Optimizations of instantiation (no longer creates table until
necessary).
This commit is contained in:
Bruce Hill
parent
fa456525df
commit
04c20ab009
99
limmutable.c
99
limmutable.c
@ -38,60 +38,43 @@ static int SHARED_CLASS_METATABLE;
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static int Lcreate_instance(lua_State *L)
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{
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int n_args = lua_gettop(L);
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// arg 1: class table, ...
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lua_getfield(L, 1, "__fields");
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// Stack: [__fields]
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size_t n = lua_objlen(L,-1);
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if ((size_t)n_args-1 != n) {
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lua_pushstring(L, "incorrect number of arguments: expected ");
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lua_pushinteger(L, n);
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lua_pushstring(L, ", but got ");
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lua_pushinteger(L, n_args-1);
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lua_concat(L, 4);
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lua_error(L);
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}
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lua_pop(L,1);
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// Stack: []
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lua_createtable(L, n, 0);
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// Stack [inst]
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size_t n = lua_objlen(L, -1);
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lua_pop(L, 1);
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// Copy in all the values, and simultaneously compute the hash:
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// Compute the hash:
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lua_Integer hash = (lua_Integer)lua_topointer(L, 1); // Hash depends on the metatable used in creation
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for (lua_Integer i=1; i <=(lua_Integer)n; i++) {
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lua_pushvalue(L, i+1);
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// Stack [inst, args[i+1]]
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lua_Integer item_hash;
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switch (lua_type(L, -1)) {
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case LUA_TNIL:
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switch (lua_type(L, 1+i)) {
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case LUA_TNIL: case LUA_TNONE:
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// Arbitrarily chosen value
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item_hash = 0x97167da9;
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break;
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case LUA_TNUMBER:
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{
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// Cast float bits to integer
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lua_Number n = lua_tonumber(L, -1);
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lua_Number n = lua_tonumber(L, 1+i);
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item_hash = *((lua_Integer*)&n);
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break;
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}
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case LUA_TBOOLEAN:
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// Arbitrarily chosen values
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item_hash = lua_toboolean(L, -1)? 0x82684f71 : 0x88d66f2a;
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item_hash = lua_toboolean(L, 1+i)? 0x82684f71 : 0x88d66f2a;
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break;
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case LUA_TTABLE:
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case LUA_TFUNCTION:
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case LUA_TUSERDATA:
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case LUA_TTHREAD:
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case LUA_TLIGHTUSERDATA:
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item_hash = (lua_Integer)lua_topointer(L, -1);
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item_hash = (lua_Integer)lua_topointer(L, 1+i);
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break;
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case LUA_TSTRING:
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{
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// Algorithm taken from Lua 5.3's implementation
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size_t len;
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const char *str = lua_tolstring(L, -1, &len);
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const char *str = lua_tolstring(L, 1+i, &len);
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item_hash = len ^ 0xd2e9e9ac; // Arbitrary seed
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size_t step = (len >> LUAI_HASHLIMIT) + 1;
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for (; len >= step; len -= step)
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@ -102,81 +85,83 @@ static int Lcreate_instance(lua_State *L)
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item_hash = 0;
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}
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hash = (1000003 * hash) ^ item_hash;
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lua_rawseti(L, -2, i);
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// Stack [inst]
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}
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lua_getfield(L, 1, "__instances");
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// Stack: [inst, buckets]
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// Stack: [buckets]
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// Find bucket
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lua_rawgeti(L, -1, hash);
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// Stack: [inst, buckets, bucket]
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// Stack: [buckets, bucket]
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if (lua_isnil(L, -1)) {
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// Make a new bucket
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// Stack: [inst, buckets, nil]
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// Stack: [buckets, nil]
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lua_pop(L, 1);
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// Stack: [inst, buckets]
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// Stack: [buckets]
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lua_createtable(L, 1, 0);
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// Stack: [inst, buckets, bucket]
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// Stack: [buckets, bucket]
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lua_pushlightuserdata(L, (void*)&SHARED_BUCKET_METATABLE);
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lua_gettable(L, LUA_REGISTRYINDEX);
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// Stack: [inst, buckets, bucket, {'__mode'='k'}]
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// Stack: [buckets, bucket, {'__mode'='k'}]
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lua_setmetatable(L, -2);
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// Stack: [inst, buckets, bucket]
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// Stack: [buckets, bucket]
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lua_pushvalue(L, -1);
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// Stack: [inst, buckets, bucket, bucket]
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// Stack: [buckets, bucket, bucket]
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lua_rawseti(L, -3, hash);
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// Stack: [inst, buckets, bucket]
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// Stack: [buckets, bucket]
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}
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// Stack: [inst, buckets, bucket]
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// Stack: [buckets, bucket]
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// scan bucket
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lua_pushnil(L);
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while (lua_next(L, -2) != 0) { // for hash_collider_inst, hash_collider in pairs(bucket) do
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider]
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int bucket_item_matches = 1;
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// Perform a full equality check
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lua_pushnil(L);
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while (lua_next(L, -2) != 0) { // for i, collider_value in pairs(hash_collider) do
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value]
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if (!lua_rawequal(L, -1, 1+lua_tonumber(L, -2))) { // If the i'th entry doesn't match the i'th arg
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bucket_item_matches = 0;
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value]
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lua_pop(L, 3);
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// Stack: [inst, buckets, bucket, hash_collider_inst]
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// Stack: [buckets, bucket, hash_collider_inst]
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break; // go to next item in the bucket
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} else {
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i, value]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider, i, value]
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lua_pop(L, 1);
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider, i]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider, i]
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}
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}
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if (bucket_item_matches) {
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// Stack: [inst, buckets, bucket, hash_collider_inst, hash_collider]
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// Stack: [buckets, bucket, hash_collider_inst, hash_collider]
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lua_pop(L, 1);
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// Found matching singleton
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return 1;
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}
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}
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// failed to find a singleton
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// Stack: [inst, buckets, bucket]
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// Failed to find an existing instance, so create a new one
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// Stack: [buckets, bucket]
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lua_Integer* userdata = (lua_Integer*)lua_newuserdata(L, sizeof(lua_Integer));
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*userdata = hash;
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// Stack [inst, buckets, bucket, inst_userdata]
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// Stack [buckets, bucket, inst_userdata]
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lua_pushvalue(L, 1);
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// Stack [inst, buckets, bucket, inst_userdata, metatable]
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// Stack [buckets, bucket, inst_userdata, metatable]
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lua_setmetatable(L, -2);
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// Stack [inst, buckets, bucket, inst_userdata]
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// Stack [buckets, bucket, inst_userdata]
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lua_pushvalue(L, -1);
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// Stack [inst, buckets, bucket, inst_userdata, inst_userdata]
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lua_pushvalue(L, -5);
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// Stack [inst, buckets, bucket, inst_userdata, inst_userdata, inst]
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lua_settable(L, -4); // buckets[inst_userdata] = inst
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// Stack [inst, buckets, bucket, inst_userdata]
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// Stack [buckets, bucket, inst_userdata, inst_userdata]
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lua_createtable(L, n, 0); // Create the table to store the instance's data
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// Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table]
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for (lua_Integer i=1; i <=(lua_Integer)n; i++) {
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lua_pushvalue(L, i+1);
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// Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table, arg #1+i]
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lua_rawseti(L, -2, i);
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}
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// Stack [buckets, bucket, inst_userdata, inst_userdata, inst_table]
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lua_settable(L, -4); // buckets[inst_userdata] = inst_table
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// Stack [buckets, bucket, inst_userdata]
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return 1;
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}
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@ -177,7 +177,7 @@ test("Testing spoofing", function()
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local t = {99,100}
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setmetatable(t, Vec)
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assert(not pcall(function() return t.x end))
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assert(not pcall(function() return Vec(88) end))
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assert(not pcall(function() return Vec.__index(88, 9) end))
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assert(not pcall(function() return Vec.__tostring(t) end))
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end)
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