LanguageClient: send partial document in update notification

Reduce the amount of transferred data between client and server by
sending events which just contain the changed part of the document
instead of the full content if the server supports those events.

Change-Id: I596930c405bd7a71e4219e328b449fca67664750
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/languageserverprotocol/textsynchronization.h

@@ -83,7 +83,7 @@ public:
     void setTextDocument(const VersionedTextDocumentIdentifier &textDocument)
     { insert(textDocumentKey, textDocument); }
 
-    class TextDocumentContentChangeEvent : public JsonObject
+    class LANGUAGESERVERPROTOCOL_EXPORT TextDocumentContentChangeEvent : public JsonObject
     {
         /*
          * An event describing a change to a text document. If range and rangeLength are omitted

src/plugins/languageclient/client.cpp

@@ -131,7 +131,7 @@ Client::~Client()
     }
     for (const DocumentUri &uri : m_diagnostics.keys())
         removeDiagnostics(uri);
-    updateEditorToolBar(m_openedDocument);
+    updateEditorToolBar(m_openedDocument.keys());
 }
 
 static ClientCapabilities generateClientCapabilities()
@@ -287,11 +287,13 @@ bool Client::openDocument(Core::IDocument *document)
     item.setText(QString::fromUtf8(document->contents()));
     item.setVersion(textDocument ? textDocument->document()->revision() : 0);
 
-    connect(document, &Core::IDocument::contentsChanged, this,
-            [this, document](){
-        documentContentsChanged(document);
-    });
     if (textDocument) {
+        connect(textDocument,
+                &TextEditor::TextDocument::contentsChangedWithPosition,
+                this,
+                [this, textDocument](int position, int charsRemoved, int charsAdded) {
+                    documentContentsChanged(textDocument, position, charsRemoved, charsAdded);
+                });
         textDocument->completionAssistProvider();
         m_resetAssistProvider << textDocument;
         m_completionProvider.setTriggerCharacters(
@@ -304,9 +306,11 @@ bool Client::openDocument(Core::IDocument *document)
         connect(textDocument, &QObject::destroyed, this, [this, textDocument]{
             m_resetAssistProvider.remove(textDocument);
         });
+        m_openedDocument.insert(document->filePath(), textDocument->plainText());
+    } else {
+        m_openedDocument.insert(document->filePath(), QString());
     }
 
-    m_openedDocument.append(document->filePath());
     sendContent(DidOpenTextDocumentNotification(DidOpenTextDocumentParams(item)));
     if (textDocument)
         requestDocumentSymbols(textDocument);
@@ -410,7 +414,10 @@ void Client::documentWillSave(Core::IDocument *document)
     sendContent(WillSaveTextDocumentNotification(params));
 }
 
-void Client::documentContentsChanged(Core::IDocument *document)
+void Client::documentContentsChanged(TextEditor::TextDocument *document,
+                                     int position,
+                                     int charsRemoved,
+                                     int charsAdded)
 {
     if (!m_openedDocument.contains(document->filePath()))
         return;
@@ -430,7 +437,21 @@ void Client::documentContentsChanged(Core::IDocument *document)
         const auto uri = DocumentUri::fromFileName(document->filePath());
         VersionedTextDocumentIdentifier docId(uri);
         docId.setVersion(textDocument ? textDocument->document()->revision() : 0);
-        const DidChangeTextDocumentParams params(docId, QString::fromUtf8(document->contents()));
+        DidChangeTextDocumentParams params;
+        params.setTextDocument(docId);
+        if (syncKind == TextDocumentSyncKind::Incremental) {
+            DidChangeTextDocumentParams::TextDocumentContentChangeEvent change;
+            QTextDocument oldDoc(m_openedDocument[document->filePath()]);
+            QTextCursor cursor(&oldDoc);
+            cursor.setPosition(position + charsRemoved);
+            cursor.setPosition(position, QTextCursor::KeepAnchor);
+            change.setRange(Range(cursor));
+            change.setText(document->textAt(position, charsAdded));
+            params.setContentChanges({change});
+        } else {
+            params.setContentChanges({document->plainText()});
+        }
+        m_openedDocument[document->filePath()] = document->plainText();
         sendContent(DidChangeTextDocumentNotification(params));
     }
 
@@ -830,7 +851,7 @@ bool Client::reset()
     m_state = Uninitialized;
     m_responseHandlers.clear();
     m_clientInterface->resetBuffer();
-    updateEditorToolBar(m_openedDocument);
+    updateEditorToolBar(m_openedDocument.keys());
     m_openedDocument.clear();
     m_serverCapabilities = ServerCapabilities();
     m_dynamicCapabilities.reset();

src/plugins/languageclient/client.h

@@ -96,7 +96,10 @@ public:
     bool documentOpen(const Core::IDocument *document) const;
     void documentContentsSaved(Core::IDocument *document);
     void documentWillSave(Core::IDocument *document);
-    void documentContentsChanged(Core::IDocument *document);
+    void documentContentsChanged(TextEditor::TextDocument *document,
+                                 int position,
+                                 int charsRemoved,
+                                 int charsAdded);
     void registerCapabilities(const QList<LanguageServerProtocol::Registration> &registrations);
     void unregisterCapabilities(const QList<LanguageServerProtocol::Unregistration> &unregistrations);
     bool findLinkAt(LanguageServerProtocol::GotoDefinitionRequest &request);
@@ -190,7 +193,7 @@ private:
     QHash<QByteArray, ContentHandler> m_contentHandler;
     QString m_displayName;
     LanguageFilter m_languagFilter;
-    QList<Utils::FileName> m_openedDocument;
+    QMap<Utils::FileName, QString> m_openedDocument;
     Core::Id m_id;
     LanguageServerProtocol::ServerCapabilities m_serverCapabilities;
     DynamicCapabilities m_dynamicCapabilities;