wac_graph/
plug.rs

1use crate::{
2    types::{are_semver_compatible, SubtypeChecker},
3    CompositionGraph, PackageId,
4};
5use thiserror::Error;
6
7/// Represents an error that can occur when plugging components together.
8#[derive(Debug, Error)]
9pub enum PlugError {
10    /// The socket component had no matching imports for the plugs that were provided
11    #[error("the socket component had no matching imports for the plugs that were provided")]
12    NoPlugHappened,
13    /// An error occurred when building the composition graph
14    #[error("an error occurred when building the composition graph")]
15    GraphError {
16        /// The underlying graph error
17        #[source]
18        source: anyhow::Error,
19    },
20}
21
22/// Take the exports of the plug components and plug them into the socket component.
23///
24/// Note that the `PackageId`s in `plugs` and `socket` must be registered with the `graph`
25/// before calling this function.
26pub fn plug(
27    graph: &mut CompositionGraph,
28    plugs: Vec<PackageId>,
29    socket: PackageId,
30) -> Result<(), PlugError> {
31    let socket_instantiation = graph.instantiate(socket);
32
33    for plug in plugs {
34        // Collect matching (plug_export_name, socket_import_name) pairs.
35        // The names may differ when matched via semver compatibility.
36        let mut plug_exports: Vec<(String, String)> = Vec::new();
37        let mut cache = Default::default();
38        let mut checker = SubtypeChecker::new(&mut cache);
39        for (name, plug_ty) in &graph.types()[graph[plug].ty()].exports {
40            // Try exact name match first, then fall back to semver-compatible match
41            let matching_import = graph.types()[graph[socket].ty()]
42                .imports
43                .get(name)
44                .map(|ty| (name.clone(), ty))
45                .or_else(|| {
46                    graph.types()[graph[socket].ty()]
47                        .imports
48                        .iter()
49                        .find(|(import_name, _)| are_semver_compatible(name, import_name))
50                        .map(|(import_name, ty)| (import_name.clone(), ty))
51                });
52
53            if let Some((socket_name, socket_ty)) = matching_import {
54                if checker
55                    .is_subtype(*plug_ty, graph.types(), *socket_ty, graph.types())
56                    .is_ok()
57                {
58                    plug_exports.push((name.clone(), socket_name));
59                }
60            }
61        }
62
63        // Instantiate the plug component
64        let mut plug_instantiation = None;
65        for (plug_name, socket_name) in plug_exports {
66            log::debug!("using export `{plug_name}` for plug");
67            let plug_instantiation =
68                *plug_instantiation.get_or_insert_with(|| graph.instantiate(plug));
69            let export = graph
70                .alias_instance_export(plug_instantiation, &plug_name)
71                .map_err(|err| PlugError::GraphError { source: err.into() })?;
72            graph
73                .set_instantiation_argument(socket_instantiation, &socket_name, export)
74                .map_err(|err| PlugError::GraphError { source: err.into() })?;
75        }
76    }
77
78    // Check we've actually done any plugging.
79    if graph
80        .get_instantiation_arguments(socket_instantiation)
81        .next()
82        .is_none()
83    {
84        return Err(PlugError::NoPlugHappened);
85    }
86
87    // Export all exports from the socket component.
88    for name in graph.types()[graph[socket].ty()]
89        .exports
90        .keys()
91        .cloned()
92        .collect::<Vec<_>>()
93    {
94        let export = graph
95            .alias_instance_export(socket_instantiation, &name)
96            .map_err(|err| PlugError::GraphError { source: err.into() })?;
97
98        graph
99            .export(export, &name)
100            .map_err(|err| PlugError::GraphError { source: err.into() })?;
101    }
102
103    Ok(())
104}
wac_graph/plug.rs

wac_graph/
plug.rs
