> Box<dyn Any>
{
self
}
fn rc_any(self: Rc<Self>) -> Rc<dyn Any>
{
self
}
}
impl CastFromSync for dyn Any + Sync + Send + 'static
{
fn arc_any(self: Arc<Self>) -> Arc<dyn Any + Sync + Send + 'static>
{
self
}
}
|
