feat: add handler for document prepare rename requests

lsp_3_17/handler.go

@@ -83,6 +83,7 @@ type Handler struct {
 	documentRangeFormatting    DocumentRangeFormattingHandlerFunc
 	documentOnTypeFormatting   DocumentOnTypeFormattingHandlerFunc
 	documentRename             DocumentRenameHandlerFunc
+	documentPrepareRename      DocumentPrepareRenameHandlerFunc
 
 	isInitialized bool
 	// Provides a mapping of method names to the respective handlers

lsp_3_17/handler_language_features.go

@@ -291,6 +291,14 @@ func WithDocumentRenameHandler(handler DocumentRenameHandlerFunc) HandlerOption
 	}
 }
 
+// WithDocumentPrepareRenameHandler sets the handler for the
+// `textDocument/prepareRename` request.
+func WithDocumentPrepareRenameHandler(handler DocumentPrepareRenameHandlerFunc) HandlerOption {
+	return func(root *Handler) {
+		root.SetDocumentPrepareRenameHandler(handler)
+	}
+}
+
 // SetGotoDeclarationHandler sets the handler for the `textDocument/declaration` request.
 func (h *Handler) SetGotoDeclarationHandler(handler GotoDeclarationHandlerFunc) {
 	h.mu.Lock()
@@ -611,6 +619,14 @@ func (h *Handler) SetDocumentRenameHandler(handler DocumentRenameHandlerFunc) {
 	h.messageHandlers[MethodDocumentRename] = createDocumentRenameHandler(h)
 }
 
+// SetDocumentPrepareRenameHandler sets the handler for the `textDocument/prepareRename` request.
+func (h *Handler) SetDocumentPrepareRenameHandler(handler DocumentPrepareRenameHandlerFunc) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	h.documentPrepareRename = handler
+	h.messageHandlers[MethodDocumentPrepareRename] = createDocumentPrepareRenameHandler(h)
+}
+
 func createGotoDeclarationHandler(root *Handler) common.Handler {
 	return common.HandlerFunc(
 		func(
@@ -1330,3 +1346,21 @@ func createDocumentRenameHandler(root *Handler) common.Handler {
 		},
 	)
 }
+
+func createDocumentPrepareRenameHandler(root *Handler) common.Handler {
+	return common.HandlerFunc(
+		func(
+			ctx *common.LSPContext,
+		) (r any, validMethod bool, validParams bool, err error) {
+			validMethod = true
+			if root.documentPrepareRename != nil {
+				var params PrepareRenameParams
+				if err = json.Unmarshal(ctx.Params, &params); err == nil {
+					validParams = true
+					r, err = root.documentPrepareRename(ctx, &params)
+				}
+			}
+			return
+		},
+	)
+}

lsp_3_17/handler_language_features_test.go

@@ -2547,3 +2547,62 @@ func (s *HandlerTestSuite) Test_calls_document_rename_request_handler() {
 	s.Require().NoError(err)
 	s.Require().Equal(workspaceEdit, returnedWorkspaceEdit)
 }
+
+func (s *HandlerTestSuite) Test_calls_document_prepare_rename_request_handler() {
+	logger, err := zap.NewDevelopment()
+	s.Require().NoError(err)
+
+	ctx, cancel := context.WithTimeout(context.Background(), server.DefaultTimeout)
+	defer cancel()
+
+	rangeWithPlaceholder := RangeWithPlaceholder{
+		Range: Range{
+			Start: Position{
+				Line:      300,
+				Character: 24,
+			},
+			End: Position{
+				Line:      300,
+				Character: 115,
+			},
+		},
+		Placeholder: "user.go",
+	}
+	serverHandler := NewHandler(
+		WithDocumentPrepareRenameHandler(
+			func(ctx *common.LSPContext, params *PrepareRenameParams) (any, error) {
+				return rangeWithPlaceholder, nil
+			},
+		),
+	)
+	// Emulate the LSP initialisation process.
+	serverHandler.SetInitialized(true)
+	srv := server.NewServer(serverHandler, true, nil, nil)
+
+	container := createTestConnectionsContainer(srv.NewHandler())
+
+	go srv.Serve(container.serverConn, logger)
+
+	clientLSPContext := server.NewLSPContext(ctx, container.clientConn, nil)
+
+	prepareRenameParams := &PrepareRenameParams{
+		TextDocumentPositionParams: TextDocumentPositionParams{
+			TextDocument: TextDocumentIdentifier{
+				URI: "file:///test_doc_prepare_rename.go",
+			},
+			Position: Position{
+				Line:      320,
+				Character: 24,
+			},
+		},
+	}
+
+	returnedRangeWithPlaceholder := RangeWithPlaceholder{}
+	err = clientLSPContext.Call(
+		MethodDocumentPrepareRename,
+		prepareRenameParams,
+		&returnedRangeWithPlaceholder,
+	)
+	s.Require().NoError(err)
+	s.Require().Equal(rangeWithPlaceholder, returnedRangeWithPlaceholder)
+}

lsp_3_17/language_features.go

@@ -2946,3 +2946,36 @@ type RenameParams struct {
 	// appropriate message set.
 	NewName string `json:"newName"`
 }
+
+// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareRename
+
+const MethodDocumentPrepareRename = Method("textDocument/prepareRename")
+
+// DocumentPrepareRenameHandlerFunc is the function signature for the textDocument/prepareRename
+// request handler that can be registered for a language server.
+//
+// Returns: Range | RangeWithPlaceholder | PrepareRenameDefaultBehavior | nil
+type DocumentPrepareRenameHandlerFunc func(
+	ctx *common.LSPContext,
+	params *PrepareRenameParams,
+) (any, error)
+
+// PrepareRenameParams contains parameters for the textDocument/prepareRename requests.
+type PrepareRenameParams struct {
+	TextDocumentPositionParams
+	WorkDoneProgressParams
+}
+
+// RangeWithPlaceholder is a range with a placeholder
+// which can be returned in the response for a textDocument/prepareRename
+// request.
+type RangeWithPlaceholder struct {
+	Range       Range  `json:"range"`
+	Placeholder string `json:"placeholder"`
+}
+
+// PrepareRenameDefaultBehavior is a default behavior which can be returned in the response
+// for a textDocument/prepareRename request.
+type PrepareRenameDefaultBehavior struct {
+	DefaultBehavior bool `json:"defaultBehavior"`
+}