string.sub

3 files changed, 18 insertions, 2 deletions

diff --git a/src/lauxlib.js b/src/lauxlib.js
index f77fe5e..3ee04a4 100644
--- a/src/lauxlib.js
+++ b/src/lauxlib.js
@@ -54,7 +54,7 @@ const findfield = function(L, objidx, level) {
 const pushglobalfuncname = function(L, ar) {
     let top = lapi.lua_gettop(L);
     ldebug.lua_getinfo(L, 'f', ar);  /* push function */
-    lapi.lua_getfield(L, lua.LUA_REGISTRYINDEX, lua.LUA_LOADED_TABLE);
+    lapi.lua_getfield(L, lua.LUA_REGISTRYINDEX, LUA_LOADED_TABLE);
     if (findfield(L, top + 1, 2)) {
         let name = lapi.lua_tostring(L, -1);
         if (name.startsWith("_G.")) {
diff --git a/src/lobject.js b/src/lobject.js
index 719d7a6..e1c3e97 100644
--- a/src/lobject.js
+++ b/src/lobject.js
@@ -452,8 +452,10 @@ module.exports.LocVar         = LocVar;
 module.exports.TValue         = TValue;
 module.exports.Table          = Table;
 module.exports.UTF8BUFFSZ     = UTF8BUFFSZ;
+module.exports.intarith       = intarith;
 module.exports.luaO_chunkid   = luaO_chunkid;
 module.exports.luaO_hexavalue = luaO_hexavalue;
 module.exports.luaO_int2fb    = luaO_int2fb;
 module.exports.luaO_str2num   = luaO_str2num;
-module.exports.luaO_utf8desc  = luaO_utf8desc;
\ No newline at end of file
+module.exports.luaO_utf8desc  = luaO_utf8desc;
+module.exports.numarith       = numarith;
\ No newline at end of file
diff --git a/src/lstrlib.js b/src/lstrlib.js
index b3d5aea..1d3a7cc 100644
--- a/src/lstrlib.js
+++ b/src/lstrlib.js
@@ -18,6 +18,19 @@ const posrelat = function(pos, len) {
     else return len + pos + 1;
 };
 
+const str_sub = function(L) {
+    let s = lauxlib.luaL_checkstring(L, 1);
+    let l = s.length;
+    let start = posrelat(lauxlib.luaL_checkinteger(L, 2), l);
+    let end = posrelat(lauxlib.luaL_optinteger(L, 3, -1), l);
+    if (start < 1) start = 1;
+    if (end > l) end = l;
+    if (start <= end)
+        lapi.lua_pushstring(L, s.slice(start - 1, (start - 1) + (end - start + 1)));
+    else lapi.lua_pushliteral(L, "");
+    return 1;
+};
+
 const str_len = function(L) {
     lapi.lua_pushinteger(L, lauxlib.luaL_checkstring(L, 1).length);
     return 1;
@@ -371,6 +384,7 @@ const strlib = {
     "lower":   str_lower,
     "rep":     str_rep,
     "reverse": str_reverse,
+    "sub":     str_sub,
     "upper":   str_upper
 };