Bruce/lua-immutable
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
a3fcf87b2c
lua-immutable/limmutable.c
Bruce Hill a3fcf87b2c Initial working version.
2018-06-04 00:45:56 -07:00

853 lines
28 KiB
C
Raw Blame History

/*
* immutable.c
* An immutable table library by Bruce Hill. This library returns a single function
* that can be used to declare immutable classes, like so:
*
* immutable = require 'immutable'
* local Foo = immutable({"baz","qux"}, {class_var=5})
* local foo = Foo("hello", 99)
* assert(foo.baz == "hello")
* assert(not pcall(function() foo.x = 'mutable' end))
* local t = {[foo]="it works"}
* assert(t[Foo("hello", 99)] == "it works")
* assert(foo.class_var == 5)
*
* Instances *are* garbage collected.
*
* Class layout:
* __instances: weak-valued map from hash -> hash bucket
* hash buckets: weak-keyed map from instance userdata -> table of values
* __buckets: weak-keyed map from instance userdata -> hash bucket (used to manage hash bucket lifetimes)
* __fields: list of named fields
* __indices: map from field names to the index in the instance table where the value is stored
* metamethods, methods, class variables, etc.
*/
#include "lua.h"
#include "lauxlib.h"
// The C API changed from 5.1 to 5.2, so these shims help the code compile on >=5.2
#if LUA_VERSION_NUM >= 502
#define lua_objlen(L, i) lua_rawlen(L, i)
#define luaL_register(L, _, R) luaL_setfuncs(L, R, 0)
#endif
// Lua 5.3 introduced lua_isinteger, fall back to lua_isnumber
#if LUA_VERSION_NUM < 503
#define lua_isinteger(L, i) lua_isnumber(L, i)
#endif
#if !defined(LUAI_HASHLIMIT)
#define LUAI_HASHLIMIT 5
#endif
// This is used to create a unique light userdata to store in the registry to allow all
// hash buckets to share the same {__mode='k'} metatable
static int WEAK_KEY_METATABLE;
// This is used to create a unique light userdata to store in the registry to allow all
// __instances tables to share the same {__mode='v'} metatable
static int WEAK_VALUE_METATABLE;
// This is used to create a unique light userdata to store in the registry to allow all
// constructed classes to have the same metatable:
// {__new=Lcreate_instance, __tostring=function(cls) return cls.name or 'immutable(...)' end}
static int SHARED_CLASS_METATABLE;
typedef struct {
int hash;
size_t len;
} immutable_info_t;
static int Lcreate_instance(lua_State *L)
{
int num_args = lua_gettop(L)-1;
lua_getfield(L, 1, "__fields");
int num_fields = lua_objlen(L, -1);
lua_pop(L, 1);
// arg 1: class table, ...
lua_getfield(L, 1, "__new");
if (! lua_isnil(L, -1)) {
// stack: cls, ..., __new
lua_pushvalue(L, 1);
// stack: cls, ..., __new, cls
lua_rotate(L, 2, 2);
// stack: cls, __new, cls, ...
lua_call(L, num_args+1, LUA_MULTRET);
num_args = lua_gettop(L)-1;
// stack: cls, ...
} else {
lua_pop(L, 1);
}
// Compute the hash:
unsigned long long ull_hash = 0x9a937c4d; // Seed
for (lua_Integer i=1; i <=(lua_Integer)num_fields || i <=(lua_Integer)num_args; i++) {
unsigned long long item_hash;
int type = i > num_args ? LUA_TNIL : lua_type(L, 1+i);
switch (type) {
case LUA_TNIL: case LUA_TNONE:
// Arbitrarily chosen value
item_hash = 0x97167da9;
break;
case LUA_TNUMBER:
{
// Cast float bits to integer
lua_Number num = lua_tonumber(L, 1+i);
item_hash = *((lua_Integer*)&num);
if (item_hash == 0) {
item_hash = 0x2887c992;
}
break;
}
case LUA_TBOOLEAN:
// Arbitrarily chosen values
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 = (1000003 * type) ^ (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+i, &len);
item_hash = len ^ 0xd2e9e9ac; // Arbitrary seed
size_t step = (len >> LUAI_HASHLIMIT) + 1;
for (; len >= step; len -= step)
item_hash ^= ((item_hash<<5) + (item_hash>>2) + (unsigned char)(str[len - 1]));
break;
}
default:
item_hash = 0;
}
ull_hash = (1000003 * ull_hash) ^ item_hash;
}
int hash = (int)ull_hash;
lua_getfield(L, 1, "__instances");
// Stack: [__instances]
// Find bucket
lua_rawgeti(L, -1, hash);
// Stack: [__instances, bucket]
if (lua_isnil(L, -1)) {
// Make a new bucket
// Stack: [__instances, nil]
lua_pop(L, 1);
// Stack: [__instances]
lua_createtable(L, 0, 1);
// Stack: [__instances, bucket]
lua_pushlightuserdata(L, (void*)&WEAK_KEY_METATABLE);
lua_gettable(L, LUA_REGISTRYINDEX);
// Stack: [__instances, bucket, {__mode='k'}]
lua_setmetatable(L, -2);
// Stack: [__instances, bucket]
lua_pushvalue(L, -1);
// Stack: [__instances, bucket, bucket]
lua_rawseti(L, -3, hash);
// Stack: [__instances, bucket]
} else {
// Stack: [__instances, bucket]
// scan bucket
lua_pushnil(L);
while (lua_next(L, -2) != 0) { // for hash_collider_inst, hash_collider in pairs(bucket) do
// Stack: [__instances, bucket, hash_collider_inst, hash_collider]
// Shallow equality check:
lua_pushnil(L);
while (lua_next(L, -2) != 0) { // for i, collider_value in pairs(hash_collider) do
// Stack: [__instances, 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
// Stack: [__instances, bucket, hash_collider_inst, hash_collider, i, value]
lua_pop(L, 3);
// Stack: [__instances, bucket, hash_collider_inst]
goto next_bucket_item;
} else {
// Stack: [__instances, bucket, hash_collider_inst, hash_collider, i, value]
lua_pop(L, 1);
// Stack: [__instances, bucket, hash_collider_inst, hash_collider, i]
}
}
// bucket item matches
// Stack: [__instances, bucket, hash_collider_inst, hash_collider]
lua_pop(L, 1);
return 1;
next_bucket_item: ;
}
}
lua_insert(L, -2);
// Stack: [bucket, __instances]
lua_pop(L, 1);
// Stack: [bucket]
int bucket_index = lua_gettop(L);
// Failed to find an existing instance, so create a new one
// Stack: [bucket]
immutable_info_t *userdata = (immutable_info_t*)lua_newuserdata(L, sizeof(immutable_info_t));
// Stack [bucket, inst_userdata]
int userdata_index = lua_gettop(L);
userdata->hash = hash;
userdata->len = num_fields > num_args ? num_fields : num_args;
lua_pushvalue(L, 1);
// Stack [bucket, inst_userdata, cls]
lua_setmetatable(L, -2);
// Stack [bucket, inst_userdata]
lua_createtable(L, userdata->len, 0); // Create the table to store the instance's data
// Stack [bucket, inst_userdata, inst_table]
for (lua_Integer i=1; i <= (lua_Integer)num_args; i++) {
lua_pushvalue(L, i+1);
// Stack [bucket, inst_userdata, inst_table, arg #1+i]
lua_rawseti(L, -2, i);
}
// Set up a ref to the bucket so its lifetime is tied to inst_userdata
lua_getfield(L, 1, "__buckets");
// Stack [bucket, inst_userdata, inst_table, __buckets]
lua_pushvalue(L, userdata_index);
// Stack [bucket, inst_userdata, inst_table, __buckets, inst_userdata]
lua_pushvalue(L, bucket_index);
// Stack [bucket, inst_userdata, inst_table, __buckets, inst_userdata, bucket]
lua_settable(L, -3);
lua_pop(L, 1);
// Stack [bucket, inst_userdata, inst_table]
lua_pushvalue(L, userdata_index);
// Stack [bucket, inst_userdata, inst_table, inst_userdata]
lua_rotate(L, bucket_index, 1);
// Stack [inst_userdata, bucket, inst_userdata, inst_table]
lua_settable(L, -3); // buckets[inst_userdata] = inst_table
lua_pop(L, 1);
// Stack [inst_userdata]
lua_gc(L, LUA_GCSTEP, 3);
return 1;
}
static int Lfrom_table(lua_State *L)
{
lua_getfield(L, 1, "__fields");
int fields_index = lua_gettop(L);
int num_fields = lua_objlen(L, -1);
int num_values = num_fields + lua_objlen(L, 2);
// Compute the hash:
unsigned long long ull_hash = 0x9a937c4d; // Seed
for (lua_Integer i=1; i <=(lua_Integer)num_values; i++) {
unsigned long long item_hash;
// Stack: [fields]
if (i <= num_fields) {
lua_rawgeti(L, fields_index, i);
// Stack: [fields, fields[i]]
lua_gettable(L, 2);
// Stack: [fields, table[fields[i]]]
} else {
lua_rawgeti(L, 2, i - num_fields);
// Stack: [fields, table[i-num_fields]]
}
// Stack: [fields, value[i]]
int type = lua_type(L, -1);
switch (type) {
case LUA_TNIL: case LUA_TNONE:
// Arbitrarily chosen value
item_hash = 0x97167da9;
break;
case LUA_TNUMBER:
{
// Cast float bits to integer
lua_Number num = lua_tonumber(L, -1);
item_hash = *((lua_Integer*)&num);
if (item_hash == 0) {
item_hash = 0x2887c992;
}
break;
}
case LUA_TBOOLEAN:
// Arbitrarily chosen values
item_hash = lua_toboolean(L, -1)? 0x82684f71 : 0x88d66f2a;
break;
case LUA_TTABLE:
case LUA_TFUNCTION:
case LUA_TUSERDATA:
case LUA_TTHREAD:
case LUA_TLIGHTUSERDATA:
item_hash = (1000003 * type) ^ (lua_Integer)lua_topointer(L, -1);
break;
case LUA_TSTRING:
{
// Algorithm taken from Lua 5.3's implementation
size_t len;
const char *str = lua_tolstring(L, -1, &len);
item_hash = len ^ 0xd2e9e9ac; // Arbitrary seed
size_t step = (len >> LUAI_HASHLIMIT) + 1;
for (; len >= step; len -= step)
item_hash ^= ((item_hash<<5) + (item_hash>>2) + (unsigned char)(str[len - 1]));
break;
}
default:
item_hash = 0;
}
ull_hash = (1000003 * ull_hash) ^ item_hash;
lua_pop(L, 1);
// Stack: [fields]
}
int hash = (int)ull_hash;
lua_getfield(L, 1, "__instances");
// Stack: [fields, __instances]
// Find bucket
lua_rawgeti(L, -1, hash);
// Stack: [fields, __instances, bucket]
if (lua_isnil(L, -1)) {
// Make a new bucket
// Stack: [fields, __instances, nil]
lua_pop(L, 1);
// Stack: [fields, __instances]
lua_createtable(L, 0, 1);
// Stack: [fields, __instances, bucket]
lua_pushlightuserdata(L, (void*)&WEAK_KEY_METATABLE);
lua_gettable(L, LUA_REGISTRYINDEX);
// Stack: [fields, __instances, bucket, {__mode='k'}]
lua_setmetatable(L, -2);
// Stack: [fields, __instances, bucket]
lua_pushvalue(L, -1);
// Stack: [fields, __instances, bucket, bucket]
lua_rawseti(L, -3, hash);
// Stack: [fields, __instances, bucket]
} else {
// Stack: [fields, __instances, bucket]
// scan bucket
lua_pushnil(L);
while (lua_next(L, -2) != 0) { // for hash_collider_inst, hash_collider in pairs(bucket) do
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider]
// Shallow equality check:
lua_pushnil(L);
while (lua_next(L, -2) != 0) { // for i, collider_value in pairs(hash_collider) do
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider, i, value]
int i = lua_tonumber(L, -2);
if (i <= num_fields) {
lua_rawgeti(L, fields_index, i);
lua_gettable(L, 2);
} else {
lua_rawgeti(L, 2, i-num_fields);
}
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider, i, value, table_value]
if (!lua_rawequal(L, -1, -2)) { // If the i'th entry doesn't match the i'th arg
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider, i, value, table_value]
lua_pop(L, 4);
// Stack: [fields, __instances, bucket, hash_collider_inst]
goto next_bucket_item;
} else {
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider, i, value, table_value]
lua_pop(L, 2);
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider, i]
}
}
// bucket item matches
// Stack: [fields, __instances, bucket, hash_collider_inst, hash_collider]
lua_pop(L, 1);
return 1;
next_bucket_item: ;
}
}
lua_insert(L, -2);
// Stack: [fields, bucket, __instances]
lua_pop(L, 1);
// Stack: [fields, bucket]
int bucket_index = lua_gettop(L);
// Failed to find an existing instance, so create a new one
// Stack: [fields, bucket]
immutable_info_t *userdata = (immutable_info_t*)lua_newuserdata(L, sizeof(immutable_info_t));
// Stack [fields, bucket, inst_userdata]
int userdata_index = lua_gettop(L);
userdata->hash = hash;
userdata->len = num_values;
lua_pushvalue(L, 1);
// Stack [fields, bucket, inst_userdata, cls]
lua_setmetatable(L, -2);
// Stack [fields, bucket, inst_userdata]
lua_createtable(L, userdata->len, 0); // Create the table to store the instance's data
// Stack [fields, bucket, inst_userdata, inst_table]
for (lua_Integer i=1; i <= (lua_Integer)num_fields; i++) {
lua_rawgeti(L, fields_index, i);
lua_gettable(L, 2);
lua_rawseti(L, -2, i);
}
for (lua_Integer i=num_fields+1; i <= num_values; i++) {
lua_rawgeti(L, 2, i-num_fields);
lua_rawseti(L, -2, i);
}
// Set up a ref to the bucket so its lifetime is tied to inst_userdata
lua_getfield(L, 1, "__buckets");
// Stack [fields, bucket, inst_userdata, inst_table, __buckets]
lua_pushvalue(L, userdata_index);
// Stack [fields, bucket, inst_userdata, inst_table, __buckets, inst_userdata]
lua_pushvalue(L, bucket_index);
// Stack [fields, bucket, inst_userdata, inst_table, __buckets, inst_userdata, bucket]
lua_settable(L, -3);
lua_pop(L, 1);
// Stack [fields, bucket, inst_userdata, inst_table]
lua_pushvalue(L, userdata_index);
// Stack [fields, bucket, inst_userdata, inst_table, inst_userdata]
lua_rotate(L, bucket_index, 1);
// Stack [fields, inst_userdata, bucket, inst_userdata, inst_table]
lua_settable(L, -3); // buckets[inst_userdata] = inst_table
lua_pop(L, 1);
// Stack [fields, inst_userdata]
lua_gc(L, LUA_GCSTEP, 3);
return 1;
}
static int Lis_instance(lua_State *L)
{
if (lua_type(L, 2) != LUA_TUSERDATA) {
lua_pushboolean(L, 0);
return 1;
}
lua_getmetatable(L, 2);
lua_pushboolean(L, lua_rawequal(L, -1, 1));
return 1;
}
static int Llen(lua_State *L)
{
luaL_checktype(L, 1, LUA_TUSERDATA);
if (! lua_getmetatable(L, 1)) {
luaL_error(L, "invalid type");
}
immutable_info_t *info = (immutable_info_t *)lua_touserdata(L, 1);
lua_getfield(L, -1, "__fields");
size_t len = info->len - lua_objlen(L, -1);
lua_pushinteger(L, len);
return 1;
}
static int Linst_index(lua_State *L)
{
// Return inst[key], <whether inst has key>
luaL_checktype(L, 1, LUA_TUSERDATA);
if (! lua_getmetatable(L, 1)) {
luaL_error(L, "invalid type");
}
// Stack: [mt]
immutable_info_t *info = (immutable_info_t*)lua_touserdata(L, 1);
if (! info) {
luaL_error(L, "invalid type");
}
lua_getfield(L, -1, "__fields");
size_t num_fields = lua_objlen(L, -1);
lua_pop(L, 1);
// Stack: [mt]
lua_getfield(L, -1, "__indices");
// Stack: [mt, indices]
lua_pushvalue(L, 2);
lua_gettable(L, -2);
// Stack: [mt, indices, index]
int index;
if (lua_isnil(L, -1)) {
if (! lua_isinteger(L, 2)) {
return 0;
}
index = lua_tointeger(L, 2) + num_fields;
} else {
index = lua_tointeger(L, -1);
}
lua_pop(L, 2);
// Stack: [mt]
if (! (0 < index && index <= (int)info->len)) {
return 0;
}
// Stack: [mt]
lua_getfield(L, -1, "__instances");
// Stack: [mt, buckets]
lua_rawgeti(L, -1, info->hash);
// Stack: [mt, buckets, bucket]
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find hash bucket");
}
lua_pushvalue(L, 1);
// Stack: [mt, buckets, bucket, inst_udata]
lua_rawget(L, -2);
// Stack: [mt, buckets, bucket, inst_table]
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find instance");
}
lua_rawgeti(L, -1, index);
lua_pushboolean(L, 1);
return 2;
}
static int Lindex(lua_State *L)
{
int ret = Linst_index(L);
if (ret > 0) {
if (ret > 1) {
lua_pop(L, ret-1);
}
return 1;
}
// Fall back to class:
lua_getmetatable(L, 1);
// Stack: [..., mt]
lua_pushvalue(L, 2);
// Stack: [..., mt, key]
lua_gettable(L, -2);
// Stack: [..., mt, value]
if (! lua_isnil(L, -1)) {
return 1;
}
return 0;
}
static int Ltostring(lua_State *L)
{
luaL_Buffer b;
luaL_buffinit(L, &b);
if (! lua_getmetatable(L, 1)) {
luaL_error(L, "invalid type");
}
int cls_index = lua_gettop(L);
// Stack: [mt]
lua_getfield(L, cls_index, "name");
if (!lua_isnil(L, -1)) {
luaL_addvalue(&b);
} else {
lua_pop(L, 1);
}
luaL_addstring(&b, "(");
lua_getfield(L, cls_index, "__instances");
// Stack: [mt, buckets]
immutable_info_t *info = (immutable_info_t*)lua_touserdata(L, 1);
if (! info) {
luaL_error(L, "invalid type");
}
lua_rawgeti(L, -1, info->hash);
// Stack: [mt, buckets, bucket]
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find hash bucket");
}
lua_pushvalue(L, 1);
// Stack: [mt, buckets, bucket, inst_udata]
lua_rawget(L, -2);
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find instance table");
}
int inst_table_index = lua_gettop(L);
// Stack: [mt, buckets, bucket, inst_table]
lua_getglobal(L, "tostring");
int tostring_index = lua_gettop(L);
// Stack: [mt, buckets, bucket, inst_table, tostring]
int n = info->len, i = 1;
if (i <= n) {
goto first_list_item;
}
while (++i <= n) {
// Stack: [mt, buckets, bucket, inst_table, tostring, ???]
luaL_addstring(&b, ", ");
first_list_item:
lua_pushvalue(L, tostring_index);
// Stack: [mt, buckets, bucket, inst_table, tostring, ???, tostring]
lua_rawgeti(L, inst_table_index, i);
// Stack: [mt, buckets, bucket, inst_table, tostring, ???, tostring, value]
int quotes = lua_type(L, -1) == LUA_TSTRING;
lua_call(L, 1, 1);
if (quotes) {
luaL_addchar(&b, '"');
}
// Stack: [mt, buckets, bucket, inst_table, tostring, ???, value string]
// TODO: properly escape strings? str:gsub('["\\]',"\\%1"):gsub("\n","\\n")
luaL_addvalue(&b);
// Stack: [mt, buckets, bucket, inst_table, tostring, ???]
if (quotes) {
luaL_addchar(&b, '"');
}
}
luaL_addstring(&b, ")");
luaL_pushresult(&b);
return 1;
}
static int Lnexti(lua_State *L)
{
if (! lua_getmetatable(L, 1)) {
luaL_error(L, "invalid type");
}
// Stack: [mt]
lua_getfield(L, -1, "__instances");
// Stack: [mt, buckets]
immutable_info_t *info = (immutable_info_t*)lua_touserdata(L, 1);
if (! info) {
luaL_error(L, "invalid type");
}
int i = lua_isnil(L, 2) ? 1 : lua_tointeger(L, 2)+1;
if (i > (int)info->len) {
return 0;
}
lua_rawgeti(L, -1, info->hash);
// Stack: [mt, buckets, bucket]
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find hash bucket");
}
lua_pushvalue(L, 1);
// Stack: [mt, buckets, bucket, inst_udata]
lua_rawget(L, -2);
// Stack: [mt, buckets, bucket, inst_table]
lua_pushinteger(L, i);
// Stack: [mt, buckets, bucket, inst_table, i]
lua_getfield(L, -5, "__fields");
// Stack: [mt, buckets, bucket, inst_table, i, __fields]
i += lua_objlen(L, -1);
lua_pop(L, 1);
lua_rawgeti(L, -2, i);
// Stack: [mt, buckets, bucket, inst_table, i, table[i]]
return 2;
}
static int Lipairs(lua_State *L)
{
lua_pushcfunction(L, Lnexti);
// Stack: [Lnexti]
lua_pushvalue(L, 1);
// Stack: [Lnexti, inst_udata]
lua_pushnil(L);
// Stack: [Lnexti, inst_udata, nil]
return 3;
}
static int Lnext(lua_State *L)
{
if (! lua_getmetatable(L, 1)) {
luaL_error(L, "invalid type");
}
int cls_index = lua_gettop(L);
// Stack: [mt]
lua_getfield(L, cls_index, "__fields");
int fields_index = lua_gettop(L);
lua_getfield(L, cls_index, "__indices");
int indices_index = lua_gettop(L);
lua_getfield(L, cls_index, "__instances");
// Stack: [..., buckets]
immutable_info_t *info = (immutable_info_t*)lua_touserdata(L, 1);
if (! info) {
luaL_error(L, "invalid type");
}
lua_rawgeti(L, -1, info->hash);
// Stack: [..., buckets, bucket]
if (lua_isnil(L, -1)) {
luaL_error(L, "Failed to find hash bucket");
}
lua_pushvalue(L, 1);
// Stack: [..., buckets, bucket, inst_udata]
lua_rawget(L, -2);
// Stack: [..., buckets, bucket, inst_table]
size_t num_fields = lua_objlen(L, fields_index);
int index;
if (lua_isnil(L, 2)) {
index = 1;
} else {
lua_pushvalue(L, 2);
// Stack: [..., buckets, bucket, inst_table, k]
lua_gettable(L, indices_index);
// Stack: [..., buckets, bucket, inst_table, i]
if (! lua_isnil(L, -1)) {
index = lua_tointeger(L, -1) + 1;
} else {
index = lua_tointeger(L, 2) + num_fields + 1;
}
lua_pop(L, 1);
}
// Stack: [..., buckets, bucket, inst_table]
if (! (0 < index && index <= (int)info->len)) {
return 0;
}
// Now find field name
if (index <= (int)num_fields) {
lua_rawgeti(L, fields_index, index);
} else {
lua_pushinteger(L, index - num_fields);
}
// Stack: [..., buckets, bucket, inst_table, k2]
lua_rawgeti(L, -2, index);
// Stack: [..., buckets, bucket, inst_table, k2, value2]
return 2;
}
static int Lpairs(lua_State *L)
{
lua_pushcfunction(L, Lnext);
// Stack: [Lnext]
lua_pushvalue(L, 1);
// Stack: [Lnext, inst_udata]
lua_pushnil(L);
// Stack: [Lnext, inst_udata, nil]
return 3;
}
static int Lhash(lua_State *L)
{
luaL_checktype(L, 1, LUA_TUSERDATA);
immutable_info_t *info = (immutable_info_t *)lua_touserdata(L, 1);
lua_pushinteger(L, info->hash);
return 1;
}
static const luaL_Reg Rinstance_metamethods[] =
{
{"__len", Llen},
{"__rawlen", Llen},
{"__index", Lindex},
{"__rawindex", Linst_index},
{"__tostring", Ltostring},
{"__rawtostring", Ltostring},
{"__ipairs", Lipairs},
{"__rawipairs", Lipairs},
{"__pairs", Lpairs},
{"__rawpairs", Lpairs},
{"__hash", Lhash},
{"from_table", Lfrom_table},
{"is_instance", Lis_instance},
{NULL, NULL}
};
static int Lmake_class(lua_State *L)
{
size_t num_args = lua_gettop(L);
// immutable([fields], [methods/metamethods])
lua_createtable(L, 0, 24); // Rough guess of number of fields from Rinstance_metamethods + __fields, etc.
// Stack: [CLS]
// Populate CLS.__len, CLS.__index, CLS.__pairs, etc.
luaL_register(L,NULL,Rinstance_metamethods);
// If methods were passed in, copy them over, overwriting defaults if desired
if (num_args >= 2 && lua_type(L, 2) == LUA_TTABLE) {
// Stack: [CLS]
lua_pushnil(L);
// Stack: [CLS, nil]
while (lua_next(L, 2) != 0) {
// Stack: [CLS, method_name, method_value]
lua_pushvalue(L, -2);
// Stack: [CLS, method_name, method_value, method_name]
lua_insert(L, -2);
// Stack: [CLS, method_name, method_name, method_value]
lua_settable(L, -4);
// Stack: [CLS, method_name]
}
// Stack: [CLS]
}
// Stack: [CLS]
lua_createtable(L, 0, 32); // Rough guess: at least 32 instances concurrently
// Stack: [CLS, __instances]
lua_pushlightuserdata(L, (void*)&WEAK_VALUE_METATABLE);
lua_gettable(L, LUA_REGISTRYINDEX);
// Stack: [CLS, __instances, {__mode='v'}]
lua_setmetatable(L, -2);
// Stack: [CLS, __instances]
lua_setfield(L, -2, "__instances");
// Stack: [CLS]
lua_createtable(L, 0, 32); // Rough guess: at least 32 instances concurrently
// Stack: [CLS, __buckets]
lua_pushlightuserdata(L, (void*)&WEAK_KEY_METATABLE);
lua_gettable(L, LUA_REGISTRYINDEX);
// Stack: [CLS, __buckets, {__mode='k'}]
lua_setmetatable(L, -2);
// Stack: [CLS, __buckets]
lua_setfield(L, -2, "__buckets");
// Stack: [CLS]
switch (num_args == 0 ? LUA_TNIL : lua_type(L, 1)) {
case LUA_TTABLE: {
// CLS.__fields = arg1
lua_pushvalue(L, 1);
// Stack: [CLS, __fields]
lua_setfield(L, -2, "__fields");
// Stack: [CLS]
size_t n = lua_objlen(L, 1);
lua_createtable(L, 0, n);
// Stack: [CLS, __indices]
lua_pushnil(L);
while (lua_next(L, 1) != 0) {
// Stack: [CLS, __indices, i, fieldname]
lua_pushvalue(L, -2);
// Stack: [CLS, __indices, i, fieldname, i]
lua_settable(L, -4);
// Stack: [CLS, __indices, i]
}
lua_setfield(L, -2, "__indices");
break;
}
case LUA_TNIL: case LUA_TNONE: {
// If no fields were passed in, set __fields and __indices to empty tables
lua_createtable(L, 0, 0);
lua_setfield(L, -2, "__fields");
lua_createtable(L, 0, 0);
lua_setfield(L, -2, "__indices");
break;
}
default: {
luaL_error(L, "immutable expected the fields to be either table or nil");
}
}
// Stack: [CLS]
lua_pushlightuserdata(L, (void*)&SHARED_CLASS_METATABLE);
lua_gettable(L, LUA_REGISTRYINDEX);
lua_setmetatable(L, -2);
// Stack [CLS]
return 1;
}
static int Lclass_tostring(lua_State *L)
{
lua_getfield(L, 1, "name");
if (lua_isnil(L, -1)) {
lua_pushfstring(L, "immutable type: %p", lua_topointer(L, 1));
}
return 1;
}
static const luaL_Reg Rclass_metamethods[] =
{
{ "__call", Lcreate_instance},
{ "__tostring", Lclass_tostring},
{ NULL, NULL}
};
LUALIB_API int luaopen_immutable(lua_State *L)
{
lua_pushlightuserdata(L, (void*)&WEAK_VALUE_METATABLE);
lua_createtable(L, 0, 1);
lua_pushstring(L, "v");
lua_setfield(L, -2, "__mode");
lua_settable(L, LUA_REGISTRYINDEX);
lua_pushlightuserdata(L, (void*)&WEAK_KEY_METATABLE);
lua_createtable(L, 0, 1);
lua_pushstring(L, "k");
lua_setfield(L, -2, "__mode");
lua_settable(L, LUA_REGISTRYINDEX);
lua_pushlightuserdata(L, (void*)&SHARED_CLASS_METATABLE);
lua_createtable(L, 0, 2);
luaL_register(L,NULL,Rclass_metamethods);
lua_settable(L, LUA_REGISTRYINDEX);
lua_pushcfunction(L, Lmake_class);
return 1;
}
Reference in New Issue View Git Blame Copy Permalink