vim-patch:8.1.0720: cannot easily change the current quickfx list index

Problem:    Cannot easily change the current quickfx list index.
Solution:   Add the "idx" argument to setqflist(). (Yegappan Lakshmanan,
            closes vim/vim#3701)
5b69c22fd2

src/nvim/quickfix.c

@@ -2936,19 +2936,20 @@ static int qf_jump_to_buffer(qf_info_T *qi, int qf_index, qfline_T *qf_ptr,
   return retval;
 }
 
-/// Jump to a quickfix line.
-/// If dir == FORWARD go "errornr" valid entries forward.
-/// If dir == BACKWARD go "errornr" valid entries backward.
-/// If dir == FORWARD_FILE go "errornr" valid entries files backward.
-/// If dir == BACKWARD_FILE go "errornr" valid entries files backward.
-/// else if "errornr" is zero, redisplay the same line
-/// else go to entry "errornr".
+/// Jump to a quickfix line and try to use an existing window.
 void qf_jump(qf_info_T *qi, int dir, int errornr, int forceit)
 {
   qf_jump_newwin(qi, dir, errornr, forceit, false);
 }
 
-// As qf_info().
+// Jump to a quickfix line.
+// If dir == 0 go to entry "errornr".
+// If dir == FORWARD go "errornr" valid entries forward.
+// If dir == BACKWARD go "errornr" valid entries backward.
+// If dir == FORWARD_FILE go "errornr" valid entries files backward.
+// If dir == BACKWARD_FILE go "errornr" valid entries files backward
+// else if "errornr" is zero, redisplay the same line
+// If 'forceit' is true, then can discard changes to the current buffer.
 // If 'newwin' is true, then open the file in a new window.
 static void qf_jump_newwin(qf_info_T *qi, int dir, int errornr, int forceit,
                            bool newwin)
@@ -3297,7 +3298,7 @@ void qf_history(exarg_T *eap)
   qf_info_T *qi = qf_cmd_get_stack(eap, false);
   int i;
 
-  if (qf_stack_empty(qi) || qf_list_empty(qf_get_curlist(qi))) {
+  if (qf_stack_empty(qi)) {
     MSG(_("No entries"));
   } else {
     for (i = 0; i < qi->qf_listcount; i++) {
@@ -6134,6 +6135,49 @@ static int qf_setprop_context(qf_list_T *qfl, dictitem_T *di)
   return OK;
 }
 
+// Set the current index in the specified quickfix list
+static int qf_setprop_curidx(qf_info_T *qi, qf_list_T *qfl,
+                             const dictitem_T *di)
+  FUNC_ATTR_NONNULL_ALL
+{
+  int  newidx;
+
+  // If the specified index is '$', then use the last entry
+  if (di->di_tv.v_type == VAR_STRING
+      && di->di_tv.vval.v_string != NULL
+      && STRCMP(di->di_tv.vval.v_string, "$") == 0) {
+    newidx = qfl->qf_count;
+  } else {
+    // Otherwise use the specified index
+    bool denote = false;
+    newidx = (int)tv_get_number_chk(&di->di_tv, &denote);
+    if (denote) {
+      return FAIL;
+    }
+  }
+
+  if (newidx < 1) {  // sanity check
+    return FAIL;
+  }
+  if (newidx > qfl->qf_count) {
+    newidx = qfl->qf_count;
+  }
+  const int old_qfidx = qfl->qf_index;
+  qfline_T *const qf_ptr = get_nth_entry(qfl, newidx, &newidx);
+  if (qf_ptr == NULL) {
+    return FAIL;
+  }
+  qfl->qf_ptr = qf_ptr;
+  qfl->qf_index = newidx;
+
+  // If the current list is modified and it is displayed in the quickfix
+  // window, then Update it.
+  if (qi->qf_lists[qi->qf_curlist].qf_id == qfl->qf_id) {
+    qf_win_pos_update(qi, old_qfidx);
+  }
+  return OK;
+}
+
 /// Set quickfix/location list properties (title, items, context).
 /// Also used to add items from parsing a list of lines.
 /// Used by the setqflist() and setloclist() Vim script functions.
@@ -6169,6 +6213,9 @@ static int qf_set_properties(qf_info_T *qi, const dict_T *what, int action,
   if ((di = tv_dict_find(what, S_LEN("context"))) != NULL) {
     retval = qf_setprop_context(qfl, di);
   }
+  if ((di = tv_dict_find(what, S_LEN("idx"))) != NULL) {
+    retval = qf_setprop_curidx(qi, qfl, di);
+  }
 
   if (retval == OK) {
     qf_list_changed(qfl);

src/nvim/testdir/test_quickfix.vim

@@ -1916,6 +1916,13 @@ func HistoryTest(cchar)
   call g:Xsetlist([], 'f')
   let l = split(execute(a:cchar . 'hist'), "\n")
   call assert_equal('No entries', l[0])
+
+  " An empty list should still show the stack history
+  call g:Xsetlist([])
+  let res = split(execute(a:cchar . 'hist'), "\n")
+  call assert_equal('> error list 1 of 1; 0 ' . common, res[0])
+
+  call g:Xsetlist([], 'f')
 endfunc
 
 func Test_history()
@@ -2173,6 +2180,56 @@ func Test_qf_property()
     call Xproperty_tests('l')
 endfunc
 
+" Test for setting the current index in the location/quickfix list
+func Xtest_setqfidx(cchar)
+  call s:setup_commands(a:cchar)
+
+  Xgetexpr "F1:10:1:Line1\nF2:20:2:Line2\nF3:30:3:Line3"
+  Xgetexpr "F4:10:1:Line1\nF5:20:2:Line2\nF6:30:3:Line3"
+  Xgetexpr "F7:10:1:Line1\nF8:20:2:Line2\nF9:30:3:Line3"
+
+  call g:Xsetlist([], 'a', {'nr' : 3, 'idx' : 2})
+  call g:Xsetlist([], 'a', {'nr' : 2, 'idx' : 2})
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : 3})
+  Xolder 2
+  Xopen
+  call assert_equal(3, line('.'))
+  Xnewer
+  call assert_equal(2, line('.'))
+  Xnewer
+  call assert_equal(2, line('.'))
+  " Update the current index with the quickfix window open
+  wincmd w
+  call g:Xsetlist([], 'a', {'nr' : 3, 'idx' : 3})
+  Xopen
+  call assert_equal(3, line('.'))
+  Xclose
+
+  " Set the current index to the last entry
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : '$'})
+  call assert_equal(3, g:Xgetlist({'nr' : 1, 'idx' : 0}).idx)
+  " A large value should set the index to the last index
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : 1})
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : 999})
+  call assert_equal(3, g:Xgetlist({'nr' : 1, 'idx' : 0}).idx)
+  " Invalid index values
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : -1})
+  call assert_equal(3, g:Xgetlist({'nr' : 1, 'idx' : 0}).idx)
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : 0})
+  call assert_equal(3, g:Xgetlist({'nr' : 1, 'idx' : 0}).idx)
+  call g:Xsetlist([], 'a', {'nr' : 1, 'idx' : 'xx'})
+  call assert_equal(3, g:Xgetlist({'nr' : 1, 'idx' : 0}).idx)
+  call assert_fails("call g:Xsetlist([], 'a', {'nr':1, 'idx':[]})", 'E745:')
+
+  call g:Xsetlist([], 'f')
+  new | only
+endfunc
+
+func Test_setqfidx()
+  call Xtest_setqfidx('c')
+  call Xtest_setqfidx('l')
+endfunc
+
 " Tests for the QuickFixCmdPre/QuickFixCmdPost autocommands
 func QfAutoCmdHandler(loc, cmd)
   call add(g:acmds, a:loc . a:cmd)