forked from Orchid/orchid
125 lines
4.4 KiB
Rust
125 lines
4.4 KiB
Rust
use std::num::NonZeroU64;
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use orchid_api_derive::{Coding, Hierarchy};
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use orchid_api_traits::Request;
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use crate::atom::Atom;
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use crate::error::OrcError;
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use crate::interner::TStrv;
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use crate::location::Location;
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use crate::proto::{ExtHostNotif, ExtHostReq};
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use crate::system::SysId;
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/// An arbitrary ID associated with an expression on the host side. Incoming
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/// tickets always come with some lifetime guarantee, which can be extended with
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/// [Acquire].
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///
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/// The ID is globally unique within its lifetime, but may be reused.
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#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Coding)]
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pub struct ExprTicket(pub NonZeroU64);
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/// Acquire a strong reference to an expression. This keeps it alive until a
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/// corresponding [Release] is emitted. The number of times a system has
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/// acquired an expression is counted, and it is the system's responsibility to
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/// ensure that acquires and releases pair up. Behaviour in case of a
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/// superfluous free is not defined.
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///
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/// Some contexts may specify that an ingress [ExprTicket] is owned, this means
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/// that acquiring it is not necessary.
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///
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/// This can be called with a foreign system to signal that an owned reference
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/// is being passed, though [Relocate] may be a better fit.
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExprNotif, ExtHostNotif)]
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pub struct Acquire(pub SysId, pub ExprTicket);
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/// Release a reference either previously acquired through either [Acquire]
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/// or by receiving an owned reference. The number of times a system has
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/// acquired an expression is counted, and it is the system's responsibility to
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/// ensure that acquires and releases pair up. Behaviour in case of excessive
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/// freeing is not defined.
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExprNotif, ExtHostNotif)]
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pub struct Release(pub SysId, pub ExprTicket);
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/// Decrement the reference count for one system and increment it for another,
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/// to indicate passing an owned reference. Equivalent to [Acquire] followed by
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/// [Release].
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExprNotif, ExtHostNotif)]
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pub struct Move {
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pub dec: SysId,
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pub inc: SysId,
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pub expr: ExprTicket,
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}
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/// A description of a new expression. It is used as the return value of
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/// [crate::atom::Call] or [crate::atom::CallRef], or a constant in the
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/// [crate::tree::Tree].
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#[derive(Clone, Debug, Coding)]
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pub enum Clause {
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/// Apply the lhs as a function to the rhs
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Call(Box<Expr>, Box<Expr>),
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/// Lambda function. The number operates as an argument name
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Lambda(u64, Box<Expr>),
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/// Binds the argument passed to the lambda with the same ID in the same
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/// template
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Arg(u64),
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/// Insert the specified host-expression in the template here. When the clause
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/// is used in the const tree, this variant is forbidden.
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Slot(ExprTicket),
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/// The lhs must be fully processed before the rhs can be processed.
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/// Equivalent to Haskell's function of the same name
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Seq(Box<Expr>, Box<Expr>),
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/// Insert a new atom in the tree. When the clause is used in the const tree,
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/// the atom must be trivial. This is always a newly constructed atom, if you
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/// want to reference an existing atom, use the corresponding [ExprTicket].
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/// Because the atom is newly constructed, it also must belong to this system.
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/// For convenience, [SysId::MAX] is also accepted as referring to this
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/// system.
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NewAtom(Atom),
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/// An atom, specifically an atom that already exists. This form is only ever
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/// returned from [Inspect], and it's borrowed from the expression being
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/// inspected.
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Atom(ExprTicket, Atom),
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/// A reference to a constant
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Const(TStrv),
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/// A static runtime error.
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Bottom(Vec<OrcError>),
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}
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#[derive(Clone, Debug, Coding)]
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pub struct Expr {
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pub clause: Clause,
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pub location: Location,
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}
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#[derive(Clone, Debug, Coding)]
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pub struct Details {
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pub expr: Expr,
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pub refcount: u32,
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}
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExprReq, ExtHostReq)]
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pub struct Inspect(pub ExprTicket);
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impl Request for Inspect {
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type Response = Details;
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}
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExtHostReq)]
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#[extendable]
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pub enum ExprReq {
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Inspect(Inspect),
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}
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#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, Coding, Hierarchy)]
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#[extends(ExtHostNotif)]
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#[extendable]
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pub enum ExprNotif {
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Acquire(Acquire),
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Release(Release),
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Move(Move),
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}
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