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
|
use std::fmt::{self, Debug, Formatter};
use super::{cast, CastInfo, FromValue, IntoValue, Reflect, Value};
use crate::diag::StrResult;
/// A value that indicates the absence of any other value.
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub struct NoneValue;
impl Reflect for NoneValue {
fn describe() -> CastInfo {
CastInfo::Type("none")
}
fn castable(value: &Value) -> bool {
matches!(value, Value::None)
}
}
impl IntoValue for NoneValue {
fn into_value(self) -> Value {
Value::None
}
}
impl FromValue for NoneValue {
fn from_value(value: Value) -> StrResult<Self> {
match value {
Value::None => Ok(Self),
_ => Err(Self::error(&value)),
}
}
}
impl Debug for NoneValue {
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
f.pad("none")
}
}
cast! {
(),
self => Value::None,
_: NoneValue => (),
}
impl<T: Reflect> Reflect for Option<T> {
fn describe() -> CastInfo {
T::describe() + NoneValue::describe()
}
fn castable(value: &Value) -> bool {
NoneValue::castable(value) || T::castable(value)
}
}
impl<T: IntoValue> IntoValue for Option<T> {
fn into_value(self) -> Value {
match self {
Some(v) => v.into_value(),
None => Value::None,
}
}
}
impl<T: FromValue> FromValue for Option<T> {
fn from_value(value: Value) -> StrResult<Self> {
match value {
Value::None => Ok(None),
v if T::castable(&v) => Ok(Some(T::from_value(v)?)),
_ => Err(Self::error(&value)),
}
}
}
|
