From 396387cead17de963197f0f5af5a0d89860ec6f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Saulius=20Menkevi=C4=8Dius?=
 <sauliusmenkevicius@fastmail.com>
Date: Thu, 19 May 2022 22:39:09 +0300
Subject: [PATCH] Fix another long-standing incremental document
 synchronisation bug

Most apparent on nvim for some reason.
---
 CHANGELOG.md                              |  5 ++++-
 src/CSharpLanguageServer/RoslynHelpers.fs | 24 +++++++++++++----------
 src/CSharpLanguageServer/Server.fs        |  2 +-
 3 files changed, 19 insertions(+), 12 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5cb3d1fe..a977c1f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,9 @@
 # Changelog
 
-## (unreleased)
+## 0.5.1 - 2022-05-19 / Straigiškė 
+- Fix another long-standing bug with incremental document synchronisation;
+  - very visible on nvim but affects all editors/clients;
+  - reported by @Decodetalkers https://github.com/razzmatazz/csharp-language-server/issues/31;
 - Improve textDocument/completion:
   - provide `CompletionItem.FilterText` and `CompletionItem.SortText`;
 
diff --git a/src/CSharpLanguageServer/RoslynHelpers.fs b/src/CSharpLanguageServer/RoslynHelpers.fs
index 0ad8d36c..89261d6b 100644
--- a/src/CSharpLanguageServer/RoslynHelpers.fs
+++ b/src/CSharpLanguageServer/RoslynHelpers.fs
@@ -70,18 +70,22 @@ let lspLocationForRoslynLocation(loc: Microsoft.CodeAnalysis.Location): Types.Lo
         { Uri = "";
           Range = { Start = { Line=0; Character=0; }; End = { Line=0; Character=0; } } }
 
-let lspContentChangeEventToRoslynTextChange (sourceText: SourceText) (change: Types.TextDocumentContentChangeEvent) =
-    let changeTextSpan =
-        change.Range.Value
-        |> roslynLinePositionSpanForLspRange
-        |> sourceText.Lines.GetTextSpan
+let applyLspContentChangesOnRoslynSourceText
+        (changes: Types.TextDocumentContentChangeEvent[])
+        (initialSourceText: SourceText) =
 
-    TextChange(changeTextSpan, change.Text)
+    let applyLspContentChangeOnRoslynSourceText (sourceText: SourceText) (change: Types.TextDocumentContentChangeEvent) =
+        match change.Range with
+        | Some changeRange ->
+            let changeTextSpan =
+                changeRange |> roslynLinePositionSpanForLspRange
+                            |> sourceText.Lines.GetTextSpan
 
-let applyLspContentChangesOnRoslynSourceText (changes: Types.TextDocumentContentChangeEvent[]) (sourceText: SourceText) =
-    changes
-    |> Seq.map (lspContentChangeEventToRoslynTextChange sourceText)
-    |> sourceText.WithChanges
+            TextChange(changeTextSpan, change.Text) |> sourceText.WithChanges
+
+        | None -> SourceText.From(change.Text)
+
+    changes |> Seq.fold applyLspContentChangeOnRoslynSourceText initialSourceText
 
 let lspDocChangesFromSolutionDiff
         originalSolution
diff --git a/src/CSharpLanguageServer/Server.fs b/src/CSharpLanguageServer/Server.fs
index 7f139694..8e1aa4f6 100644
--- a/src/CSharpLanguageServer/Server.fs
+++ b/src/CSharpLanguageServer/Server.fs
@@ -630,7 +630,7 @@ let setupServerHandlers options lspClient =
                                  }
                         TextDocumentSync =
                             Some { TextDocumentSyncOptions.Default with
-                                     OpenClose = None
+                                     OpenClose = Some true
                                      Save = Some { IncludeText = Some true }
                                      Change = Some TextDocumentSyncKind.Incremental
                                  }