api: Support getting the number of a window/tabpage

In order to provide better compatibility with the classic bindings, the
API needs to provide the ability to query the number (really index) of
the window/tabpage.

This is needed for neovim/python-client#87, as discussed in
neovim/neovim#1898.

Signed-off-by: James McCoy <jamessan@jamessan.com>

5 files changed, 103 insertions, 25 deletions

diff --git a/src/nvim/api/tabpage.c b/src/nvim/api/tabpage.c
index 8b1fb041e2..fa00988ae3 100644
--- a/src/nvim/api/tabpage.c
+++ b/src/nvim/api/tabpage.c
@@ -159,6 +159,23 @@ Window nvim_tabpage_get_win(Tabpage tabpage, Error *err)
   }
 }
 
+/// Gets the tab page number
+///
+/// @param tabpage The tabpage handle
+/// @param[out] err Details of an error that may have occurred
+/// @return The tabpage number
+Integer nvim_tabpage_get_number(Tabpage tabpage, Error *err)
+{
+  Integer rv = 0;
+  tabpage_T *tab = find_tab_by_handle(tabpage, err);
+
+  if (!tab) {
+    return rv;
+  }
+
+  return tabpage_index(tab);
+}
+
 /// Checks if a tab page is valid
 ///
 /// @param tabpage The tab page handle
diff --git a/src/nvim/api/window.c b/src/nvim/api/window.c
index 166e43f698..382f65e7d9 100644
--- a/src/nvim/api/window.c
+++ b/src/nvim/api/window.c
@@ -341,6 +341,26 @@ Tabpage nvim_win_get_tabpage(Window window, Error *err)
   return rv;
 }
 
+/// Gets the window number
+///
+/// @param window The window handle
+/// @param[out] err Details of an error that may have occurred
+/// @return The window number
+Integer nvim_win_get_number(Window window, Error *err)
+{
+  Integer rv = 0;
+  win_T *win = find_window_by_handle(window, err);
+
+  if (!win) {
+    return rv;
+  }
+
+  int tabnr;
+  win_get_tabwin(window, &tabnr, (int *)&rv);
+
+  return rv;
+}
+
 /// Checks if a window is valid
 ///
 /// @param window The window handle
diff --git a/src/nvim/window.c b/src/nvim/window.c
index e9a66ad907..2cc99b8dfa 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -5716,45 +5716,46 @@ int win_getid(typval_T *argvars)
 
 int win_gotoid(typval_T *argvars)
 {
-  win_T *wp;
-  tabpage_T   *tp;
   int id = get_tv_number(&argvars[0]);
 
-  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
-    for (wp = tp == curtab ? firstwin : tp->tp_firstwin;
-         wp != NULL; wp = wp->w_next) {
-      if (wp->handle == id) {
-        goto_tabpage_win(tp, wp);
-        return 1;
-      }
+  FOR_ALL_TAB_WINDOWS(tp, wp) {
+    if (wp->handle == id) {
+      goto_tabpage_win(tp, wp);
+      return 1;
     }
   }
   return 0;
 }
 
-void win_id2tabwin(typval_T *argvars, list_T *list)
+void win_get_tabwin(handle_T id, int *tabnr, int *winnr)
 {
-  win_T *wp;
-  tabpage_T   *tp;
-  int winnr = 1;
-  int tabnr = 1;
-  int id = get_tv_number(&argvars[0]);
+  *tabnr = 0;
+  *winnr = 0;
 
-  for (tp = first_tabpage; tp != NULL; tp = tp->tp_next) {
-    for (wp = tp == curtab ? firstwin : tp->tp_firstwin;
-         wp != NULL; wp = wp->w_next) {
+  int tnum = 1, wnum = 1;
+  FOR_ALL_TABS(tp) {
+    FOR_ALL_WINDOWS_IN_TAB(wp, tp) {
       if (wp->handle == id) {
-        list_append_number(list, tabnr);
-        list_append_number(list, winnr);
+        *winnr = wnum;
+        *tabnr = tnum;
         return;
       }
-      winnr++;
+      wnum++;
     }
-    tabnr++;
-    winnr = 1;
+    tnum++;
+    wnum = 1;
   }
-  list_append_number(list, 0);
-  list_append_number(list, 0);
+}
+
+void win_id2tabwin(typval_T *argvars, list_T *list)
+{
+  int winnr = 1;
+  int tabnr = 1;
+  int id = get_tv_number(&argvars[0]);
+
+  win_get_tabwin(id, &tabnr, &winnr);
+  list_append_number(list, tabnr);
+  list_append_number(list, winnr);
 }
 
 int win_id2win(typval_T *argvars)
diff --git a/test/functional/api/tabpage_spec.lua b/test/functional/api/tabpage_spec.lua
index 47dede8b44..90940e9577 100644
--- a/test/functional/api/tabpage_spec.lua
+++ b/test/functional/api/tabpage_spec.lua
@@ -51,6 +51,22 @@ describe('tabpage_* functions', function()
     end)
   end)
 
+  describe('get_number', function()
+    it('works', function()
+      local tabs = nvim('list_tabpages')
+      eq(1, tabpage('get_number', tabs[1]))
+
+      nvim('command', 'tabnew')
+      local tab1, tab2 = unpack(nvim('list_tabpages'))
+      eq(1, tabpage('get_number', tab1))
+      eq(2, tabpage('get_number', tab2))
+
+      nvim('command', '-tabmove')
+      eq(2, tabpage('get_number', tab1))
+      eq(1, tabpage('get_number', tab2))
+    end)
+  end)
+
   describe('is_valid', function()
     it('works', function()
       nvim('command', 'tabnew')
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index 2c43e4db2c..bf2bf55fb3 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -200,6 +200,30 @@ describe('window_* functions', function()
     end)
   end)
 
+  describe('get_number', function()
+    it('works', function()
+      local wins = nvim('list_wins')
+      eq(1, window('get_number', wins[1]))
+
+      nvim('command', 'split')
+      local win1, win2 = unpack(nvim('list_wins'))
+      eq(1, window('get_number', win1))
+      eq(2, window('get_number', win2))
+
+      nvim('command', 'wincmd J')
+      eq(2, window('get_number', win1))
+      eq(1, window('get_number', win2))
+
+      nvim('command', 'tabnew')
+      local win3 = nvim('list_wins')[3]
+      -- First tab page
+      eq(2, window('get_number', win1))
+      eq(1, window('get_number', win2))
+      -- Second tab page
+      eq(1, window('get_number', win3))
+    end)
+  end)
+
   describe('is_valid', function()
     it('works', function()
       nvim('command', 'split')