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use super::*;
/// A value that can be automatically determined.
#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
pub enum Smart<T> {
/// The value should be determined smartly based on the circumstances.
Auto,
/// A specific value.
Custom(T),
}
impl<T> Smart<T> {
/// Whether the value is `Auto`.
pub fn is_auto(&self) -> bool {
matches!(self, Self::Auto)
}
/// Whether this holds a custom value.
pub fn is_custom(&self) -> bool {
matches!(self, Self::Custom(_))
}
/// Returns a reference the contained custom value.
/// If the value is [`Smart::Auto`], `None` is returned.
pub fn as_custom(self) -> Option<T> {
match self {
Self::Auto => None,
Self::Custom(x) => Some(x),
}
}
/// Map the contained custom value with `f`.
pub fn map<F, U>(self, f: F) -> Smart<U>
where
F: FnOnce(T) -> U,
{
match self {
Self::Auto => Smart::Auto,
Self::Custom(x) => Smart::Custom(f(x)),
}
}
/// Map the contained custom value with `f` if it contains a custom value,
/// otherwise returns `default`.
pub fn map_or<F, U>(self, default: U, f: F) -> U
where
F: FnOnce(T) -> U,
{
match self {
Self::Auto => default,
Self::Custom(x) => f(x),
}
}
/// Keeps `self` if it contains a custom value, otherwise returns `other`.
pub fn or(self, other: Smart<T>) -> Self {
match self {
Self::Custom(x) => Self::Custom(x),
Self::Auto => other,
}
}
/// Returns the contained custom value or a provided default value.
pub fn unwrap_or(self, default: T) -> T {
match self {
Self::Auto => default,
Self::Custom(x) => x,
}
}
/// Returns the contained custom value or computes a default value.
pub fn unwrap_or_else<F>(self, f: F) -> T
where
F: FnOnce() -> T,
{
match self {
Self::Auto => f(),
Self::Custom(x) => x,
}
}
/// Returns the contained custom value or the default value.
pub fn unwrap_or_default(self) -> T
where
T: Default,
{
self.unwrap_or_else(T::default)
}
}
impl<T> Default for Smart<T> {
fn default() -> Self {
Self::Auto
}
}
impl<T: Cast> Cast for Smart<T> {
fn is(value: &Value) -> bool {
matches!(value, Value::Auto) || T::is(value)
}
fn cast(value: Value) -> StrResult<Self> {
match value {
Value::Auto => Ok(Self::Auto),
v if T::is(&v) => Ok(Self::Custom(T::cast(v)?)),
_ => <Self as Cast>::error(value),
}
}
fn describe() -> CastInfo {
T::describe() + CastInfo::Type("auto")
}
}
impl<T: Resolve> Resolve for Smart<T> {
type Output = Smart<T::Output>;
fn resolve(self, styles: StyleChain) -> Self::Output {
self.map(|v| v.resolve(styles))
}
}
impl<T> Fold for Smart<T>
where
T: Fold,
T::Output: Default,
{
type Output = Smart<T::Output>;
fn fold(self, outer: Self::Output) -> Self::Output {
self.map(|inner| inner.fold(outer.unwrap_or_default()))
}
}
impl<T: Into<Value>> From<Smart<T>> for Value {
fn from(v: Smart<T>) -> Self {
match v {
Smart::Custom(v) => v.into(),
Smart::Auto => Value::Auto,
}
}
}
|
