From ac1696789ee11b6bcad6ee4b561d323885a4971a Mon Sep 17 00:00:00 2001
From: Rebecca Stambler <rstambler@golang.org>
Date: Mon, 4 Mar 2019 17:50:16 -0500
Subject: [PATCH] internal/lsp: temporarily disable incremental changes

It is difficult to debug gopls in combination with the incremental
changes feature. Because gopls is slow (caching CL is in progress), it
seems like the incremental changes can sometimes produce strange
behavior. Disable it for now until we can prioritize work on it.

Change-Id: I931aa39756f198d1af21dca359acc83ca3392c4c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/165023
Reviewed-by: Michael Matloob <matloob@golang.org>
---
 internal/lsp/server.go | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/internal/lsp/server.go b/internal/lsp/server.go
index 121b7216..93b99729 100644
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@@ -69,6 +69,8 @@ type server struct {
 	signatureHelpEnabled bool
 	snippetsSupported    bool
 
+	textDocumentSyncKind protocol.TextDocumentSyncKind
+
 	viewMu sync.Mutex
 	view   source.View
 }
@@ -98,6 +100,10 @@ func (s *server) Initialize(ctx context.Context, params *protocol.InitializePara
 		return nil, err
 	}
 
+	// TODO(rstambler): Change this default to protocol.Incremental (or add a
+	// flag). Disabled for now to simplify debugging.
+	s.textDocumentSyncKind = protocol.Full
+
 	s.view = cache.NewView(&packages.Config{
 		Context: ctx,
 		Dir:     rootPath,
@@ -124,7 +130,7 @@ func (s *server) Initialize(ctx context.Context, params *protocol.InitializePara
 				TriggerCharacters: []string{"(", ","},
 			},
 			TextDocumentSync: protocol.TextDocumentSyncOptions{
-				Change:    float64(protocol.Incremental),
+				Change:    float64(s.textDocumentSyncKind),
 				OpenClose: true,
 			},
 			TypeDefinitionProvider: true,
@@ -186,6 +192,7 @@ func bytesOffset(content []byte, pos protocol.Position) int {
 		if line == int(pos.Line) && char == int(pos.Character) {
 			return offset
 		}
+
 		r, size := utf8.DecodeRune(content)
 		char++
 		// The offsets are based on a UTF-16 string representation.
@@ -250,9 +257,21 @@ func (s *server) DidChange(ctx context.Context, params *protocol.DidChangeTextDo
 		return jsonrpc2.NewErrorf(jsonrpc2.CodeInternalError, "no content changes provided")
 	}
 
-	text, err := s.applyChanges(ctx, params)
-	if err != nil {
-		return err
+	var text string
+	switch s.textDocumentSyncKind {
+	case protocol.Incremental:
+		var err error
+		text, err = s.applyChanges(ctx, params)
+		if err != nil {
+			return err
+		}
+	case protocol.Full:
+		// We expect the full content of file, i.e. a single change with no range.
+		change := params.ContentChanges[0]
+		if change.RangeLength != 0 {
+			return jsonrpc2.NewErrorf(jsonrpc2.CodeInternalError, "unexpected change range provided")
+		}
+		text = change.Text
 	}
 	s.cacheAndDiagnose(ctx, params.TextDocument.URI, text)
 	return nil