internal/lsp: fix typo on 'textDocument/foldingRange' method

LSP specification define 'foldingRange', not 'foldingRanges'.
Just trims end of 's' and rename interface method name.

ref: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/specification.md#folding-range-request-leftwards_arrow_with_hook

Change-Id: Ie2a91f6c0bdd99b8ae9000ba87c24118b264b934
Reviewed-on: https://go-review.googlesource.com/c/tools/+/173079
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

internal/lsp/protocol/server.go

@@ -49,7 +49,7 @@ type Server interface {
 	RangeFormatting(context.Context, *DocumentRangeFormattingParams) ([]TextEdit, error)
 	OnTypeFormatting(context.Context, *DocumentOnTypeFormattingParams) ([]TextEdit, error)
 	Rename(context.Context, *RenameParams) ([]WorkspaceEdit, error)
-	FoldingRanges(context.Context, *FoldingRangeParams) ([]FoldingRange, error)
+	FoldingRange(context.Context, *FoldingRangeParams) ([]FoldingRange, error)
 }
 
 func serverHandler(log xlog.Logger, server Server) jsonrpc2.Handler {
@@ -454,7 +454,7 @@ func serverHandler(log xlog.Logger, server Server) jsonrpc2.Handler {
 				sendParseError(ctx, log, conn, r, err)
 				return
 			}
-			resp, err := server.FoldingRanges(ctx, &params)
+			resp, err := server.FoldingRange(ctx, &params)
 			if err := conn.Reply(ctx, r, resp, err); err != nil {
 				log.Errorf(ctx, "%v", err)
 			}
@@ -714,9 +714,9 @@ func (s *serverDispatcher) Rename(ctx context.Context, params *RenameParams) ([]
 	return result, nil
 }
 
-func (s *serverDispatcher) FoldingRanges(ctx context.Context, params *FoldingRangeParams) ([]FoldingRange, error) {
+func (s *serverDispatcher) FoldingRange(ctx context.Context, params *FoldingRangeParams) ([]FoldingRange, error) {
 	var result []FoldingRange
-	if err := s.Conn.Call(ctx, "textDocument/foldingRanges", params, &result); err != nil {
+	if err := s.Conn.Call(ctx, "textDocument/foldingRange", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil

internal/lsp/server.go

@@ -242,8 +242,8 @@ func (s *Server) Rename(context.Context, *protocol.RenameParams) ([]protocol.Wor
 	return nil, notImplemented("Rename")
 }
 
-func (s *Server) FoldingRanges(context.Context, *protocol.FoldingRangeParams) ([]protocol.FoldingRange, error) {
-	return nil, notImplemented("FoldingRanges")
+func (s *Server) FoldingRange(context.Context, *protocol.FoldingRangeParams) ([]protocol.FoldingRange, error) {
+	return nil, notImplemented("FoldingRange")
 }
 
 func notImplemented(method string) *jsonrpc2.Error {