126 lines
3.8 KiB
Rust
126 lines
3.8 KiB
Rust
//! This module introduces [`Option`]-like concepts into RADN typesystem using [`Nullable`].
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use crate::core::*;
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use super::{inlining::*, point::*, *};
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/// Nullable reference type. Made for use as a linking element in data structures.
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pub enum Nullable<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> {
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/// Unlike original Python implementation, stores the factory only in the null case.
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Null(A::Fctr),
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NotNull(Point<'a, Ctx, A>),
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}
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/// Nullable reference factory.
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#[derive(Clone)]
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pub struct NullableFactory<F> {
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/// Factory of the referenced object.
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factory: F,
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> Serializable for Nullable<'a, Ctx, A> {
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fn serialize(&self, serializer: &mut dyn Serializer) {
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serializer.write(match self {
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Nullable::Null(_) => &HASH_ZEROS,
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Nullable::NotNull(point) => &point.point,
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})
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}
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> Mentionable<'a, Ctx> for Nullable<'a, Ctx, A> {
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type Fctr = NullableFactory<A::Fctr>;
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fn factory(&self) -> Self::Fctr {
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match self {
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Nullable::Null(factory) => NullableFactory {
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factory: factory.clone(),
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},
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Nullable::NotNull(point) => NullableFactory {
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factory: point.origin.factory(),
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},
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}
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}
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fn points_typed(&self, points: &mut impl TakesPoints<'a, Ctx>) {
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match self {
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Nullable::Null(_) => {}
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Nullable::NotNull(point) => points.take(point),
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}
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}
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}
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impl<'a, Ctx: 'a + Context, F: Factory<'a, Ctx>> Factory<'a, Ctx> for NullableFactory<F> {
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type Mtbl = Nullable<'a, Ctx, F::Mtbl>;
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type ParseError = PointParseError;
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fn deserialize(
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&self,
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deserializer: &mut dyn Deserializer,
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resolver: std::rc::Rc<dyn Resolver<'a, Ctx>>,
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addresses: &mut Addresses,
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) -> ParseResult<'a, Ctx, Self> {
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let factory = self.factory.clone();
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let address = addresses.next(deserializer)?;
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Ok(if address.point == HASH_ZEROS {
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Nullable::Null(factory)
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} else {
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Nullable::NotNull(Point::from_address(address, factory, resolver))
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})
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}
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fn unexpected_tail(&self, tail: &[u8]) -> Self::ParseError {
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PointParseError::WrongLength(HASH_SIZE + tail.len())
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}
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> Nullable<'a, Ctx, Nullable<'a, Ctx, A>> {
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/// Reduce [Nullable] nesting.
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pub fn join(&self) -> Resolution<'a, Ctx, Nullable<'a, Ctx, A>> {
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match self {
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Self::Null(nullable_factory) => {
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let NullableFactory { factory } = nullable_factory;
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Ctx::T::pure(Ok(Rc::new(Nullable::Null(factory.clone()))))
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}
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Self::NotNull(point) => point.resolve(),
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}
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}
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> Nullable<'a, Ctx, A> {
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fn from_mentionable(mentionable: Rc<A>) -> Self {
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Self::NotNull(mentionable.into())
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}
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}
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impl<F> NullableFactory<F> {
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pub fn new(factory: F) -> Self {
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Self { factory }
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}
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> Clone for Nullable<'a, Ctx, A> {
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fn clone(&self) -> Self {
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match self {
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Self::Null(factory) => Self::Null(factory.clone()),
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Self::NotNull(point) => Self::NotNull(point.clone()),
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}
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}
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}
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impl<F> AlwaysConstSize for NullableFactory<F> {
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const _SIZE: usize = HASH_SIZE;
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> From<Rc<A>> for Nullable<'a, Ctx, A> {
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fn from(value: Rc<A>) -> Self {
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Self::from_mentionable(value)
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}
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}
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impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>> From<A> for Nullable<'a, Ctx, A> {
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fn from(value: A) -> Self {
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Self::from_mentionable(value.into())
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}
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}
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