1 files changed, 85 insertions, 3 deletions

diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index 0009420281..3ba4d0d70c 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -40,6 +40,7 @@
 #include "nvim/undo.h"
 #include "nvim/version.h"
 #include "nvim/vim.h"
+#include "nvim/window.h"
 
 static int in_fast_callback = 0;
 
@@ -1839,11 +1840,12 @@ cleanup:
   xfree(info);
 }
 
-void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
+/// @param preview Invoke the callback as a |:command-preview| handler.
+int nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap, bool preview)
 {
   lua_State *const lstate = global_lstate;
 
-  nlua_pushref(lstate, cmd->uc_luaref);
+  nlua_pushref(lstate, preview ? cmd->uc_preview_luaref : cmd->uc_luaref);
 
   lua_newtable(lstate);
   lua_pushboolean(lstate, eap->forceit == 1);
@@ -1913,7 +1915,87 @@ void nlua_do_ucmd(ucmd_T *cmd, exarg_T *eap)
   lua_pushstring(lstate, buf);
   lua_setfield(lstate, -2, "mods");
 
-  if (nlua_pcall(lstate, 1, 0)) {
+  lua_newtable(lstate);  // smods table
+
+  lua_pushinteger(lstate, cmdmod.tab);
+  lua_setfield(lstate, -2, "tab");
+
+  lua_pushinteger(lstate, eap->verbose_save != -1 ? p_verbose : -1);
+  lua_setfield(lstate, -2, "verbose");
+
+  if (cmdmod.split & WSP_ABOVE) {
+    lua_pushstring(lstate, "aboveleft");
+  } else if (cmdmod.split & WSP_BELOW) {
+    lua_pushstring(lstate, "belowright");
+  } else if (cmdmod.split & WSP_TOP) {
+    lua_pushstring(lstate, "topleft");
+  } else if (cmdmod.split & WSP_BOT) {
+    lua_pushstring(lstate, "botright");
+  } else {
+    lua_pushstring(lstate, "");
+  }
+  lua_setfield(lstate, -2, "split");
+
+  lua_pushboolean(lstate, cmdmod.split & WSP_VERT);
+  lua_setfield(lstate, -2, "vertical");
+  lua_pushboolean(lstate, eap->save_msg_silent != -1 ? (msg_silent != 0) : 0);
+  lua_setfield(lstate, -2, "silent");
+  lua_pushboolean(lstate, eap->did_esilent);
+  lua_setfield(lstate, -2, "emsg_silent");
+  lua_pushboolean(lstate, eap->did_sandbox);
+  lua_setfield(lstate, -2, "sandbox");
+  lua_pushboolean(lstate, cmdmod.save_ei != NULL);
+  lua_setfield(lstate, -2, "noautocmd");
+
+  typedef struct {
+    bool *set;
+    char *name;
+  } mod_entry_T;
+  static mod_entry_T mod_entries[] = {
+    { &cmdmod.browse, "browse" },
+    { &cmdmod.confirm, "confirm" },
+    { &cmdmod.hide, "hide" },
+    { &cmdmod.keepalt, "keepalt" },
+    { &cmdmod.keepjumps, "keepjumps" },
+    { &cmdmod.keepmarks, "keepmarks" },
+    { &cmdmod.keeppatterns, "keeppatterns" },
+    { &cmdmod.lockmarks, "lockmarks" },
+    { &cmdmod.noswapfile, "noswapfile" }
+  };
+
+  // The modifiers that are simple flags
+  for (size_t i = 0; i < ARRAY_SIZE(mod_entries); i++) {
+    lua_pushboolean(lstate, *mod_entries[i].set);
+    lua_setfield(lstate, -2, mod_entries[i].name);
+  }
+
+  lua_setfield(lstate, -2, "smods");
+
+  if (preview) {
+    lua_pushinteger(lstate, cmdpreview_get_ns());
+
+    handle_T cmdpreview_bufnr = cmdpreview_get_bufnr();
+    if (cmdpreview_bufnr != 0) {
+      lua_pushinteger(lstate, cmdpreview_bufnr);
+    } else {
+      lua_pushnil(lstate);
+    }
+  }
+
+  if (nlua_pcall(lstate, preview ? 3 : 1, preview ? 1 : 0)) {
     nlua_error(lstate, _("Error executing Lua callback: %.*s"));
+    return 0;
   }
+
+  int retv = 0;
+
+  if (preview) {
+    if (lua_isnumber(lstate, -1) && (retv = (int)lua_tointeger(lstate, -1)) >= 0 && retv <= 2) {
+      lua_pop(lstate, 1);
+    } else {
+      retv = 0;
+    }
+  }
+
+  return retv;
 }