implement proper lsp-workspace support

fix typo

Co-authored-by: LeoniePhiline <[email protected]>

helix-loader/src/config.rs

@@ -9,35 +9,38 @@ pub fn default_lang_config() -> toml::Value {
 
 /// User configured languages.toml file, merged with the default config.
 pub fn user_lang_config() -> Result<toml::Value, toml::de::Error> {
-    let config = [crate::config_dir(), crate::find_workspace().join(".helix")]
-        .into_iter()
-        .map(|path| path.join("languages.toml"))
-        .filter_map(|file| {
-            std::fs::read_to_string(file)
-                .map(|config| toml::from_str(&config))
-                .ok()
-        })
-        .collect::<Result<Vec<_>, _>>()?
-        .into_iter()
-        .fold(default_lang_config(), |a, b| {
-            // combines for example
-            // b:
-            //   [[language]]
-            //   name = "toml"
-            //   language-server = { command = "taplo", args = ["lsp", "stdio"] }
-            //
-            // a:
-            //   [[language]]
-            //   language-server = { command = "/usr/bin/taplo" }
-            //
-            // into:
-            //   [[language]]
-            //   name = "toml"
-            //   language-server = { command = "/usr/bin/taplo" }
-            //
-            // thus it overrides the third depth-level of b with values of a if they exist, but otherwise merges their values
-            crate::merge_toml_values(a, b, 3)
-        });
+    let config = [
+        crate::config_dir(),
+        crate::find_workspace().0.join(".helix"),
+    ]
+    .into_iter()
+    .map(|path| path.join("languages.toml"))
+    .filter_map(|file| {
+        std::fs::read_to_string(file)
+            .map(|config| toml::from_str(&config))
+            .ok()
+    })
+    .collect::<Result<Vec<_>, _>>()?
+    .into_iter()
+    .fold(default_lang_config(), |a, b| {
+        // combines for example
+        // b:
+        //   [[language]]
+        //   name = "toml"
+        //   language-server = { command = "taplo", args = ["lsp", "stdio"] }
+        //
+        // a:
+        //   [[language]]
+        //   language-server = { command = "/usr/bin/taplo" }
+        //
+        // into:
+        //   [[language]]
+        //   name = "toml"
+        //   language-server = { command = "/usr/bin/taplo" }
+        //
+        // thus it overrides the third depth-level of b with values of a if they exist, but otherwise merges their values
+        crate::merge_toml_values(a, b, 3)
+    });
 
     Ok(config)
 }

helix-loader/src/lib.rs

@@ -76,7 +76,7 @@ pub fn config_file() -> PathBuf {
 }
 
 pub fn workspace_config_file() -> PathBuf {
-    find_workspace().join(".helix").join("config.toml")
+    find_workspace().0.join(".helix").join("config.toml")
 }
 
 pub fn lang_config_file() -> PathBuf {
@@ -230,14 +230,19 @@ mod merge_toml_tests {
 }
 
 /// Finds the current workspace folder.
-/// Used as a ceiling dir for root resolve, for the filepicker and other related
-pub fn find_workspace() -> PathBuf {
+/// Used as a ceiling dir for LSP root resolution, the filepicker and potentially as a future filewatching root
+///
+/// This function starts searching the FS upward from the CWD
+/// and returns the first directory that contains either `.git` or `.helix`.
+/// If no workspace was found returns (CWD, true).
+/// Otherwise (workspace, false) is returned
+pub fn find_workspace() -> (PathBuf, bool) {
     let current_dir = std::env::current_dir().expect("unable to determine current directory");
     for ancestor in current_dir.ancestors() {
         if ancestor.join(".git").exists() || ancestor.join(".helix").exists() {
-            return ancestor.to_owned();
+            return (ancestor.to_owned(), false);
         }
     }
 
-    current_dir
+    (current_dir, true)
 }

helix-lsp/Cargo.toml

@@ -26,3 +26,4 @@ thiserror = "1.0"
 tokio = { version = "1.26", features = ["rt", "rt-multi-thread", "io-util", "io-std", "time", "process", "macros", "fs", "parking_lot", "sync"] }
 tokio-stream = "0.1.12"
 which = "4.4"
+parking_lot = "0.12.1"

helix-lsp/src/client.rs

@@ -1,13 +1,17 @@
 use crate::{
-    find_root, jsonrpc,
+    find_lsp_workspace, jsonrpc,
     transport::{Payload, Transport},
     Call, Error, OffsetEncoding, Result,
 };
 
-use helix_core::{ChangeSet, Rope};
+use helix_core::{find_workspace, ChangeSet, Rope};
 use helix_loader::{self, VERSION_AND_GIT_HASH};
-use lsp::PositionEncodingKind;
+use lsp::{
+    notification::DidChangeWorkspaceFolders, DidChangeWorkspaceFoldersParams, OneOf,
+    PositionEncodingKind, WorkspaceFolder, WorkspaceFoldersChangeEvent,
+};
 use lsp_types as lsp;
+use parking_lot::Mutex;
 use serde::Deserialize;
 use serde_json::Value;
 use std::future::Future;
@@ -26,6 +30,17 @@ use tokio::{
     },
 };
 
+fn workspace_for_uri(uri: lsp::Url) -> WorkspaceFolder {
+    lsp::WorkspaceFolder {
+        name: uri
+            .path_segments()
+            .and_then(|segments| segments.last())
+            .map(|basename| basename.to_string())
+            .unwrap_or_default(),
+        uri,
+    }
+}
+
 #[derive(Debug)]
 pub struct Client {
     id: usize,
@@ -36,11 +51,126 @@ pub struct Client {
     config: Option<Value>,
     root_path: std::path::PathBuf,
     root_uri: Option<lsp::Url>,
-    workspace_folders: Vec<lsp::WorkspaceFolder>,
+    workspace_folders: Mutex<Vec<lsp::WorkspaceFolder>>,
+    initalize_notify: Arc<Notify>,
+    /// workspace folders added while the server is still initalizing
     req_timeout: u64,
 }
 
 impl Client {
+    pub fn try_add_doc(
+        self: &Arc<Self>,
+        root_markers: &[String],
+        manual_roots: &[PathBuf],
+        doc_path: Option<&std::path::PathBuf>,
+        may_support_workspace: bool,
+    ) -> bool {
+        let (workspace, workspace_is_cwd) = find_workspace();
+        let root = find_lsp_workspace(
+            doc_path
+                .and_then(|x| x.parent().and_then(|x| x.to_str()))
+                .unwrap_or("."),
+            root_markers,
+            manual_roots,
+            &workspace,
+            workspace_is_cwd,
+        );
+        let root_uri = root
+            .as_ref()
+            .and_then(|root| lsp::Url::from_file_path(root).ok());
+
+        if self.root_path == root.unwrap_or(workspace)
+            || root_uri.as_ref().map_or(false, |root_uri| {
+                self.workspace_folders
+                    .lock()
+                    .iter()
+                    .any(|workspace| &workspace.uri == root_uri)
+            })
+        {
+            // workspace URI is already register we can use this client
+            return true;
+        }
+
+        // this server definitly doesn't support muiltiple workspace, no need to check capabilities
+        if !may_support_workspace {
+            return false;
+        }
+
+        // TODO refactor to use let .. else when msrv is raised to 1.65
+        let capabilities = if let Some(capabilities) = self.capabilities.get() {
+            capabilities
+        } else {
+            let client = Arc::clone(self);
+            // initalization hasn't finished yet, deal with this new root later
+            // TODO: In the edgecase that a **new root** is added
+            // for an LSP that **doesn't support workspace_folders** before initaliation is finished
+            // the new roots are ignored.
+            // That particular edgecase would require retroactively spawning new LSP
+            // clients and therefore also require us to retroactively update the corresponding
+            // documents LSP client handle. It's doable but a pretty weird edgecase so let's
+            // wait and see if anyone ever runs into it.
+            tokio::spawn(async move {
+                client.initalize_notify.notified().await;
+                if let Some(workspace_folders_caps) = client
+                    .capabilities()
+                    .workspace
+                    .as_ref()
+                    .and_then(|cap| cap.workspace_folders.as_ref())
+                    .filter(|cap| cap.supported.unwrap_or(false))
+                {
+                    client.add_workspace_folder(
+                        root_uri,
+                        &workspace_folders_caps.change_notifications,
+                    );
+                }
+            });
+            return true;
+        };
+
+        if let Some(workspace_folders_caps) = capabilities
+            .workspace
+            .as_ref()
+            .and_then(|cap| cap.workspace_folders.as_ref())
+            .filter(|cap| cap.supported.unwrap_or(false))
+        {
+            self.add_workspace_folder(root_uri, &workspace_folders_caps.change_notifications);
+            true
+        } else {
+            // the server doesn't support multi workspaces, we need a new client
+            false
+        }
+    }
+
+    fn add_workspace_folder(
+        &self,
+        root_uri: Option<lsp::Url>,
+        change_notifications: &Option<OneOf<bool, String>>,
+    ) {
+        // root_uri is None just means that there isn't really any LSP workspace
+        // associated with this file. For servers that support multiple workspaces
+        // there is just one server so we can always just use that shared instance.
+        // No need to add a new workspace root here as there is no logical root for this file
+        // let the server deal with this
+        // TODO: Refactor to use let .. else once MSRV reaches 1.65
+        let root_uri = if let Some(root_uri) = root_uri {
+            root_uri
+        } else {
+            return;
+        };
+
+        // server supports workspace folders, let's add the new root to the list
+        self.workspace_folders
+            .lock()
+            .push(workspace_for_uri(root_uri.clone()));
+        if &Some(OneOf::Left(false)) == change_notifications {
+            // server specifically opted out of DidWorkspaceChange notifications
+            // let's assume the server will request the workspace folders himself
+            // and that we can therefore reuse the client (but are done now)
+            return;
+        }
+        tokio::spawn(self.did_change_workspace(vec![workspace_for_uri(root_uri)], Vec::new()));
+    }
+
     #[allow(clippy::type_complexity)]
     #[allow(clippy::too_many_arguments)]
     pub fn start(
@@ -76,30 +206,25 @@ impl Client {
 
         let (server_rx, server_tx, initialize_notify) =
             Transport::start(reader, writer, stderr, id);
-
-        let root_path = find_root(
+        let (workspace, workspace_is_cwd) = find_workspace();
+        let root = find_lsp_workspace(
             doc_path
                 .and_then(|x| x.parent().and_then(|x| x.to_str()))
                 .unwrap_or("."),
             root_markers,
             manual_roots,
+            &workspace,
+            workspace_is_cwd,
         );
 
-        let root_uri = lsp::Url::from_file_path(root_path.clone()).ok();
+        // `root_uri` and `workspace_folder` can be empty in case there is no workspace
+        // `root_url` can not, use `workspace` as a fallback
+        let root_path = root.clone().unwrap_or_else(|| workspace.clone());
+        let root_uri = root.and_then(|root| lsp::Url::from_file_path(root).ok());
 
-        // TODO: support multiple workspace folders
         let workspace_folders = root_uri
             .clone()
-            .map(|root| {
-                vec![lsp::WorkspaceFolder {
-                    name: root
-                        .path_segments()
-                        .and_then(|segments| segments.last())
-                        .map(|basename| basename.to_string())
-                        .unwrap_or_default(),
-                    uri: root,
-                }]
-            })
+            .map(|root| vec![workspace_for_uri(root)])
             .unwrap_or_default();
 
         let client = Self {
@@ -110,10 +235,10 @@ impl Client {
             capabilities: OnceCell::new(),
             config,
             req_timeout,
-
             root_path,
             root_uri,
-            workspace_folders,
+            workspace_folders: Mutex::new(workspace_folders),
+            initalize_notify: initialize_notify.clone(),
         };
 
         Ok((client, server_rx, initialize_notify))
@@ -169,8 +294,10 @@ impl Client {
         self.config.as_ref()
     }
 
-    pub fn workspace_folders(&self) -> &[lsp::WorkspaceFolder] {
-        &self.workspace_folders
+    pub async fn workspace_folders(
+        &self,
+    ) -> parking_lot::MutexGuard<'_, Vec<lsp::WorkspaceFolder>> {
+        self.workspace_folders.lock()
     }
 
     /// Execute a RPC request on the language server.
@@ -298,7 +425,7 @@ impl Client {
         #[allow(deprecated)]
         let params = lsp::InitializeParams {
             process_id: Some(std::process::id()),
-            workspace_folders: Some(self.workspace_folders.clone()),
+            workspace_folders: Some(self.workspace_folders.lock().clone()),
             // root_path is obsolete, but some clients like pyright still use it so we specify both.
             // clients will prefer _uri if possible
             root_path: self.root_path.to_str().map(|path| path.to_owned()),
@@ -450,6 +577,16 @@ impl Client {
         )
     }
 
+    pub fn did_change_workspace(
+        &self,
+        added: Vec<WorkspaceFolder>,
+        removed: Vec<WorkspaceFolder>,
+    ) -> impl Future<Output = Result<()>> {
+        self.notify::<DidChangeWorkspaceFolders>(DidChangeWorkspaceFoldersParams {
+            event: WorkspaceFoldersChangeEvent { added, removed },
+        })
+    }
+
     // -------------------------------------------------------------------------------------------
     // Text document
     // -------------------------------------------------------------------------------------------