python: Re-land usage of source file path in toolchain picker (#31893)

This reverts commit 1e55e88c18.

Closes #ISSUE

Release Notes:

- Python toolchain selector now uses path to the closest pyproject.toml
as a basis for picking a toolchain. All files under the same
pyproject.toml (in filesystem hierarchy) will share a single virtual
environment. It is possible to have multiple Python virtual environments
selected for disjoint parts of the same project.

crates/project/src/manifest_tree.rs

@@ -11,16 +11,17 @@ use std::{
     borrow::Borrow,
     collections::{BTreeMap, hash_map::Entry},
     ops::ControlFlow,
+    path::Path,
     sync::Arc,
 };
 
 use collections::HashMap;
 use gpui::{App, AppContext as _, Context, Entity, EventEmitter, Subscription};
-use language::{LspAdapterDelegate, ManifestName, ManifestQuery};
+use language::{ManifestDelegate, ManifestName, ManifestQuery};
 pub use manifest_store::ManifestProviders;
 use path_trie::{LabelPresence, RootPathTrie, TriePath};
 use settings::{SettingsStore, WorktreeId};
-use worktree::{Event as WorktreeEvent, Worktree};
+use worktree::{Event as WorktreeEvent, Snapshot, Worktree};
 
 use crate::{
     ProjectPath,
@@ -89,7 +90,7 @@ pub(crate) enum ManifestTreeEvent {
 impl EventEmitter<ManifestTreeEvent> for ManifestTree {}
 
 impl ManifestTree {
-    pub(crate) fn new(worktree_store: Entity<WorktreeStore>, cx: &mut App) -> Entity<Self> {
+    pub fn new(worktree_store: Entity<WorktreeStore>, cx: &mut App) -> Entity<Self> {
         cx.new(|cx| Self {
             root_points: Default::default(),
             _subscriptions: [
@@ -106,11 +107,11 @@ impl ManifestTree {
             worktree_store,
         })
     }
-    fn root_for_path(
+    pub(crate) fn root_for_path(
         &mut self,
         ProjectPath { worktree_id, path }: ProjectPath,
         manifests: &mut dyn Iterator<Item = ManifestName>,
-        delegate: Arc<dyn LspAdapterDelegate>,
+        delegate: Arc<dyn ManifestDelegate>,
         cx: &mut App,
     ) -> BTreeMap<ManifestName, ProjectPath> {
         debug_assert_eq!(delegate.worktree_id(), worktree_id);
@@ -218,3 +219,26 @@ impl ManifestTree {
         }
     }
 }
+
+pub(crate) struct ManifestQueryDelegate {
+    worktree: Snapshot,
+}
+impl ManifestQueryDelegate {
+    pub fn new(worktree: Snapshot) -> Self {
+        Self { worktree }
+    }
+}
+
+impl ManifestDelegate for ManifestQueryDelegate {
+    fn exists(&self, path: &Path, is_dir: Option<bool>) -> bool {
+        self.worktree.entry_for_path(path).map_or(false, |entry| {
+            is_dir.map_or(true, |is_required_to_be_dir| {
+                is_required_to_be_dir == entry.is_dir()
+            })
+        })
+    }
+
+    fn worktree_id(&self) -> WorktreeId {
+        self.worktree.id()
+    }
+}