*: Start hiding list implementation

Most of files, except for eval.c and eval/* were only processed by perl.

8 files changed, 541 insertions, 492 deletions

diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index 629873998e..e5a1e150f9 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -798,7 +798,7 @@ bool object_to_vim(Object obj, typval_T *tv, Error *err)
 
         tv_list_append(list, li);
       }
-      list->lv_refcount++;
+      tv_list_ref(list);
 
       tv->v_type = VAR_LIST;
       tv->vval.v_list = list;
diff --git a/src/nvim/channel.c b/src/nvim/channel.c
index 40af470bde..ff8dbd3d33 100644
--- a/src/nvim/channel.c
+++ b/src/nvim/channel.c
@@ -673,7 +673,7 @@ static void on_channel_event(void **args)
     argv[1].v_type = VAR_LIST;
     argv[1].v_lock = VAR_UNLOCKED;
     argv[1].vval.v_list = ev->received;
-    argv[1].vval.v_list->lv_refcount++;
+    tv_list_ref(argv[1].vval.v_list);
   } else {
     argv[1].v_type = VAR_NUMBER;
     argv[1].v_lock = VAR_UNLOCKED;
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index 56aedb1b4e..edf016fc41 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -564,8 +564,8 @@ void eval_init(void)
   dict_T *const msgpack_types_dict = tv_dict_alloc();
   for (size_t i = 0; i < ARRAY_SIZE(msgpack_type_names); i++) {
     list_T *const type_list = tv_list_alloc();
-    type_list->lv_lock = VAR_FIXED;
-    type_list->lv_refcount = 1;
+    tv_list_set_lock(type_list, VAR_FIXED);
+    tv_list_ref(type_list);
     dictitem_T *const di = tv_dict_item_alloc(msgpack_type_names[i]);
     di->di_flags |= DI_FLAGS_RO|DI_FLAGS_FIX;
     di->di_tv = (typval_T) {
@@ -1014,7 +1014,7 @@ char_u *eval_to_string(char_u *arg, char_u **nextcmd, int convert)
       ga_init(&ga, (int)sizeof(char), 80);
       if (tv.vval.v_list != NULL) {
         tv_list_join(&ga, tv.vval.v_list, "\n");
-        if (tv.vval.v_list->lv_len > 0) {
+        if (tv_list_len(tv.vval.v_list) > 0) {
           ga_append(&ga, NL);
         }
       }
@@ -1143,27 +1143,31 @@ list_T *eval_spell_expr(char_u *badword, char_u *expr)
   return list;
 }
 
-/*
- * "list" is supposed to contain two items: a word and a number.  Return the
- * word in "pp" and the number as the return value.
- * Return -1 if anything isn't right.
- * Used to get the good word and score from the eval_spell_expr() result.
- */
-int get_spellword(list_T *list, const char **pp)
+/// Get spell word from an entry from spellsuggest=expr:
+///
+/// Entry in question is supposed to be a list (to be checked by the caller)
+/// with two items: a word and a score represented as an unsigned number
+/// (whether it actually is unsigned is not checked).
+///
+/// Used to get the good word and score from the eval_spell_expr() result.
+///
+/// @param[in]  list  List to get values from.
+/// @param[out]  ret_word  Suggested word. Not initialized if return value is
+///                        -1.
+///
+/// @return -1 in case of error, score otherwise.
+int get_spellword(list_T *const list, const char **ret_word)
 {
-  listitem_T  *li;
-
-  li = list->lv_first;
-  if (li == NULL) {
+  if (tv_list_len(list) != 2) {
+    EMSG(_("E5700: Expression from 'spellsuggest' must yield lists with "
+           "exactly two values"));
     return -1;
   }
-  *pp = tv_get_string(&li->li_tv);
-
-  li = li->li_next;
-  if (li == NULL) {
+  *ret_word = tv_list_find_str(list, 0);
+  if (*ret_word == NULL) {
     return -1;
   }
-  return tv_get_number(&li->li_tv);
+  return tv_list_find_nr(list, -1, NULL);
 }
 
 
@@ -1504,9 +1508,7 @@ ex_let_vars (
 )
 {
   char_u *arg = arg_start;
-  list_T      *l;
   int i;
-  listitem_T  *item;
   typval_T ltv;
 
   if (*arg != '[') {
@@ -1518,13 +1520,12 @@ ex_let_vars (
     return OK;
   }
 
-  /*
-   * ":let [v1, v2] = list" or ":for [v1, v2] in listlist"
-   */
-  if (tv->v_type != VAR_LIST || (l = tv->vval.v_list) == NULL) {
+  // ":let [v1, v2] = list" or ":for [v1, v2] in listlist"
+  if (tv->v_type != VAR_LIST) {
     EMSG(_(e_listreq));
     return FAIL;
   }
+  list_T *const l = tv->vval.v_list;
 
   i = tv_list_len(l);
   if (semicolon == 0 && var_count < i) {
@@ -1535,29 +1536,33 @@ ex_let_vars (
     EMSG(_("E688: More targets than List items"));
     return FAIL;
   }
+  // l may actually be NULL, but it should fail with E688 or even earlier if you
+  // try to do ":let [] = v:_null_list".
+  assert(l != NULL);
 
-  item = l->lv_first;
+  listitem_T *item = tv_list_first(l);
   while (*arg != ']') {
     arg = skipwhite(arg + 1);
-    arg = ex_let_one(arg, &item->li_tv, TRUE, (char_u *)",;]", nextchars);
-    item = item->li_next;
-    if (arg == NULL)
+    arg = ex_let_one(arg, TV_LIST_ITEM_TV(item), TRUE, (char_u *)",;]", nextchars);
+    item = TV_LIST_ITEM_NEXT(l, item);
+    if (arg == NULL) {
       return FAIL;
+    }
 
     arg = skipwhite(arg);
     if (*arg == ';') {
       /* Put the rest of the list (may be empty) in the var after ';'.
        * Create a new list for this. */
-      l = tv_list_alloc();
+      list_T *const rest_list = tv_list_alloc();
       while (item != NULL) {
-        tv_list_append_tv(l, &item->li_tv);
-        item = item->li_next;
+        tv_list_append_tv(rest_list, TV_LIST_ITEM_TV(item));
+        item = TV_LIST_ITEM_NEXT(l, item);
       }
 
       ltv.v_type = VAR_LIST;
       ltv.v_lock = 0;
-      ltv.vval.v_list = l;
-      l->lv_refcount = 1;
+      ltv.vval.v_list = rest_list;
+      tv_list_ref(rest_list);
 
       arg = ex_let_one(skipwhite(arg + 1), &ltv, false,
                        (char_u *)"]", nextchars);
@@ -2310,7 +2315,7 @@ static char_u *get_lval(char_u *const name, typval_T *const rettv,
         }
       }
 
-      lp->ll_tv = &lp->ll_li->li_tv;
+      lp->ll_tv = TV_LIST_ITEM_TV(lp->ll_li);
     }
   }
 
@@ -2375,45 +2380,49 @@ static void set_var_lval(lval_T *lp, char_u *endp, typval_T *rettv,
     int ll_n1 = lp->ll_n1;
 
     // Check whether any of the list items is locked
-    for (listitem_T *ri = rettv->vval.v_list->lv_first;
+    for (listitem_T *ri = tv_list_first(rettv->vval.v_list);
          ri != NULL && ll_li != NULL; ) {
-      if (tv_check_lock(ll_li->li_tv.v_lock, (const char *)lp->ll_name,
+      if (tv_check_lock(TV_LIST_ITEM_TV(ll_li)->v_lock,
+                        (const char *)lp->ll_name,
                         TV_CSTRING)) {
         return;
       }
-      ri = ri->li_next;
+      ri = TV_LIST_ITEM_NEXT(rettv->vval.v_list, ri);
       if (ri == NULL || (!lp->ll_empty2 && lp->ll_n2 == ll_n1)) {
         break;
       }
-      ll_li = ll_li->li_next;
+      ll_li = TV_LIST_ITEM_NEXT(lp->ll_list, ll_li);
       ll_n1++;
     }
 
     /*
      * Assign the List values to the list items.
      */
-    for (ri = rettv->vval.v_list->lv_first; ri != NULL; ) {
+    for (ri = tv_list_first(rettv->vval.v_list); ri != NULL; ) {
       if (op != NULL && *op != '=') {
-        eexe_mod_op(&lp->ll_li->li_tv, &ri->li_tv, (const char *)op);
+        eexe_mod_op(TV_LIST_ITEM_TV(lp->ll_li), TV_LIST_ITEM_TV(ri),
+                    (const char *)op);
       } else {
-        tv_clear(&lp->ll_li->li_tv);
-        tv_copy(&ri->li_tv, &lp->ll_li->li_tv);
+        tv_clear(TV_LIST_ITEM_TV(lp->ll_li));
+        tv_copy(TV_LIST_ITEM_TV(ri), TV_LIST_ITEM_TV(lp->ll_li));
       }
-      ri = ri->li_next;
-      if (ri == NULL || (!lp->ll_empty2 && lp->ll_n2 == lp->ll_n1))
+      ri = TV_LIST_ITEM_NEXT(rettv->vval.v_list, ri);
+      if (ri == NULL || (!lp->ll_empty2 && lp->ll_n2 == lp->ll_n1)) {
         break;
-      if (lp->ll_li->li_next == NULL) {
+      }
+      if (TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li) == NULL) {
         // Need to add an empty item.
         tv_list_append_number(lp->ll_list, 0);
-        assert(lp->ll_li->li_next);
+        assert(TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li));
       }
-      lp->ll_li = lp->ll_li->li_next;
-      ++lp->ll_n1;
+      lp->ll_li = TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li);
+      lp->ll_n1++;
     }
     if (ri != NULL)
       EMSG(_("E710: List value has more items than target"));
     else if (lp->ll_empty2
-             ? (lp->ll_li != NULL && lp->ll_li->li_next != NULL)
+             ? (lp->ll_li != NULL
+                && TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li) != NULL)
              : lp->ll_n1 != lp->ll_n2)
       EMSG(_("E711: List value has not enough items"));
   } else {
@@ -2514,7 +2523,7 @@ void *eval_for_line(const char_u *arg, bool *errp, char_u **nextcmdp, int skip)
          * list being used in "tv". */
         fi->fi_list = l;
         tv_list_watch_add(l, &fi->fi_lw);
-        fi->fi_lw.lw_item = l->lv_first;
+        fi->fi_lw.lw_item = tv_list_first(l);
       }
     }
   }
@@ -2532,21 +2541,18 @@ void *eval_for_line(const char_u *arg, bool *errp, char_u **nextcmdp, int skip)
  * Return TRUE when a valid item was found, FALSE when at end of list or
  * something wrong.
  */
-int next_for_item(void *fi_void, char_u *arg)
+bool next_for_item(void *fi_void, char_u *arg)
 {
-  forinfo_T   *fi = (forinfo_T *)fi_void;
-  int result;
-  listitem_T  *item;
+  forinfo_T *fi = (forinfo_T *)fi_void;
 
-  item = fi->fi_lw.lw_item;
-  if (item == NULL)
-    result = FALSE;
-  else {
-    fi->fi_lw.lw_item = item->li_next;
-    result = (ex_let_vars(arg, &item->li_tv, TRUE,
-                  fi->fi_semicolon, fi->fi_varcount, NULL) == OK);
+  listitem_T *item = fi->fi_lw.lw_item;
+  if (item == NULL) {
+    return false;
+  } else {
+    fi->fi_lw.lw_item = TV_LIST_ITEM_NEXT(fi->fi_list, item);
+    return (ex_let_vars(arg, TV_LIST_ITEM_TV(item), true,
+                        fi->fi_semicolon, fi->fi_varcount, NULL) == OK);
   }
-  return result;
 }
 
 // TODO(ZyX-I): move to eval/ex_cmds
@@ -2869,9 +2875,9 @@ static int do_unlet_var(lval_T *const lp, char_u *const name_end, int forceit)
       ret = FAIL;
     }
     *name_end = cc;
-  } else if ((lp->ll_list != NULL
-              && tv_check_lock(lp->ll_list->lv_lock, (const char *)lp->ll_name,
-                               lp->ll_name_len))
+  } else if (tv_check_lock(tv_list_locked(lp->ll_list),
+                           (const char *)lp->ll_name,
+                           lp->ll_name_len)
              || (lp->ll_dict != NULL
                  && tv_check_lock(lp->ll_dict->dv_lock,
                                   (const char *)lp->ll_name,
@@ -2883,8 +2889,9 @@ static int do_unlet_var(lval_T *const lp, char_u *const name_end, int forceit)
     int ll_n1 = lp->ll_n1;
 
     while (ll_li != NULL && (lp->ll_empty2 || lp->ll_n2 >= ll_n1)) {
-      li = ll_li->li_next;
-      if (tv_check_lock(ll_li->li_tv.v_lock, (const char *)lp->ll_name,
+      li = TV_LIST_ITEM_NEXT(lp->ll_list, ll_li);
+      if (tv_check_lock(TV_LIST_ITEM_TV(ll_li)->v_lock,
+                        (const char *)lp->ll_name,
                         lp->ll_name_len)) {
         return false;
       }
@@ -2892,12 +2899,12 @@ static int do_unlet_var(lval_T *const lp, char_u *const name_end, int forceit)
       ll_n1++;
     }
 
-    /* Delete a range of List items. */
+    // Delete a range of List items.
     while (lp->ll_li != NULL && (lp->ll_empty2 || lp->ll_n2 >= lp->ll_n1)) {
-      li = lp->ll_li->li_next;
+      li = TV_LIST_ITEM_NEXT(lp->ll_list, lp->ll_li);
       tv_list_item_remove(lp->ll_list, lp->ll_li);
       lp->ll_li = li;
-      ++lp->ll_n1;
+      lp->ll_n1++;
     }
   } else {
     if (lp->ll_list != NULL) {
@@ -3043,13 +3050,13 @@ static int do_lock_var(lval_T *lp, char_u *const name_end, const int deep,
 
     /* (un)lock a range of List items. */
     while (li != NULL && (lp->ll_empty2 || lp->ll_n2 >= lp->ll_n1)) {
-      tv_item_lock(&li->li_tv, deep, lock);
-      li = li->li_next;
-      ++lp->ll_n1;
+      tv_item_lock(TV_LIST_ITEM_TV(li), deep, lock);
+      li = TV_LIST_ITEM_NEXT(lp->ll_list, li);
+      lp->ll_n1++;
     }
   } else if (lp->ll_list != NULL) {
     // (un)lock a List item.
-    tv_item_lock(&lp->ll_li->li_tv, deep, lock);
+    tv_item_lock(TV_LIST_ITEM_TV(lp->ll_li), deep, lock);
   } else {
     // (un)lock a Dictionary item.
     tv_item_lock(&lp->ll_di->di_tv, deep, lock);
@@ -4511,15 +4518,15 @@ eval_index (
           l = tv_list_alloc();
           item = tv_list_find(rettv->vval.v_list, n1);
           while (n1++ <= n2) {
-            tv_list_append_tv(l, &item->li_tv);
-            item = item->li_next;
+            tv_list_append_tv(l, TV_LIST_ITEM_TV(item));
+            item = TV_LIST_ITEM_NEXT(l, item);
           }
           tv_clear(rettv);
           rettv->v_type = VAR_LIST;
           rettv->vval.v_list = l;
-          l->lv_refcount++;
+          tv_list_ref(l);
         } else {
-          tv_copy(&tv_list_find(rettv->vval.v_list, n1)->li_tv, &var1);
+          tv_copy(TV_LIST_ITEM_TV(tv_list_find(rettv->vval.v_list, n1)), &var1);
           tv_clear(rettv);
           *rettv = var1;
         }
@@ -4877,22 +4884,23 @@ static int get_list_tv(char_u **arg, typval_T *rettv, int evaluate)
       goto failret;
     if (evaluate) {
       item = tv_list_item_alloc();
-      item->li_tv = tv;
-      item->li_tv.v_lock = 0;
+      *TV_LIST_ITEM_TV(item) = tv;
+      TV_LIST_ITEM_TV(item)->v_lock = VAR_UNLOCKED;
       tv_list_append(l, item);
     }
 
-    if (**arg == ']')
+    if (**arg == ']') {
       break;
+    }
     if (**arg != ',') {
-      EMSG2(_("E696: Missing comma in List: %s"), *arg);
+      emsgf(_("E696: Missing comma in List: %s"), *arg);
       goto failret;
     }
     *arg = skipwhite(*arg + 1);
   }
 
   if (**arg != ']') {
-    EMSG2(_("E697: Missing end of List ']': %s"), *arg);
+    emsgf(_("E697: Missing end of List ']': %s"), *arg);
 failret:
     if (evaluate) {
       tv_list_free(l);
@@ -4904,7 +4912,7 @@ failret:
   if (evaluate) {
     rettv->v_type = VAR_LIST;
     rettv->vval.v_list = l;
-    ++l->lv_refcount;
+    tv_list_ref(l);
   }
 
   return OK;
@@ -5260,6 +5268,7 @@ static int free_unref_items(int copyID)
   for (ll = gc_first_list; ll != NULL; ll = ll_next) {
     ll_next = ll->lv_used_next;
     if ((ll->lv_copyID & COPYID_MASK) != (copyID & COPYID_MASK)
+        // FIXME: Abstract away lv_watch.
         && ll->lv_watch == NULL) {
       // Free the List and ordinary items it contains, but don't recurse
       // into Lists and Dictionaries, they will be in the list of dicts
@@ -5329,10 +5338,13 @@ bool set_ref_in_list(list_T *l, int copyID, ht_stack_T **ht_stack)
       // Mark each item in the list.  If the item contains a hashtab
       // it is added to ht_stack, if it contains a list it is added to
       // list_stack.
-      for (listitem_T *li = cur_l->lv_first; !abort && li != NULL;
-           li = li->li_next) {
-        abort = set_ref_in_item(&li->li_tv, copyID, ht_stack, &list_stack);
-      }
+      TV_LIST_ITER(cur_l, li, {
+        abort = set_ref_in_item(TV_LIST_ITEM_TV(li), copyID, ht_stack,
+                                &list_stack);
+        if (abort) {
+          break;
+        }
+      });
     }
 
     if (list_stack == NULL) {
@@ -6535,7 +6547,7 @@ static void f_add(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   rettv->vval.v_number = 1;   /* Default: Failed */
   if (argvars[0].v_type == VAR_LIST) {
     if ((l = argvars[0].vval.v_list) != NULL
-        && !tv_check_lock(l->lv_lock, "add() argument", TV_TRANSLATE)) {
+        && !tv_check_lock(tv_list_locked(l), "add() argument", TV_TRANSLATE)) {
       tv_list_append_tv(l, &argvars[1]);
       tv_copy(&argvars[0], rettv);
     }
@@ -6586,9 +6598,10 @@ static void f_append(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       && u_save(lnum, lnum + 1) == OK) {
     if (argvars[1].v_type == VAR_LIST) {
       l = argvars[1].vval.v_list;
-      if (l == NULL)
+      if (l == NULL) {
         return;
-      li = l->lv_first;
+      }
+      li = tv_list_first(l);
     }
     for (;; ) {
       if (l == NULL) {
@@ -6596,7 +6609,7 @@ static void f_append(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       } else if (li == NULL) {
         break;  // End of list.
       } else {
-        tv = &li->li_tv;  // Append item from list.
+        tv = TV_LIST_ITEM_TV(li);  // Append item from list.
       }
       const char *const line = tv_get_string_chk(tv);
       if (line == NULL) {  // Type error.
@@ -6608,7 +6621,7 @@ static void f_append(typval_T *argvars, typval_T *rettv, FunPtr fptr)
       if (l == NULL) {
         break;
       }
-      li = li->li_next;
+      li = TV_LIST_ITEM_NEXT(l, li);
     }
 
     appended_lines_mark(lnum, added);
@@ -7247,30 +7260,26 @@ static void f_byteidxcomp(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 int func_call(char_u *name, typval_T *args, partial_T *partial,
               dict_T *selfdict, typval_T *rettv)
 {
-  listitem_T  *item;
   typval_T argv[MAX_FUNC_ARGS + 1];
   int argc = 0;
   int dummy;
   int r = 0;
 
-  for (item = args->vval.v_list->lv_first; item != NULL;
-       item = item->li_next) {
+  TV_LIST_ITER(args->vval.v_list, item, {
     if (argc == MAX_FUNC_ARGS - (partial == NULL ? 0 : partial->pt_argc)) {
       EMSG(_("E699: Too many arguments"));
-      break;
+      goto func_call_skip_call;
     }
-    /* Make a copy of each argument.  This is needed to be able to set
-     * v_lock to VAR_FIXED in the copy without changing the original list.
-     */
-    tv_copy(&item->li_tv, &argv[argc++]);
-  }
+    // Make a copy of each argument.  This is needed to be able to set
+    // v_lock to VAR_FIXED in the copy without changing the original list.
+    tv_copy(TV_LIST_ITEM_TV(item), &argv[argc++]);
+  });
 
-  if (item == NULL) {
-    r = call_func(name, (int)STRLEN(name), rettv, argc, argv, NULL,
-                  curwin->w_cursor.lnum, curwin->w_cursor.lnum,
-                  &dummy, true, partial, selfdict);
-  }
+  r = call_func(name, (int)STRLEN(name), rettv, argc, argv, NULL,
+                curwin->w_cursor.lnum, curwin->w_cursor.lnum,
+                &dummy, true, partial, selfdict);
 
+func_call_skip_call:
   // Free the arguments.
   while (argc > 0) {
     tv_clear(&argv[--argc]);
@@ -7595,7 +7604,7 @@ static void f_count(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     long idx;
 
     if ((l = argvars[0].vval.v_list) != NULL) {
-      li = l->lv_first;
+      li = tv_list_first(l);
       if (argvars[2].v_type != VAR_UNKNOWN) {
         bool error = false;
 
@@ -7613,9 +7622,11 @@ static void f_count(typval_T *argvars, typval_T *rettv, FunPtr fptr)
           li = NULL;
       }
 
-      for (; li != NULL; li = li->li_next)
-        if (tv_equal(&li->li_tv, &argvars[1], ic, FALSE))
-          ++n;
+      for (; li != NULL; li = TV_LIST_ITEM_NEXT(l, li)) {
+        if (tv_equal(TV_LIST_ITEM_TV(li), &argvars[1], ic, false)) {
+          n++;
+        }
+      }
     }
   } else if (argvars[0].v_type == VAR_DICT) {
     int todo;
@@ -7933,34 +7944,51 @@ static void f_empty(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   bool n = true;
 
   switch (argvars[0].v_type) {
-  case VAR_STRING:
-  case VAR_FUNC:
-    n = argvars[0].vval.v_string == NULL
-        || *argvars[0].vval.v_string == NUL;
-    break;
-  case VAR_PARTIAL:
-    n = false;
-    break;
-  case VAR_NUMBER:
-    n = argvars[0].vval.v_number == 0;
-    break;
-  case VAR_FLOAT:
-    n = argvars[0].vval.v_float == 0.0;
-    break;
-  case VAR_LIST:
-    n = argvars[0].vval.v_list == NULL
-        || argvars[0].vval.v_list->lv_first == NULL;
-    break;
-  case VAR_DICT:
-    n = argvars[0].vval.v_dict == NULL
-        || argvars[0].vval.v_dict->dv_hashtab.ht_used == 0;
-    break;
-  case VAR_SPECIAL:
-    n = argvars[0].vval.v_special != kSpecialVarTrue;
-    break;
-  case VAR_UNKNOWN:
-    EMSG2(_(e_intern2), "f_empty(UNKNOWN)");
-    break;
+    case VAR_STRING:
+    case VAR_FUNC: {
+      n = argvars[0].vval.v_string == NULL
+          || *argvars[0].vval.v_string == NUL;
+      break;
+    }
+    case VAR_PARTIAL: {
+      n = false;
+      break;
+    }
+    case VAR_NUMBER: {
+      n = argvars[0].vval.v_number == 0;
+      break;
+    }
+    case VAR_FLOAT: {
+      n = argvars[0].vval.v_float == 0.0;
+      break;
+    }
+    case VAR_LIST: {
+      n = (tv_list_len(argvars[0].vval.v_list) == 0);
+      break;
+    }
+    case VAR_DICT: {
+      n = (tv_dict_len(argvars[0].vval.v_dict) == 0);
+      break;
+    }
+    case VAR_SPECIAL: {
+      // Using switch to get warning if SpecialVarValue receives more values.
+      switch (argvars[0].vval.v_special) {
+        case kSpecialVarTrue: {
+          n = false;
+          break;
+        }
+        case kSpecialVarFalse:
+        case kSpecialVarNull: {
+          n = true;
+          break;
+        }
+      }
+      break;
+    }
+    case VAR_UNKNOWN: {
+      EMSG2(_(e_intern2), "f_empty(UNKNOWN)");
+      break;
+    }
   }
 
   rettv->vval.v_number = n;
@@ -8024,17 +8052,22 @@ static void f_executable(typval_T *argvars, typval_T *rettv, FunPtr fptr)
           && os_can_exe((const char_u *)name, NULL, false)));
 }
 
+typedef struct {
+  const list_T *const l;
+  const listitem_T *li;
+} GetListLineCookie;
+
 static char_u *get_list_line(int c, void *cookie, int indent)
 {
-  const listitem_T **const p = (const listitem_T **)cookie;
-  const listitem_T *item = *p;
+  GetListLineCookie *const p = (GetListLineCookie *)cookie;
 
+  const listitem_T *const item = p->li;
   if (item == NULL) {
     return NULL;
   }
   char buf[NUMBUFLEN];
-  const char *const s = tv_get_string_buf_chk(&item->li_tv, buf);
-  *p = item->li_next;
+  const char *const s = tv_get_string_buf_chk(TV_LIST_ITEM_TV(item), buf);
+  p->li = TV_LIST_ITEM_NEXT(p->l, item);
   return (char_u *)(s == NULL ? NULL : xstrdup(s));
 }
 
@@ -8076,11 +8109,14 @@ static void f_execute(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     do_cmdline_cmd(tv_get_string(&argvars[0]));
   } else if (argvars[0].vval.v_list != NULL) {
     list_T *const list = argvars[0].vval.v_list;
-    list->lv_refcount++;
-    listitem_T *const item = list->lv_first;
-    do_cmdline(NULL, get_list_line, (void *)&item,
+    tv_list_ref(list);
+    GetListLineCookie cookie = {
+      .l = list,
+      .li = tv_list_first(list),
+    };
+    do_cmdline(NULL, get_list_line, (void *)&cookie,
                DOCMD_NOWAIT|DOCMD_VERBOSE|DOCMD_REPEAT|DOCMD_KEYTYPED);
-    list->lv_refcount--;
+    tv_list_unref(list);
   }
   msg_silent = save_msg_silent;
   emsg_silent = save_emsg_silent;
@@ -8262,14 +8298,7 @@ static void f_extend(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
     list_T *const l1 = argvars[0].vval.v_list;
     list_T *const l2 = argvars[1].vval.v_list;
-    if (l1 == NULL) {
-      const bool locked = tv_check_lock(VAR_FIXED, arg_errmsg, TV_TRANSLATE);
-      (void)locked;
-      assert(locked == true);
-    } else if (l2 == NULL) {
-      // Do nothing
-      tv_copy(&argvars[0], rettv);
-    } else if (!tv_check_lock(l1->lv_lock, arg_errmsg, TV_TRANSLATE)) {
+    if (!tv_check_lock(tv_list_locked(l1), arg_errmsg, TV_TRANSLATE)) {
       listitem_T *item;
       if (argvars[2].v_type != VAR_UNKNOWN) {
         before = (long)tv_get_number_chk(&argvars[2], &error);
@@ -8277,7 +8306,7 @@ static void f_extend(typval_T *argvars, typval_T *rettv, FunPtr fptr)
           return;  // Type error; errmsg already given.
         }
 
-        if (before == l1->lv_len) {
+        if (before == tv_list_len(l1)) {
           item = NULL;
         } else {
           item = tv_list_find(l1, before);
@@ -8286,8 +8315,9 @@ static void f_extend(typval_T *argvars, typval_T *rettv, FunPtr fptr)
             return;
           }
         }
-      } else
+      } else {
         item = NULL;
+      }
       tv_list_extend(l1, l2, item);
 
       tv_copy(&argvars[0], rettv);
@@ -8459,7 +8489,8 @@ static void filter_map(typval_T *argvars, typval_T *rettv, int map)
   if (argvars[0].v_type == VAR_LIST) {
     tv_copy(&argvars[0], rettv);
     if ((l = argvars[0].vval.v_list) == NULL
-        || (!map && tv_check_lock(l->lv_lock, arg_errmsg, TV_TRANSLATE))) {
+        || (!map && tv_check_lock(tv_list_locked(l), arg_errmsg,
+                                  TV_TRANSLATE))) {
       return;
     }
   } else if (argvars[0].v_type == VAR_DICT) {
@@ -8522,14 +8553,15 @@ static void filter_map(typval_T *argvars, typval_T *rettv, int map)
     } else {
       vimvars[VV_KEY].vv_type = VAR_NUMBER;
 
-      for (li = l->lv_first; li != NULL; li = nli) {
+      for (li = tv_list_first(l); li != NULL; li = nli) {
         if (map
-            && tv_check_lock(li->li_tv.v_lock, arg_errmsg, TV_TRANSLATE)) {
+            && tv_check_lock(TV_LIST_ITEM_TV(li)->v_lock, arg_errmsg,
+                             TV_TRANSLATE)) {
           break;
         }
-        nli = li->li_next;
+        nli = TV_LIST_ITEM_NEXT(l, li);
         vimvars[VV_KEY].vv_nr = idx;
-        if (filter_map_one(&li->li_tv, expr, map, &rem) == FAIL
+        if (filter_map_one(TV_LIST_ITEM_TV(li), expr, map, &rem) == FAIL
             || did_emsg)
           break;
         if (!map && rem) {
@@ -8935,7 +8967,7 @@ static void common_function(typval_T *argvars, typval_T *rettv,
           goto theend;
         }
         list = argvars[arg_idx].vval.v_list;
-        if (list == NULL || list->lv_len == 0) {
+        if (list == NULL || tv_list_len(list) == 0) {
           arg_idx = 0;
         }
       }
@@ -8946,7 +8978,7 @@ static void common_function(typval_T *argvars, typval_T *rettv,
       // result is a VAR_PARTIAL
       if (arg_idx > 0 || (arg_pt != NULL && arg_pt->pt_argc > 0)) {
         const int arg_len = (arg_pt == NULL ? 0 : arg_pt->pt_argc);
-        const int lv_len = (list == NULL ? 0 : list->lv_len);
+        const int lv_len = tv_list_len(list);
 
         pt->pt_argc = arg_len + lv_len;
         pt->pt_argv = xmalloc(sizeof(pt->pt_argv[0]) * pt->pt_argc);
@@ -8955,11 +8987,9 @@ static void common_function(typval_T *argvars, typval_T *rettv,
           tv_copy(&arg_pt->pt_argv[i], &pt->pt_argv[i]);
         }
         if (lv_len > 0) {
-          for (listitem_T *li = list->lv_first;
-               li != NULL;
-               li = li->li_next) {
-            tv_copy(&li->li_tv, &pt->pt_argv[i++]);
-          }
+          TV_LIST_ITER(list, li, {
+            tv_copy(TV_LIST_ITEM_TV(li), &pt->pt_argv[i++]);
+          });
         }
       }
 
@@ -9045,7 +9075,7 @@ static void f_get(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
       li = tv_list_find(l, tv_get_number_chk(&argvars[1], &error));
       if (!error && li != NULL) {
-        tv = &li->li_tv;
+        tv = TV_LIST_ITEM_TV(li);
       }
     }
   } else if (argvars[0].v_type == VAR_DICT) {
@@ -10067,7 +10097,7 @@ static void f_getreg(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     if (rettv->vval.v_list == NULL) {
       rettv->vval.v_list = tv_list_alloc();
     }
-    rettv->vval.v_list->lv_refcount++;
+    tv_list_ref(rettv->vval.v_list);
   } else {
     rettv->v_type = VAR_STRING;
     rettv->vval.v_string = get_reg_contents(regname, arg2 ? kGRegExprSrc : 0);
@@ -11024,39 +11054,40 @@ static void f_indent(typval_T *argvars, typval_T *rettv, FunPtr fptr)
  */
 static void f_index(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  list_T      *l;
-  listitem_T  *item;
   long idx = 0;
-  int ic = FALSE;
+  bool ic = false;
 
   rettv->vval.v_number = -1;
   if (argvars[0].v_type != VAR_LIST) {
     EMSG(_(e_listreq));
     return;
   }
-  l = argvars[0].vval.v_list;
+  list_T *const l = argvars[0].vval.v_list;
   if (l != NULL) {
-    item = l->lv_first;
+    listitem_T *item = tv_list_first(l);
     if (argvars[2].v_type != VAR_UNKNOWN) {
       bool error = false;
 
       // Start at specified item.  Use the cached index that tv_list_find()
       // sets, so that a negative number also works.
-      item = tv_list_find(l, tv_get_number_chk(&argvars[2], &error));
-      idx = l->lv_idx;
-      if (argvars[3].v_type != VAR_UNKNOWN) {
-        ic = tv_get_number_chk(&argvars[3], &error);
-      }
-      if (error) {
+      idx = tv_list_uidx(l, tv_get_number_chk(&argvars[2], &error));
+      if (error || idx == -1) {
         item = NULL;
+      } else {
+        item = tv_list_find(l, idx);
+        assert(item != NULL);
+      }
+      if (argvars[3].v_type != VAR_UNKNOWN) {
+        ic = !!tv_get_number_chk(&argvars[3], &error);
       }
     }
 
-    for (; item != NULL; item = item->li_next, ++idx)
-      if (tv_equal(&item->li_tv, &argvars[1], ic, FALSE)) {
+    for (; item != NULL; item = TV_LIST_ITEM_NEXT(l, item), idx++) {
+      if (tv_equal(TV_LIST_ITEM_TV(item), &argvars[1], ic, false)) {
         rettv->vval.v_number = idx;
         break;
       }
+    }
   }
 }
 
@@ -11220,7 +11251,6 @@ static void f_inputdialog(typval_T *argvars, typval_T *rettv, FunPtr fptr)
  */
 static void f_inputlist(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
-  listitem_T  *li;
   int selected;
   int mouse_used;
 
@@ -11235,15 +11265,16 @@ static void f_inputlist(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   msg_scroll = TRUE;
   msg_clr_eos();
 
-  for (li = argvars[0].vval.v_list->lv_first; li != NULL; li = li->li_next) {
-    msg_puts(tv_get_string(&li->li_tv));
+  TV_LIST_ITER_CONST(argvars[0].vval.v_list, li, {
+    msg_puts(tv_get_string(TV_LIST_ITEM_TV(li)));
     msg_putchar('\n');
-  }
+  });
 
-  /* Ask for choice. */
+  // Ask for choice.
   selected = prompt_for_number(&mouse_used);
-  if (mouse_used)
+  if (mouse_used) {
     selected -= lines_left;
+  }
 
   rettv->vval.v_number = selected;
 }
@@ -11299,9 +11330,8 @@ static void f_insert(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   if (argvars[0].v_type != VAR_LIST) {
     EMSG2(_(e_listarg), "insert()");
-  } else if ((l = argvars[0].vval.v_list) != NULL
-             && !tv_check_lock(l->lv_lock, N_("insert() argument"),
-                               TV_TRANSLATE)) {
+  } else if (!tv_check_lock(tv_list_locked((l = argvars[0].vval.v_list)),
+                            N_("insert() argument"), TV_TRANSLATE)) {
     long before = 0;
     if (argvars[2].v_type != VAR_UNKNOWN) {
       before = tv_get_number_chk(&argvars[2], &error);
@@ -11312,7 +11342,7 @@ static void f_insert(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     }
 
     listitem_T *item = NULL;
-    if (before != l->lv_len) {
+    if (before != tv_list_len(l)) {
       item = tv_list_find(l, before);
       if (item == NULL) {
         EMSGN(_(e_listidx), before);
@@ -11376,7 +11406,7 @@ static void f_islocked(typval_T *argvars, typval_T *rettv, FunPtr fptr)
         EMSG2(_(e_dictkey), lv.ll_newkey);
       } else if (lv.ll_list != NULL) {
         // List item.
-        rettv->vval.v_number = tv_islocked(&lv.ll_li->li_tv);
+        rettv->vval.v_number = tv_islocked(TV_LIST_ITEM_TV(lv.ll_li));
       } else {
         // Dictionary item.
         rettv->vval.v_number = tv_islocked(&lv.ll_di->di_tv);
@@ -11413,32 +11443,32 @@ static void dict_list(typval_T *const tv, typval_T *const rettv,
 
     switch (what) {
       case kDictListKeys: {
-        li->li_tv.v_type = VAR_STRING;
-        li->li_tv.v_lock = VAR_UNLOCKED;
-        li->li_tv.vval.v_string = vim_strsave(di->di_key);
+        TV_LIST_ITEM_TV(li)->v_type = VAR_STRING;
+        TV_LIST_ITEM_TV(li)->v_lock = VAR_UNLOCKED;
+        TV_LIST_ITEM_TV(li)->vval.v_string = vim_strsave(di->di_key);
         break;
       }
       case kDictListValues: {
-        tv_copy(&di->di_tv, &li->li_tv);
+        tv_copy(&di->di_tv, TV_LIST_ITEM_TV(li));
         break;
       }
       case kDictListItems: {
         // items()
         list_T *const sub_l = tv_list_alloc();
-        li->li_tv.v_type = VAR_LIST;
-        li->li_tv.v_lock = VAR_UNLOCKED;
-        li->li_tv.vval.v_list = sub_l;
-        sub_l->lv_refcount++;
+        TV_LIST_ITEM_TV(li)->v_type = VAR_LIST;
+        TV_LIST_ITEM_TV(li)->v_lock = VAR_UNLOCKED;
+        TV_LIST_ITEM_TV(li)->vval.v_list = sub_l;
+        tv_list_ref(sub_l);
 
         listitem_T *sub_li = tv_list_item_alloc();
         tv_list_append(sub_l, sub_li);
-        sub_li->li_tv.v_type = VAR_STRING;
-        sub_li->li_tv.v_lock = VAR_UNLOCKED;
-        sub_li->li_tv.vval.v_string = vim_strsave(di->di_key);
+        TV_LIST_ITEM_TV(sub_li)->v_type = VAR_STRING;
+        TV_LIST_ITEM_TV(sub_li)->v_lock = VAR_UNLOCKED;
+        TV_LIST_ITEM_TV(sub_li)->vval.v_string = vim_strsave(di->di_key);
 
         sub_li = tv_list_item_alloc();
         tv_list_append(sub_l, sub_li);
-        tv_copy(&di->di_tv, &sub_li->li_tv);
+        tv_copy(&di->di_tv, TV_LIST_ITEM_TV(sub_li));
         break;
       }
     }
@@ -11536,15 +11566,13 @@ static char **tv_to_argv(typval_T *cmd_tv, const char