diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9619f371..49b0012e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.22)
 project(clice)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 23)
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS_RELEASE} -g -O0 -fno-rtti ")
 
diff --git a/include/LSP/Protocol.h b/include/LSP/Protocol.h
index ad4d32ba..919b79ec 100644
--- a/include/LSP/Protocol.h
+++ b/include/LSP/Protocol.h
@@ -5,6 +5,8 @@
 #include <optional>
 #include <string_view>
 
+#include "SemanticTokens.h"
+
 namespace clice {
 
 // Defined by JSON RPC.
@@ -473,6 +475,22 @@ struct DocumentOnTypeFormattingOptions {
     /// moreTriggerCharacter?: string[];
 };
 
+struct SemanticTokensOptions {
+    /// The legend used by the server
+    SemanticTokensLegend legend;
+
+    /// Server supports providing semantic tokens for a specific range of a document.
+    bool range = false;  // TODO: further check
+
+    struct Full {
+        /// Server supports providing semantic tokens for a full document.
+        bool delta = true;
+    };
+
+    /// Server supports providing semantic tokens for a full document.
+    Full full;
+};
+
 struct ServerCapabilities {
     /// The position encoding the server picked from the encodings offered
     /// by the client via the client capability `general.positionEncodings`.
@@ -567,7 +585,7 @@ struct ServerCapabilities {
     bool callHierarchyProvider = true;
 
     /// The server provides semantic tokens support.
-    // TODO: semanticTokensProvider?: SemanticTokensOptions
+    SemanticTokensOptions semanticTokensProvider;
 
     /// Whether server provides moniker support.
     bool monikerProvider = false;  // TODO: further discussion
@@ -607,4 +625,85 @@ struct InitializeResult {
     ServerInfo serverInfo;
 };
 
+/*===================================================/
+/                                                    /
+/=======   Text Document Synchronization   ==========/
+/                                                    /
+/===================================================*/
+
+/// An item to transfer a text document from the client to the server.
+struct TextDocumentItem {
+    /// The text document's URI.
+    std::string_view uri;
+
+    /// The text document's language identifier.
+    std::string_view languageId;
+
+    /// he version number of this document (it will increase after each change, including undo/redo).
+    int version;
+
+    /// The content of the opened text document.
+    std::string_view text;
+};
+
+/// Text documents are identified using a URI. On the protocol level, URIs are passed as strings.
+struct TextDocumentIdentifier {
+    /// The text document's URI.
+    std::string_view uri;
+};
+
+struct VersionedTextDocumentIdentifier {
+    /// The text document's URI.
+    std::string_view uri;
+
+    /// The version number of this document.
+    ///
+    /// The version number of a document will increase after each change,
+    /// including undo/redo. The number doesn't need to be consecutive.
+    int version;
+};
+
+struct DidOpenTextDocumentParams {
+    /// The document that was opened.
+    TextDocumentItem textDocument;
+};
+
+struct TextDocumentContentChangeEvent {
+    // TODO:
+};
+
+struct DidChangeTextDocumentParams {
+    /// The document that did change. The version number points
+    /// to the version after all provided content changes have
+    /// been applied.
+    VersionedTextDocumentIdentifier textDocument;
+
+    /// The actual content changes. The content changes describe single state
+    /// changes to the document. So if there are two content changes c1 (at
+    /// array index 0) and c2 (at array index 1) for a document in state S then
+    /// c1 moves the document from S to S' and c2 from S' to S''. So c1 is
+    /// computed on the state S and c2 is computed on the state S'.
+    ///
+    /// To mirror the content of a document using change events use the following
+    /// approach:
+    /// - start with the same initial content
+    /// - apply the 'textDocument/didChange' notifications in the order you receive them.
+    /// - apply the `TextDocumentContentChangeEvent`s in a single notification in the order you receive them.
+    std::vector<TextDocumentContentChangeEvent> contentChanges;
+};
+
+struct DidCloseTextDocumentParams {
+    /// The document that was closed.
+    TextDocumentIdentifier textDocument;
+};
+
+struct DidSaveTextDocumentParams {
+    /// The document that was saved.
+    TextDocumentIdentifier textDocument;
+
+    /// Optional the content when saved. Depends on the includeText value
+    /// when the save notification was requested.
+    std::optional<std::string_view> text;
+};
+
 }  // namespace clice
diff --git a/include/LSP/SemanticTokens.h b/include/LSP/SemanticTokens.h
index abf15194..6ed1c86f 100644
--- a/include/LSP/SemanticTokens.h
+++ b/include/LSP/SemanticTokens.h
@@ -45,4 +45,9 @@ enum SemanticTokenModifiers {
     DefaultLibrary
 };
 
+struct SemanticTokensLegend {
+    std::vector<std::string> tokenTypes;
+    std::vector<std::string> tokenModifiers;
+};
+
 }  // namespace clice
diff --git a/include/LSP/Server.h b/include/LSP/Server.h
index 4dae3107..7e206871 100644
--- a/include/LSP/Server.h
+++ b/include/LSP/Server.h
@@ -25,9 +25,13 @@ public:
     /===================================================*/
 
     // Server lifecycle
-    void initialize(InitializeParams& params);
+    void initialize(const InitializeParams& params);
 
     // Text Document Synchronization
+    void didOpen(this Server& self, const DidOpenTextDocumentParams& params);
+    void didChange(this Server& self, const DidChangeTextDocumentParams& params);
+    void didClose(this Server& self, const DidCloseTextDocumentParams& params);
+    void didSave(this Server& self, const DidSaveTextDocumentParams& params);
 
     // Language Features
     void declaration();
diff --git a/include/LSP/Uri.h b/include/LSP/Uri.h
new file mode 100644
index 00000000..e69de29b
diff --git a/src/LSP/Server.cpp b/src/LSP/Server.cpp
index 21e09a91..c89f6a94 100644
--- a/src/LSP/Server.cpp
+++ b/src/LSP/Server.cpp
@@ -36,6 +36,10 @@ void Server::handle_message(std::string_view message) {
                 {"result", clice::serialize(InitializeResult{})}
             };
             transport->send(json.dump());
+        } else if(method == "textDocument/didOpen") {
+            // didOpen();
+            auto params = deserialize<DidOpenTextDocumentParams>(input["params"]);
+            logger::info("serialize successfully: {}", serialize(params).dump());
         }
     } catch(std::exception& e) {
         logger::error("failed to parse JSON: {}", e.what());