feat(ir): dependents and dependencies

This commit is contained in:
multisn8 2024-01-19 02:01:30 +01:00
parent 29269e2fcd
commit 66639771ac
Signed by: multisamplednight
GPG key ID: 6D525AA147CBDAE2
3 changed files with 126 additions and 12 deletions

1
Cargo.lock generated
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@ -375,6 +375,7 @@ dependencies = [
name = "ir"
version = "0.1.0"
dependencies = [
"either",
"ron",
"serde",
]

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@ -6,6 +6,7 @@ edition = "2021"
# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
[dependencies]
either = "1.9"
ron = "0.8"
serde = { version = "1.0.193", features = ["derive"] }

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@ -1,8 +1,6 @@
use std::{
collections::{BTreeMap, BTreeSet},
ops::RangeInclusive,
};
use std::{collections::BTreeSet, iter, ops::RangeInclusive};
use either::Either;
use instruction::SocketCount;
use serde::{Deserialize, Serialize};
@ -72,6 +70,56 @@ pub struct GraphIr {
}
impl GraphIr {
/// Look "forwards" in the graph to see what other instructions this instruction feeds into.
///
/// The output slots represent the top-level iterator,
/// and each one's connections are emitted one level below.
///
/// Just [`Iterator::flatten`] if you are not interested in the slots.
///
/// The same caveats as for [`GraphIr::resolve`] apply.
#[must_use]
pub fn dependents(
&self,
subject: &id::Instruction,
) -> Option<impl Iterator<Item = impl Iterator<Item = &id::Instruction>> + '_> {
let (subject, kind) = self.instructions.get_key_value(subject)?;
let SocketCount { inputs, .. } = kind.socket_count();
Some((0..inputs).map(|idx| {
let output = id::Output(socket(subject, idx));
self.edges
.get(&output)
.map_or(Either::Right(iter::empty()), |targets| {
Either::Left(targets.iter().map(|input| &input.socket().belongs_to))
})
}))
}
/// Look "backwards" in the graph,
/// and find out what instructions need to be done before this one.
/// The input slots are visited in order.
///
/// - The iterator returns individually [`Some`]`(`[`None`]`)` if the corresponding slot is
/// not connected.
///
/// The same caveats as for [`GraphIr::resolve`] apply.
#[must_use]
pub fn dependencies(
&self,
subject: &id::Instruction,
) -> Option<impl Iterator<Item = Option<&id::Instruction>> + '_> {
let (subject, kind) = self.instructions.get_key_value(subject)?;
let SocketCount { inputs, .. } = kind.socket_count();
Some((0..inputs).map(|idx| {
let input = id::Input(socket(subject, idx));
self.rev_edges
.get(&input)
.map(|output| &output.socket().belongs_to)
}))
}
// TODO: this function, but actually the whole module, screams for tests
/// Returns the instruction corresponding to the given ID.
/// Returns [`None`] if there is no such instruction in this graph IR.
@ -82,8 +130,8 @@ impl GraphIr {
/// to actually have multiple [`GraphIr`]s at one point in time.
/// Open an issue if that poses a problem for you.
#[must_use]
pub fn resolve<'ir>(&'ir self, id: &id::Instruction) -> Option<Instruction<'ir>> {
let (id, kind) = self.instructions.get_key_value(id)?;
pub fn resolve<'ir>(&'ir self, subject: &id::Instruction) -> Option<Instruction<'ir>> {
let (id, kind) = self.instructions.get_key_value(subject)?;
// just try each slot and see if it's connected
// very crude, but it works for a proof of concept
@ -131,17 +179,73 @@ impl GraphIr {
self.resolve(&output.socket().belongs_to)
}
/// Returns the order in which the instructions could be visited
/// in order to ensure that all dependencies are resolved
/// before a vertex is visited.
///
/// # Panics
///
/// Panics if there are any cycles in the IR, as it needs to be a DAG.
#[must_use]
// yes, this function could actually return an iterator and be lazy
// no, not today
pub fn topological_sort(&self) -> Vec<Instruction> {
// count how many incoming edges each vertex has
// chances are the BTreeMap is overkill
let incoming_counts: BTreeMap<_, _> = self
.rev_edges
.iter()
.map(|(input, _)| (self.owner_of_input(input), 1))
let input_counts: Map<_, usize> =
self.rev_edges
.iter()
.fold(Map::new(), |mut count, (input, _)| {
*count.entry(input.socket().belongs_to.clone()).or_default() += 1;
count
});
// could experiment with a VecDeque here
let mut active_queue = Vec::new();
// what vertices can we start with? in other words, which ones have 0 inputs?
let unresolved_input_count: Map<id::Instruction, usize> = input_counts
.into_iter()
.filter_map(|(instr, count)| {
dbg!(count);
if count == 0 {
active_queue.push(instr);
None
} else {
Some((instr, count))
}
})
.collect();
todo!()
// then let's find the order!
let mut order = Vec::new();
while let Some(current) = active_queue.pop() {
// now that this vertex is visited and resolved,
// make sure all dependents notice that
for dependent in self
.dependents(&current)
.expect("graph to be consistent")
.flatten()
{
dbg!(dependent);
}
order.push(self.resolve(&current).expect("graph to be consistent"));
}
assert!(
!unresolved_input_count.is_empty(),
concat!(
"topological sort didn't cover all instructions\n",
"either there are unconnected inputs, or there is a cycle\n",
"unresolved instructions:\n",
"{:#?}"
),
unresolved_input_count
);
order
}
}
@ -192,3 +296,11 @@ impl From<RangeInclusive<usize>> for Span {
}
}
}
/// Constructs an [`id::Socket`] a bit more tersely.
fn socket(id: &id::Instruction, idx: u16) -> id::Socket {
id::Socket {
belongs_to: id.clone(),
idx: id::SocketIdx(idx),
}
}