lsp: Implement textDocument/signatureHelp for `ProjectClientState::…

…Local` environment (#12909)

Closes #5155
Closes #4879


# Purpose
There was no way to know what to put in function signatures or struct
fields other than hovering at the moment. Therefore, it was necessary to
implement LSP's `textDocument/signatureHelp`.

I tried my best to match the surrounding coding style, but since this is
my first contribution, I believe there are various aspects that may be
lacking. I would greatly appreciate your code review.

# Description
When the window is displayed, the current argument or field at the
cursor's position is automatically bolded. If the cursor moves and there
is nothing to display, the window closes automatically.
To minimize changes and reduce the burden of review and debugging, the
SignatureHelp feature is implemented only when `is_local` is `true`.
Some `unimplemented!()` macros are embedded, but rest assured that they
are not called in this implementation.

# How to try it out
Press `cmd + i` (MacOS), `ctrl + i` (Linux).

# Enable auto signature help (2 ways)
### Add `"auto_signature_help": true` to `settings.json`
<img width="426" alt="image"
src="https://github.com/zed-industries/zed/assets/55743826/61310c39-47f9-4586-94b0-ae519dc3b37c">

Or

### Press `Auto Signature Help`. (Default `false`)
<img width="226" alt="image"
src="https://github.com/zed-industries/zed/assets/55743826/34155215-1eb5-4621-b09b-55df2f1ab6a8">

# Disable to show signature help after completion
### Add `"show_signature_help_after_completion": false` to
`settings.json`
<img width="438" alt="image"
src="https://github.com/zed-industries/zed/assets/55743826/5e5bacac-62e0-4921-9243-17e1e72d5eb6">

# Movie

https://github.com/zed-industries/zed/assets/55743826/77c12d51-b0a5-415d-8901-f93ef92098e7

# Screen Shot
<img width="628" alt="image"
src="https://github.com/zed-industries/zed/assets/55743826/3ebcf4b6-2b94-4dea-97f9-ac4f33e0291e">

<img width="637" alt="image"
src="https://github.com/zed-industries/zed/assets/55743826/6dc3eb4d-beee-460b-8dbe-d6eec6379b76">

Release Notes:

- Show function signature popovers
([4879](#4879),
[5155](#5155))

---------

Co-authored-by: Kirill Bulatov <[email protected]>

assets/keymaps/default-linux.json

@@ -100,6 +100,7 @@
       "ctrl-k ctrl-r": "editor::RevertSelectedHunks",
       "ctrl-'": "editor::ToggleHunkDiff",
       "ctrl-\"": "editor::ExpandAllHunkDiffs",
+      "ctrl-i": "editor::ShowSignatureHelp",
       "alt-g b": "editor::ToggleGitBlame"
     }
   },

assets/keymaps/default-macos.json

@@ -126,7 +126,8 @@
       "cmd-alt-z": "editor::RevertSelectedHunks",
       "cmd-'": "editor::ToggleHunkDiff",
       "cmd-\"": "editor::ExpandAllHunkDiffs",
-      "cmd-alt-g b": "editor::ToggleGitBlame"
+      "cmd-alt-g b": "editor::ToggleGitBlame",
+      "cmd-i": "editor::ShowSignatureHelp"
     }
   },
   {

assets/settings/default.json

@@ -116,6 +116,11 @@
   // The debounce delay before re-querying the language server for completion
   // documentation when not included in original completion list.
   "completion_documentation_secondary_query_debounce": 300,
+  // Show method signatures in the editor, when inside parentheses.
+  "auto_signature_help": false,
+  /// Whether to show the signature help after completion or a bracket pair inserted.
+  /// If `auto_signature_help` is enabled, this setting will be treated as enabled also.
+  "show_signature_help_after_edits": true,
   // Whether to show wrap guides (vertical rulers) in the editor.
   // Setting this to true will show a guide at the 'preferred_line_length' value
   // if softwrap is set to 'preferred_line_length', and will show any

crates/collab/src/rpc.rs

@@ -642,7 +642,10 @@ impl Server {
                         app_state.config.openai_api_key.clone(),
                     )
                 })
-            });
+            })
+            .add_request_handler(user_handler(
+                forward_read_only_project_request::<proto::GetSignatureHelp>,
+            ));
 
         Arc::new(server)
     }

crates/editor/src/actions.rs

@@ -286,12 +286,14 @@ gpui::actions!(
         SelectPageUp,
         ShowCharacterPalette,
         ShowInlineCompletion,
+        ShowSignatureHelp,
         ShuffleLines,
         SortLinesCaseInsensitive,
         SortLinesCaseSensitive,
         SplitSelectionIntoLines,
         Tab,
         TabPrev,
+        ToggleAutoSignatureHelp,
         ToggleGitBlame,
         ToggleGitBlameInline,
         ToggleSelectionMenu,

crates/editor/src/editor.rs

@@ -39,8 +39,10 @@ pub mod tasks;
 
 #[cfg(test)]
 mod editor_tests;
+mod signature_help;
 #[cfg(any(test, feature = "test-support"))]
 pub mod test;
+
 use ::git::diff::{DiffHunk, DiffHunkStatus};
 use ::git::{parse_git_remote_url, BuildPermalinkParams, GitHostingProviderRegistry};
 pub(crate) use actions::*;
@@ -154,6 +156,7 @@ use workspace::{
 use workspace::{OpenInTerminal, OpenTerminal, TabBarSettings, Toast};
 
 use crate::hover_links::find_url;
+use crate::signature_help::{SignatureHelpHiddenBy, SignatureHelpState};
 
 pub const FILE_HEADER_HEIGHT: u8 = 1;
 pub const MULTI_BUFFER_EXCERPT_HEADER_HEIGHT: u8 = 1;
@@ -501,6 +504,8 @@ pub struct Editor {
     context_menu: RwLock<Option<ContextMenu>>,
     mouse_context_menu: Option<MouseContextMenu>,
     completion_tasks: Vec<(CompletionId, Task<Option<()>>)>,
+    signature_help_state: SignatureHelpState,
+    auto_signature_help: Option<bool>,
     find_all_references_task_sources: Vec<Anchor>,
     next_completion_id: CompletionId,
     completion_documentation_pre_resolve_debounce: DebouncedDelay,
@@ -1819,6 +1824,8 @@ impl Editor {
             context_menu: RwLock::new(None),
             mouse_context_menu: None,
             completion_tasks: Default::default(),
+            signature_help_state: SignatureHelpState::default(),
+            auto_signature_help: None,
             find_all_references_task_sources: Vec::new(),
             next_completion_id: 0,
             completion_documentation_pre_resolve_debounce: DebouncedDelay::new(),
@@ -2411,6 +2418,15 @@ impl Editor {
                 self.request_autoscroll(autoscroll, cx);
             }
             self.selections_did_change(true, &old_cursor_position, request_completions, cx);
+
+            if self.should_open_signature_help_automatically(
+                &old_cursor_position,
+                self.signature_help_state.backspace_pressed(),
+                cx,
+            ) {
+                self.show_signature_help(&ShowSignatureHelp, cx);
+            }
+            self.signature_help_state.set_backspace_pressed(false);
         }
 
         result
@@ -2866,6 +2882,10 @@ impl Editor {
             return true;
         }
 
+        if self.hide_signature_help(cx, SignatureHelpHiddenBy::Escape) {
+            return true;
+        }
+
         if self.hide_context_menu(cx).is_some() {
             return true;
         }
@@ -2942,7 +2962,7 @@ impl Editor {
         }
 
         let selections = self.selections.all_adjusted(cx);
-        let mut brace_inserted = false;
+        let mut bracket_inserted = false;
         let mut edits = Vec::new();
         let mut linked_edits = HashMap::<_, Vec<_>>::default();
         let mut new_selections = Vec::with_capacity(selections.len());
@@ -3004,6 +3024,7 @@ impl Editor {
                                         ),
                                         &bracket_pair.start[..prefix_len],
                                     ));
+
                             if autoclose
                                 && bracket_pair.close
                                 && following_text_allows_autoclose
@@ -3021,7 +3042,7 @@ impl Editor {
                                     selection.range(),
                                     format!("{}{}", text, bracket_pair.end).into(),
                                 ));
-                                brace_inserted = true;
+                                bracket_inserted = true;
                                 continue;
                             }
                         }
@@ -3067,7 +3088,7 @@ impl Editor {
                             selection.end..selection.end,
                             bracket_pair.end.as_str().into(),
                         ));
-                        brace_inserted = true;
+                        bracket_inserted = true;
                         new_selections.push((
                             Selection {
                                 id: selection.id,
@@ -3224,14 +3245,22 @@ impl Editor {
                 s.select(new_selections)
             });
 
-            if !brace_inserted && EditorSettings::get_global(cx).use_on_type_format {
+            if !bracket_inserted && EditorSettings::get_global(cx).use_on_type_format {
                 if let Some(on_type_format_task) =
                     this.trigger_on_type_formatting(text.to_string(), cx)
                 {
                     on_type_format_task.detach_and_log_err(cx);
                 }
             }
 
+            let editor_settings = EditorSettings::get_global(cx);
+            if bracket_inserted
+                && (editor_settings.auto_signature_help
+                    || editor_settings.show_signature_help_after_edits)
+            {
+                this.show_signature_help(&ShowSignatureHelp, cx);
+            }
+
             let trigger_in_words = !had_active_inline_completion;
             this.trigger_completion_on_input(&text, trigger_in_words, cx);
             linked_editing_ranges::refresh_linked_ranges(this, cx);
@@ -4305,6 +4334,14 @@ impl Editor {
             true,
             cx,
         );
+
+        let editor_settings = EditorSettings::get_global(cx);
+        if editor_settings.show_signature_help_after_edits || editor_settings.auto_signature_help {
+            // After the code completion is finished, users often want to know what signatures are needed.
+            // so we should automatically call signature_help
+            self.show_signature_help(&ShowSignatureHelp, cx);
+        }
+
         Some(cx.foreground_executor().spawn(async move {
             apply_edits.await?;
             Ok(())
@@ -5328,6 +5365,7 @@ impl Editor {
                 }
             }
 
+            this.signature_help_state.set_backspace_pressed(true);
             this.change_selections(Some(Autoscroll::fit()), cx, |s| s.select(selections));
             this.insert("", cx);
             let empty_str: Arc<str> = Arc::from("");

crates/editor/src/editor_settings.rs

@@ -26,6 +26,8 @@ pub struct EditorSettings {
     #[serde(default)]
     pub double_click_in_multibuffer: DoubleClickInMultibuffer,
     pub search_wrap: bool,
+    pub auto_signature_help: bool,
+    pub show_signature_help_after_edits: bool,
     #[serde(default)]
     pub jupyter: Jupyter,
 }
@@ -234,6 +236,16 @@ pub struct EditorSettingsContent {
     /// Default: true
     pub search_wrap: Option<bool>,
 
+    /// Whether to automatically show a signature help pop-up or not.
+    ///
+    /// Default: false
+    pub auto_signature_help: Option<bool>,
+
+    /// Whether to show the signature help pop-up after completions or bracket pairs inserted.
+    ///
+    /// Default: true
+    pub show_signature_help_after_edits: Option<bool>,
+
     /// Jupyter REPL settings.
     pub jupyter: Option<Jupyter>,
 }