40 lines
865 B
Rust
40 lines
865 B
Rust
use std::fmt::{self, Debug, Formatter};
|
|
|
|
use super::{CastInfo, FromValue, IntoValue, Reflect, Value};
|
|
use crate::diag::StrResult;
|
|
|
|
/// A value that indicates a smart default.
|
|
#[derive(Default, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
|
|
pub struct AutoValue;
|
|
|
|
impl IntoValue for AutoValue {
|
|
fn into_value(self) -> Value {
|
|
Value::Auto
|
|
}
|
|
}
|
|
|
|
impl FromValue for AutoValue {
|
|
fn from_value(value: Value) -> StrResult<Self> {
|
|
match value {
|
|
Value::Auto => Ok(Self),
|
|
_ => Err(Self::error(&value)),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl Reflect for AutoValue {
|
|
fn describe() -> CastInfo {
|
|
CastInfo::Type("auto")
|
|
}
|
|
|
|
fn castable(value: &Value) -> bool {
|
|
matches!(value, Value::Auto)
|
|
}
|
|
}
|
|
|
|
impl Debug for AutoValue {
|
|
fn fmt(&self, f: &mut Formatter) -> fmt::Result {
|
|
f.pad("auto")
|
|
}
|
|
}
|