forked from M-Labs/nac3
73 lines
1.6 KiB
Rust
73 lines
1.6 KiB
Rust
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use crate::constant;
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use crate::fold::Fold;
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pub(crate) trait Foldable<T, U> {
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type Mapped;
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fn fold<F: Fold<T, TargetU = U> + ?Sized>(
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self,
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folder: &mut F,
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) -> Result<Self::Mapped, F::Error>;
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}
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impl<T, U, X> Foldable<T, U> for Vec<X>
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where
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X: Foldable<T, U>,
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{
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type Mapped = Vec<X::Mapped>;
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fn fold<F: Fold<T, TargetU = U> + ?Sized>(
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self,
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folder: &mut F,
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) -> Result<Self::Mapped, F::Error> {
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self.into_iter().map(|x| x.fold(folder)).collect()
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}
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}
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impl<T, U, X> Foldable<T, U> for Option<X>
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where
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X: Foldable<T, U>,
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{
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type Mapped = Option<X::Mapped>;
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fn fold<F: Fold<T, TargetU = U> + ?Sized>(
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self,
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folder: &mut F,
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) -> Result<Self::Mapped, F::Error> {
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self.map(|x| x.fold(folder)).transpose()
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}
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}
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impl<T, U, X> Foldable<T, U> for Box<X>
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where
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X: Foldable<T, U>,
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{
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type Mapped = Box<X::Mapped>;
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fn fold<F: Fold<T, TargetU = U> + ?Sized>(
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self,
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folder: &mut F,
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) -> Result<Self::Mapped, F::Error> {
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(*self).fold(folder).map(Box::new)
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}
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}
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macro_rules! simple_fold {
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($($t:ty),+$(,)?) => {
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$(impl<T, U> $crate::fold_helpers::Foldable<T, U> for $t {
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type Mapped = Self;
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#[inline]
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fn fold<F: Fold<T, TargetU = U> + ?Sized>(
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self,
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_folder: &mut F,
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) -> Result<Self::Mapped, F::Error> {
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Ok(self)
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}
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})+
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};
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}
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simple_fold!(
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usize,
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String,
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bool,
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constant::Constant,
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constant::ConversionFlag
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);
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