lua: Add ability to pass tables with __call

vim-patch:8.2.1054: not so easy to pass a lua function to Vim
vim-patch:8.2.1084: Lua: registering function has useless code

I think I have also opened up the possibility for people to use these
callbacks elsewhere, since I've added a new struct that we should be
able to use.

Also, this should allow us to determine what the state of a list is in
Lua or a dictionary in Lua, since we now can track the luaref as we go.

4 files changed, 15 insertions, 5 deletions

diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index 1071e75c06..99014d1a09 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -824,9 +824,12 @@ static void f_call(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   } else if (argvars[0].v_type == VAR_PARTIAL) {
     partial = argvars[0].vval.v_partial;
     func = partial_name(partial);
+  } else if (nlua_is_table_from_lua(&argvars[0])) {
+    func = nlua_register_table_as_callable(&argvars[0]);
   } else {
     func = (char_u *)tv_get_string(&argvars[0]);
   }
+
   if (*func == NUL) {
     return;             // type error or empty name
   }
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index 0daaf6c878..89ca2db59b 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -16,6 +16,7 @@
 #include "nvim/eval/typval_encode.h"
 #include "nvim/eval.h"
 #include "nvim/eval/userfunc.h"
+#include "nvim/lua/executor.h"
 #include "nvim/types.h"
 #include "nvim/assert.h"
 #include "nvim/memory.h"
@@ -301,6 +302,7 @@ void tv_list_free_list(list_T *const l)
   }
   list_log(l, NULL, NULL, "freelist");
 
+  nlua_free_typval_list(l);
   xfree(l);
 }
 
@@ -1374,6 +1376,7 @@ void tv_dict_free_dict(dict_T *const d)
     d->dv_used_next->dv_used_prev = d->dv_used_prev;
   }
 
+  nlua_free_typval_dict(d);
   xfree(d);
 }
 
diff --git a/src/nvim/eval/typval.h b/src/nvim/eval/typval.h
index cb13bec50d..503a32a81e 100644
--- a/src/nvim/eval/typval.h
+++ b/src/nvim/eval/typval.h
@@ -180,6 +180,8 @@ struct listvar_S {
   int lv_idx;  ///< Index of a cached item, used for optimising repeated l[idx].
   int lv_copyID;  ///< ID used by deepcopy().
   VarLockStatus lv_lock;  ///< Zero, VAR_LOCKED, VAR_FIXED.
+
+  LuaRef lua_table_ref;
 };
 
 // Static list with 10 items. Use tv_list_init_static10() to initialize.
@@ -245,6 +247,8 @@ struct dictvar_S {
   dict_T *dv_used_next;   ///< Next dictionary in used dictionaries list.
   dict_T *dv_used_prev;   ///< Previous dictionary in used dictionaries list.
   QUEUE watchers;         ///< Dictionary key watchers set by user code.
+
+  LuaRef lua_table_ref;
 };
 
 /// Type used for script ID
@@ -271,9 +275,10 @@ typedef struct {
 /// Number of fixed variables used for arguments
 #define FIXVAR_CNT 12
 
-/// Callback interface for C function reference
+/// Callback interface for C function reference>
+///     Used for managing functions that were registered with |register_cfunc|
 typedef int (*cfunc_T)(int argcount, typval_T *argvars, typval_T *rettv, void *state);  // NOLINT
-/// Callback to clear cfunc_T
+/// Callback to clear cfunc_T and any associated state.
 typedef void (*cfunc_free_T)(void *state);
 
 // Structure to hold info for a function that is currently being executed.
diff --git a/src/nvim/eval/userfunc.c b/src/nvim/eval/userfunc.c
index ca2f4a32ca..229f0e8dde 100644
--- a/src/nvim/eval/userfunc.c
+++ b/src/nvim/eval/userfunc.c
@@ -3458,7 +3458,6 @@ char_u *register_cfunc(cfunc_T cb, cfunc_free_T cb_free, void *state)
 {
   char_u *name = get_lambda_name();
   ufunc_T *fp = NULL;
-  int flags = FC_CFUNC;
 
   fp = xcalloc(1, offsetof(ufunc_T, uf_name) + STRLEN(name) + 1);
   if (fp == NULL) {
@@ -3467,7 +3466,7 @@ char_u *register_cfunc(cfunc_T cb, cfunc_free_T cb_free, void *state)
 
   fp->uf_refcount = 1;
   fp->uf_varargs = true;
-  fp->uf_flags = flags;
+  fp->uf_flags = FC_CFUNC;
   fp->uf_calls = 0;
   fp->uf_script_ctx = current_sctx;
   fp->uf_cb = cb;
@@ -3477,5 +3476,5 @@ char_u *register_cfunc(cfunc_T cb, cfunc_free_T cb_free, void *state)
   STRCPY(fp->uf_name, name);
   hash_add(&func_hashtab, UF2HIKEY(fp));
 
-  return name;
+  return fp->uf_name;
 }