Rework Window creation, avoid using the same window in multiple clients

src/buffer.cc

@@ -388,18 +388,16 @@ void Buffer::erase(BufferIterator begin, BufferIterator end)
     do_erase(begin, end);
 }
 
-Window* Buffer::get_or_create_window()
+Window& Buffer::new_window()
 {
-    if (m_windows.empty())
-        m_windows.push_front(std::unique_ptr<Window>(new Window(*this)));
-
-    return m_windows.front().get();
+    m_windows.emplace_back(new Window(*this));
+    return *m_windows.back();
 }
 
-void Buffer::delete_window(Window* window)
+void Buffer::delete_window(Window& window)
 {
-    assert(&window->buffer() == this);
-    auto window_it = std::find(m_windows.begin(), m_windows.end(), window);
+    assert(&window.buffer() == this);
+    auto window_it = std::find(m_windows.begin(), m_windows.end(), &window);
     assert(window_it != m_windows.end());
     m_windows.erase(window_it);
 }

src/buffer.hh

@@ -143,8 +143,11 @@ public:
 
     const String& name() const { return m_name; }
 
-    Window* get_or_create_window();
-    void delete_window(Window* window);
+    // Window handling
+    using WindowList = std::vector<std::unique_ptr<Window>>;
+    const WindowList& windows() const { return m_windows; }
+    Window& new_window();
+    void    delete_window(Window& window);
 
     // returns true if the buffer is in a different state than
     // the last time it was saved
@@ -216,7 +219,7 @@ private:
     void apply_modification(const Modification& modification);
     void revert_modification(const Modification& modification);
 
-    std::list<std::unique_ptr<Window>> m_windows;
+    WindowList m_windows;
 
     size_t m_last_save_undo_index;
     size_t m_timestamp;

src/client_manager.cc

@@ -8,7 +8,7 @@ namespace Kakoune
 void ClientManager::create_client(std::unique_ptr<UserInterface>&& ui,
                                   Buffer& buffer, int event_fd)
 {
-    m_clients.emplace_back(std::move(ui), *buffer.get_or_create_window());
+    m_clients.emplace_back(std::move(ui), get_unused_window_for_buffer(buffer));
 
     InputHandler*  input_handler = m_clients.back().input_handler.get();
     Context*       context = m_clients.back().context.get();
@@ -43,4 +43,18 @@ void ClientManager::remove_client_by_context(Context& context)
     assert(false);
 }
 
+Window& ClientManager::get_unused_window_for_buffer(Buffer& buffer) const
+{
+    for (auto& w : buffer.windows())
+    {
+        auto it = std::find_if(m_clients.begin(), m_clients.end(),
+                               [&](const Client& client) {
+                                   return &client.context->window() == w.get();
+                               });
+        if (it == m_clients.end())
+            return *w;
+    }
+    return buffer.new_window();
+}
+
 }

src/client_manager.hh

@@ -19,6 +19,8 @@ public:
     bool   empty() const { return m_clients.empty(); }
     size_t count() const { return m_clients.size(); }
 
+    Window& get_unused_window_for_buffer(Buffer& buffer) const;
+
 private:
     struct Client
     {

src/commands.cc

@@ -282,13 +282,13 @@ void edit(const CommandParameters& params, Context& context)
     }
 
     BufferManager::instance().set_last_used_buffer(*buffer);
-    Window& window = *buffer->get_or_create_window();
+    Window& window = ClientManager::instance().get_unused_window_for_buffer(*buffer);
 
     if (param_count > 1)
     {
         int line = std::max(0, str_to_int(parser[1]) - 1);
         int column = param_count > 2 ?
-                         std::max(0, str_to_int(parser[2]) - 1) : 0;
+                     std::max(0, str_to_int(parser[2]) - 1) : 0;
 
         window.select(window.buffer().iterator_at({ line,  column }));
         window.center_selection();
@@ -378,7 +378,8 @@ void show_buffer(const CommandParameters& params, Context& context)
         throw runtime_error("buffer " + buffer_name + " does not exists");
 
     BufferManager::instance().set_last_used_buffer(*buffer);
-    context.change_editor(*buffer->get_or_create_window());
+    Window& window = ClientManager::instance().get_unused_window_for_buffer(*buffer);
+    context.change_editor(window);
 }
 
 void delete_buffer(const CommandParameters& params, Context& context)
@@ -408,7 +409,8 @@ void delete_buffer(const CommandParameters& params, Context& context)
         {
             if (buf != buffer)
             {
-               context.change_editor(*buf->get_or_create_window());
+               Window& w = ClientManager::instance().get_unused_window_for_buffer(*buf);
+               context.change_editor(w);
                break;
             }
         }