vim-patch:8.0.1039: cannot change a line in not current buffer

Problem:    Cannot change a line in a buffer other than the current one.
Solution:   Add setbufline(). (Yasuhiro Matsumoto, Ozaki Kiichi, closes vim/vim#1953)
b31cf2bb0b

runtime/doc/eval.txt

@@ -2286,6 +2286,9 @@ searchpos({pattern} [, {flags} [, {stopline} [, {timeout}]]])
 server2client({clientid}, {string})
 				Number	send reply string
 serverlist()			String	get a list of available servers
+setbufline( {expr}, {lnum}, {line})
+				Number	set line {lnum} to {line} in buffer
+					{expr}
 setbufvar({expr}, {varname}, {val})	set {varname} in buffer {expr} to {val}
 setcharsearch({dict})		Dict	set character search from {dict}
 setcmdpos({pos})		Number	set cursor position in command-line
@@ -6997,6 +7000,19 @@ serverstop({address})					*serverstop()*
 		If |v:servername| is stopped it is set to the next available
 		address returned by |serverlist()|.
 
+setbufline({expr}, {lnum}, {text})			*setbufline()*
+		Set line {lnum} to {text} in buffer {expr}.  To insert
+		lines use |append()|.
+
+		For the use of {expr}, see |bufname()| above.
+
+		{lnum} is used like with |setline()|.
+		This works like |setline()| for the specified buffer.
+		On success 0 is returned, on failure 1 is returned.
+
+		If {expr} is not a valid buffer or {lnum} is not valid, an
+		error message is given.
+
 setbufvar({expr}, {varname}, {val})			*setbufvar()*
 		Set option or local variable {varname} in buffer {expr} to
 		{val}.
@@ -7064,13 +7080,19 @@ setfperm({fname}, {mode})				*setfperm()* *chmod*
 
 setline({lnum}, {text})					*setline()*
 		Set line {lnum} of the current buffer to {text}.  To insert
-		lines use |append()|.
+		lines use |append()|. To set lines in another buffer use
+		|setbufline()|.
+
 		{lnum} is used like with |getline()|.
 		When {lnum} is just below the last line the {text} will be
 		added as a new line.
+
 		If this succeeds, 0 is returned.  If this fails (most likely
-		because {lnum} is invalid) 1 is returned.  Example: >
+		because {lnum} is invalid) 1 is returned.
+
+		Example: >
 			:call setline(5, strftime("%c"))
+
 <		When {text} is a |List| then line {lnum} and following lines
 		will be set to the items in the list.  Example: >
 			:call setline(5, ['aaa', 'bbb', 'ccc'])

src/nvim/eval.c

@@ -14843,6 +14843,105 @@ static void f_serverstop(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   }
 }
 
+/// Set line or list of lines in buffer "buf".
+static void set_buffer_lines(buf_T *buf, linenr_T lnum, typval_T *lines,
+                             typval_T *rettv)
+{
+  list_T      *l = NULL;
+  listitem_T  *li = NULL;
+  long        added = 0;
+  linenr_T    lcount;
+  buf_T       *curbuf_save;
+  int         is_curbuf = buf == curbuf;
+
+  if (buf == NULL || buf->b_ml.ml_mfp == NULL || lnum < 1) {
+    rettv->vval.v_number = 1;  // FAIL
+    return;
+  }
+
+  curbuf_save = curbuf;
+  curbuf = buf;
+
+  lcount = curbuf->b_ml.ml_line_count;
+
+  const char *line = NULL;
+
+  if (lines->v_type == VAR_LIST) {
+    l = lines->vval.v_list;
+    li = tv_list_first(l);
+  } else {
+    line = tv_get_string_chk(lines);
+  }
+
+  // Default result is zero == OK.
+  for (;; ) {
+    if (lines->v_type == VAR_LIST) {
+      // List argument, get next string.
+      if (li == NULL) {
+        break;
+      }
+      line = tv_get_string_chk(TV_LIST_ITEM_TV(li));
+      li = TV_LIST_ITEM_NEXT(l, li);
+    }
+
+    rettv->vval.v_number = 1;  // FAIL
+    if (line == NULL || lnum < 1 || lnum > curbuf->b_ml.ml_line_count + 1) {
+      break;
+    }
+
+    /* When coming here from Insert mode, sync undo, so that this can be
+     * undone separately from what was previously inserted. */
+    if (u_sync_once == 2) {
+      u_sync_once = 1;       /* notify that u_sync() was called */
+      u_sync(TRUE);
+    }
+
+    if (lnum <= curbuf->b_ml.ml_line_count) {
+      // Existing line, replace it.
+      if (u_savesub(lnum) == OK
+          && ml_replace(lnum, (char_u *)line, true) == OK) {
+        changed_bytes(lnum, 0);
+        if (is_curbuf && lnum == curwin->w_cursor.lnum) {
+          check_cursor_col();
+        }
+        rettv->vval.v_number = 0;  // OK
+      }
+    } else if (added > 0 || u_save(lnum - 1, lnum) == OK) {
+      // lnum is one past the last line, append the line.
+      added++;
+      if (ml_append(lnum - 1, (char_u *)line, 0, false) == OK) {
+        rettv->vval.v_number = 0;  // OK
+      }
+    }
+
+    if (l == NULL)                      /* only one string argument */
+      break;
+    ++lnum;
+  }
+
+  if (added > 0) {
+    appended_lines_mark(lcount, added);
+  }
+
+  curbuf = curbuf_save;
+}
+
+/// "setbufline()" function
+static void f_setbufline(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+    linenr_T lnum;
+    buf_T    *buf;
+
+    buf = tv_get_buf(&argvars[0], false);
+    if (buf == NULL) {
+      rettv->vval.v_number = 1;  // FAIL
+    } else {
+      lnum = tv_get_lnum_buf(&argvars[1], buf);
+
+      set_buffer_lines(buf, lnum, &argvars[2], rettv);
+    }
+}
+
 /*
  * "setbufvar()" function
  */
@@ -14975,67 +15074,8 @@ static void f_setfperm(typval_T *argvars, typval_T *rettv, FunPtr fptr)
  */
 static void f_setline(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  list_T      *l = NULL;
-  listitem_T  *li = NULL;
-  long added = 0;
-  linenr_T lcount = curbuf->b_ml.ml_line_count;
-
   linenr_T lnum = tv_get_lnum(&argvars[0]);
-  const char *line = NULL;
-  if (argvars[1].v_type == VAR_LIST) {
-    l = argvars[1].vval.v_list;
-    li = tv_list_first(l);
-  } else {
-    line = tv_get_string_chk(&argvars[1]);
-  }
-
-  // Default result is zero == OK.
-  for (;; ) {
-    if (argvars[1].v_type == VAR_LIST) {
-      // List argument, get next string.
-      if (li == NULL) {
-        break;
-      }
-      line = tv_get_string_chk(TV_LIST_ITEM_TV(li));
-      li = TV_LIST_ITEM_NEXT(l, li);
-    }
-
-    rettv->vval.v_number = 1;  // FAIL
-    if (line == NULL || lnum < 1 || lnum > curbuf->b_ml.ml_line_count + 1) {
-      break;
-    }
-
-    /* When coming here from Insert mode, sync undo, so that this can be
-     * undone separately from what was previously inserted. */
-    if (u_sync_once == 2) {
-      u_sync_once = 1;       /* notify that u_sync() was called */
-      u_sync(TRUE);
-    }
-
-    if (lnum <= curbuf->b_ml.ml_line_count) {
-      // Existing line, replace it.
-      if (u_savesub(lnum) == OK
-          && ml_replace(lnum, (char_u *)line, true) == OK) {
-        changed_bytes(lnum, 0);
-        if (lnum == curwin->w_cursor.lnum)
-          check_cursor_col();
-        rettv->vval.v_number = 0;               /* OK */
-      }
-    } else if (added > 0 || u_save(lnum - 1, lnum) == OK) {
-      // lnum is one past the last line, append the line.
-      added++;
-      if (ml_append(lnum - 1, (char_u *)line, 0, false) == OK) {
-        rettv->vval.v_number = 0;  // OK
-      }
-    }
-
-    if (l == NULL)                      /* only one string argument */
-      break;
-    ++lnum;
-  }
-
-  if (added > 0)
-    appended_lines_mark(lcount, added);
+  set_buffer_lines(curbuf, lnum, &argvars[1], rettv);
 }
 
 /// Create quickfix/location list from VimL values

src/nvim/eval.lua

@@ -263,6 +263,7 @@ return {
     serverlist={},
     serverstart={args={0, 1}},
     serverstop={args=1},
+    setbufline={args=3},
     setbufvar={args=3},
     setcharsearch={args=1},
     setcmdpos={args=1},

src/nvim/testdir/test_bufline.vim

@@ -0,0 +1,26 @@
+" Tests for setbufline() and getbufline()
+
+func Test_setbufline_getbufline()
+  new
+  let b = bufnr('%')
+  hide
+  call assert_equal(0, setbufline(b, 1, ['foo', 'bar']))
+  call assert_equal(['foo'], getbufline(b, 1))
+  call assert_equal(['bar'], getbufline(b, 2))
+  call assert_equal(['foo', 'bar'], getbufline(b, 1, 2))
+  exe "bd!" b
+  call assert_equal([], getbufline(b, 1, 2))
+
+  split Xtest
+  call setline(1, ['a', 'b', 'c'])
+  let b = bufnr('%')
+  wincmd w
+  call assert_equal(1, setbufline(b, 5, ['x']))
+  call assert_equal(1, setbufline(1234, 1, ['x']))
+  call assert_equal(0, setbufline(b, 4, ['d', 'e']))
+  call assert_equal(['c'], getbufline(b, 3))
+  call assert_equal(['d'], getbufline(b, 4))
+  call assert_equal(['e'], getbufline(b, 5))
+  call assert_equal([], getbufline(b, 6))
+  exe "bwipe! " . b
+endfunc