diff --git a/limmutable.c b/limmutable.c index 959695e..22a7cb4 100644 --- a/limmutable.c +++ b/limmutable.c @@ -38,60 +38,43 @@ static int SHARED_CLASS_METATABLE; static int Lcreate_instance(lua_State *L) { - int n_args = lua_gettop(L); // arg 1: class table, ... - lua_getfield(L, 1, "__fields"); - // Stack: [__fields] - size_t n = lua_objlen(L,-1); - if ((size_t)n_args-1 != n) { - lua_pushstring(L, "incorrect number of arguments: expected "); - lua_pushinteger(L, n); - lua_pushstring(L, ", but got "); - lua_pushinteger(L, n_args-1); - lua_concat(L, 4); - lua_error(L); - } - lua_pop(L,1); - // Stack: [] - - lua_createtable(L, n, 0); - // Stack [inst] + size_t n = lua_objlen(L, -1); + lua_pop(L, 1); - // Copy in all the values, and simultaneously compute the hash: + // Compute the hash: lua_Integer hash = (lua_Integer)lua_topointer(L, 1); // Hash depends on the metatable used in creation for (lua_Integer i=1; i <=(lua_Integer)n; i++) { - lua_pushvalue(L, i+1); - // Stack [inst, args[i+1]] lua_Integer item_hash; - switch (lua_type(L, -1)) { - case LUA_TNIL: + switch (lua_type(L, 1+i)) { + case LUA_TNIL: case LUA_TNONE: // Arbitrarily chosen value item_hash = 0x97167da9; break; case LUA_TNUMBER: { // Cast float bits to integer - lua_Number n = lua_tonumber(L, -1); + lua_Number n = lua_tonumber(L, 1+i); item_hash = *((lua_Integer*)&n); break; } case LUA_TBOOLEAN: // Arbitrarily chosen values - item_hash = lua_toboolean(L, -1)? 0x82684f71 : 0x88d66f2a; + item_hash = lua_toboolean(L, 1+i)? 0x82684f71 : 0x88d66f2a; break; case LUA_TTABLE: case LUA_TFUNCTION: case LUA_TUSERDATA: case LUA_TTHREAD: case LUA_TLIGHTUSERDATA: - item_hash = (lua_Integer)lua_topointer(L, -1); + item_hash = (lua_Integer)lua_topointer(L, 1+i); break; case LUA_TSTRING: { // Algorithm taken from Lua 5.3's implementation size_t len; - const char *str = lua_tolstring(L, -1, &len); + const char *str = lua_tolstring(L, 1+i, &len); item_hash = len ^ 0xd2e9e9ac; // Arbitrary seed size_t step = (len >> LUAI_HASHLIMIT) + 1; for (; len >= step; len -= step) @@ -102,81 +85,83 @@ static int Lcreate_instance(lua_State *L) item_hash = 0; } hash = (1000003 * hash) ^ item_hash; - lua_rawseti(L, -2, i); - // Stack [inst] } lua_getfield(L, 1, "__instances"); - // Stack: [inst, buckets] + // Stack: [buckets] // Find bucket lua_rawgeti(L, -1, hash); - // Stack: [inst, buckets, bucket] + // Stack: [buckets, bucket] if (lua_isnil(L, -1)) { // Make a new bucket - // Stack: [inst, buckets, nil] + // Stack: [buckets, nil] lua_pop(L, 1); - // Stack: [inst, buckets] + // Stack: [buckets] lua_createtable(L, 1, 0); - // Stack: [inst, buckets, bucket] + // Stack: [buckets, bucket] lua_pushlightuserdata(L, (void*)&SHARED_BUCKET_METATABLE); lua_gettable(L, LUA_REGISTRYINDEX); - // Stack: [inst, buckets, bucket, {'__mode'='k'}] + // Stack: [buckets, bucket, {'__mode'='k'}] lua_setmetatable(L, -2); - // Stack: [inst, buckets, bucket] + // Stack: [buckets, bucket] lua_pushvalue(L, -1); - // Stack: [inst, buckets, bucket, bucket] + // Stack: [buckets, bucket, bucket] lua_rawseti(L, -3, hash); - // Stack: [inst, buckets, bucket] + // Stack: [buckets, bucket] } - // Stack: [inst, buckets, bucket] + // Stack: [buckets, bucket] // scan bucket lua_pushnil(L); while (lua_next(L, -2) != 0) { // for hash_collider_inst, hash_collider in pairs(bucket) do - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider] int bucket_item_matches = 1; // Perform a full equality check lua_pushnil(L); while (lua_next(L, -2) != 0) { // for i, collider_value in pairs(hash_collider) do - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value] if (!lua_rawequal(L, -1, 1+lua_tonumber(L, -2))) { // If the i'th entry doesn't match the i'th arg bucket_item_matches = 0; - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value] lua_pop(L, 3); - // Stack: [inst, buckets, bucket, hash_collider_inst] + // Stack: [buckets, bucket, hash_collider_inst] break; // go to next item in the bucket } else { - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value] lua_pop(L, 1); - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider, i] } } if (bucket_item_matches) { - // Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider] + // Stack: [buckets, bucket, hash_collider_inst, hash_collider] lua_pop(L, 1); // Found matching singleton return 1; } } - // failed to find a singleton - // Stack: [inst, buckets, bucket] - + // Failed to find an existing instance, so create a new one + // Stack: [buckets, bucket] lua_Integer* userdata = (lua_Integer*)lua_newuserdata(L, sizeof(lua_Integer)); *userdata = hash; - // Stack [inst, buckets, bucket, inst_userdata] + // Stack [buckets, bucket, inst_userdata] lua_pushvalue(L, 1); - // Stack [inst, buckets, bucket, inst_userdata, metatable] + // Stack [buckets, bucket, inst_userdata, metatable] lua_setmetatable(L, -2); - // Stack [inst, buckets, bucket, inst_userdata] - + // Stack [buckets, bucket, inst_userdata] lua_pushvalue(L, -1); - // Stack [inst, buckets, bucket, inst_userdata, inst_userdata] - lua_pushvalue(L, -5); - // Stack [inst, buckets, bucket, inst_userdata, inst_userdata, inst] - lua_settable(L, -4); // buckets[inst_userdata] = inst - // Stack [inst, buckets, bucket, inst_userdata] + // Stack [buckets, bucket, inst_userdata, inst_userdata] + lua_createtable(L, n, 0); // Create the table to store the instance's data + // Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table] + for (lua_Integer i=1; i <=(lua_Integer)n; i++) { + lua_pushvalue(L, i+1); + // Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table, arg #1+i] + lua_rawseti(L, -2, i); + } + // Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table] + lua_settable(L, -4); // buckets[inst_userdata] = inst_table + // Stack [buckets, bucket, inst_userdata] return 1; } diff --git a/tests.lua b/tests.lua index 0c5ed7e..d73373a 100644 --- a/tests.lua +++ b/tests.lua @@ -177,7 +177,7 @@ test("Testing spoofing", function() local t = {99,100} setmetatable(t, Vec) assert(not pcall(function() return t.x end)) - assert(not pcall(function() return Vec(88) end)) + assert(not pcall(function() return Vec.__index(88, 9) end)) assert(not pcall(function() return Vec.__tostring(t) end)) end)