wac_graph/
plug.rs

1use crate::{types::SubtypeChecker, CompositionGraph, PackageId};
2use thiserror::Error;
3
4/// Represents an error that can occur when plugging components together.
5#[derive(Debug, Error)]
6pub enum PlugError {
7    /// The socket component had no matching imports for the plugs that were provided
8    #[error("the socket component had no matching imports for the plugs that were provided")]
9    NoPlugHappened,
10    /// An error occurred when building the composition graph
11    #[error("an error occurred when building the composition graph")]
12    GraphError {
13        /// The underlying graph error
14        #[source]
15        source: anyhow::Error,
16    },
17}
18
19/// Take the exports of the plug components and plug them into the socket component.
20///
21/// Note that the `PackageId`s in `plugs` and `socket` must be registered with the `graph`
22/// before calling this function.
23pub fn plug(
24    graph: &mut CompositionGraph,
25    plugs: Vec<PackageId>,
26    socket: PackageId,
27) -> Result<(), PlugError> {
28    let socket_instantiation = graph.instantiate(socket);
29
30    for plug in plugs {
31        let mut plug_exports = Vec::new();
32        let mut cache = Default::default();
33        let mut checker = SubtypeChecker::new(&mut cache);
34        for (name, plug_ty) in &graph.types()[graph[plug].ty()].exports {
35            if let Some(socket_ty) = graph.types()[graph[socket].ty()].imports.get(name) {
36                if checker
37                    .is_subtype(*plug_ty, graph.types(), *socket_ty, graph.types())
38                    .is_ok()
39                {
40                    plug_exports.push(name.clone());
41                }
42            }
43        }
44
45        // Instantiate the plug component
46        let mut plug_instantiation = None;
47        for plug_name in plug_exports {
48            log::debug!("using export `{plug_name}` for plug");
49            let plug_instantiation =
50                *plug_instantiation.get_or_insert_with(|| graph.instantiate(plug));
51            let export = graph
52                .alias_instance_export(plug_instantiation, &plug_name)
53                .map_err(|err| PlugError::GraphError { source: err.into() })?;
54            graph
55                .set_instantiation_argument(socket_instantiation, &plug_name, export)
56                .map_err(|err| PlugError::GraphError { source: err.into() })?;
57        }
58    }
59
60    // Check we've actually done any plugging.
61    if graph
62        .get_instantiation_arguments(socket_instantiation)
63        .next()
64        .is_none()
65    {
66        return Err(PlugError::NoPlugHappened);
67    }
68
69    // Export all exports from the socket component.
70    for name in graph.types()[graph[socket].ty()]
71        .exports
72        .keys()
73        .cloned()
74        .collect::<Vec<_>>()
75    {
76        let export = graph
77            .alias_instance_export(socket_instantiation, &name)
78            .map_err(|err| PlugError::GraphError { source: err.into() })?;
79
80        graph
81            .export(export, &name)
82            .map_err(|err| PlugError::GraphError { source: err.into() })?;
83    }
84
85    Ok(())
86}
wac_graph/plug.rs

wac_graph/
plug.rs
