1 files changed, 89 insertions, 10 deletions

diff --git a/helix-lsp/src/client.rs b/helix-lsp/src/client.rs
index 65c6954d..b1a73247 100644
--- a/helix-lsp/src/client.rs
+++ b/helix-lsp/src/client.rs
@@ -4,7 +4,7 @@ use crate::{
     Call, Error, OffsetEncoding, Result,
 };
 
-use helix_core::{find_workspace, path, ChangeSet, Rope};
+use helix_core::{find_workspace, path, syntax::LanguageServerFeature, ChangeSet, Rope};
 use helix_loader::{self, VERSION_AND_GIT_HASH};
 use lsp::{
     notification::DidChangeWorkspaceFolders, DidChangeWorkspaceFoldersParams, OneOf,
@@ -276,6 +276,93 @@ impl Client {
             .expect("language server not yet initialized!")
     }
 
+    #[inline] // TODO inline?
+    pub fn supports_feature(&self, feature: LanguageServerFeature) -> bool {
+        let capabilities = match self.capabilities.get() {
+            Some(capabilities) => capabilities,
+            None => return false, // not initialized, TODO unwrap/expect instead?
+        };
+        match feature {
+            LanguageServerFeature::Format => matches!(
+                capabilities.document_formatting_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::GotoDeclaration => matches!(
+                capabilities.declaration_provider,
+                Some(
+                    lsp::DeclarationCapability::Simple(true)
+                        | lsp::DeclarationCapability::RegistrationOptions(_)
+                        | lsp::DeclarationCapability::Options(_),
+                )
+            ),
+            LanguageServerFeature::GotoDefinition => matches!(
+                capabilities.definition_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::GotoTypeDefinition => matches!(
+                capabilities.type_definition_provider,
+                Some(
+                    lsp::TypeDefinitionProviderCapability::Simple(true)
+                        | lsp::TypeDefinitionProviderCapability::Options(_),
+                )
+            ),
+            LanguageServerFeature::GotoReference => matches!(
+                capabilities.references_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::GotoImplementation => matches!(
+                capabilities.implementation_provider,
+                Some(
+                    lsp::ImplementationProviderCapability::Simple(true)
+                        | lsp::ImplementationProviderCapability::Options(_),
+                )
+            ),
+            LanguageServerFeature::SignatureHelp => capabilities.signature_help_provider.is_some(),
+            LanguageServerFeature::Hover => matches!(
+                capabilities.hover_provider,
+                Some(
+                    lsp::HoverProviderCapability::Simple(true)
+                        | lsp::HoverProviderCapability::Options(_),
+                )
+            ),
+            LanguageServerFeature::DocumentHighlight => matches!(
+                capabilities.document_highlight_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::Completion => capabilities.completion_provider.is_some(),
+            LanguageServerFeature::CodeAction => matches!(
+                capabilities.code_action_provider,
+                Some(
+                    lsp::CodeActionProviderCapability::Simple(true)
+                        | lsp::CodeActionProviderCapability::Options(_),
+                )
+            ),
+            LanguageServerFeature::WorkspaceCommand => {
+                capabilities.execute_command_provider.is_some()
+            }
+            LanguageServerFeature::DocumentSymbols => matches!(
+                capabilities.document_symbol_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::WorkspaceSymbols => matches!(
+                capabilities.workspace_symbol_provider,
+                Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::Diagnostics => true, // there's no extra server capability
+            LanguageServerFeature::RenameSymbol => matches!(
+                capabilities.rename_provider,
+                Some(lsp::OneOf::Left(true)) | Some(lsp::OneOf::Right(_))
+            ),
+            LanguageServerFeature::InlayHints => matches!(
+                capabilities.inlay_hint_provider,
+                Some(
+                    lsp::OneOf::Left(true)
+                        | lsp::OneOf::Right(lsp::InlayHintServerCapabilities::Options(_))
+                )
+            ),
+        }
+    }
+
     pub fn offset_encoding(&self) -> OffsetEncoding {
         self.capabilities()
             .position_encoding
@@ -1301,21 +1388,13 @@ impl Client {
         Some(self.call::<lsp::request::CodeActionRequest>(params))
     }
 
-    pub fn supports_rename(&self) -> bool {
-        let capabilities = self.capabilities.get().unwrap();
-        matches!(
-            capabilities.rename_provider,
-            Some(lsp::OneOf::Left(true) | lsp::OneOf::Right(_))
-        )
-    }
-
     pub fn rename_symbol(
         &self,
         text_document: lsp::TextDocumentIdentifier,
         position: lsp::Position,
         new_name: String,
     ) -> Option<impl Future<Output = Result<lsp::WorkspaceEdit>>> {
-        if !self.supports_rename() {
+        if !self.supports_feature(LanguageServerFeature::RenameSymbol) {
             return None;
         }