--- /dev/null
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package lsp
+
+import (
+ "context"
+
+ "golang.org/x/tools/internal/event"
+ "golang.org/x/tools/internal/lsp/debug/tag"
+ "golang.org/x/tools/internal/lsp/protocol"
+ "golang.org/x/tools/internal/lsp/source"
+)
+
+func (s *Server) signatureHelp(ctx context.Context, params *protocol.SignatureHelpParams) (*protocol.SignatureHelp, error) {
+ snapshot, fh, ok, release, err := s.beginFileRequest(ctx, params.TextDocument.URI, source.Go)
+ defer release()
+ if !ok {
+ return nil, err
+ }
+ info, activeParameter, err := source.SignatureHelp(ctx, snapshot, fh, params.Position)
+ if err != nil {
+ event.Error(ctx, "no signature help", err, tag.Position.Of(params.Position))
+ return nil, nil
+ }
+ return &protocol.SignatureHelp{
+ Signatures: []protocol.SignatureInformation{*info},
+ ActiveParameter: float64(activeParameter),
+ }, nil
+}