feat(unstable): Workspaces support (#20410)

This commit adds unstable workspace support. This is extremely
bare-bones and
minimal first-pass at this.

With this change `deno.json` supports specifying `workspaces` key, that
accepts a list of subdirectories. Each workspace can have its own import
map. It's required to specify a `"name"` and `"version"` properties in the
configuration file for the workspace:

```jsonc
// deno.json
{
  "workspaces": [
     "a",
     "b"
  },
  "imports": {
    "express": "npm:express@5"
   }
}
```
``` jsonc
// a/deno.json
{
  "name": "a",
  "version": "1.0.2",
  "imports": {
    "kleur": "npm:kleur"
  }
}
```
```jsonc
// b/deno.json
{
  "name": "b",
  "version": "0.51.0",
  "imports": {
    "chalk": "npm:chalk"
  }
}
```

`--unstable-workspaces` flag is required to use this feature:
```
$ deno run --unstable-workspaces mod.ts
```

---------

Co-authored-by: David Sherret <dsherret@gmail.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/cli/module_loader.rs b/cli/module_loader.rs
index c8b2a36df..d8ab2d8c9 100644
--- a/cli/module_loader.rs
+++ b/cli/module_loader.rs
@@ -8,6 +8,7 @@ use crate::cache::ParsedSourceCache;
 use crate::emit::Emitter;
 use crate::graph_util::graph_lock_or_exit;
 use crate::graph_util::graph_valid_with_cli_options;
+use crate::graph_util::workspace_config_to_workspace_members;
 use crate::graph_util::FileWatcherReporter;
 use crate::graph_util::ModuleGraphBuilder;
 use crate::graph_util::ModuleGraphContainer;
@@ -119,6 +120,12 @@ impl ModuleLoadPreparer {
 
     let mut cache = self.module_graph_builder.create_fetch_cacher(permissions);
     let maybe_imports = self.options.to_maybe_imports()?;
+    let maybe_workspace_config = self.options.maybe_workspace_config();
+    let workspace_members = if let Some(wc) = maybe_workspace_config {
+      workspace_config_to_workspace_members(wc)?
+    } else {
+      vec![]
+    };
     let graph_resolver = self.resolver.as_graph_resolver();
     let graph_npm_resolver = self.resolver.as_graph_npm_resolver();
     let maybe_file_watcher_reporter = self
@@ -152,8 +159,7 @@ impl ModuleLoadPreparer {
           npm_resolver: Some(graph_npm_resolver),
           module_analyzer: Some(&analyzer),
           reporter: maybe_file_watcher_reporter,
-          // todo(dsherret): workspace support
-          workspace_members: vec![],
+          workspace_members,
         },
       )
       .await?;