Buffer: support creation of temporary windows to apply commands when no windows are in context

src/buffer.cc

@@ -243,6 +243,11 @@ void Buffer::delete_window(Window* window)
     m_windows.erase(window_it);
 }
 
+std::unique_ptr<Window> Buffer::create_temporary_window()
+{
+    return std::unique_ptr<Window>(new Window(*this));
+}
+
 bool Buffer::is_modified() const
 {
     size_t history_cursor_index = m_history_cursor - m_history.begin();

src/buffer.hh

@@ -151,6 +151,8 @@ public:
     Window* get_or_create_window();
     void delete_window(Window* window);
 
+    std::unique_ptr<Window> create_temporary_window();
+
     bool is_modified() const;
     Type type() const { return m_type; }
     void notify_saved();

src/main.cc

@@ -1048,6 +1048,12 @@ void exec_string(const CommandParameters& params,
         return keys[pos++];
     };
 
+    std::unique_ptr<Window> temp_window;
+    if (not context.has_window())
+       temp_window = context.buffer().create_temporary_window();
+
+    Window& window = context.has_window() ? context.window() : *temp_window;
+
     int count = 0;
     while(pos < keys.size())
     {
@@ -1059,7 +1065,7 @@ void exec_string(const CommandParameters& params,
         {
             auto it = keymap.find(key);
             if (it != keymap.end())
-                it->second(context.window(), count);
+                it->second(window, count);
             count = 0;
         }
     }