new function 'luaV_flttointeger' to convert floats to integers (without

string coercions) + string operands to bitwise operations handled
by string metamethods

lstrlib.c

@@ -1,5 +1,5 @@
 /*
-** $Id: lstrlib.c,v 1.256 2017/05/19 16:29:40 roberto Exp roberto $
+** $Id: lstrlib.c,v 1.257 2017/07/07 16:34:32 roberto Exp roberto $
 ** Standard library for string operations and pattern-matching
 ** See Copyright Notice in lua.h
 */
@@ -220,17 +220,49 @@ static int tonum (lua_State *L, int arg) {
 }
 
 
+static int toint (lua_State *L, int arg) {
+  if (!tonum(L, arg))
+    return 0;  /* not coercible to a number */
+  else if (lua_isinteger(L, arg))
+    return 1;  /* already an integer */
+  else {  /* a float */
+    int ok;
+    lua_Integer n = lua_tointegerx(L, arg, &ok);
+    if (!ok)
+      return 0;
+    else {
+      lua_pop(L, 1);  /* remove the float */
+      lua_pushinteger(L, n);  /* push an integer */
+      return 1;
+    }
+  }
+}
+
+
+static void trymt (lua_State *L, const char *mtname) {
+  lua_settop(L, 2);  /* back to the original arguments */
+  if (lua_type(L, 2) == LUA_TSTRING || !luaL_getmetafield(L, 2, mtname))
+    luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
+                  luaL_typename(L, -2), luaL_typename(L, -1));
+  lua_insert(L, -3);  /* put metamethod before arguments */
+  lua_call(L, 2, 1);  /* call metamethod */
+}
+
+
 static int arith (lua_State *L, int op, const char *mtname) {
   if (tonum(L, 1) && tonum(L, 2))
     lua_arith(L, op);  /* result will be on the top */
-  else {
-    lua_settop(L, 2);  /* back to the original arguments */
-    if (lua_type(L, 2) == LUA_TSTRING || !luaL_getmetafield(L, 2, mtname))
-      return luaL_error(L, "attempt to %s a '%s' with a '%s'", mtname + 2,
-                           luaL_typename(L, -2), luaL_typename(L, -1));
-    lua_insert(L, -3);  /* put metamethod before arguments */
-    lua_call(L, 2, 1);  /* call metamethod */
-  }
+  else
+    trymt(L, mtname);
+  return 1;
+}
+
+
+static int bitwise (lua_State *L, int op, const char *mtname) {
+  if (toint(L, 1) && toint(L, 2))
+    lua_arith(L, op);  /* result will be on the top */
+  else
+    trymt(L, mtname);
   return 1;
 }
 
@@ -267,6 +299,30 @@ static int arith_unm (lua_State *L) {
   return arith(L, LUA_OPUNM, "__unm");
 }
 
+static int bitwise_band (lua_State *L) {
+  return bitwise(L, LUA_OPBAND, "__band");
+}
+
+static int bitwise_bor (lua_State *L) {
+  return bitwise(L, LUA_OPBOR, "__bor");
+}
+
+static int bitwise_bxor (lua_State *L) {
+  return bitwise(L, LUA_OPBXOR, "__bxor");
+}
+
+static int bitwise_shl (lua_State *L) {
+  return bitwise(L, LUA_OPSHL, "__shl");
+}
+
+static int bitwise_shr (lua_State *L) {
+  return bitwise(L, LUA_OPSHR, "__shr");
+}
+
+static int bitwise_bnot (lua_State *L) {
+  return bitwise(L, LUA_OPBNOT, "__bnot");
+}
+
 
 static const luaL_Reg stringmetamethods[] = {
   {"__add", arith_add},
@@ -277,6 +333,12 @@ static const luaL_Reg stringmetamethods[] = {
   {"__div", arith_div},
   {"__idiv", arith_idiv},
   {"__unm", arith_unm},
+  {"__band", bitwise_band},
+  {"__bor", bitwise_bor},
+  {"__bxor", bitwise_bxor},
+  {"__shl", bitwise_shl},
+  {"__shr", bitwise_shr},
+  {"__bnot", bitwise_bnot},
   {"__index", NULL},  /* placeholder */
   {NULL, NULL}
 };