vim-patch:8.1.1140: not easy to find out what neighbors a window has (#9873)

Problem:    Not easy to find out what neighbors a window has.
Solution:   Add more arguments to winnr(). (Yegappan Lakshmanan)

https://github.com/vim/vim/commit/46ad288b9b2a6eb0430cf802ff5ce68a58629897

3 files changed, 141 insertions, 39 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 9a67b01307..86333acbef 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -16755,6 +16755,7 @@ static int get_winnr(tabpage_T *tp, typval_T *argvar)
 
   twin = (tp == curtab) ? curwin : tp->tp_curwin;
   if (argvar->v_type != VAR_UNKNOWN) {
+    bool invalid_arg = false;
     const char *const arg = tv_get_string_chk(argvar);
     if (arg == NULL) {
       nr = 0;  // Type error; errmsg already given.
@@ -16766,6 +16767,31 @@ static int get_winnr(tabpage_T *tp, typval_T *argvar)
         nr = 0;
       }
     } else {
+      // Extract the window count (if specified). e.g. winnr('3j')
+      char_u *endp;
+      long count = strtol((char *)arg, (char **)&endp, 10);
+      if (count <= 0) {
+        // if count is not specified, default to 1
+        count = 1;
+      }
+      if (endp != NULL && *endp != '\0') {
+        if (strequal((char *)endp, "j")) {
+          twin = win_vert_neighbor(tp, twin, false, count);
+        } else if (strequal((char *)endp, "k")) {
+          twin = win_vert_neighbor(tp, twin, true, count);
+        } else if (strequal((char *)endp, "h")) {
+          twin = win_horz_neighbor(tp, twin, true, count);
+        } else if (strequal((char *)endp, "l")) {
+          twin = win_horz_neighbor(tp, twin, false, count);
+        } else {
+          invalid_arg = true;
+        }
+      } else {
+        invalid_arg = true;
+      }
+    }
+
+    if (invalid_arg) {
       EMSG2(_(e_invexpr2), arg);
       nr = 0;
     }
diff --git a/src/nvim/testdir/test_window_cmd.vim b/src/nvim/testdir/test_window_cmd.vim
index 57fb36abb8..d3b496635d 100644
--- a/src/nvim/testdir/test_window_cmd.vim
+++ b/src/nvim/testdir/test_window_cmd.vim
@@ -646,4 +646,49 @@ func Test_relative_cursor_second_line_after_resize()
   let &so = so_save
 endfunc
 
+" Tests for the winnr() function
+func Test_winnr()
+  only | tabonly
+  call assert_equal(1, winnr('j'))
+  call assert_equal(1, winnr('k'))
+  call assert_equal(1, winnr('h'))
+  call assert_equal(1, winnr('l'))
+
+  " create a set of horizontally and vertically split windows
+  leftabove new | wincmd p
+  leftabove new | wincmd p
+  rightbelow new | wincmd p
+  rightbelow new | wincmd p
+  leftabove vnew | wincmd p
+  leftabove vnew | wincmd p
+  rightbelow vnew | wincmd p
+  rightbelow vnew | wincmd p
+
+  call assert_equal(8, winnr('j'))
+  call assert_equal(2, winnr('k'))
+  call assert_equal(4, winnr('h'))
+  call assert_equal(6, winnr('l'))
+  call assert_equal(9, winnr('2j'))
+  call assert_equal(1, winnr('2k'))
+  call assert_equal(3, winnr('2h'))
+  call assert_equal(7, winnr('2l'))
+
+  " Error cases
+  call assert_fails("echo winnr('0.2k')", 'E15:')
+  call assert_equal(2, winnr('-2k'))
+  call assert_fails("echo winnr('-2xj')", 'E15:')
+  call assert_fails("echo winnr('j2j')", 'E15:')
+  call assert_fails("echo winnr('ll')", 'E15:')
+  call assert_fails("echo winnr('5')", 'E15:')
+  call assert_equal(4, winnr('0h'))
+
+  tabnew
+  call assert_equal(8, tabpagewinnr(1, 'j'))
+  call assert_equal(2, tabpagewinnr(1, 'k'))
+  call assert_equal(4, tabpagewinnr(1, 'h'))
+  call assert_equal(6, tabpagewinnr(1, 'l'))
+
+  only | tabonly
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/nvim/window.c b/src/nvim/window.c
index e135d7436d..237338f974 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -4019,24 +4019,25 @@ tabpage_T *win_find_tabpage(win_T *win)
   return NULL;
 }
 
-/*
- * Move to window above or below "count" times.
- */
-static void 
-win_goto_ver (
-    int up,                         /* TRUE to go to win above */
-    long count
-)
+/// Get the above or below neighbor window of the specified window.
+///
+/// Returns the specified window if the neighbor is not found.
+/// Returns the previous window if the specifiecied window is a floating window.
+///
+/// @param up     true for the above neighbor
+/// @param count  nth neighbor window
+///
+/// @return       found window
+win_T *win_vert_neighbor(tabpage_T *tp, win_T *wp, bool up, long count)
 {
   frame_T     *fr;
   frame_T     *nfr;
   frame_T     *foundfr;
 
-  foundfr = curwin->w_frame;
+  foundfr = wp->w_frame;
 
-  if (curwin->w_floating) {
-    win_goto(prevwin);
-    return;
+  if (wp->w_floating) {
+    return prevwin;
   }
 
   while (count--) {
@@ -4046,14 +4047,17 @@ win_goto_ver (
      */
     fr = foundfr;
     for (;; ) {
-      if (fr == topframe)
+      if (fr == tp->tp_topframe) {
         goto end;
-      if (up)
+      }
+      if (up) {
         nfr = fr->fr_prev;
-      else
+      } else {
         nfr = fr->fr_next;
-      if (fr->fr_parent->fr_layout == FR_COL && nfr != NULL)
+      }
+      if (fr->fr_parent->fr_layout == FR_COL && nfr != NULL) {
         break;
+      }
       fr = fr->fr_parent;
     }
 
@@ -4067,11 +4071,12 @@ win_goto_ver (
       }
       fr = nfr->fr_child;
       if (nfr->fr_layout == FR_ROW) {
-        /* Find the frame at the cursor row. */
+        // Find the frame at the cursor row.
         while (fr->fr_next != NULL
                && frame2win(fr)->w_wincol + fr->fr_width
-               <= curwin->w_wincol + curwin->w_wcol)
+               <= wp->w_wincol + wp->w_wcol) {
           fr = fr->fr_next;
+        }
       }
       if (nfr->fr_layout == FR_COL && up)
         while (fr->fr_next != NULL)
@@ -4080,28 +4085,40 @@ win_goto_ver (
     }
   }
 end:
-  if (foundfr != NULL)
-    win_goto(foundfr->fr_win);
+  return foundfr != NULL ? foundfr->fr_win : NULL;
 }
 
-/*
- * Move to left or right window.
- */
-static void 
-win_goto_hor (
-    int left,                       /* TRUE to go to left win */
-    long count
-)
+/// Move to window above or below "count" times.
+///
+/// @param up     true to go to win above
+/// @param count  go count times into direction
+static void win_goto_ver(bool up, long count)
+{
+  win_T *win = win_vert_neighbor(curtab, curwin, up, count);
+  if (win != NULL) {
+    win_goto(win);
+  }
+}
+
+/// Get the left or right neighbor window of the specified window.
+///
+/// Returns the specified window if the neighbor is not found.
+/// Returns the previous window if the specifiecied window is a floating window.
+///
+/// @param left  true for the left neighbor
+/// @param count nth neighbor window
+///
+/// @return      found window
+win_T *win_horz_neighbor(tabpage_T *tp, win_T *wp, bool left, long count)
 {
   frame_T     *fr;
   frame_T     *nfr;
   frame_T     *foundfr;
 
-  foundfr = curwin->w_frame;
+  foundfr = wp->w_frame;
 
-  if (curwin->w_floating) {
-    win_goto(prevwin);
-    return;
+  if (wp->w_floating) {
+    return prevwin;
   }
 
   while (count--) {
@@ -4111,14 +4128,17 @@ win_goto_hor (
      */
     fr = foundfr;
     for (;; ) {
-      if (fr == topframe)
+      if (fr == tp->tp_topframe) {
         goto end;
-      if (left)
+      }
+      if (left) {
         nfr = fr->fr_prev;
-      else
+      } else {
         nfr = fr->fr_next;
-      if (fr->fr_parent->fr_layout == FR_ROW && nfr != NULL)
+      }
+      if (fr->fr_parent->fr_layout == FR_ROW && nfr != NULL) {
         break;
+      }
       fr = fr->fr_parent;
     }
 
@@ -4135,7 +4155,7 @@ win_goto_hor (
         /* Find the frame at the cursor row. */
         while (fr->fr_next != NULL
                && frame2win(fr)->w_winrow + fr->fr_height
-               <= curwin->w_winrow + curwin->w_wrow)
+               <= wp->w_winrow + wp->w_wrow)
           fr = fr->fr_next;
       }
       if (nfr->fr_layout == FR_ROW && left)
@@ -4145,8 +4165,19 @@ win_goto_hor (
     }
   }
 end:
-  if (foundfr != NULL)
-    win_goto(foundfr->fr_win);
+  return foundfr != NULL ? foundfr->fr_win : NULL;
+}
+
+/// Move to left or right window.
+///
+/// @param left   true to go to left window
+/// @param count  go count times into direction
+static void win_goto_hor(bool left, long count)
+{
+  win_T *win = win_horz_neighbor(curtab, curwin, left, count);
+  if (win != NULL) {
+    win_goto(win);
+  }
 }
 
 /*