tame/tamer/src/asg/graph/object/tpl.rs

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// Templates represented on the ASG
//
// Copyright (C) 2014-2023 Ryan Specialty, LLC.
//
// This file is part of TAME.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//! Templates on the ASG.
use std::fmt::Display;
use super::{
tamer: src::asg: Scaffolding for metasyntactic variables Also known as metavariables or template parameters. This is a bit of a tortured excursion, trying to figure out how I want to best represent this. I have a number of pages of hand-written notes that I'd like to distill over time, but the rendered graph ontology (via `asg-ontviz`) demonstrates the broad idea. `AirTpl::TplApply` highlights some remaining questions. What I had _wanted_ to do is to separate the concepts of application and expansion, and support partial application and such. But it's going to be too much work for now, when it isn't needed---partial application can be worked around by simply creating new templates and duplicating params, as we do today, although that sucks and is a maintenance issue. But I'd rather address that head-on in the future. So it's looking like Option B is going to be the approach for now, with templates being closed (as in, no free metavariables) and expanded at the same time. This simplifies the parser and error conditions significantly and makes it easier to utilize anonymous templates, since it'll still be the active context. My intent is to get at least the graph construction sorted out---not the actual expansion and binding yet---enough that I can use templates to represent parts of NIR that do not have proper graph representations or desugaring yet, so that I can spit them back out again in the `xmli` file and incrementally handle them. That was an option I had considered some months ago, but didn't want to entertain it at the time because I wasn't sure what doing so would look like; while it was an attractive approach since it pushes existing primitives into the template system (something I've wanted to do for years), I didn't want to potentially tank performance or compromise the design for it after I had spent so much effort on all of this so far. But my efforts have yielded a system that significantly exceeds my initial performance expectations, with a decent abstractions, and so this seems viable. DEV-13708
2023-03-15 11:49:13 -04:00
Expr, Ident, Meta, Object, ObjectIndex, ObjectRel, ObjectRelFrom,
ObjectRelTo, ObjectRelTy, ObjectRelatable,
};
use crate::{asg::Asg, f::Functor, parse::util::SPair, span::Span};
/// Template with associated name.
#[derive(Debug, PartialEq, Eq)]
pub struct Tpl(Span);
impl Tpl {
pub fn span(&self) -> Span {
match self {
Self(span) => *span,
}
}
pub fn new(span: Span) -> Self {
Self(span)
}
}
impl Functor<Span> for Tpl {
fn map(self, f: impl FnOnce(Span) -> Span) -> Self::Target {
match self {
Self(span) => Self(f(span)),
}
}
}
impl Display for Tpl {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
write!(f, "template")
}
}
object_rel! {
/// Templates may expand into nearly any context,
/// and must therefore be able to contain just about anything.
Tpl -> {
tree Ident,
tree Expr,
tamer: src::asg: Scaffolding for metasyntactic variables Also known as metavariables or template parameters. This is a bit of a tortured excursion, trying to figure out how I want to best represent this. I have a number of pages of hand-written notes that I'd like to distill over time, but the rendered graph ontology (via `asg-ontviz`) demonstrates the broad idea. `AirTpl::TplApply` highlights some remaining questions. What I had _wanted_ to do is to separate the concepts of application and expansion, and support partial application and such. But it's going to be too much work for now, when it isn't needed---partial application can be worked around by simply creating new templates and duplicating params, as we do today, although that sucks and is a maintenance issue. But I'd rather address that head-on in the future. So it's looking like Option B is going to be the approach for now, with templates being closed (as in, no free metavariables) and expanded at the same time. This simplifies the parser and error conditions significantly and makes it easier to utilize anonymous templates, since it'll still be the active context. My intent is to get at least the graph construction sorted out---not the actual expansion and binding yet---enough that I can use templates to represent parts of NIR that do not have proper graph representations or desugaring yet, so that I can spit them back out again in the `xmli` file and incrementally handle them. That was an option I had considered some months ago, but didn't want to entertain it at the time because I wasn't sure what doing so would look like; while it was an attractive approach since it pushes existing primitives into the template system (something I've wanted to do for years), I didn't want to potentially tank performance or compromise the design for it after I had spent so much effort on all of this so far. But my efforts have yielded a system that significantly exceeds my initial performance expectations, with a decent abstractions, and so this seems viable. DEV-13708
2023-03-15 11:49:13 -04:00
tree Meta,
}
}
impl ObjectIndex<Tpl> {
/// Attempt to complete a template definition.
///
/// This updates the span of the template to encompass the entire
/// definition.
pub fn close(self, asg: &mut Asg, close_span: Span) -> Self {
self.map_obj(asg, |tpl| {
tpl.map(|open_span| {
open_span.merge(close_span).unwrap_or(open_span)
})
})
}
/// Apply a named template `id` to the context of `self`.
///
/// During evaluation,
/// this application will expand the template in place,
/// re-binding metavariables to the context of `self`.
pub fn apply_named_tpl(self, asg: &mut Asg, id: SPair) -> Self {
let oi_apply = asg.lookup_or_missing(id);
// TODO: span
self.add_edge_to(asg, oi_apply, None)
}
/// Directly reference this template from another object
/// `oi_target_parent`,
/// indicating the intent to expand the template in place.
///
/// This direct reference allows applying anonymous templates.
///
/// The term "expansion" is equivalent to the application of a closed
/// template.
/// If this template is _not_ closed,
/// it will result in an error during evaluation.
pub fn expand_into<O: ObjectRelTo<Tpl>>(
self,
asg: &mut Asg,
oi_target_parent: ObjectIndex<O>,
) -> Self {
self.add_edge_from(asg, oi_target_parent, None)
}
}