Avoid unnecessary allocations in NCursesUI::Window::draw calls

Pass an ArrayView<DisplayAtom> instead of a DisplayLine& so that
the newly common case of passing a single atom does not require
constructing a Vector.

src/display_buffer.hh

@@ -30,6 +30,9 @@ public:
     DisplayAtom(String str, Face face)
         : face(face), m_type(Text), m_text(std::move(str)) {}
 
+    explicit DisplayAtom(String str)
+        : DisplayAtom(std::move(str), Face{}) {}
+
     StringView content() const;
     ColumnCount length() const;
 

src/ncurses_ui.cc

@@ -66,10 +66,8 @@ void NCursesUI::Window::move_cursor(DisplayCoord coord)
     wmove(win, (int)coord.line, (int)coord.column);
 }
 
-void NCursesUI::Window::draw_line(Palette& palette,
-                                  const DisplayLine& line,
-                                  ColumnCount width,
-                                  const Face& default_face)
+void NCursesUI::Window::draw(Palette& palette, ConstArrayView<DisplayAtom> atoms,
+                             ColumnCount max_width, const Face& default_face)
 {
     auto add_str = [&](StringView str) { waddnstr(win, str.begin(), (int)str.length()); };
 
@@ -101,7 +99,7 @@ void NCursesUI::Window::draw_line(Palette& palette,
 
     wbkgdset(win, COLOR_PAIR(palette.get_color_pair(default_face)));
     ColumnCount column = 0;
-    for (const DisplayAtom& atom : line)
+    for (const DisplayAtom& atom : atoms)
     {
         set_face(atom.face);
 
@@ -109,7 +107,7 @@ void NCursesUI::Window::draw_line(Palette& palette,
         if (content.empty())
             continue;
 
-        const auto remaining_columns = width - column;
+        const auto remaining_columns = max_width - column;
         if (content.back() == '\n' and
             content.column_length() - 1 < remaining_columns)
         {
@@ -123,7 +121,7 @@ void NCursesUI::Window::draw_line(Palette& palette,
             column += content.column_length();
         }
     }
-    if (column < width)
+    if (column < max_width)
         wclrtoeol(win);
 }
 
@@ -465,16 +463,15 @@ void NCursesUI::draw(const DisplayBuffer& display_buffer,
     for (const DisplayLine& line : display_buffer.lines())
     {
         m_window.move_cursor(line_index);
-        m_window.draw_line(m_palette, line, dim.column, default_face);
+        m_window.draw(m_palette, line.atoms(), dim.column, default_face);
         ++line_index;
     }
 
     auto face = merge_faces(default_face, padding_face);
-    DisplayLine line("~", {});
     while (line_index < dim.line + line_offset)
     {
         m_window.move_cursor(line_index++);
-        m_window.draw_line(m_palette, line, dim.column, face);
+        m_window.draw(m_palette, DisplayAtom("~"), dim.column, face);
     }
 
     m_dirty = true;
@@ -487,7 +484,7 @@ void NCursesUI::draw_status(const DisplayLine& status_line,
     const LineCount status_line_pos = m_status_on_top ? 0 : m_dimensions.line;
     m_window.move_cursor(status_line_pos);
 
-    m_window.draw_line(m_palette, status_line, m_dimensions.column, default_face);
+    m_window.draw(m_palette, status_line.atoms(), m_dimensions.column, default_face);
 
     const auto mode_len = mode_line.length();
     m_status_len = status_line.length();
@@ -496,7 +493,7 @@ void NCursesUI::draw_status(const DisplayLine& status_line,
     {
         ColumnCount col = m_dimensions.column - mode_len;
         m_window.move_cursor({status_line_pos, col});
-        m_window.draw_line(m_palette, mode_line, m_dimensions.column - col, default_face);
+        m_window.draw(m_palette, mode_line.atoms(), m_dimensions.column - col, default_face);
     }
     else if (remaining > 2)
     {
@@ -507,7 +504,7 @@ void NCursesUI::draw_status(const DisplayLine& status_line,
 
         ColumnCount col = m_dimensions.column - remaining + 1;
         m_window.move_cursor({status_line_pos, col});
-        m_window.draw_line(m_palette, trimmed_mode_line, m_dimensions.column - col, default_face);
+        m_window.draw(m_palette, trimmed_mode_line.atoms(), m_dimensions.column - col, default_face);
     }
 
     if (m_set_title)
@@ -803,8 +800,8 @@ void NCursesUI::draw_menu()
         ColumnCount pos = 0;
 
         m_menu.move_cursor({0, 0});
-        m_menu.draw_line(m_palette, DisplayLine(m_menu.first_item > 0 ? "< " : "  ", {}),
-                         m_menu.size.column, m_menu.bg);
+        m_menu.draw(m_palette, DisplayAtom(m_menu.first_item > 0 ? "< " : "  "),
+                    m_menu.size.column, m_menu.bg);
 
         int i = m_menu.first_item;
         for (; i < item_count and pos < win_width; ++i)
@@ -812,14 +809,14 @@ void NCursesUI::draw_menu()
             const DisplayLine& item = m_menu.items[i];
             const ColumnCount item_width = item.length();
             auto& face = i == m_menu.selected_item ? m_menu.fg : m_menu.bg;
-            m_menu.draw_line(m_palette, item, win_width - pos, face);
-            m_menu.draw_line(m_palette, DisplayLine(item_width > win_width - pos ? "…" : " ", {}),
+            m_menu.draw(m_palette, item.atoms(), win_width - pos, face);
+            m_menu.draw(m_palette, DisplayAtom(item_width > win_width - pos ? "…" : " "),
                              win_width - pos - item_width, m_menu.bg);
             pos += item_width + 1;
         }
 
         auto end_str = String{' ', pos > win_width ? 0 : win_width - pos + 1} + (i == item_count ? " " : ">");
-        m_menu.draw_line(m_palette, DisplayLine(end_str, {}), m_menu.size.column - pos, m_menu.bg);
+        m_menu.draw(m_palette, DisplayAtom(end_str), m_menu.size.column - pos, m_menu.bg);
 
         m_dirty = true;
         return;
@@ -850,14 +847,14 @@ void NCursesUI::draw_menu()
             if (item_idx < item_count)
             {
                 const DisplayLine& item = m_menu.items[item_idx];
-                m_menu.draw_line(m_palette, item, column_width, face);
+                m_menu.draw(m_palette, item.atoms(), column_width, face);
                 column = item.length();
             }
-            m_menu.draw_line(m_palette, DisplayLine(String{' ', column_width - column}, {}), column_width - column, face);
+            m_menu.draw(m_palette, DisplayAtom(String{' ', column_width - column}), column_width - column, face);
         }
         const bool is_mark = line >= mark_line and line < mark_line + mark_height;
         m_menu.move_cursor({line, m_menu.size.column - 1});
-        m_menu.draw_line(m_palette, DisplayLine(is_mark ? "█" : "░", {}), 1, m_menu.bg);
+        m_menu.draw(m_palette, DisplayAtom(is_mark ? "█" : "░"), 1, m_menu.bg);
     }
     m_dirty = true;
 }
@@ -1185,7 +1182,7 @@ void NCursesUI::info_show(StringView title, StringView content,
     for (auto line = 0_line; line < info_box.size.line; ++line)
     {
         m_info.move_cursor(line);
-        m_info.draw_line(m_palette, DisplayLine(info_box.contents[(int)line], {}), info_box.size.column, face);
+        m_info.draw(m_palette, DisplayAtom(info_box.contents[(int)line]), info_box.size.column, face);
     }
     m_dirty = true;
 }

src/ncurses_ui.hh

@@ -15,6 +15,8 @@
 namespace Kakoune
 {
 
+class DisplayAtom;
+
 struct NCursesWin;
 
 class NCursesUI : public UserInterface, public Singleton<NCursesUI>
@@ -101,10 +103,8 @@ private:
         void refresh(bool force);
         void move_cursor(DisplayCoord coord);
         void mark_dirty(LineCount pos, LineCount count);
-        void draw_line(Palette& palette,
-                       const DisplayLine& line,
-                       ColumnCount width,
-                       const Face& default_face);
+        void draw(Palette& palette, ConstArrayView<DisplayAtom> atoms,
+                  ColumnCount width, const Face& default_face);
 
         explicit operator bool() const { return win; }