LanguageServers/Cpp: Add 'FindDeclaration' capability

The C++ LanguageServer can now find the matching declaration for
variable names, function calls, struct/class types and properties.

When clicking on one of the above with Ctrl pressed, HackStudio will
ask the language server to find a matching declaration, and navigate
to the result in the Editor. :^)

Userland/DevTools/HackStudio/LanguageServers/Cpp/AutoCompleteEngine.h

@@ -41,6 +41,13 @@ public:
     virtual void on_edit([[maybe_unused]] const String& file) {};
     virtual void file_opened([[maybe_unused]] const String& file) {};
 
+    struct ProjectPosition {
+        String file;
+        size_t line;
+        size_t column;
+    };
+    virtual Optional<ProjectPosition> find_declaration_of(const String&, const GUI::TextPosition&) { return {}; };
+
 protected:
     const FileDB& filedb() const { return m_filedb; }
 

Userland/DevTools/HackStudio/LanguageServers/Cpp/ClientConnection.cpp

@@ -128,7 +128,7 @@ void ClientConnection::handle(const Messages::LanguageServer::SetFileContent& me
 
 void ClientConnection::handle(const Messages::LanguageServer::SetAutoCompleteMode& message)
 {
-#ifdef DEBUG_CPP_LANGUAGE_SERVER
+#ifdef CPP_LANGUAGE_SERVER_DEBUG
     dbgln("SetAutoCompleteMode: {}", message.mode());
 #endif
     if (message.mode() == "Parser")
@@ -137,4 +137,23 @@ void ClientConnection::handle(const Messages::LanguageServer::SetAutoCompleteMod
         m_autocomplete_engine = make<LexerAutoComplete>(m_filedb);
 }
 
+void ClientConnection::handle(const Messages::LanguageServer::FindDeclaration& message)
+{
+    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "FindDeclaration: {} {}:{}", message.file_name(), message.line(), message.column());
+    auto document = m_filedb.get(message.file_name());
+    if (!document) {
+        dbgln("file {} has not been opened", message.file_name());
+        return;
+    }
+
+    GUI::TextPosition identifier_position = { (size_t)message.line(), (size_t)message.column() };
+    auto location = m_autocomplete_engine->find_declaration_of(message.file_name(), identifier_position);
+    if (!location.has_value()) {
+        dbgln("could not find declaration");
+        return;
+    }
+    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "declaration location: {} {}:{}", location.value().file, location.value().line, location.value().column);
+    post_message(Messages::LanguageClient::DeclarationLocation(location.value().file, location.value().line, location.value().column));
+}
+
 }

Userland/DevTools/HackStudio/LanguageServers/Cpp/ClientConnection.h

@@ -57,6 +57,7 @@ private:
     virtual void handle(const Messages::LanguageServer::SetFileContent&) override;
     virtual void handle(const Messages::LanguageServer::AutoCompleteSuggestions&) override;
     virtual void handle(const Messages::LanguageServer::SetAutoCompleteMode&) override;
+    virtual void handle(const Messages::LanguageServer::FindDeclaration&) override;
 
     FileDB m_filedb;
     OwnPtr<AutoCompleteEngine> m_autocomplete_engine;

Userland/DevTools/HackStudio/LanguageServers/Cpp/ParserAutoComplete.cpp

@@ -33,16 +33,6 @@
 #include <LibCpp/Preprocessor.h>
 #include <LibRegex/Regex.h>
 
-// #define AUTOCOMPLETE_VERBOSE
-
-#ifdef AUTOCOMPLETE_VERBOSE
-#    define VERBOSE(fmt, ...) dbgln(fmt, ##__VA_ARGS__)
-#else
-#    define VERBOSE(fmt, ...) \
-        do {                  \
-        } while (0)
-#endif
-
 namespace LanguageServers::Cpp {
 
 ParserAutoComplete::ParserAutoComplete(const FileDB& filedb)
@@ -77,7 +67,7 @@ OwnPtr<ParserAutoComplete::DocumentData> ParserAutoComplete::create_document_dat
     for (auto& path : document_data->preprocessor.included_paths()) {
         get_or_create_document_data(document_path_from_include_path(path));
     }
-#ifdef DEBUG_AUTOCOMPLETE
+#ifdef CPP_LANGUAGE_SERVER_DEBUG
     root->dump(0);
 #endif
     return move(document_data);
@@ -99,12 +89,12 @@ Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::get_suggestions(con
 {
     Cpp::Position position { autocomplete_position.line(), autocomplete_position.column() > 0 ? autocomplete_position.column() - 1 : 0 };
 
-    VERBOSE("ParserAutoComplete position {}:{}", position.line, position.column);
+    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "ParserAutoComplete position {}:{}", position.line, position.column);
 
     const auto& document = get_or_create_document_data(file);
     auto node = document.parser.node_at(position);
     if (!node) {
-        VERBOSE("no node at position {}:{}", position.line, position.column);
+        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "no node at position {}:{}", position.line, position.column);
         return {};
     }
 
@@ -130,17 +120,22 @@ Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::get_suggestions(con
     return autocomplete_name(document, *node, partial_text.view());
 }
 
-Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::autocomplete_name(const DocumentData& document, const ASTNode& node, const StringView& partial_text) const
+NonnullRefPtrVector<Declaration> ParserAutoComplete::get_available_declarations(const DocumentData& document, const ASTNode& node) const
 {
     const Cpp::ASTNode* current = &node;
-    NonnullRefPtrVector<Cpp::Declaration> available_declarations;
+    NonnullRefPtrVector<Declaration> available_declarations;
     while (current) {
         available_declarations.append(current->declarations());
         current = current->parent();
     }
 
     available_declarations.append(get_declarations_in_outer_scope_including_headers(document));
+    return available_declarations;
+}
 
+Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::autocomplete_name(const DocumentData& document, const ASTNode& node, const StringView& partial_text) const
+{
+    auto available_declarations = get_available_declarations(document, node);
     Vector<StringView> available_names;
     auto add_name = [&available_names](auto& name) {
         if (name.is_null() || name.is_empty())
@@ -173,7 +168,7 @@ Vector<GUI::AutocompleteProvider::Entry> ParserAutoComplete::autocomplete_proper
 {
     auto type = type_of(document, *parent.m_object);
     if (type.is_null()) {
-        VERBOSE("Could not infer type of object");
+        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "Could not infer type of object");
         return {};
     }
 
@@ -321,4 +316,47 @@ void ParserAutoComplete::file_opened([[maybe_unused]] const String& file)
     set_document_data(file, create_document_data_for(file));
 }
 
+Optional<AutoCompleteEngine::ProjectPosition> ParserAutoComplete::find_declaration_of(const String& file_name, const GUI::TextPosition& identifier_position)
+{
+    const auto& document = get_or_create_document_data(file_name);
+    auto node = document.parser.node_at(Cpp::Position { identifier_position.line(), identifier_position.column() });
+    if (!node) {
+        dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "no node at position {}:{}", identifier_position.line(), identifier_position.column());
+        return {};
+    }
+    auto decl = find_declaration_of(document, *node);
+    if (!decl)
+        return {};
+
+    return ProjectPosition { decl->filename(), decl->start().line, decl->start().column };
+}
+
+RefPtr<Declaration> ParserAutoComplete::find_declaration_of(const DocumentData& document_data, const ASTNode& node) const
+{
+    dbgln_if(CPP_LANGUAGE_SERVER_DEBUG, "find_declaration_of: {}", document_data.parser.text_of_node(node));
+    auto declarations = get_available_declarations(document_data, node);
+    for (auto& decl : declarations) {
+        if (node.is_identifier() && decl.is_variable_or_parameter_declaration()) {
+            if (((Cpp::VariableOrParameterDeclaration&)decl).m_name == static_cast<const Identifier&>(node).m_name)
+                return decl;
+        }
+        if (node.is_type() && decl.is_struct_or_class()) {
+            if (((Cpp::StructOrClassDeclaration&)decl).m_name == static_cast<const Type&>(node).m_name)
+                return decl;
+        }
+        if (node.is_function_call() && decl.is_function()) {
+            if (((Cpp::FunctionDeclaration&)decl).m_name == static_cast<const FunctionCall&>(node).m_name)
+                return decl;
+        }
+        if (is_property(node) && decl.is_struct_or_class()) {
+            for (auto& member : ((Cpp::StructOrClassDeclaration&)decl).m_members) {
+                ASSERT(node.is_identifier());
+                if (member.m_name == ((const Identifier&)node).m_name)
+                    return member;
+            }
+        }
+    }
+    return {};
+}
+
 }

Userland/DevTools/HackStudio/LanguageServers/Cpp/ParserAutoComplete.h

@@ -47,10 +47,11 @@ public:
     virtual Vector<GUI::AutocompleteProvider::Entry> get_suggestions(const String& file, const GUI::TextPosition& autocomplete_position) override;
     virtual void on_edit(const String& file) override;
     virtual void file_opened([[maybe_unused]] const String& file) override;
+    virtual Optional<ProjectPosition> find_declaration_of(const String& file_name, const GUI::TextPosition& identifier_position) override;
 
 private:
     struct DocumentData {
-        DocumentData(String&& text);
+        DocumentData(String&& text, const String& filename);
         String text;
         Preprocessor preprocessor;
         Parser parser;
@@ -63,6 +64,8 @@ private:
     String type_of_variable(const Identifier&) const;
     bool is_property(const ASTNode&) const;
     bool is_empty_property(const DocumentData&, const ASTNode&, const Position& autocomplete_position) const;
+    RefPtr<Declaration> find_declaration_of(const DocumentData&, const ASTNode&) const;
+    NonnullRefPtrVector<Declaration> get_available_declarations(const DocumentData&, const ASTNode&) const;
 
     struct PropertyInfo {
         StringView name;

Userland/DevTools/HackStudio/LanguageServers/LanguageClient.ipc

@@ -1,4 +1,5 @@
 endpoint LanguageClient = 8002
 {
     AutoCompleteSuggestions(Vector<GUI::AutocompleteProvider::Entry> suggestions) =|
+    DeclarationLocation(String file_name, i32 line, i32 column) =|
 }

Userland/DevTools/HackStudio/LanguageServers/LanguageServer.ipc

@@ -9,4 +9,6 @@ endpoint LanguageServer = 8001
 
     AutoCompleteSuggestions(String file_name, i32 cursor_line, i32 cursor_column) =|
     SetAutoCompleteMode(String mode) =|
+    FindDeclaration(String file_name, i32 line, i32 column) =|
+
 }

Userland/DevTools/HackStudio/LanguageServers/Shell/ClientConnection.h

@@ -57,6 +57,7 @@ private:
     virtual void handle(const Messages::LanguageServer::SetFileContent&) override;
     virtual void handle(const Messages::LanguageServer::AutoCompleteSuggestions&) override;
     virtual void handle(const Messages::LanguageServer::SetAutoCompleteMode&) override { }
+    virtual void handle(const Messages::LanguageServer::FindDeclaration&) override {};
 
     RefPtr<GUI::TextDocument> document_for(const String& file_name);