assert

2 files changed, 14 insertions, 3 deletions

diff --git a/src/lauxlib.js b/src/lauxlib.js
index c44780e..e295fe6 100644
--- a/src/lauxlib.js
+++ b/src/lauxlib.js
@@ -12,9 +12,7 @@ const CT     = lua.constant_types;
 const LUA_LOADED_TABLE = "_LOADED"
 
 const panic = function(L) {
-    let msg = `PANIC: unprotected error in call to Lua API (${lapi.lua_tostring(L, -1)})`;
-    console.error(msg);
-    return 0;
+    throw new Error(`PANIC: unprotected error in call to Lua API (${lapi.lua_tostring(L, -1)})`);
 };
 
 // const luaL_argerror = function(L, arg, extramsg) {
diff --git a/src/lbaselib.js b/src/lbaselib.js
index 9cc4fb1..fa0349b 100644
--- a/src/lbaselib.js
+++ b/src/lbaselib.js
@@ -165,6 +165,18 @@ const luaB_error = function(L) {
     return lapi.lua_error(L);
 };
 
+const luaB_assert = function(L) {
+    if (lapi.lua_toboolean(L, 1))  /* condition is true? */
+        return lapi.lua_gettop(L);  /* return all arguments */
+    else {
+        lauxlib.luaL_checkany(L, 1);  /* there must be a condition */
+        lapi.lua_remove(L, 1);  /* remove it */
+        lapi.lua_pushliteral(L, "assertion failed!");  /* default message */
+        lapi.lua_settop(L, 1);  /* leave only message (default if no other one) */
+        return luaB_error(L);  /* call 'error' */
+    }
+};
+
 const luaB_select = function(L) {
     let n = lapi.lua_gettop(L);
     if (lapi.lua_type(L, 1) === CT.LUA_TSTRING && lapi.lua_tostring(L, 1) === "#") {
@@ -220,6 +232,7 @@ const luaB_xpcall = function(L) {
 
 const base_funcs = {
     "collectgarbage": function () {},
+    "assert":         luaB_assert,
     "print":          luaB_print,
     "tostring":       luaB_tostring,
     "tonumber":       luaB_tonumber,