444 lines
15 KiB
Rust
444 lines
15 KiB
Rust
// ASG IR
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//
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// Copyright (C) 2014-2023 Ryan Specialty, LLC.
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//
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// This file is part of TAME.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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//! Intermediate representation for construction of the
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//! [abstract semantic graph (ASG)](super) (AIR).
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//!
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//! AIR serves as an abstraction layer between higher-level parsers and the
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//! aggregate ASG.
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//! It allows parsers to operate as a raw stream of data without having to
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//! worry about ownership of or references to the ASG,
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//! and allows for multiple such parsers to be joined.
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//!
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//! AIR is _not_ intended to replace the API of the ASG---it
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//! is intended as a termination point for the parsing pipeline,
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//! and as such implements a subset of the ASG's API that is suitable
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//! for aggregating raw data from source and object files.
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//! Given that it does so little and is so close to the [`Asg`] API,
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//! one might say that the abstraction is as light as air,
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//! but that would surely result in face-palming and so we're not going
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//! air such cringeworthy dad jokes here.
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use super::{graph::object::Pkg, Asg, AsgError, ObjectIndex};
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use crate::{
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asg::graph::object::Tpl,
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diagnose::Annotate,
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diagnostic_unreachable,
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fmt::{DisplayWrapper, TtQuote},
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parse::{prelude::*, util::SPair},
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sym::SymbolId,
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};
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use std::fmt::{Debug, Display};
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#[macro_use]
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mod ir;
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pub use ir::Air;
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mod expr;
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use expr::AirExprAggregate;
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pub type IdentSym = SymbolId;
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pub type DepSym = SymbolId;
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/// AIR parser state.
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#[derive(Debug, PartialEq, Eq, Default)]
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pub enum AirAggregate {
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/// Parser is not currently performing any work.
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#[default]
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Empty,
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/// Expecting a package-level token.
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PkgHead(ObjectIndex<Pkg>, AirExprAggregate),
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/// Parsing an expression.
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///
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/// This expects to inherit an [`AirExprAggregate`] from the prior state
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/// so that we are not continuously re-allocating its stack for each
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/// new expression root.
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PkgExpr(ObjectIndex<Pkg>, AirExprAggregate),
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/// Parser is in template parsing mode.
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///
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/// All objects encountered until the closing [`Air::TplClose`] will be
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/// parented to this template rather than the parent [`Pkg`].
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/// See [`Air::TplOpen`] for more information.
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PkgTpl(ObjectIndex<Pkg>, AirExprAggregate, AirTplAggregate),
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}
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impl Display for AirAggregate {
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fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
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use AirAggregate::*;
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match self {
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Empty => write!(f, "awaiting AIR input for ASG"),
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PkgHead(_, _) => {
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write!(f, "expecting package header or an expression")
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}
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PkgExpr(_, expr) => {
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write!(f, "defining a package expression: {expr}")
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}
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PkgTpl(_, _, tpl) => {
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write!(f, "building a template: {tpl}",)
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}
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}
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}
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}
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impl ParseState for AirAggregate {
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type Token = Air;
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type Object = ();
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type Error = AsgError;
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/// Destination [`Asg`] that this parser lowers into.
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///
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/// This ASG will be yielded by [`crate::parse::Parser::finalize`].
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type Context = Asg;
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fn parse_token(
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self,
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tok: Self::Token,
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asg: &mut Self::Context,
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) -> crate::parse::TransitionResult<Self> {
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use ir::{
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AirIdent::*, AirPkg::*, AirSubsets::*, AirTodo::*, AirTpl::*,
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};
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use AirAggregate::*;
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// TODO: Seems to be about time for refactoring this...
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match (self, tok.into()) {
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(st, AirTodo(Todo(_))) => Transition(st).incomplete(),
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(Empty, AirPkg(PkgOpen(span))) => {
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let oi_pkg = asg.create(Pkg::new(span)).root(asg);
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Transition(PkgHead(
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oi_pkg,
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AirExprAggregate::new_in_pkg(oi_pkg),
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))
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.incomplete()
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}
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(PkgHead(oi_pkg, expr), AirPkg(PkgOpen(span))) => {
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Transition(PkgHead(oi_pkg, expr))
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.err(AsgError::NestedPkgOpen(span, oi_pkg.span()))
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}
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(PkgExpr(oi_pkg, expr), AirPkg(PkgOpen(span))) => {
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Transition(PkgExpr(oi_pkg, expr))
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.err(AsgError::NestedPkgOpen(span, oi_pkg.span()))
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}
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// No expression was started.
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(PkgHead(oi_pkg, _expr), AirPkg(PkgClose(span))) => {
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oi_pkg.close(asg, span);
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Transition(Empty).incomplete()
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}
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(PkgHead(..), AirBind(ident)) => {
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todo!("PkgBody AirBind {ident:?}")
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}
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(PkgHead(oi_pkg, expr), tok @ AirExpr(..)) => {
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Transition(PkgExpr(oi_pkg, expr))
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.incomplete()
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.with_lookahead(tok)
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}
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// Note that templates may preempt expressions at any point,
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// unlike in NIR at the time of writing.
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(
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PkgHead(oi_pkg, expr) | PkgExpr(oi_pkg, expr),
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tok @ AirTpl(..),
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) => Transition(PkgTpl(
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oi_pkg,
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expr,
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AirTplAggregate::define_in_pkg(oi_pkg),
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))
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.incomplete()
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.with_lookahead(tok),
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// Note: We unfortunately can't match on `AirExpr | AirBind`
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// and delegate in the same block
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// (without having to duplicate type checks and then handle
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// unreachable paths)
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// because of the different inner types.
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(PkgExpr(oi_pkg, expr), AirExpr(etok)) => {
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Self::delegate_expr(asg, oi_pkg, expr, etok)
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}
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(PkgExpr(oi_pkg, expr), AirBind(etok)) => {
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Self::delegate_expr(asg, oi_pkg, expr, etok)
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}
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// Templates can contain just about anything,
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// so completely hand over parsing when we're in template mode.
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(PkgTpl(oi_pkg, stored_expr, tplst), tok) => {
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Self::delegate_tpl(asg, oi_pkg, stored_expr, tplst, tok.into())
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}
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(Empty, AirTpl(TplClose(..))) => {
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todo!("Empty AirTpl::TplClose")
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}
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(Empty, AirPkg(PkgClose(span))) => {
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Transition(Empty).err(AsgError::InvalidPkgCloseContext(span))
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}
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(PkgExpr(oi_pkg, expr), AirPkg(PkgClose(span))) => {
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match expr.is_accepting(asg) {
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true => {
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// TODO: this is duplicated with the above
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oi_pkg.close(asg, span);
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Transition(Empty).incomplete()
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}
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false => Transition(PkgExpr(oi_pkg, expr))
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.err(AsgError::InvalidPkgCloseContext(span)),
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}
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}
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(Empty, tok @ (AirExpr(..) | AirBind(..) | AirTpl(TplOpen(_)))) => {
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Transition(Empty).err(AsgError::PkgExpected(tok.span()))
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}
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(Empty, AirIdent(IdentDecl(name, kind, src))) => {
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asg.declare(name, kind, src).map(|_| ()).transition(Empty)
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}
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(Empty, AirIdent(IdentExternDecl(name, kind, src))) => asg
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.declare_extern(name, kind, src)
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.map(|_| ())
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.transition(Empty),
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(Empty, AirIdent(IdentDep(sym, dep))) => {
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asg.add_dep_lookup(sym, dep);
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Transition(Empty).incomplete()
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}
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(Empty, AirIdent(IdentFragment(sym, text))) => {
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asg.set_fragment(sym, text).map(|_| ()).transition(Empty)
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}
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(Empty, AirIdent(IdentRoot(sym))) => {
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let obj = asg.lookup_or_missing(sym);
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asg.add_root(obj);
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Transition(Empty).incomplete()
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}
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(st, tok @ AirIdent(..)) => todo!("{st:?}, {tok:?}"),
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}
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}
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fn is_accepting(&self, _: &Self::Context) -> bool {
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matches!(self, Self::Empty)
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}
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}
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impl AirAggregate {
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/// Delegate to the expression parser [`AirExprAggregate`].
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///
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/// TODO: This ought to be further reduced into primitives in the core
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/// [`crate::parse`] framework.
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fn delegate_expr(
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asg: &mut <Self as ParseState>::Context,
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oi_pkg: ObjectIndex<Pkg>,
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expr: AirExprAggregate,
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etok: impl Into<<AirExprAggregate as ParseState>::Token>,
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) -> TransitionResult<Self> {
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let tok = etok.into();
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let tokspan = tok.span();
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expr.parse_token(tok, asg).branch_dead::<Self, _>(
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// TODO: Enforce using type system to avoid need for this
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// runtime check and prove that it is indeed impossible
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// (which otherwise could fail to be the case due to changes
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// since this was written).
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|_, ()| {
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diagnostic_unreachable!(
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vec![tokspan.internal_error(
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"unexpected dead state transition at this token"
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)],
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"AirExprAggregate should not have dead states"
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)
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},
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|expr, result, ()| {
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result
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.map(ParseStatus::reflexivity)
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.transition(Self::PkgExpr(oi_pkg, expr))
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},
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(),
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)
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}
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/// Delegate to the expression parser [`AirTplAggregate`].
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///
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/// After template parsing is complete
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/// (when reaching a dead state),
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/// the stored expression [`AirExprAggregate`] is reinstated,
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/// allowing parsing to continue where it left off before being
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/// preempted by template parsing.
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fn delegate_tpl(
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asg: &mut <Self as ParseState>::Context,
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oi_pkg: ObjectIndex<Pkg>,
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stored_expr: AirExprAggregate,
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tplst: AirTplAggregate,
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tok: Air,
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) -> TransitionResult<Self> {
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tplst
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.parse_token(tok, asg)
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.branch_dead::<Self, AirExprAggregate>(
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|_, stored_expr| {
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Transition(Self::PkgExpr(oi_pkg, stored_expr)).incomplete()
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},
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|tplst, result, stored_expr| {
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result
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.map(ParseStatus::reflexivity)
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.transition(Self::PkgTpl(oi_pkg, stored_expr, tplst))
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},
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stored_expr,
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)
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}
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}
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/// Template parser and token aggregator.
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///
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/// A template consists of
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///
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/// - Metadata about the template,
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/// including its parameters; and
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/// - A collection of [`Air`] tokens representing the body of the
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/// template that will be expanded into the application site when the
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/// template is applied.
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///
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/// This contains an embedded [`AirExprAggregate`] parser for handling
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/// expressions just the same as [`AirAggregate`] does with packages.
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#[derive(Debug, PartialEq, Eq)]
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pub enum AirTplAggregate {
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/// Ready for a template,
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/// defined as part of the given package.
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///
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/// This state also include the template header;
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/// unlike NIR,
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/// AIR has no restrictions on when template header tokens are
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/// provided,
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/// which simplifies AIR generation.
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///
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/// The expression parser [`AirExprAggregate`] is initialized at this
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/// state to avoid re-allocating its stack for adjacent templates.
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/// This will not save any allocations if,
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/// after reaching a dead state,
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/// the caller
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/// (or parent parser)
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/// chooses to deallocate us.
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Ready(ObjectIndex<Pkg>, AirExprAggregate),
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/// Aggregating tokens into a template.
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BuildingTpl(
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ObjectIndex<Pkg>,
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ObjectIndex<Tpl>,
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AirExprAggregate,
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Option<SPair>,
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),
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}
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impl Display for AirTplAggregate {
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fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
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match self {
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Self::Ready(_, _) => write!(f, "ready for template definition"),
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Self::BuildingTpl(_, expr, _, None) => {
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write!(f, "building anonymous template with {expr}")
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}
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Self::BuildingTpl(_, expr, _, Some(name)) => {
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write!(
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f,
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"building named template {} with {expr}",
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TtQuote::wrap(name)
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)
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}
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}
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}
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}
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impl ParseState for AirTplAggregate {
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type Token = Air;
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type Object = ();
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type Error = AsgError;
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type Context = Asg;
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fn parse_token(
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self,
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tok: Self::Token,
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asg: &mut Self::Context,
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) -> TransitionResult<Self::Super> {
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use ir::{AirBind::*, AirSubsets::*, AirTodo::*, AirTpl::*};
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use AirTplAggregate::*;
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match (self, tok.into()) {
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(st, AirTodo(Todo(_))) => Transition(st).incomplete(),
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(Ready(oi_pkg, expr), AirTpl(TplOpen(span))) => {
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let oi_tpl = asg.create(Tpl::new(span));
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Transition(BuildingTpl(oi_pkg, oi_tpl, expr, None)).incomplete()
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}
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(
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BuildingTpl(oi_pkg, oi_tpl, expr, _),
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AirBind(BindIdent(name)),
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) => asg
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.lookup_or_missing(name)
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.bind_definition(asg, name, oi_tpl)
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.map(|oi_ident| oi_pkg.defines(asg, oi_ident))
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.map(|_| ())
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.transition(BuildingTpl(oi_pkg, oi_tpl, expr, Some(name))),
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(BuildingTpl(oi_pkg, oi_tpl, expr, _), AirTpl(TplClose(span))) => {
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oi_tpl.close(asg, span);
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Transition(Ready(oi_pkg, expr)).incomplete()
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}
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(BuildingTpl(..), AirPkg(_)) => {
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todo!("template cannot define packages")
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}
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(BuildingTpl(..), tok) => todo!("BuildingTpl body: {tok:?}"),
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(st @ Ready(..), AirTpl(TplClose(span))) => {
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Transition(st).err(AsgError::UnbalancedTpl(span))
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}
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(
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st @ Ready(..),
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tok @ (AirPkg(..) | AirExpr(..) | AirBind(..) | AirIdent(..)),
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) => Transition(st).dead(tok.into()),
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}
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}
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fn is_accepting(&self, _: &Self::Context) -> bool {
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matches!(self, Self::Ready(..))
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}
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}
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impl AirTplAggregate {
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fn define_in_pkg(oi_pkg: ObjectIndex<Pkg>) -> Self {
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Self::Ready(oi_pkg, AirExprAggregate::new_in_pkg(oi_pkg))
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}
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}
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#[cfg(test)]
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mod test;
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