refactor: ins_compl_show_pum() (#19938)

This marks the remaining part of Vim patch 8.2.3953 as ported, because
ins_compl_upd_pum() has been removed.

vim-patch:8.2.3953: insert completion code is too complicated

Problem:    Insert completion code is too complicated.
Solution:   More refactoring.  Move function arguments into a struct.
            (Yegappan Lakshmanan, closes vim/vim#9437)
6ad84ab3e4

src/nvim/insexpand.c

@@ -1108,43 +1108,24 @@ static void trigger_complete_changed_event(int cur)
   restore_v_event(v_event, &save_v_event);
 }
 
-/// Show the popup menu for the list of matches.
-/// Also adjusts "compl_shown_match" to an entry that is actually displayed.
-void ins_compl_show_pum(void)
+/// Build a popup menu to show the completion matches.
+///
+/// @return  the popup menu entry that should be selected,
+///          -1 if nothing should be selected.
+static int ins_compl_build_pum(void)
 {
-  compl_T *compl;
-  compl_T *shown_compl = NULL;
-  bool did_find_shown_match = false;
-  bool shown_match_ok = false;
-  int i;
-  int cur = -1;
-  colnr_T col;
-  int lead_len = 0;
-  bool array_changed = false;
-
-  if (!pum_wanted() || !pum_enough_matches()) {
-    return;
-  }
-
-  // Dirty hard-coded hack: remove any matchparen highlighting.
-  do_cmdline_cmd("if exists('g:loaded_matchparen')|3match none|endif");
-
-  // Update the screen before drawing the popup menu over it.
-  update_screen(0);
-
-  if (compl_match_array == NULL) {
-    array_changed = true;
   // Need to build the popup menu list.
   compl_match_arraysize = 0;
-    compl = compl_first_match;
+  compl_T *compl = compl_first_match;
+
   // If it's user complete function and refresh_always,
   // do not use "compl_leader" as prefix filter.
   if (ins_compl_need_restart()) {
     XFREE_CLEAR(compl_leader);
   }
-    if (compl_leader != NULL) {
-      lead_len = (int)STRLEN(compl_leader);
-    }
+
+  const int lead_len = compl_leader != NULL ? (int)STRLEN(compl_leader) : 0;
+
   do {
     if (!match_at_original_text(compl)
         && (compl_leader == NULL
@@ -1153,19 +1134,22 @@ void ins_compl_show_pum(void)
     }
     compl = compl->cp_next;
   } while (compl != NULL && !is_first_match(compl));
+
   if (compl_match_arraysize == 0) {
-      return;
+    return -1;
   }
 
   assert(compl_match_arraysize >= 0);
   compl_match_array = xcalloc((size_t)compl_match_arraysize, sizeof(pumitem_T));
+
   // If the current match is the original text don't find the first
   // match after it, don't highlight anything.
-    if (match_at_original_text(compl_shown_match)) {
-      shown_match_ok = true;
-    }
+  bool shown_match_ok = match_at_original_text(compl_shown_match);
 
-    i = 0;
+  compl_T *shown_compl = NULL;
+  bool did_find_shown_match = false;
+  int cur = -1;
+  int i = 0;
   compl = compl_first_match;
   do {
     if (!match_at_original_text(compl)
@@ -1187,16 +1171,14 @@ void ins_compl_show_pum(void)
       }
 
       if (compl->cp_text[CPT_ABBR] != NULL) {
-          compl_match_array[i].pum_text =
-            compl->cp_text[CPT_ABBR];
+        compl_match_array[i].pum_text = compl->cp_text[CPT_ABBR];
       } else {
         compl_match_array[i].pum_text = compl->cp_str;
       }
       compl_match_array[i].pum_kind = compl->cp_text[CPT_KIND];
       compl_match_array[i].pum_info = compl->cp_text[CPT_INFO];
       if (compl->cp_text[CPT_MENU] != NULL) {
-          compl_match_array[i++].pum_extra =
-            compl->cp_text[CPT_MENU];
+        compl_match_array[i++].pum_extra = compl->cp_text[CPT_MENU];
       } else {
         compl_match_array[i++].pum_extra = compl->cp_fname;
       }
@@ -1224,25 +1206,53 @@ void ins_compl_show_pum(void)
   if (!shown_match_ok) {  // no displayed match at all
     cur = -1;
   }
+
+  return cur;
+}
+
+/// Show the popup menu for the list of matches.
+/// Also adjusts "compl_shown_match" to an entry that is actually displayed.
+void ins_compl_show_pum(void)
+{
+  if (!pum_wanted() || !pum_enough_matches()) {
+    return;
+  }
+
+  // Dirty hard-coded hack: remove any matchparen highlighting.
+  do_cmdline_cmd("if exists('g:loaded_matchparen')|3match none|endif");
+
+  // Update the screen before drawing the popup menu over it.
+  update_screen(0);
+
+  int cur = -1;
+  bool array_changed = false;
+
+  if (compl_match_array == NULL) {
+    array_changed = true;
+    // Need to build the popup menu list.
+    cur = ins_compl_build_pum();
   } else {
     // popup menu already exists, only need to find the current item.
-    for (i = 0; i < compl_match_arraysize; i++) {
+    for (int i = 0; i < compl_match_arraysize; i++) {
       if (compl_match_array[i].pum_text == compl_shown_match->cp_str
-          || compl_match_array[i].pum_text
-          == compl_shown_match->cp_text[CPT_ABBR]) {
+          || compl_match_array[i].pum_text == compl_shown_match->cp_text[CPT_ABBR]) {
         cur = i;
         break;
       }
     }
   }
 
+  if (compl_match_array == NULL) {
+    return;
+  }
+
   // In Replace mode when a $ is displayed at the end of the line only
   // part of the screen would be updated.  We do need to redraw here.
   dollar_vcol = -1;
 
   // Compute the screen column of the start of the completed text.
   // Use the cursor to get all wrapping and other settings right.
-  col = curwin->w_cursor.col;
+  const colnr_T col = curwin->w_cursor.col;
   curwin->w_cursor.col = compl_col;
   pum_selected_item = cur;
   pum_display(compl_match_array, compl_match_arraysize, cur, array_changed, 0);