refactor(ui): devirtualize the ui layer

- The defined interface for the UI is only the RPC protocol. The original
  UI interface as an array of function pointers fill no function.
- On the server, all the UI:s are all RPC channels.
  - ui.c is only used on the server.
  - The compositor is a preprocessing step for single-grid UI:s
- on the client, ui_client and tui talk directly to each other
  - we still do module separation, as ui_client.c could form the basis
    of a libnvim client module later.

Items for later PR:s
- vim.ui_attach is still an unhappy child, reconsider based on plugin experience.
- the flags in ui_events.in.h are still a mess. Can be simplified now.
- UX for remote attachment needs more work.
- startup for client can be simplified further (think of the millisecs we can save)

3 files changed, 33 insertions, 94 deletions

diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index e4134133ac..32b294c0ce 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -29,41 +29,6 @@
 #include "nvim/vim.h"
 #include "nvim/window.h"
 
-typedef struct {
-  uint64_t channel_id;
-
-#define UI_BUF_SIZE 4096  ///< total buffer size for pending msgpack data.
-  /// guaranteed size available for each new event (so packing of simple events
-  /// and the header of grid_line will never fail)
-#define EVENT_BUF_SIZE 256
-  char buf[UI_BUF_SIZE];  ///< buffer of packed but not yet sent msgpack data
-  char *buf_wptr;  ///< write head of buffer
-  const char *cur_event;  ///< name of current event (might get multiple arglists)
-  Array call_buf;  ///< buffer for constructing a single arg list (max 16 elements!)
-
-  // state for write_cb, while packing a single arglist to msgpack. This
-  // might fail due to buffer overflow.
-  size_t pack_totlen;
-  bool buf_overflow;
-  char *temp_buf;
-
-  // We start packing the two outermost msgpack arrays before knowing the total
-  // number of elements. Thus track the location where array size will need
-  // to be written in the msgpack buffer, once the specific array is finished.
-  char *nevents_pos;
-  char *ncalls_pos;
-  uint32_t nevents;  ///< number of distinct events (top-level args to "redraw"
-  uint32_t ncalls;  ///< number of calls made to the current event (plus one for the name!)
-  bool flushed_events;  ///< events where sent to client without "flush" event
-
-  int hl_id;  // Current highlight for legacy put event.
-  Integer cursor_row, cursor_col;  // Intended visible cursor position.
-
-  // Position of legacy cursor, used both for drawing and visible user cursor.
-  Integer client_row, client_col;
-  bool wildmenu_active;
-} UIData;
-
 #define BUF_POS(data) ((size_t)((data)->buf_wptr - (data)->buf))
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
@@ -143,8 +108,6 @@ void remote_ui_disconnect(uint64_t channel_id)
   UIData *data = ui->data;
   kv_destroy(data->call_buf);
   pmap_del(uint64_t)(&connected_uis, channel_id);
-  xfree(data);
-  ui->data = NULL;  // Flag UI as "stopped".
   ui_detach_impl(ui, channel_id);
   xfree(ui);
 }
@@ -204,32 +167,6 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height, Dictiona
   ui->pum_col = -1.0;
   ui->rgb = true;
   ui->override = false;
-  ui->grid_resize = remote_ui_grid_resize;
-  ui->grid_clear = remote_ui_grid_clear;
-  ui->grid_cursor_goto = remote_ui_grid_cursor_goto;
-  ui->mode_info_set = remote_ui_mode_info_set;
-  ui->update_menu = remote_ui_update_menu;
-  ui->busy_start = remote_ui_busy_start;
-  ui->busy_stop = remote_ui_busy_stop;
-  ui->mouse_on = remote_ui_mouse_on;
-  ui->mouse_off = remote_ui_mouse_off;
-  ui->mode_change = remote_ui_mode_change;
-  ui->grid_scroll = remote_ui_grid_scroll;
-  ui->hl_attr_define = remote_ui_hl_attr_define;
-  ui->hl_group_set = remote_ui_hl_group_set;
-  ui->raw_line = remote_ui_raw_line;
-  ui->bell = remote_ui_bell;
-  ui->visual_bell = remote_ui_visual_bell;
-  ui->default_colors_set = remote_ui_default_colors_set;
-  ui->flush = remote_ui_flush;
-  ui->suspend = remote_ui_suspend;
-  ui->set_title = remote_ui_set_title;
-  ui->set_icon = remote_ui_set_icon;
-  ui->option_set = remote_ui_option_set;
-  ui->msg_set_pos = remote_ui_msg_set_pos;
-  ui->event = remote_ui_event;
-  ui->inspect = remote_ui_inspect;
-  ui->win_viewport = remote_ui_win_viewport;
 
   CLEAR_FIELD(ui->ui_ext);
 
@@ -252,7 +189,7 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height, Dictiona
     ui->ui_ext[kUICmdline] = true;
   }
 
-  UIData *data = xmalloc(sizeof(UIData));
+  UIData *data = ui->data;
   data->channel_id = channel_id;
   data->cur_event = NULL;
   data->hl_id = 0;
@@ -267,7 +204,6 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height, Dictiona
   data->wildmenu_active = false;
   data->call_buf = (Array)ARRAY_DICT_INIT;
   kv_ensure_space(data->call_buf, 16);
-  ui->data = data;
 
   pmap_put(uint64_t)(&connected_uis, channel_id, ui);
   ui_attach_impl(ui, channel_id);
@@ -313,6 +249,10 @@ void nvim_ui_detach(uint64_t channel_id, Error *err)
   remote_ui_disconnect(channel_id);
 }
 
+// TODO(bfredl): use me to detach a specifc ui from the server
+void remote_ui_stop(UI *ui)
+{}
+
 void nvim_ui_try_resize(uint64_t channel_id, Integer width, Integer height, Error *err)
   FUNC_API_SINCE(1) FUNC_API_REMOTE_ONLY
 {
@@ -684,7 +624,7 @@ static void push_call(UI *ui, const char *name, Array args)
   data->ncalls++;
 }
 
-static void remote_ui_grid_clear(UI *ui, Integer grid)
+void remote_ui_grid_clear(UI *ui, Integer grid)
 {
   UIData *data = ui->data;
   Array args = data->call_buf;
@@ -695,7 +635,7 @@ static void remote_ui_grid_clear(UI *ui, Integer grid)
   push_call(ui, name, args);
 }
 
-static void remote_ui_grid_resize(UI *ui, Integer grid, Integer width, Integer height)
+void remote_ui_grid_resize(UI *ui, Integer grid, Integer width, Integer height)
 {
   UIData *data = ui->data;
   Array args = data->call_buf;
@@ -708,8 +648,8 @@ static void remote_ui_grid_resize(UI *ui, Integer grid, Integer width, Integer h
   push_call(ui, name, args);
 }
 
-static void remote_ui_grid_scroll(UI *ui, Integer grid, Integer top, Integer bot, Integer left,
-                                  Integer right, Integer rows, Integer cols)
+void remote_ui_grid_scroll(UI *ui, Integer grid, Integer top, Integer bot, Integer left,
+                           Integer right, Integer rows, Integer cols)
 {
   UIData *data = ui->data;
   if (ui->ui_ext[kUILinegrid]) {
@@ -745,8 +685,8 @@ static void remote_ui_grid_scroll(UI *ui, Integer grid, Integer top, Integer bot
   }
 }
 
-static void remote_ui_default_colors_set(UI *ui, Integer rgb_fg, Integer rgb_bg, Integer rgb_sp,
-                                         Integer cterm_fg, Integer cterm_bg)
+void remote_ui_default_colors_set(UI *ui, Integer rgb_fg, Integer rgb_bg, Integer rgb_sp,
+                                  Integer cterm_fg, Integer cterm_bg)
 {
   if (!ui->ui_ext[kUITermColors]) {
     HL_SET_DEFAULT_COLORS(rgb_fg, rgb_bg, rgb_sp);
@@ -776,8 +716,8 @@ static void remote_ui_default_colors_set(UI *ui, Integer rgb_fg, Integer rgb_bg,
   }
 }
 
-static void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAttrs cterm_attrs,
-                                     Array info)
+void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAttrs cterm_attrs,
+                              Array info)
 {
   if (!ui->ui_ext[kUILinegrid]) {
     return;
@@ -802,7 +742,7 @@ static void remote_ui_hl_attr_define(UI *ui, Integer id, HlAttrs rgb_attrs, HlAt
   push_call(ui, "hl_attr_define", args);
 }
 
-static void remote_ui_highlight_set(UI *ui, int id)
+void remote_ui_highlight_set(UI *ui, int id)
 {
   UIData *data = ui->data;
   Array args = data->call_buf;
@@ -818,7 +758,7 @@ static void remote_ui_highlight_set(UI *ui, int id)
 }
 
 /// "true" cursor used only for input focus
-static void remote_ui_grid_cursor_goto(UI *ui, Integer grid, Integer row, Integer col)
+void remote_ui_grid_cursor_goto(UI *ui, Integer grid, Integer row, Integer col)
 {
   if (ui->ui_ext[kUILinegrid]) {
     UIData *data = ui->data;
@@ -836,7 +776,7 @@ static void remote_ui_grid_cursor_goto(UI *ui, Integer grid, Integer row, Intege
 }
 
 /// emulated cursor used both for drawing and for input focus
-static void remote_ui_cursor_goto(UI *ui, Integer row, Integer col)
+void remote_ui_cursor_goto(UI *ui, Integer row, Integer col)
 {
   UIData *data = ui->data;
   if (data->client_row == row && data->client_col == col) {
@@ -850,7 +790,7 @@ static void remote_ui_cursor_goto(UI *ui, Integer row, Integer col)
   push_call(ui, "cursor_goto", args);
 }
 
-static void remote_ui_put(UI *ui, const char *cell)
+void remote_ui_put(UI *ui, const char *cell)
 {
   UIData *data = ui->data;
   data->client_col++;
@@ -859,9 +799,9 @@ static void remote_ui_put(UI *ui, const char *cell)
   push_call(ui, "put", args);
 }
 
-static void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Integer endcol,
-                               Integer clearcol, Integer clearattr, LineFlags flags,
-                               const schar_T *chunk, const sattr_T *attrs)
+void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startcol, Integer endcol,
+                        Integer clearcol, Integer clearattr, LineFlags flags, const schar_T *chunk,
+                        const sattr_T *attrs)
 {
   UIData *data = ui->data;
   if (ui->ui_ext[kUILinegrid]) {
@@ -953,7 +893,7 @@ static void remote_ui_raw_line(UI *ui, Integer grid, Integer row, Integer startc
 ///
 /// This might happen multiple times before the actual ui_flush, if the
 /// total redraw size is large!
-static void remote_ui_flush_buf(UI *ui)
+void remote_ui_flush_buf(UI *ui)
 {
   UIData *data = ui->data;
   if (!data->nevents_pos) {
@@ -980,7 +920,7 @@ static void remote_ui_flush_buf(UI *ui)
 ///
 /// Clients can know this happened by a final "flush" event at the end of the
 /// "redraw" batch.
-static void remote_ui_flush(UI *ui)
+void remote_ui_flush(UI *ui)
 {
   UIData *data = ui->data;
   if (data->nevents > 0 || data->flushed_events) {
@@ -1025,7 +965,7 @@ static Array translate_firstarg(UI *ui, Array args, Arena *arena)
   return new_args;
 }
 
-static void remote_ui_event(UI *ui, char *name, Array args)
+void remote_ui_event(UI *ui, char *name, Array args)
 {
   Arena arena = ARENA_EMPTY;
   UIData *data = ui->data;
@@ -1092,7 +1032,7 @@ free_ret:
   arena_mem_free(arena_finish(&arena));
 }
 
-static void remote_ui_inspect(UI *ui, Dictionary *info)
+void remote_ui_inspect(UI *ui, Dictionary *info)
 {
   UIData *data = ui->data;
   PUT(*info, "chan", INTEGER_OBJ((Integer)data->channel_id));
diff --git a/src/nvim/api/ui.h b/src/nvim/api/ui.h
index bc70406acb..b3fe0fa2bb 100644
--- a/src/nvim/api/ui.h
+++ b/src/nvim/api/ui.h
@@ -5,8 +5,10 @@
 
 #include "nvim/api/private/defs.h"
 #include "nvim/map.h"
+#include "nvim/ui.h"
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "api/ui.h.generated.h"
+# include "ui_events_remote.h.generated.h"
 #endif
 #endif  // NVIM_API_UI_H
diff --git a/src/nvim/api/ui_events.in.h b/src/nvim/api/ui_events.in.h
index d5c79272b7..a08e8dbfeb 100644
--- a/src/nvim/api/ui_events.in.h
+++ b/src/nvim/api/ui_events.in.h
@@ -37,7 +37,7 @@ void set_title(String title)
 void set_icon(String icon)
   FUNC_API_SINCE(3);
 void screenshot(String path)
-  FUNC_API_SINCE(7) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(7);
 void option_set(String name, Object value)
   FUNC_API_SINCE(4);
 // Stop event is not exported as such, represented by EOF in the msgpack stream.
@@ -75,7 +75,7 @@ void default_colors_set(Integer rgb_fg, Integer rgb_bg, Integer rgb_sp, Integer
 void hl_attr_define(Integer id, HlAttrs rgb_attrs, HlAttrs cterm_attrs, Array info)
   FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL;
 void hl_group_set(String name, Integer id)
-  FUNC_API_SINCE(6);
+  FUNC_API_SINCE(6) FUNC_API_CLIENT_IGNORE;
 void grid_resize(Integer grid, Integer width, Integer height)
   FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_COMPOSITOR_IMPL FUNC_API_CLIENT_IMPL;
 void grid_clear(Integer grid)
@@ -97,9 +97,6 @@ void raw_line(Integer grid, Integer row, Integer startcol, Integer endcol, Integ
               Integer clearattr, LineFlags flags, const schar_T *chunk, const sattr_T *attrs)
   FUNC_API_NOEXPORT FUNC_API_COMPOSITOR_IMPL;
 
-void event(char *name, Array args)
-  FUNC_API_NOEXPORT FUNC_API_COMPOSITOR_IMPL;
-
 void win_pos(Integer grid, Window win, Integer startrow, Integer startcol, Integer width,
              Integer height)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
@@ -114,11 +111,11 @@ void win_close(Integer grid)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
 
 void msg_set_pos(Integer grid, Integer row, Boolean scrolled, String sep_char)
-  FUNC_API_SINCE(6) FUNC_API_COMPOSITOR_IMPL;
+  FUNC_API_SINCE(6) FUNC_API_COMPOSITOR_IMPL FUNC_API_CLIENT_IGNORE;
 
 void win_viewport(Integer grid, Window win, Integer topline, Integer botline, Integer curline,
                   Integer curcol, Integer line_count)
-  FUNC_API_SINCE(7) FUNC_API_BRIDGE_IMPL;
+  FUNC_API_SINCE(7) FUNC_API_CLIENT_IGNORE;
 
 void win_extmark(Integer grid, Window win, Integer ns_id, Integer mark_id, Integer row, Integer col)
   FUNC_API_SINCE(10) FUNC_API_REMOTE_ONLY;
@@ -150,11 +147,11 @@ void cmdline_block_hide(void)
   FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 
 void wildmenu_show(Array items)
-  FUNC_API_SINCE(3) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 void wildmenu_select(Integer selected)
-  FUNC_API_SINCE(3) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 void wildmenu_hide(void)
-  FUNC_API_SINCE(3) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(3) FUNC_API_REMOTE_ONLY;
 
 void msg_show(String kind, Array content, Boolean replace_last)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;