Introduce Menu completion flags to auto select best candidate

src/command_manager.cc

@@ -726,7 +726,7 @@ Completions CommandManager::complete(const Context& context,
             context, flags, params, tokens.size() - 2,
             cursor_pos_in_token), start);
 
-        if (not completions.quoted and token.type == Token::Type::Raw)
+        if (not (completions.flags & Completions::Flags::Quoted) and token.type == Token::Type::Raw)
         {
             for (auto& c : completions.candidates)
                 c = (not c.empty() and contains("%'\"", c[0]) ? "\\" : "") + escape(c, "; \t", '\\');

src/commands.cc

@@ -102,12 +102,30 @@ make_completer(Completers&&... completers)
     return {std::forward<Completers>(completers)...};
 }
 
+template<typename Completer>
+auto add_flags(Completer&& completer, Completions::Flags completions_flags)
+{
+    return [=](const Context& context, CompletionFlags flags, const String& prefix, ByteCount cursor_pos) {
+        Completions res = completer(context, flags, prefix, cursor_pos);
+        res.flags |= completions_flags;
+        return res;
+    };
+}
+
+template<typename Completer>
+auto menu(Completer&& completer)
+{
+    return add_flags(std::forward<Completer>(completer), Completions::Flags::Menu);
+}
+
+template<bool menu>
 auto filename_completer = make_completer(
     [](const Context& context, CompletionFlags flags, const String& prefix, ByteCount cursor_pos)
     { return Completions{ 0_byte, cursor_pos,
                           complete_filename(prefix,
                                             context.options()["ignored_files"].get<Regex>(),
-                                            cursor_pos, FilenameFlags::Expand) }; });
+                                            cursor_pos, FilenameFlags::Expand),
+                                            menu ? Completions::Flags::Menu : Completions::Flags::None}; });
 
 template<bool ignore_current = false>
 static Completions complete_buffer_name(const Context& context, CompletionFlags flags,
@@ -165,9 +183,6 @@ auto make_single_word_completer(std::function<String (const Context&)> func)
             return { 0_byte, cursor_pos, complete(prefix, cursor_pos, candidate) }; });
 }
 
-auto buffer_completer = make_completer(complete_buffer_name<false>);
-auto other_buffer_completer = make_completer(complete_buffer_name<true>);
-
 const ParameterDesc no_params{ {}, ParameterDesc::Flags::None, 0, 0 };
 const ParameterDesc single_param{ {}, ParameterDesc::Flags::None, 1, 1 };
 const ParameterDesc single_optional_param{ {}, ParameterDesc::Flags::None, 0, 1 };
@@ -190,7 +205,9 @@ static Completions complete_command_name(const Context& context, CompletionFlags
 
 struct ShellScriptCompleter
 {
-    ShellScriptCompleter(String shell_script) : m_shell_script{std::move(shell_script)} {}
+    ShellScriptCompleter(String shell_script,
+                         Completions::Flags flags = Completions::Flags::None)
+      : m_shell_script{std::move(shell_script)}, m_flags(flags) {}
 
     Completions operator()(const Context& context, CompletionFlags flags,
                            CommandParameters params, size_t token_to_complete,
@@ -211,15 +228,18 @@ struct ShellScriptCompleter
         for (auto&& candidate : output | split<StringView>('\n'))
             candidates.push_back(candidate.str());
 
-        return {0_byte, pos_in_token, std::move(candidates)};
+        return {0_byte, pos_in_token, std::move(candidates), m_flags};
     }
 private:
     String m_shell_script;
+    Completions::Flags m_flags;
 };
 
 struct ShellCandidatesCompleter
 {
-    ShellCandidatesCompleter(String shell_script) : m_shell_script{std::move(shell_script)} {}
+    ShellCandidatesCompleter(String shell_script,
+                             Completions::Flags flags = Completions::Flags::None)
+      : m_shell_script{std::move(shell_script)}, m_flags(flags) {}
 
     Completions operator()(const Context& context, CompletionFlags flags,
                            CommandParameters params, size_t token_to_complete,
@@ -263,13 +283,14 @@ struct ShellCandidatesCompleter
             return true;
         });
 
-        return Completions{ 0_byte, pos_in_token, std::move(res) };
+        return Completions{0_byte, pos_in_token, std::move(res), m_flags};
     }
 
 private:
     String m_shell_script;
     Vector<std::pair<String, UsedLetters>, MemoryDomain::Completion> m_candidates;
     int m_token = -1;
+    Completions::Flags m_flags;
 };
 
 template<typename Completer>
@@ -421,7 +442,7 @@ const CommandDesc edit_cmd = {
     edit_params,
     CommandFlags::None,
     CommandHelper{},
-    filename_completer,
+    filename_completer<false>,
     edit<false>
 };
 
@@ -433,7 +454,7 @@ const CommandDesc force_edit_cmd = {
     edit_params,
     CommandFlags::None,
     CommandHelper{},
-    filename_completer,
+    filename_completer<false>,
     edit<true>
 };
 
@@ -480,7 +501,7 @@ const CommandDesc write_cmd = {
     write_params,
     CommandFlags::None,
     CommandHelper{},
-    filename_completer,
+    filename_completer<false>,
     write_buffer,
 };
 
@@ -492,7 +513,7 @@ const CommandDesc force_write_cmd = {
     write_params,
     CommandFlags::None,
     CommandHelper{},
-    filename_completer,
+    filename_completer<false>,
     write_buffer<true>,
 };
 
@@ -688,7 +709,7 @@ const CommandDesc buffer_cmd = {
     single_param,
     CommandFlags::None,
     CommandHelper{},
-    other_buffer_completer,
+    make_completer(menu(complete_buffer_name<true>)),
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         Buffer& buffer = BufferManager::instance().get_buffer(parser[0]);
@@ -775,7 +796,7 @@ const CommandDesc delete_buffer_cmd = {
     single_optional_param,
     CommandFlags::None,
     CommandHelper{},
-    buffer_completer,
+    make_completer(menu(complete_buffer_name<false>)),
     delete_buffer<false>
 };
 
@@ -787,7 +808,7 @@ const CommandDesc force_delete_buffer_cmd = {
     single_optional_param,
     CommandFlags::None,
     CommandHelper{},
-    buffer_completer,
+    make_completer(menu(complete_buffer_name<false>)),
     delete_buffer<true>
 };
 
@@ -1037,6 +1058,9 @@ void define_command(const ParametersParser& parser, Context& context, const Shel
     if (parser.get_switch("hidden"))
         flags = CommandFlags::Hidden;
 
+    const Completions::Flags completions_flags = parser.get_switch("menu") ?
+        Completions::Flags::Menu : Completions::Flags::None;
+
     const String& commands = parser[1];
     CommandFunc cmd;
     ParameterDesc desc;
@@ -1073,7 +1097,7 @@ void define_command(const ParametersParser& parser, Context& context, const Shel
     CommandCompleter completer;
     if (parser.get_switch("file-completion"))
     {
-        completer = [](const Context& context, CompletionFlags flags,
+        completer = [=](const Context& context, CompletionFlags flags,
                        CommandParameters params,
                        size_t token_to_complete, ByteCount pos_in_token)
         {
@@ -1081,37 +1105,40 @@ void define_command(const ParametersParser& parser, Context& context, const Shel
              auto& ignored_files = context.options()["ignored_files"].get<Regex>();
              return Completions{0_byte, pos_in_token,
                                 complete_filename(prefix, ignored_files,
-                                                   pos_in_token, FilenameFlags::Expand) };
+                                                  pos_in_token, FilenameFlags::Expand),
+                                completions_flags};
         };
     }
     else if (parser.get_switch("client-completion"))
     {
-        completer = [](const Context& context, CompletionFlags flags,
+        completer = [=](const Context& context, CompletionFlags flags,
                        CommandParameters params,
                        size_t token_to_complete, ByteCount pos_in_token)
         {
              const String& prefix = params[token_to_complete];
              auto& cm = ClientManager::instance();
              return Completions{0_byte, pos_in_token,
-                                 cm.complete_client_name(prefix, pos_in_token) };
+                                cm.complete_client_name(prefix, pos_in_token),
+                                completions_flags};
         };
     }
     else if (parser.get_switch("buffer-completion"))
     {
-        completer = [](const Context& context, CompletionFlags flags,
+        completer = [=](const Context& context, CompletionFlags flags,
                        CommandParameters params,
                        size_t token_to_complete, ByteCount pos_in_token)
         {
-             return complete_buffer_name(context, flags, params[token_to_complete], pos_in_token);
+             return add_flags(complete_buffer_name, completions_flags)(
+                 context, flags, params[token_to_complete], pos_in_token);
         };
     }
     else if (auto shell_script = parser.get_switch("shell-script-completion"))
     {
-        completer = ShellScriptCompleter{shell_script->str()};
+        completer = ShellScriptCompleter{shell_script->str(), completions_flags};
     }
     else if (auto shell_script = parser.get_switch("shell-script-candidates"))
     {
-        completer = ShellCandidatesCompleter{shell_script->str()};
+        completer = ShellCandidatesCompleter{shell_script->str(), completions_flags};
     }
     else if (parser.get_switch("command-completion"))
     {
@@ -1125,11 +1152,12 @@ void define_command(const ParametersParser& parser, Context& context, const Shel
     }
     else if (parser.get_switch("shell-completion"))
     {
-        completer = [](const Context& context, CompletionFlags flags,
+        completer = [=](const Context& context, CompletionFlags flags,
                         CommandParameters params,
                         size_t token_to_complete, ByteCount pos_in_token)
         {
-            return shell_complete(context, flags, params[token_to_complete], pos_in_token);
+            return add_flags(shell_complete, completions_flags)(
+                context, flags, params[token_to_complete], pos_in_token);
         };
     }
 
@@ -1148,6 +1176,7 @@ const CommandDesc define_command_cmd = {
           { "override",                 { false, "allow overriding an existing command" } },
           { "hidden",                   { false, "do not display the command in completion candidates" } },
           { "docstring",                { true,  "define the documentation string for command" } },
+          { "menu",                     { false, "treat completions as the only valid inputs" } },
           { "file-completion",          { false, "complete parameters using filename completion" } },
           { "client-completion",        { false, "complete parameters using client name completion" } },
           { "buffer-completion",        { false, "complete parameters using buffer name completion" } },
@@ -1368,7 +1397,7 @@ const CommandDesc source_cmd = {
     ParameterDesc{ {}, ParameterDesc::Flags::None, 1, (size_t)-1 },
     CommandFlags::None,
     CommandHelper{},
-    filename_completer,
+    filename_completer<true>,
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         const DebugFlags debug_flags = context.options()["debug"].get<DebugFlags>();
@@ -1447,7 +1476,9 @@ const CommandDesc set_option_cmd = {
                  GlobalScope::instance().option_registry().option_exists(params[start + 1]))
         {
             OptionManager& options = get_scope(params[start], context).options();
-            return { 0_byte, params[start + 2].length(), { options[params[start + 1]].get_as_string(Quoting::Kakoune) }, true };
+            return {0_byte, params[start + 2].length(),
+                    {options[params[start + 1]].get_as_string(Quoting::Kakoune)},
+                    Completions::Flags::Quoted};
         }
         return Completions{};
     },

src/completion.hh

@@ -18,10 +18,19 @@ using CandidateList = Vector<String, MemoryDomain::Completion>;
 
 struct Completions
 {
+    enum class Flags
+    {
+        None = 0,
+        Quoted = 0b1,
+        Menu = 0b10
+    };
+
+    constexpr friend bool with_bit_ops(Meta::Type<Flags>) { return true; }
+
     CandidateList candidates;
     ByteCount start;
     ByteCount end;
-    bool quoted = false;
+    Flags flags = Flags::None;
 
     Completions()
         : start(0), end(0) {}
@@ -29,8 +38,8 @@ struct Completions
     Completions(ByteCount start, ByteCount end)
         : start(start), end(end) {}
 
-    Completions(ByteCount start, ByteCount end, CandidateList candidates, bool quoted = false)
+    Completions(ByteCount start, ByteCount end, CandidateList candidates, Flags flags = Flags::None)
-        : candidates(std::move(candidates)), start(start), end(end), quoted{quoted} {}
+        : candidates(std::move(candidates)), start(start), end(end), flags{flags} {}
 };
 
 enum class CompletionFlags
@@ -54,7 +63,7 @@ Completions shell_complete(const Context& context, CompletionFlags,
 inline Completions offset_pos(Completions completion, ByteCount offset)
 {
     return {completion.start + offset, completion.end + offset,
-             std::move(completion.candidates), completion.quoted };
+            std::move(completion.candidates), completion.flags};
 }
 
 template<typename Container>

src/input_handler.cc

@@ -780,6 +780,15 @@ public:
 
         if (key == Key::Return)
         {
+            if ((m_completions.flags & Completions::Flags::Menu) and
+                m_current_completion == -1 and
+                not m_completions.candidates.empty())
+            {
+                const String& completion = m_completions.candidates.front();
+                m_line_editor.insert_from(line.char_count_to(m_completions.start),
+                                          completion);
+            }
+
             if (not context().history_disabled())
                 history_push(history, line);
             context().print_status(DisplayLine{});
@@ -1001,6 +1010,7 @@ private:
             const String& line = m_line_editor.line();
             m_completions = m_completer(context(), flags, line,
                                         line.byte_count_to(m_line_editor.cursor_pos()));
+            const bool menu = (bool)(m_completions.flags & Completions::Flags::Menu);
             if (context().has_client())
             {
                 if (m_completions.candidates.empty())
@@ -1013,8 +1023,11 @@ private:
                 const auto menu_style = (m_flags & PromptFlags::Search) ? MenuStyle::Search : MenuStyle::Prompt;
                 context().client().menu_show(items, {}, menu_style);
 
+                if (menu)
+                    context().client().menu_select(0);
+
                 auto prefix = line.substr(m_completions.start, m_completions.end - m_completions.start);
-                if (not contains(m_completions.candidates, prefix))
+                if (not menu and not contains(m_completions.candidates, prefix))
                 {
                     m_current_completion = m_completions.candidates.size();
                     m_completions.candidates.push_back(prefix.str());