Merge branch 'json-ui'

27 files changed, 861 insertions, 210 deletions

diff --git a/src/alias_registry.cc b/src/alias_registry.cc
index 6e92c006..690cde54 100644
--- a/src/alias_registry.cc
+++ b/src/alias_registry.cc
@@ -57,7 +57,7 @@ Vector<std::pair<StringView, StringView>> AliasRegistry::flatten_aliases() const
         res = m_parent->flatten_aliases();
     for (auto& alias : m_aliases)
     {
-        if (not contains(transformed(res, [](const std::pair<StringView, StringView>& val) { return val.first; }), alias.key))
+        if (not contains(res | transform([](const AliasDesc& val) { return val.first; }), alias.key))
             res.emplace_back(alias.key, alias.value);
     }
     return res;
diff --git a/src/alias_registry.hh b/src/alias_registry.hh
index 7f688e08..5ff093bb 100644
--- a/src/alias_registry.hh
+++ b/src/alias_registry.hh
@@ -20,7 +20,8 @@ public:
     using iterator = AliasMap::const_iterator;
 
     Vector<StringView> aliases_for(StringView command) const;
-    Vector<std::pair<StringView, StringView>> flatten_aliases() const;
+    using AliasDesc = std::pair<StringView, StringView>;
+    Vector<AliasDesc> flatten_aliases() const;
 
 private:
     friend class Scope;
diff --git a/src/buffer.cc b/src/buffer.cc
index e140f333..c0e25f0a 100644
--- a/src/buffer.cc
+++ b/src/buffer.cc
@@ -304,7 +304,7 @@ bool Buffer::undo()
 
     --m_history_cursor;
 
-    for (const Modification& modification : reversed(*m_history_cursor))
+    for (const Modification& modification : *m_history_cursor | reverse())
         apply_modification(modification.inverse());
     return true;
 }
diff --git a/src/buffer.inl.hh b/src/buffer.inl.hh
index d6af3d4a..8397be33 100644
--- a/src/buffer.inl.hh
+++ b/src/buffer.inl.hh
@@ -104,7 +104,8 @@ inline ByteCoord Buffer::back_coord() const
 
 inline ByteCoord Buffer::end_coord() const
 {
-    return { line_count() - 1, m_lines.back().length() };
+    return m_lines.empty() ?
+        ByteCoord{0,0} : ByteCoord{ line_count() - 1, m_lines.back().length() };
 }
 
 inline BufferIterator::BufferIterator(const Buffer& buffer, ByteCoord coord)
diff --git a/src/client.cc b/src/client.cc
index 7dd22f88..cf8b3e71 100644
--- a/src/client.cc
+++ b/src/client.cc
@@ -36,7 +36,7 @@ Client::Client(std::unique_ptr<UserInterface>&& ui,
 
     m_ui->set_ui_options(m_window->options()["ui_options"].get<UserInterface::Options>());
     m_ui->set_input_callback([this](EventMode mode) { handle_available_input(mode); });
-    m_ui_dirty = true;
+    force_redraw();
 }
 
 Client::~Client()
@@ -101,7 +101,8 @@ void Client::handle_available_input(EventMode mode)
 
 void Client::print_status(DisplayLine status_line)
 {
-    m_pending_status_line = std::move(status_line);
+    m_status_line = std::move(status_line);
+    m_ui_pending |= StatusLine;
 }
 
 DisplayLine Client::generate_mode_line() const
@@ -159,7 +160,7 @@ void Client::change_buffer(Buffer& buffer)
     context().selections_write_only() = std::move(ws.selections);
     context().set_window(*m_window);
     m_window->set_dimensions(m_ui->dimensions());
-    m_ui_dirty = true;
+    force_redraw();
 
     m_window->hooks().run_hook("WinDisplay", buffer.name(), context());
 }
@@ -174,9 +175,20 @@ static bool is_inline(InfoStyle style)
 void Client::redraw_ifn()
 {
     Window& window = context().window();
+    if (window.needs_redraw(context()))
+        m_ui_pending |= Draw;
 
-    const bool needs_redraw = window.needs_redraw(context());
-    if (needs_redraw)
+    DisplayLine mode_line = generate_mode_line();
+    if (mode_line.atoms() != m_mode_line.atoms())
+    {
+        m_ui_pending |= StatusLine;
+        m_mode_line = std::move(mode_line);
+    }
+
+    if (m_ui_pending == 0)
+        return;
+
+    if (m_ui_pending & Draw)
     {
         auto window_pos = window.position();
         m_ui->draw(window.update_display_buffer(context()), get_face("Default"));
@@ -185,42 +197,47 @@ void Client::redraw_ifn()
         if (window_pos != window.position())
         {
             if (not m_menu.items.empty() and m_menu.style == MenuStyle::Inline)
-            {
-                m_ui->menu_show(m_menu.items, window.display_position(m_menu.anchor),
-                                get_face("MenuForeground"), get_face("MenuBackground"), m_menu.style);
-                m_ui->menu_select(m_menu.selected);
-            }
+                m_ui_pending |= (MenuShow | MenuSelect);
             if (not m_info.content.empty() and is_inline(m_info.style))
-                m_ui->info_show(m_info.title, m_info.content,
-                                window.display_position(m_info.anchor),
-                                get_face("Information"), m_info.style);
+                m_ui_pending |= InfoShow;
         }
-        m_ui_dirty = true;
     }
 
-    DisplayLine mode_line = generate_mode_line();
-    if (needs_redraw or
-        m_status_line.atoms() != m_pending_status_line.atoms() or
-        mode_line.atoms() != m_mode_line.atoms())
+    if (m_ui_pending & MenuShow)
     {
-        m_mode_line = std::move(mode_line);
-        m_status_line = m_pending_status_line;
-
-        m_ui->draw_status(m_status_line, m_mode_line, get_face("StatusLine"));
-        m_ui_dirty = true;
+        const CharCoord ui_anchor = m_menu.style == MenuStyle::Inline ?
+            window.display_position(m_menu.anchor) : CharCoord{};
+        m_ui->menu_show(m_menu.items, ui_anchor,
+                        get_face("MenuForeground"), get_face("MenuBackground"),
+                        m_menu.style);
     }
+    if (m_ui_pending & MenuSelect)
+        m_ui->menu_select(m_menu.selected);
+    if (m_ui_pending & MenuHide)
+        m_ui->menu_hide();
 
-    if (m_ui_dirty)
+    if (m_ui_pending & InfoShow)
     {
-        m_ui_dirty = false;
-        m_ui->refresh();
+        const CharCoord ui_anchor = is_inline(m_info.style) ?
+            window.display_position(m_info.anchor) : CharCoord{};
+        m_ui->info_show(m_info.title, m_info.content, ui_anchor,
+                        get_face("Information"), m_info.style);
     }
+    if (m_ui_pending & InfoHide)
+        m_ui->info_hide();
+
+    if (m_ui_pending & StatusLine)
+        m_ui->draw_status(m_status_line, m_mode_line, get_face("StatusLine"));
+
+    m_ui->refresh(m_ui_pending | Refresh);
+    m_ui_pending = 0;
 }
 
 void Client::force_redraw()
 {
-    if (m_window)
-        m_window->force_redraw();
+    m_ui_pending |= Refresh | Draw | StatusLine |
+        (m_menu.items.empty() ? MenuHide : MenuShow | MenuSelect) |
+        (m_info.content.empty() ? InfoHide : InfoShow);
 }
 
 void Client::reload_buffer()
@@ -310,45 +327,43 @@ void Client::on_option_changed(const Option& option)
     if (option.name() == "ui_options")
     {
         m_ui->set_ui_options(option.get<UserInterface::Options>());
-        m_ui_dirty = true;
+        m_ui_pending |= Draw;
     }
 }
 
 void Client::menu_show(Vector<DisplayLine> choices, ByteCoord anchor, MenuStyle style)
 {
     m_menu = Menu{ std::move(choices), anchor, style, -1 };
-    CharCoord ui_anchor = style == MenuStyle::Inline ? context().window().display_position(anchor) : CharCoord{};
-    m_ui->menu_show(m_menu.items, ui_anchor, get_face("MenuForeground"), get_face("MenuBackground"), style);
-    m_ui_dirty = true;
+    m_ui_pending |= MenuShow;
+    m_ui_pending &= ~MenuHide;
 }
 
 void Client::menu_select(int selected)
 {
     m_menu.selected = selected;
-    m_ui->menu_select(selected);
-    m_ui_dirty = true;
+    m_ui_pending |= MenuSelect;
+    m_ui_pending &= ~MenuHide;
 }
 
 void Client::menu_hide()
 {
     m_menu = Menu{};
-    m_ui->menu_hide();
-    m_ui_dirty = true;
+    m_ui_pending |= MenuHide;
+    m_ui_pending &= ~(MenuShow | MenuSelect);
 }
 
 void Client::info_show(String title, String content, ByteCoord anchor, InfoStyle style)
 {
     m_info = Info{ std::move(title), std::move(content), anchor, style };
-    CharCoord ui_anchor = is_inline(style) ? context().window().display_position(anchor) : CharCoord{};
-    m_ui->info_show(m_info.title, m_info.content, ui_anchor, get_face("Information"), style);
-    m_ui_dirty = true;
+    m_ui_pending |= InfoShow;
+    m_ui_pending &= ~InfoHide;
 }
 
 void Client::info_hide()
 {
     m_info = Info{};
-    m_ui->info_hide();
-    m_ui_dirty = true;
+    m_ui_pending |= InfoHide;
+    m_ui_pending &= ~InfoShow;
 }
 
 }
diff --git a/src/client.hh b/src/client.hh
index b5d13b7d..3fa36907 100644
--- a/src/client.hh
+++ b/src/client.hh
@@ -74,7 +74,6 @@ private:
 
     DisplayLine generate_mode_line() const;
 
-    bool m_ui_dirty = false;
     std::unique_ptr<UserInterface> m_ui;
     std::unique_ptr<Window> m_window;
 
@@ -83,9 +82,21 @@ private:
     InputHandler m_input_handler;
 
     DisplayLine m_status_line;
-    DisplayLine m_pending_status_line;
     DisplayLine m_mode_line;
 
+    enum PendingUI : int
+    {
+        MenuShow   = 1 << 0,
+        MenuSelect = 1 << 1,
+        MenuHide   = 1 << 2,
+        InfoShow   = 1 << 3,
+        InfoHide   = 1 << 4,
+        StatusLine = 1 << 5,
+        Draw       = 1 << 6,
+        Refresh    = 1 << 7,
+    };
+    int m_ui_pending = 0;
+
     struct Menu
     {
         Vector<DisplayLine> items;
diff --git a/src/client_manager.cc b/src/client_manager.cc
index b625fdc5..aff88d93 100644
--- a/src/client_manager.cc
+++ b/src/client_manager.cc
@@ -87,7 +87,7 @@ void ClientManager::remove_client(Client& client, bool graceful)
 
 WindowAndSelections ClientManager::get_free_window(Buffer& buffer)
 {
-    auto it = find_if(reversed(m_free_windows),
+    auto it = find_if(m_free_windows | reverse(),
                       [&](const WindowAndSelections& ws)
                       { return &ws.window->buffer() == &buffer; });
 
@@ -177,10 +177,8 @@ void ClientManager::redraw_clients() const
 CandidateList ClientManager::complete_client_name(StringView prefix,
                                                   ByteCount cursor_pos) const
 {
-    auto c = transformed(m_clients,
-                         [](const std::unique_ptr<Client>& c) -> const String&
-                         { return c->context().name(); });
-
+    auto c = m_clients | transform([](const std::unique_ptr<Client>& c) -> const String&
+                                   { return c->context().name(); });
     return complete(prefix, cursor_pos, c);
 }
 
diff --git a/src/command_manager.cc b/src/command_manager.cc
index 8dfb5181..4902f068 100644
--- a/src/command_manager.cc
+++ b/src/command_manager.cc
@@ -512,6 +512,20 @@ CommandInfo CommandManager::command_info(const Context& context, StringView comm
     return res;
 }
 
+Completions CommandManager::complete_command_name(const Context& context,
+                                                  StringView query) const
+{
+    auto candidates = Kakoune::complete(
+        query, query.length(), concatenated(
+            m_commands
+            | filter([](const CommandMap::value_type& cmd) { return not (cmd.second.flags & CommandFlags::Hidden); })
+            | transform([](const CommandMap::value_type& cmd) { return StringView{cmd.first}; }),
+            context.aliases().flatten_aliases()
+            | transform([](AliasRegistry::AliasDesc alias) { return alias.first; })));
+
+    return {0, query.length(), std::move(candidates)};
+}
+
 Completions CommandManager::complete(const Context& context,
                                      CompletionFlags flags,
                                      StringView command_line,
@@ -533,33 +547,16 @@ Completions CommandManager::complete(const Context& context,
         }
     }
 
+    const bool is_last_token = tok_idx == tokens.size();
     // command name completion
     if (tokens.empty() or
-        (tok_idx == cmd_idx and (tok_idx == tokens.size() or
+        (tok_idx == cmd_idx and (is_last_token or
                                  tokens[tok_idx].type() == Token::Type::Raw or
                                  tokens[tok_idx].type() == Token::Type::RawQuoted)))
     {
-        const bool is_end_token = tok_idx == tokens.size();
-        ByteCount cmd_start =  is_end_token ? cursor_pos
-                                            : tokens[tok_idx].begin();
-        Completions result(cmd_start, cursor_pos);
-        StringView prefix = command_line.substr(cmd_start,
-                                                cursor_pos - cmd_start);
-
-        for (auto& command : m_commands)
-        {
-            if (command.second.flags & CommandFlags::Hidden)
-                continue;
-            if (prefix_match(command.first, prefix))
-                result.candidates.push_back(command.first);
-        }
-        for (auto& alias : context.aliases().flatten_aliases())
-        {
-            if (prefix_match(alias.first, prefix))
-                result.candidates.push_back(alias.first.str());
-        }
-        std::sort(result.candidates.begin(), result.candidates.end());
-        return result;
+        auto cmd_start = is_last_token ? cursor_pos : tokens[tok_idx].begin();
+        StringView query = command_line.substr(cmd_start, cursor_pos - cmd_start);
+        return offset_pos(complete_command_name(context, query), cmd_start);
     }
 
     kak_assert(not tokens.empty());
@@ -628,18 +625,7 @@ Completions CommandManager::complete(const Context& context,
     StringView prefix = params[token_to_complete].substr(0, pos_in_token);
 
     if (token_to_complete == 0)
-    {
-        CandidateList candidates;
-        for (auto& command : m_commands)
-        {
-            if (command.second.flags & CommandFlags::Hidden)
-                continue;
-            if (prefix_match(command.first, prefix))
-                candidates.push_back(command.first);
-        }
-        std::sort(candidates.begin(), candidates.end());
-        return {0, pos_in_token, std::move(candidates)};
-    }
+        return complete_command_name(context, prefix);
     else
     {
         const String& command_name = params[0];
diff --git a/src/command_manager.hh b/src/command_manager.hh
index dbc87e81..090ed0fb 100644
--- a/src/command_manager.hh
+++ b/src/command_manager.hh
@@ -130,6 +130,8 @@ private:
                                 const ShellContext& shell_context,
                                 CharCoord pos) const;
 
+    Completions complete_command_name(const Context& context, StringView query) const;
+
     struct CommandDescriptor
     {
         Command command;
diff --git a/src/commands.cc b/src/commands.cc
index 3a8d6132..b376f081 100644
--- a/src/commands.cc
+++ b/src/commands.cc
@@ -543,7 +543,7 @@ Completions add_highlighter_completer(
     if (token_to_complete == 1 and params[0] == "-group")
         return complete_highlighter(context, params[1], pos_in_token, true);
     else if (token_to_complete == 0 or (token_to_complete == 2 and params[0] == "-group"))
-        return { 0_byte, arg.length(), complete(arg, pos_in_token, transformed(HighlighterRegistry::instance(), HighlighterRegistry::get_id)) };
+        return { 0_byte, arg.length(), complete(arg, pos_in_token, HighlighterRegistry::instance() | transform(HighlighterRegistry::get_id)) };
     return Completions{};
 }
 
@@ -626,7 +626,7 @@ const CommandDesc rm_highlighter_cmd = {
     [](const ParametersParser& parser, Context& context, const ShellContext&)
     {
         StringView path = parser[0];
-        auto sep_it = find(reversed(path), '/');
+        auto sep_it = find(path | reverse(), '/');
         auto& group = sep_it != path.rend() ?
             get_highlighter(context, {path.begin(), sep_it.base()})
           : context.window().highlighters();
diff --git a/src/containers.hh b/src/containers.hh
index 6bf3bea6..9597a25b 100644
--- a/src/containers.hh
+++ b/src/containers.hh
@@ -8,11 +8,21 @@
 namespace Kakoune
 {
 
+template<typename Factory>
+struct ContainerView { Factory factory; };
+
+template<typename Container, typename Factory>
+auto operator| (Container&& container, ContainerView<Factory> view) ->
+    decltype(view.factory(std::forward<Container>(container)))
+{
+    return view.factory(std::forward<Container>(container));
+}
+
 template<typename Container>
-struct ReversedContainer
+struct ReverseView
 {
     using iterator = decltype(std::declval<Container>().rbegin());
-    ReversedContainer(Container& container) : m_container(container) {}
+    ReverseView(Container& container) : m_container(container) {}
 
     iterator begin() { return m_container.rbegin(); }
     iterator end()   { return m_container.rend(); }
@@ -21,122 +31,196 @@ private:
     Container& m_container;
 };
 
-template<typename Container>
-ReversedContainer<Container> reversed(Container&& container)
-{
-    return ReversedContainer<Container>(container);
-}
-
-template<typename Iterator, typename Filter>
-struct FilteredIterator : std::iterator<std::forward_iterator_tag,
-                                        typename Iterator::value_type>
+struct ReverseFactory
 {
-    FilteredIterator(Filter filter, Iterator it, Iterator end)
-        : m_it(std::move(it)), m_end(std::move(end)), m_filter(std::move(filter))
+    template<typename Container>
+    ReverseView<Container> operator()(Container&& container) const
     {
-        do_filter();
+        return {container};
     }
+};
 
-    auto operator*() -> decltype(*std::declval<Iterator>()) { return *m_it; }
-    FilteredIterator& operator++() { ++m_it; do_filter(); return *this; }
-    FilteredIterator operator++(int) { auto copy = *this; ++(*this); return copy; }
+inline ContainerView<ReverseFactory> reverse() { return {}; }
 
-    friend bool operator==(const FilteredIterator& lhs, const FilteredIterator& rhs)
-    {
-        return lhs.m_it == rhs.m_it;
-    }
+template<typename Container, typename Filter>
+struct FilterView
+{
+    using ContainerIt = decltype(begin(std::declval<Container>()));
 
-    friend bool operator!=(const FilteredIterator& lhs, const FilteredIterator& rhs)
+    struct Iterator : std::iterator<std::forward_iterator_tag,
+                                    typename ContainerIt::value_type>
     {
-        return not (lhs == rhs);
-    }
+        Iterator(const FilterView& view, ContainerIt it, ContainerIt end)
+            : m_it{std::move(it)}, m_end{std::move(end)}, m_view{view}
+        {
+            do_filter();
+        }
+
+        auto operator*() -> decltype(*std::declval<ContainerIt>()) { return *m_it; }
+        Iterator& operator++() { ++m_it; do_filter(); return *this; }
+        Iterator operator++(int) { auto copy = *this; ++(*this); return copy; }
+
+        friend bool operator==(const Iterator& lhs, const Iterator& rhs)
+        {
+            return lhs.m_it == rhs.m_it;
+        }
+
+        friend bool operator!=(const Iterator& lhs, const Iterator& rhs)
+        {
+            return not (lhs == rhs);
+        }
+
+        const ContainerIt& base() const { return m_it; }
+
+    private:
+        void do_filter()
+        {
+            while (m_it != m_end and not m_view.m_filter(*m_it))
+                ++m_it;
+        }
+
+        ContainerIt m_it;
+        ContainerIt m_end;
+        const FilterView& m_view;
+    };
+
+    FilterView(Container& container, Filter filter)
+        : m_container(container), m_filter(std::move(filter)) {}
 
-    Iterator base() const { return m_it; }
+    Iterator begin() const { return {*this, m_container.begin(), m_container.end()}; }
+    Iterator end()   const { return {*this, m_container.end(), m_container.end()}; }
 
 private:
-    void do_filter()
-    {
-        while (m_it != m_end and not m_filter(*m_it))
-            ++m_it;
-    }
-
-    Iterator m_it;
-    Iterator m_end;
-    Filter   m_filter;
+    Container& m_container;
+    Filter m_filter;
 };
 
-template<typename Container, typename Filter>
-struct FilteredContainer
+template<typename Filter>
+struct FilterFactory
 {
-    using iterator = FilteredIterator<decltype(begin(std::declval<Container>())), Filter>;
-    FilteredContainer(Container& container, Filter filter)
-        : m_container(container), m_filter(std::move(filter)) {}
+    template<typename Container>
+    FilterView<Container, Filter> operator()(Container&& container) const { return {container, std::move(m_filter)}; }
 
-    iterator begin() const { return iterator(m_filter, m_container.begin(), m_container.end()); }
-    iterator end()   const { return iterator(m_filter, m_container.end(), m_container.end()); }
-
-private:
-    Container& m_container;
     Filter m_filter;
 };
 
-template<typename Container, typename Filter>
-FilteredContainer<Container, Filter> filtered(Container&& container, Filter filter)
-{
-    return FilteredContainer<Container, Filter>(container, std::move(filter));
-}
+template<typename Filter>
+inline ContainerView<FilterFactory<Filter>> filter(Filter f) { return {{std::move(f)}}; }
 
 template<typename I, typename T>
 using TransformedResult = decltype(std::declval<T>()(*std::declval<I>()));
 
-template<typename Iterator, typename Transform>
-struct TransformedIterator : std::iterator<std::forward_iterator_tag,
-                                           typename std::remove_reference<TransformedResult<Iterator, Transform>>::type>
+template<typename Container, typename Transform>
+struct TransformView
 {
-    TransformedIterator(Transform transform, Iterator it)
-        : m_it(std::move(it)), m_transform(std::move(transform)) {}
-
-    auto operator*() -> TransformedResult<Iterator, Transform> { return m_transform(*m_it); }
-    TransformedIterator& operator++() { ++m_it; return *this; }
-    TransformedIterator operator++(int) { auto copy = *this; ++m_it; return copy; }
+    using ContainerIt = decltype(begin(std::declval<Container>()));
 
-    friend bool operator==(const TransformedIterator& lhs, const TransformedIterator& rhs)
+    struct Iterator : std::iterator<std::forward_iterator_tag,
+                                    typename std::remove_reference<TransformedResult<ContainerIt, Transform>>::type>
     {
-        return lhs.m_it == rhs.m_it;
-    }
+        Iterator(const TransformView& view, ContainerIt it)
+            : m_it{std::move(it)}, m_view{view} {}
 
-    friend bool operator!=(const TransformedIterator& lhs, const TransformedIterator& rhs)
-    {
-        return not (lhs == rhs);
-    }
+        auto operator*() -> TransformedResult<ContainerIt, Transform> { return m_view.m_transform(*m_it); }
+        Iterator& operator++() { ++m_it; return *this; }
+        Iterator operator++(int) { auto copy = *this; ++m_it; return copy; }
+
+        friend bool operator==(const Iterator& lhs, const Iterator& rhs)
+        {
+            return lhs.m_it == rhs.m_it;
+        }
+
+        friend bool operator!=(const Iterator& lhs, const Iterator& rhs)
+        {
+            return not (lhs == rhs);
+        }
+
+        ContainerIt base() const { return m_it; }
+
+    private:
+        ContainerIt m_it;
+        const TransformView& m_view;
+    };
+
+    TransformView(Container& container, Transform transform)
+        : m_container(container), m_transform(std::move(transform)) {}
 
-    Iterator base() const { return m_it; }
+    Iterator begin() const { return {*this, m_container.begin()}; }
+    Iterator end()   const { return {*this, m_container.end()}; }
 
 private:
-    Iterator m_it;
+    Container& m_container;
     Transform m_transform;
 };
 
+template<typename Transform>
+struct TransformFactory
+{
+    template<typename Container>
+    TransformView<Container, Transform> operator()(Container&& container) const { return {container, std::move(m_transform)}; }
 
-template<typename Container, typename Transform>
-struct TransformedContainer
+    Transform m_transform;
+};
+
+template<typename Transform>
+inline ContainerView<TransformFactory<Transform>> transform(Transform t) { return {{std::move(t)}}; }
+
+
+
+template<typename Container1, typename Container2>
+struct ConcatView
 {
-    using iterator = TransformedIterator<decltype(begin(std::declval<Container>())), Transform>;
-    TransformedContainer(Container& container, Transform transform)
-        : m_container(container), m_transform(std::move(transform)) {}
+    using ContainerIt1 = decltype(begin(std::declval<Container1>()));
+    using ContainerIt2 = decltype(begin(std::declval<Container2>()));
+    using ValueType = typename ContainerIt1::value_type;
+
+    struct Iterator : std::iterator<std::forward_iterator_tag, ValueType>
+    {
+        static_assert(std::is_convertible<typename ContainerIt1::value_type, ValueType>::value, "");
+        static_assert(std::is_convertible<typename ContainerIt2::value_type, ValueType>::value, "");
+
+        Iterator(ContainerIt1 it1, ContainerIt1 end1, ContainerIt2 it2)
+            : m_it1(std::move(it1)), m_end1(std::move(end1)),
+              m_it2(std::move(it2)) {}
+
+        decltype(*std::declval<ContainerIt1>()) operator*() { return is2() ? *m_it2 : *m_it1; }
+        Iterator& operator++() { if (is2()) ++m_it2; else ++m_it1; return *this; }
+        Iterator operator++(int) { auto copy = *this; ++*this; return copy; }
+
+        friend bool operator==(const Iterator& lhs, const Iterator& rhs)
+        {
+            return lhs.m_it1 == rhs.m_it1 and lhs.m_end1 == rhs.m_end1 and
+                   lhs.m_it2 == rhs.m_it2;
+        }
 
-    iterator begin() const { return iterator(m_transform, m_container.begin()); }
-    iterator end()   const { return iterator(m_transform, m_container.end()); }
+        friend bool operator!=(const Iterator& lhs, const Iterator& rhs)
+        {
+            return not (lhs == rhs);
+        }
+
+    private:
+        bool is2() const { return m_it1 == m_end1; }
+
+        ContainerIt1 m_it1;
+        ContainerIt1 m_end1;
+        ContainerIt2 m_it2;
+    };
+
+    ConcatView(Container1& container1, Container2& container2)
+        : m_container1(container1), m_container2(container2) {}
+
+    Iterator begin() const { return {m_container1.begin(), m_container1.end(), m_container2.begin()}; }
+    Iterator end()   const { return {m_container1.end(), m_container1.end(), m_container2.end()}; }
 
 private:
-    Container& m_container;
-    Transform m_transform;
+    Container1& m_container1;
+    Container2& m_container2;
 };
 
-template<typename Container, typename Transform>
-TransformedContainer<Container, Transform> transformed(Container&& container, Transform transform)
+template<typename Container1, typename Container2>
+ConcatView<Container1, Container2> concatenated(Container1&& container1, Container2&& container2)
 {
-    return TransformedContainer<Container, Transform>(container, std::move(transform));
+    return {container1, container2};
 }
 
 // Todo: move that into the following functions once we can remove the decltype
diff --git a/src/face_registry.cc b/src/face_registry.cc
index 3a5ac6e1..7da57e9c 100644
--- a/src/face_registry.cc
+++ b/src/face_registry.cc
@@ -95,9 +95,8 @@ CandidateList FaceRegistry::complete_alias_name(StringView prefix,
                                                 ByteCount cursor_pos) const
 {
     return complete(prefix, cursor_pos,
-                    transformed(m_aliases,
-                                [](const AliasMap::value_type& v) -> const String&
-                                { return v.first; }));
+                    m_aliases | transform([](const AliasMap::value_type& v) -> const String&
+                                          { return v.first; }));
 }
 
 FaceRegistry::FaceRegistry()
diff --git a/src/file.cc b/src/file.cc
index 2d3e6a82..6cf9a735 100644
--- a/src/file.cc
+++ b/src/file.cc
@@ -63,7 +63,7 @@ String parse_filename(StringView filename)
 
 std::pair<StringView, StringView> split_path(StringView path)
 {
-    auto it = find(reversed(path), '/');
+    auto it = find(path | reverse(), '/');
     if (it == path.rend())
         return { {}, path };
     const char* slash = it.base()-1;
diff --git a/src/highlighter_group.cc b/src/highlighter_group.cc
index d3755734..2d0a7a74 100644
--- a/src/highlighter_group.cc
+++ b/src/highlighter_group.cc
@@ -52,10 +52,9 @@ Completions HighlighterGroup::complete_child(StringView path, ByteCount cursor_p
 
     auto candidates = complete(
         path, cursor_pos,
-        transformed(filtered(m_highlighters,
-                             [=](const HighlighterMap::Element& hl)
-                             { return not group or hl.value->has_children(); }),
-                    HighlighterMap::get_id));
+        m_highlighters | filter([=](const HighlighterMap::Element& hl)
+                                { return not group or hl.value->has_children(); })
+                       | transform(HighlighterMap::get_id));
 
     return { 0, 0, std::move(candidates) };
 }
diff --git a/src/highlighters.cc b/src/highlighters.cc
index 740320ac..871d549c 100644
--- a/src/highlighters.cc
+++ b/src/highlighters.cc
@@ -1303,7 +1303,7 @@ public:
             return offset_pos(hl.complete_child(path.substr(offset), cursor_pos - offset, group), offset);
         }
 
-        auto container = transformed(m_groups, decltype(m_groups)::get_id);
+        auto container = m_groups | transform(decltype(m_groups)::get_id);
         return { 0, 0, complete(path, cursor_pos, container) };
     }
 
diff --git a/src/hook_manager.cc b/src/hook_manager.cc
index 81a00730..389c8504 100644
--- a/src/hook_manager.cc
+++ b/src/hook_manager.cc
@@ -31,7 +31,7 @@ CandidateList HookManager::complete_hook_group(StringView prefix, ByteCount pos_
     CandidateList res;
     for (auto& list : m_hook)
     {
-        auto container = transformed(list.value, decltype(list.value)::get_id);
+        auto container = list.value | transform(decltype(list.value)::get_id);
         for (auto& c : complete(prefix, pos_in_token, container))
         {
             if (!contains(res, c))
diff --git a/src/input_handler.cc b/src/input_handler.cc
index 3871398d..b1e71ed3 100644
--- a/src/input_handler.cc
+++ b/src/input_handler.cc
@@ -763,7 +763,11 @@ public:
             CandidateList& candidates = m_completions.candidates;
             // first try, we need to ask our completer for completions
             if (candidates.empty())
+            {
                 refresh_completions(CompletionFlags::None);
+                if (candidates.size() > 1)
+                    return;
+            }
 
             if (candidates.empty())
                 return;
diff --git a/src/json_ui.cc b/src/json_ui.cc
new file mode 100644
index 00000000..aea412b1
--- /dev/null
+++ b/src/json_ui.cc
@@ -0,0 +1,446 @@
+#include "json_ui.hh"
+
+#include "display_buffer.hh"
+#include "keys.hh"
+#include "file.hh"
+#include "event_manager.hh"
+#include "value.hh"
+#include "unit_tests.hh"
+
+#include <utility>
+
+namespace Kakoune
+{
+
+template<typename T>
+String to_json(ArrayView<const T> array)
+{
+    String res;
+    for (auto& elem : array)
+    {
+        if (not res.empty())
+            res += ", ";
+        res += to_json(elem);
+    }
+    return "[" + res + "]";
+}
+
+template<typename T, MemoryDomain D>
+String to_json(const Vector<T, D>& vec) { return to_json(ArrayView<const T>{vec}); }
+
+String to_json(int i) { return to_string(i); }
+String to_json(bool b) { return b ? "true" : "false"; }
+String to_json(StringView str)
+{
+    String res;
+    res.reserve(str.length() + 4);
+    res += '"';
+    for (auto it = str.begin(), end = str.end(); it != end; )
+    {
+        auto next = std::find_if(it, end, [](char c) {
+            return c == '\\' or c == '"' or (c >= 0 and c <= 0x1F);
+        });
+
+        res += StringView{it, next};
+        if (next == end)
+            break;
+
+        char buf[7] = {'\\', *next, 0};
+        if (*next >= 0 and *next <= 0x1F)
+            sprintf(buf, "\\u%04x", *next);
+
+        res += buf;
+        it = next+1;
+    }
+    res += '"';
+    return res;
+}
+
+String to_json(Color color)
+{
+    if (color.color == Kakoune::Color::RGB)
+    {
+        char buffer[10];
+        sprintf(buffer, R"("#%02x%02x%02x")", color.r, color.g, color.b);
+        return buffer;
+    }
+    return to_json(color_to_str(color));
+}
+
+String to_json(Attribute attributes)
+{
+    struct { Attribute attr; StringView name; }
+    attrs[] { 
+        { Attribute::Exclusive, "exclusive" },
+        { Attribute::Underline, "underline" },
+        { Attribute::Reverse, "reverse" },
+        { Attribute::Blink, "blink" },
+        { Attribute::Bold, "bold" },
+        { Attribute::Dim, "dim" },
+        { Attribute::Italic, "italic" },
+    };
+
+    String res;
+    for (auto& attr : attrs)
+    {
+        if (not (attributes & attr.attr))
+            continue;
+
+        if (not res.empty())
+            res += ", ";
+        res += to_json(attr.name);
+    }
+    return "[" + res + "]";
+}
+
+String to_json(Face face)
+{
+    return format(R"(\{ "fg": {}, "bg": {}, "attributes": {} })",
+                  to_json(face.fg), to_json(face.bg), to_json(face.attributes));
+}
+
+String to_json(const DisplayAtom& atom)
+{
+    return format(R"(\{ "face": {}, "contents": {} })", to_json(atom.face), to_json(atom.content()));
+}
+
+String to_json(const DisplayLine& line)
+{
+    return to_json(line.atoms());
+}
+
+String to_json(CharCoord coord)
+{
+    return format(R"(\{ "line": {}, "column": {} })", coord.line, coord.column);
+}
+
+String to_json(MenuStyle style)
+{
+    switch (style)
+    {
+        case MenuStyle::Prompt: return R"("prompt")";
+        case MenuStyle::Inline: return R"("inline")";
+    }
+    return "";
+}
+
+String to_json(InfoStyle style)
+{
+    switch (style)
+    {
+        case InfoStyle::Prompt: return R"("prompt")";
+        case InfoStyle::Inline: return R"("inline")";
+        case InfoStyle::InlineAbove: return R"("inlineAbove")";
+        case InfoStyle::InlineBelow: return R"("inlineBelow")";
+        case InfoStyle::MenuDoc: return R"("menuDoc")";
+    }
+    return "";
+}
+
+String concat()
+{
+    return "";
+}
+
+template<typename First, typename... Args>
+String concat(First&& first, Args&&... args)
+{
+    if (sizeof...(Args) != 0)
+        return to_json(first) + ", " + concat(args...);
+    return to_json(first);
+}
+
+template<typename... Args>
+void rpc_call(StringView method, Args&&... args)
+{
+    auto q = format(R"(\{ "jsonrpc": "2.0", "method": "{}", "params": [{}] }{})",
+                    method, concat(std::forward<Args>(args)...), "\n");
+
+    write_stdout(q);
+}
+
+JsonUI::JsonUI()
+    : m_stdin_watcher{0, [this](FDWatcher&, EventMode mode) {
+        parse_requests(mode);
+      }}, m_dimensions{24, 80}
+{
+    set_signal_handler(SIGINT, SIG_DFL);
+}
+
+void JsonUI::draw(const DisplayBuffer& display_buffer,
+                  const Face& default_face)
+{
+    rpc_call("draw", display_buffer.lines(), default_face);
+}
+
+void JsonUI::draw_status(const DisplayLine& status_line,
+                         const DisplayLine& mode_line,
+                         const Face& default_face)
+{
+    rpc_call("draw_status", status_line, mode_line, default_face);
+}
+
+bool JsonUI::is_key_available()
+{
+    return not m_pending_keys.empty();
+}
+
+Key JsonUI::get_key()
+{
+    kak_assert(not m_pending_keys.empty());
+    Key key = m_pending_keys.front();
+    m_pending_keys.erase(m_pending_keys.begin());
+    return key;
+}
+
+void JsonUI::menu_show(ConstArrayView<DisplayLine> items,
+                       CharCoord anchor, Face fg, Face bg,
+                       MenuStyle style)
+{
+    rpc_call("menu_show", items, anchor, fg, bg, style);
+}
+
+void JsonUI::menu_select(int selected)
+{
+    rpc_call("menu_show", selected);
+}
+
+void JsonUI::menu_hide()
+{
+    rpc_call("menu_hide");
+}
+
+void JsonUI::info_show(StringView title, StringView content,
+                       CharCoord anchor, Face face,
+                       InfoStyle style)
+{
+    rpc_call("info_show", title, content, anchor, face, style);
+}
+
+void JsonUI::info_hide()
+{
+    rpc_call("info_hide");
+}
+
+void JsonUI::refresh(bool force)
+{
+    rpc_call("refresh", force);
+}
+
+void JsonUI::set_input_callback(InputCallback callback)
+{
+    m_input_callback = std::move(callback);
+}
+
+void JsonUI::set_ui_options(const Options& options)
+{
+    // rpc_call("set_ui_options", options);
+}
+
+CharCoord JsonUI::dimensions()
+{
+    return m_dimensions;
+}
+
+using JsonArray = Vector<Value>;
+using JsonObject = IdMap<Value>;
+
+static bool is_digit(char c) { return c >= '0' and c <= '9'; }
+
+std::tuple<Value, const char*>
+parse_json(const char* pos, const char* end)
+{
+    using Result = std::tuple<Value, const char*>;
+
+    if (not skip_while(pos, end, is_blank))
+        return {};
+
+    if (is_digit(*pos))
+    {
+        auto digit_end = pos;
+        skip_while(digit_end, end, is_digit);
+        return Result{ Value{str_to_int({pos, end})}, digit_end };
+    }
+    if (end - pos > 4 and StringView{pos, pos+4} == "true")
+        return Result{ Value{true}, pos+4 };
+    if (end - pos > 5 and StringView{pos, pos+5} == "false")
+        return Result{ Value{false}, pos+5 };
+    if (*pos == '"')
+    {
+        String value;
+        bool escaped = false;
+        ++pos;
+        for (auto string_end = pos; string_end != end; ++string_end)
+        {
+            if (escaped)
+            {
+                escaped = false;
+                value += StringView{pos, string_end};
+                value.back() = *string_end;
+                pos = string_end+1;
+                continue;
+            }
+            if (*string_end == '\\')
+                escaped = true;
+            if (*string_end == '"')
+            {
+                value += StringView{pos, string_end};
+                return Result{std::move(value), string_end+1};
+            }
+        }
+        return {};
+    }
+    if (*pos == '[')
+    {
+        JsonArray array;
+        ++pos;
+        while (true)
+        {
+            Value element;
+            std::tie(element, pos) = parse_json(pos, end);
+            if (not element)
+                return {};
+            array.push_back(std::move(element));
+            if (not skip_while(pos, end, is_blank))
+                return {};
+
+            if (*pos == ',')
+                ++pos;
+            else if (*pos == ']')
+                return Result{std::move(array), pos+1};
+            else
+                throw runtime_error("unable to parse array, expected ',' or ']'");
+        }
+    }
+    if (*pos == '{')
+    {
+        JsonObject object;
+        ++pos;
+        while (true)
+        {
+            Value name_value;
+            std::tie(name_value, pos) = parse_json(pos, end);
+            if (not name_value)
+                return {};
+
+            String& name = name_value.as<String>();
+            if (not skip_while(pos, end, is_blank))
+                return {};
+            if (*pos++ != ':')
+                throw runtime_error("expected :");
+
+            Value element;
+            std::tie(element, pos) = parse_json(pos, end);
+            if (not element)
+                return {};
+            object.append({ std::move(name), std::move(element) });
+            if (not skip_while(pos, end, is_blank))
+                return {};
+
+            if (*pos == ',')
+                ++pos;
+            else if (*pos == '}')
+                return Result{std::move(object), pos+1};
+            else
+                throw runtime_error("unable to parse object, expected ',' or '}'");
+        }
+    }
+    throw runtime_error("Could not parse json");
+}
+
+void JsonUI::eval_json(const Value& json)
+{
+    const JsonObject& object = json.as<JsonObject>();
+    auto json_it = object.find("jsonrpc");
+    if (json_it == object.end() or json_it->value.as<String>() != "2.0")
+        throw runtime_error("invalid json rpc request");
+
+    auto method_it = object.find("method");
+    if (method_it == object.end())
+        throw runtime_error("invalid json rpc request (method missing)");
+    StringView method = method_it->value.as<String>();
+
+    auto params_it = object.find("params");
+    if (params_it == object.end())
+        throw runtime_error("invalid json rpc request (params missing)");
+    const JsonArray& params = params_it->value.as<JsonArray>();
+
+    if (method == "keys")
+    {
+        for (auto& key_val : params)
+        {
+            for (auto& key : parse_keys(key_val.as<String>()))
+                m_pending_keys.push_back(key);
+        }
+    }
+    else if (method == "resize")
+    {
+        if (params.size() != 2)
+            throw runtime_error("resize expects 2 parameters");
+
+        CharCoord dim{params[0].as<int>(), params[1].as<int>()};
+        m_dimensions = dim;
+        m_pending_keys.push_back(resize(dim));
+    }
+    else
+        throw runtime_error("unknown method");
+}
+
+static bool stdin_ready()
+{
+    fd_set  rfds;
+    FD_ZERO(&rfds);
+    FD_SET(0, &rfds);
+
+    timeval tv;
+    tv.tv_sec = 0;
+    tv.tv_usec = 0;
+
+    return select(1, &rfds, nullptr, nullptr, &tv) == 1;
+}
+
+void JsonUI::parse_requests(EventMode mode)
+{
+    constexpr size_t bufsize = 1024;
+    char buf[bufsize];
+    while (stdin_ready())
+    {
+        ssize_t size = read(0, buf, bufsize);
+        if (size == -1 or size == 0)
+            break;
+
+        m_requests += StringView{buf, buf + size};
+    }
+
+    if (not m_requests.empty())
+    {
+        Value json;
+        const char* pos;
+        std::tie(json, pos) = parse_json(m_requests.begin(), m_requests.end());
+        if (json)
+        {
+            try
+            {
+                eval_json(json);
+            }
+            catch (runtime_error& error)
+            {
+                write_stderr(format("error while executing request '{}': '{}'",
+                                    StringView{m_requests.begin(), pos}, error.what()));
+            }
+            m_requests = String{pos, m_requests.end()};
+        }
+    }
+
+    while (not m_pending_keys.empty())
+        m_input_callback(mode);
+}
+
+UnitTest test_json_parser{[]()
+{
+    StringView json = R"({ "jsonrpc": "2.0", "method": "keys", "params": [ "b", "l", "a", "h" ] })";
+    auto value = std::get<0>(parse_json(json.begin(), json.end()));
+    kak_assert(value);
+}};
+
+}
diff --git a/src/json_ui.hh b/src/json_ui.hh
new file mode 100644
index 00000000..563ff997
--- /dev/null
+++ b/src/json_ui.hh
@@ -0,0 +1,63 @@
+#ifndef json_ui_hh_INCLUDED
+#define json_ui_hh_INCLUDED
+
+#include "user_interface.hh"
+#include "event_manager.hh"
+#include "coord.hh"
+
+namespace Kakoune
+{
+
+class Value;
+
+class JsonUI : public UserInterface
+{
+public:
+    JsonUI();
+
+    JsonUI(const JsonUI&) = delete;
+    JsonUI& operator=(const JsonUI&) = delete;
+
+    void draw(const DisplayBuffer& display_buffer,
+              const Face& default_face) override;
+
+    void draw_status(const DisplayLine& status_line,
+                     const DisplayLine& mode_line,
+                     const Face& default_face) override;
+
+    bool is_key_available() override;
+    Key  get_key() override;
+
+    void menu_show(ConstArrayView<DisplayLine> items,
+                   CharCoord anchor, Face fg, Face bg,
+                   MenuStyle style) override;
+    void menu_select(int selected) override;
+    void menu_hide() override;
+
+    void info_show(StringView title, StringView content,
+                   CharCoord anchor, Face face,
+                   InfoStyle style) override;
+    void info_hide() override;
+
+    void refresh(bool force) override;
+
+    void set_input_callback(InputCallback callback) override;
+
+    void set_ui_options(const Options& options) override;
+
+    CharCoord dimensions() override;
+
+private:
+    void parse_requests(EventMode mode);
+    void eval_json(const Value& value);
+
+    InputCallback m_input_callback;
+    FDWatcher m_stdin_watcher;
+    Vector<Key> m_pending_keys;
+    CharCoord m_dimensions;
+    String m_requests;
+};
+
+}
+
+#endif // json_ui_hh_INCLUDED
diff --git a/src/main.cc b/src/main.cc
index 11f6c11d..0a9e713e 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -14,6 +14,7 @@
 #include "insert_completer.hh"
 #include "shared_string.hh"
 #include "ncurses_ui.hh"
+#include "json_ui.hh"
 #include "parameters_parser.hh"
 #include "register_manager.hh"
 #include "remote.hh"
@@ -60,9 +61,9 @@ void register_env_vars()
         }, {
             "buflist", false,
             [](StringView name, const Context& context)
-            { return join(transformed(BufferManager::instance(),
-                                      [](const SafePtr<Buffer>& b)
-                                      { return b->display_name(); }), ':'); }
+            { return join(BufferManager::instance() |
+                          transform([](const SafePtr<Buffer>& b)
+                                    { return b->display_name(); }), ':'); }
         }, {
             "timestamp", false,
             [](StringView name, const Context& context) -> String
@@ -261,6 +262,13 @@ struct convert_to_client_mode
     String buffer_name;
 };
 
+enum class UIType
+{
+    NCurses,
+    Json,
+    Dummy,
+};
+
 static Client* local_client = nullptr;
 static UserInterface* local_ui = nullptr;
 static bool convert_to_client_pending = false;
@@ -278,7 +286,7 @@ pid_t fork_server_to_background()
     return 0;
 }
 
-std::unique_ptr<UserInterface> create_local_ui(bool dummy_ui)
+std::unique_ptr<UserInterface> make_ui(UIType ui_type)
 {
     struct DummyUI : UserInterface
     {
@@ -295,13 +303,24 @@ std::unique_ptr<UserInterface> create_local_ui(bool dummy_ui)
         CharCoord dimensions() override { return {24,80}; }
         bool is_key_available() override { return false; }
         Key  get_key() override { return Key::Invalid; }
-        void refresh() override {}
+        void refresh(bool) override {}
         void set_input_callback(InputCallback) override {}
         void set_ui_options(const Options&) override {}
     };
 
-    if (dummy_ui)
-        return make_unique<DummyUI>();
+    switch (ui_type)
+    {
+        case UIType::NCurses: return make_unique<NCursesUI>();
+        case UIType::Json: return make_unique<JsonUI>();
+        case UIType::Dummy: return make_unique<DummyUI>();
+    }
+    throw logic_error{};
+}
+
+std::unique_ptr<UserInterface> create_local_ui(UIType ui_type)
+{
+    if (ui_type != UIType::NCurses)
+        return make_ui(ui_type);
 
     struct LocalUI : NCursesUI
     {
@@ -406,13 +425,12 @@ void signal_handler(int signal)
         abort();
 }
 
-int run_client(StringView session, StringView init_command)
+int run_client(StringView session, StringView init_command, UIType ui_type)
 {
     try
     {
         EventManager event_manager;
-        RemoteClient client{session, make_unique<NCursesUI>(),
-                            get_env_vars(), init_command};
+        RemoteClient client{session, make_ui(ui_type), get_env_vars(), init_command};
         while (true)
             event_manager.handle_next_events(EventMode::Normal);
     }
@@ -430,7 +448,7 @@ int run_client(StringView session, StringView init_command)
 }
 
 int run_server(StringView session, StringView init_command,
-               bool ignore_kakrc, bool daemon, bool dummy_ui,
+               bool ignore_kakrc, bool daemon, UIType ui_type,
                ConstArrayView<StringView> files, LineCount target_line)
 {
     static bool terminate = false;
@@ -502,7 +520,7 @@ int run_server(StringView session, StringView init_command,
     {
         // create buffers in reverse order so that the first given buffer
         // is the most recently created one.
-        for (auto& file : reversed(files))
+        for (auto& file : files | reverse())
         {
             try
             {
@@ -526,7 +544,7 @@ int run_server(StringView session, StringView init_command,
     if (not daemon)
     {
         local_client = client_manager.create_client(
-            create_local_ui(dummy_ui), get_env_vars(), init_command);
+            create_local_ui(ui_type), get_env_vars(), init_command);
 
         if (local_client)
         {
@@ -699,7 +717,7 @@ int main(int argc, char* argv[])
                    { "p", { true,  "just send stdin as commands to the given session" } },
                    { "f", { true,  "act as a filter, executing given keys on given files" } },
                    { "q", { false, "in filter mode, be quiet about errors applying keys" } },
-                   { "u", { false, "use a dummy user interface, for testing purposes" } },
+                   { "ui", { true, "set the type of user interface to use (ncurses, dummy, or json)" } },
                    { "l", { false, "list existing sessions" } } }
     };
     try
@@ -730,6 +748,17 @@ int main(int argc, char* argv[])
         }
 
         auto init_command = parser.get_switch("e").value_or(StringView{});
+        auto ui_name = parser.get_switch("ui").value_or("ncurses");
+        UIType ui_type;
+        if (ui_name == "ncurses") ui_type = UIType::NCurses;
+        else if (ui_name == "json") ui_type = UIType::Json;
+        else if (ui_name == "dummy") ui_type = UIType::Dummy;
+        else
+        {
+            write_stderr(format("error: unknown ui type: '{}'", ui_name));
+            return -1;
+        }
+
 
         if (auto keys = parser.get_switch("f"))
         {
@@ -754,7 +783,7 @@ int main(int argc, char* argv[])
             for (auto name : parser)
                 new_files += format("edit '{}';", escape(real_path(name), "'", '\\'));
 
-            return run_client(*server_session, new_files + init_command);
+            return run_client(*server_session, new_files + init_command, ui_type);
         }
         else
         {
@@ -780,15 +809,14 @@ int main(int argc, char* argv[])
                 return run_server(session, init_command,
                                   (bool)parser.get_switch("n"),
                                   (bool)parser.get_switch("d"),
-                                  (bool)parser.get_switch("u"),
-                                  files, target_line);
+                                  ui_type, files, target_line);
             }
             catch (convert_to_client_mode& convert)
             {
                 raise(SIGTSTP);
                 return run_client(convert.session,
                                   format("try %^buffer '{}'^; echo converted to client only mode",
-                                         escape(convert.buffer_name, "'^", '\\')));
+                                         escape(convert.buffer_name, "'^", '\\')), ui_type);
             }
         }
     }
diff --git a/src/ncurses_ui.cc b/src/ncurses_ui.cc
index 5309ecb8..308527f4 100644
--- a/src/ncurses_ui.cc
+++ b/src/ncurses_ui.cc
@@ -301,9 +301,12 @@ void NCursesUI::redraw()
     doupdate();
 }
 
-void NCursesUI::refresh()
+void NCursesUI::refresh(bool force)
 {
-    if (m_dirty)
+    if (force)
+        redrawwin(m_window);
+
+    if (m_dirty or force)
         redraw();
     m_dirty = false;
 }
@@ -491,11 +494,6 @@ Key NCursesUI::get_key()
 
     if (c > 0 and c < 27)
     {
-        if (c == control('l'))
-        {
-           redrawwin(m_window);
-           redraw();
-        }
         if (c == control('z'))
         {
             raise(SIGTSTP);
@@ -674,6 +672,10 @@ void NCursesUI::menu_show(ConstArrayView<DisplayLine> items,
     auto width = is_prompt ? maxsize.column : min(longest+1, maxsize.column);
     m_menu.create({line, anchor.column}, {height, width});
     draw_menu();
+
+    if (m_info)
+        info_show(m_info.title, m_info.content,
+                  m_info.anchor, m_info.face, m_info.style);
 }
 
 void NCursesUI::menu_select(int selected)
diff --git a/src/ncurses_ui.hh b/src/ncurses_ui.hh
index fdf1b6a7..870a3fc7 100644
--- a/src/ncurses_ui.hh
+++ b/src/ncurses_ui.hh
@@ -43,7 +43,7 @@ public:
                    InfoStyle style) override;
     void info_hide() override;
 
-    void refresh() override;
+    void refresh(bool force) override;
 
     void set_input_callback(InputCallback callback) override;
 
diff --git a/src/normal.cc b/src/normal.cc
index 4d95ff53..33c813f6 100644
--- a/src/normal.cc
+++ b/src/normal.cc
@@ -1560,6 +1560,15 @@ void ensure_forward(Context& context, NormalParams)
     context.selections().check_invariant();
 }
 
+void force_redraw(Context& context, NormalParams)
+{
+    if (context.has_client())
+    {
+        context.client().force_redraw();
+        context.client().redraw_ifn();
+    }
+}
+
 static NormalCmdDesc cmds[] =
 {
     { 'h', "move left", move<CharCount, Backward> },
@@ -1734,6 +1743,8 @@ static NormalCmdDesc cmds[] =
     { 'z', "restore selections", restore_selections<false> },
     { alt('z'), "append saved selections", restore_selections<true> },
     { 'Z', "save selections", save_selections },
+
+    { ctrl('l'), "force redraw", force_redraw },
 };
 
 KeyMap keymap = cmds;
diff --git a/src/remote.cc b/src/remote.cc
index e2756ef1..718d7f7d 100644
--- a/src/remote.cc
+++ b/src/remote.cc
@@ -255,7 +255,7 @@ public:
                      const DisplayLine& mode_line,
                      const Face& default_face) override;
 
-    void refresh() override;
+    void refresh(bool force) override;
 
     bool is_key_available() override;
     Key  get_key() override;
@@ -353,10 +353,11 @@ void RemoteUI::draw_status(const DisplayLine& status_line,
     msg.write(default_face);
 }
 
-void RemoteUI::refresh()
+void RemoteUI::refresh(bool force)
 {
     Message msg(m_socket_watcher.fd());
     msg.write(RemoteUIMsg::Refresh);
+    msg.write(force);
 }
 
 void RemoteUI::set_ui_options(const Options& options)
@@ -516,7 +517,7 @@ void RemoteClient::process_next_message()
         break;
     }
     case RemoteUIMsg::Refresh:
-        m_ui->refresh();
+        m_ui->refresh(read<bool>(socket));
         break;
     case RemoteUIMsg::SetOptions:
         m_ui->set_ui_options(read_idmap<String, MemoryDomain::Options>(socket));
diff --git a/src/selection.cc b/src/selection.cc
index f24b0939..90580bdd 100644
--- a/src/selection.cc
+++ b/src/selection.cc
@@ -555,8 +555,8 @@ String selection_to_string(const Selection& selection)
 
 String selection_list_to_string(const SelectionList& selections)
 {
-    return join(transformed(selections, [](const Selection& s)
-                            { return selection_to_string(s); }),
+    return join(selections | transform([](const Selection& s)
+                                       { return selection_to_string(s); }),
                 ':', false);
 }
 
diff --git a/src/selectors.cc b/src/selectors.cc
index 662cd6b0..1ca42a28 100644
--- a/src/selectors.cc
+++ b/src/selectors.cc
@@ -128,7 +128,7 @@ find_surrounding(Iterator begin, Iterator end,
     {
         using RevIt = std::reverse_iterator<Iterator>;
         auto res = find_closing(RevIt{pos+1}, RevIt{begin},
-                                reversed(closing), reversed(opening),
+                                closing | reverse(), opening | reverse(),
                                 init_level, nestable);
         if (not res)
             return {};
diff --git a/src/user_interface.hh b/src/user_interface.hh
index 67553922..e8a30a4b 100644
--- a/src/user_interface.hh
+++ b/src/user_interface.hh
@@ -63,7 +63,7 @@ public:
     virtual bool is_key_available() = 0;
     virtual Key  get_key() = 0;
 
-    virtual void refresh() = 0;
+    virtual void refresh(bool force) = 0;
 
     virtual void set_input_callback(InputCallback callback) = 0;