zeus/framework/lualib-src/lua-ecs/luaecs.c

#define LUA_LIB

#include <lua.h>
#include <lauxlib.h>

#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "luaecs.h"

#define MAX_COMPONENT 256
#define ENTITY_REMOVED 0
#define DEFAULT_SIZE 128
#define STRIDE_TAG 0
#define STRIDE_LUA -1
#define STRIDE_ORDER -2
#define DUMMY_PTR (void *)(uintptr_t)(~0)
#define REARRANGE_THRESHOLD 0x80000000

struct component_pool
{
	int cap;
	int n;
	int stride; // -1 means lua object
	int last_lookup;
	unsigned int *id;
	void *buffer;
};

struct entity_world
{
	unsigned int max_id;
	struct component_pool c[MAX_COMPONENT];
};

static void
init_component_pool(struct entity_world *w, int index, int stride, int opt_size)
{
	struct component_pool *c = &w->c[index];
	c->cap = opt_size;
	c->n = 0;
	c->stride = stride;
	c->id = NULL;
	if (stride > 0)
	{
		c->buffer = NULL;
	}
	else
	{
		c->buffer = DUMMY_PTR;
	}
}

static void
entity_new_type(lua_State *L, struct entity_world *w, int cid, int stride, int opt_size)
{
	if (opt_size <= 0)
	{
		opt_size = DEFAULT_SIZE;
	}
	if (cid < 0 || cid >= MAX_COMPONENT || w->c[cid].cap != 0)
	{
		luaL_error(L, "Can't new type %d", cid);
	}
	init_component_pool(w, cid, stride, opt_size);
}

static inline struct entity_world *
getW(lua_State *L)
{
	return (struct entity_world *)luaL_checkudata(L, 1, "ENTITY_WORLD");
}

static int
lnew_type(lua_State *L)
{
	struct entity_world *w = getW(L);
	int cid = luaL_checkinteger(L, 2);
	int stride = luaL_checkinteger(L, 3);
	int size = luaL_optinteger(L, 4, 0);
	entity_new_type(L, w, cid, stride, size);
	return 0;
}

static int
lcount_memory(lua_State *L)
{
	struct entity_world *w = getW(L);
	size_t sz = sizeof(*w);
	int i;
	size_t msz = sz;
	for (i = 0; i < MAX_COMPONENT; i++)
	{
		struct component_pool *c = &w->c[i];
		if (c->id)
		{
			sz += c->cap * sizeof(unsigned int);
			msz += c->n * sizeof(unsigned int);
		}
		if (c->buffer != DUMMY_PTR)
		{
			sz += c->cap * c->stride;
			msz += c->cap * c->stride;
		}
	}
	lua_pushinteger(L, sz);
	lua_pushinteger(L, msz);
	return 2;
}

static void
shrink_component_pool(lua_State *L, struct component_pool *c, int id)
{
	if (c->id == NULL)
		return;
	if (c->n == 0)
	{
		c->id = NULL;
		if (c->stride > 0)
			c->buffer = NULL;
		lua_pushnil(L);
		lua_setiuservalue(L, 1, id * 2 + 1);
		lua_pushnil(L);
		lua_setiuservalue(L, 1, id * 2 + 2);
	}
	else if (c->stride > 0 && c->n < c->cap)
	{
		c->cap = c->n;
		c->id = (unsigned int *)lua_newuserdatauv(L, c->n * sizeof(unsigned int), 0);
		lua_setiuservalue(L, 1, id * 2 + 1);
		c->buffer = lua_newuserdatauv(L, c->n * c->stride, 0);
		lua_setiuservalue(L, 1, id * 2 + 2);
	}
}

static int
lcollect_memory(lua_State *L)
{
	struct entity_world *w = getW(L);
	int i;
	for (i = 0; i < MAX_COMPONENT; i++)
	{
		shrink_component_pool(L, &w->c[i], i);
	}
	return 0;
}

static int
add_component_id_(lua_State *L, int world_index, struct entity_world *w, int cid, unsigned int eid)
{
	struct component_pool *pool = &w->c[cid];
	int cap = pool->cap;
	int index = pool->n;
	assert(pool->stride != STRIDE_ORDER);
	if (pool->n == 0)
	{
		if (pool->id == NULL)
		{
			pool->id = (unsigned int *)lua_newuserdatauv(L, cap * sizeof(unsigned int), 0);
			lua_setiuservalue(L, world_index, cid * 2 + 1);
		}
		if (pool->buffer == NULL)
		{
			pool->buffer = lua_newuserdatauv(L, cap * pool->stride, 0);
			lua_setiuservalue(L, world_index, cid * 2 + 2);
		}
		else if (pool->stride == STRIDE_LUA)
		{
			lua_newtable(L);
			lua_setiuservalue(L, world_index, cid * 2 + 2);
		}
	}
	else if (pool->n >= pool->cap)
	{
		// expand pool
		int newcap = cap * 3 / 2;
		unsigned int *newid = (unsigned int *)lua_newuserdatauv(L, newcap * sizeof(unsigned int), 0);
		lua_setiuservalue(L, world_index, cid * 2 + 1);
		memcpy(newid, pool->id, cap * sizeof(unsigned int));
		pool->id = newid;
		int stride = pool->stride;
		if (stride > 0)
		{
			void *newbuffer = lua_newuserdatauv(L, newcap * stride, 0);
			lua_setiuservalue(L, world_index, cid * 2 + 2);
			memcpy(newbuffer, pool->buffer, cap * stride);
			pool->buffer = newbuffer;
		}
		pool->cap = newcap;
	}
	++pool->n;
	pool->id[index] = eid;
	return index;
}

static inline void *
get_ptr(struct component_pool *c, int index)
{
	if (c->stride > 0)
		return (void *)((char *)c->buffer + c->stride * index);
	else
		return DUMMY_PTR;
}

static void *
add_component_(lua_State *L, int world_index, struct entity_world *w, int cid, unsigned int eid, const void *buffer)
{
	int index = add_component_id_(L, world_index, w, cid, eid);
	struct component_pool *pool = &w->c[cid];
	assert(pool->stride >= 0);
	void *ret = get_ptr(pool, index);
	if (buffer)
		memcpy(ret, buffer, pool->stride);
	return ret;
}

static inline int
check_cid(lua_State *L, struct entity_world *w, int index)
{
	int cid = luaL_checkinteger(L, index);
	struct component_pool *c = &w->c[cid];
	if (cid < 0 || cid >= MAX_COMPONENT || c->cap == 0)
	{
		luaL_error(L, "Invalid type %d", cid);
	}
	return cid;
}

static int
ladd_component(lua_State *L)
{
	struct entity_world *w = getW(L);
	unsigned int eid = luaL_checkinteger(L, 2);
	int cid = check_cid(L, w, 3);
	int stride = w->c[cid].stride;
	if (stride <= 0)
	{
		int index = add_component_id_(L, 1, w, cid, eid);
		if (stride == STRIDE_LUA)
		{
			// lua object
			lua_settop(L, 4);
			if (lua_getiuservalue(L, 1, cid * 2 + 2) != LUA_TTABLE)
			{
				luaL_error(L, "Missing lua table for %d", cid);
			}
			lua_insert(L, -2);
			lua_rawseti(L, -2, index + 1);
		}
	}
	else
	{
		size_t sz;
		const char *buffer = lua_tolstring(L, 4, &sz);
		int stride = w->c[cid].stride;
		if (buffer == NULL || sz != stride)
		{
			return luaL_error(L, "Invalid data (size=%d/%d) for type %d", (int)sz, stride, cid);
		}
		add_component_(L, 1, w, cid, eid, buffer);
	}
	return 0;
}

static int
lnew_entity(lua_State *L)
{
	struct entity_world *w = getW(L);
	unsigned int eid = ++w->max_id;
	assert(eid != 0);
	lua_pushinteger(L, eid);
	return 1;
}

static void
insert_id(lua_State *L, int world_index, struct entity_world *w, int cid, unsigned int eid)
{
	struct component_pool *c = &w->c[cid];
	assert(c->stride == STRIDE_TAG);
	int from = 0;
	int to = c->n;
	while (from < to)
	{
		int mid = (from + to) / 2;
		int aa = c->id[mid];
		if (aa == eid)
			return;
		else if (aa < eid)
		{
			from = mid + 1;
		}
		else
		{
			to = mid;
		}
	}
	// insert eid at [from]
	if (from < c->n - 1)
	{
		int i;
		// Any dup id ?
		for (i = from; i < c->n - 1; i++)
		{
			if (c->id[i] == c->id[i + 1])
			{
				memmove(c->id + from + 1, c->id + from, sizeof(unsigned int) * (i - from));
				c->id[from] = eid;
				return;
			}
		}
	}
	add_component_id_(L, world_index, w, cid, eid);
	memmove(c->id + from + 1, c->id + from, sizeof(unsigned int) * (c->n - from - 1));
	c->id[from] = eid;
}

static void
entity_enable_tag_(struct entity_world *w, int cid, int index, int tag_id, void *L, int world_index)
{
	struct component_pool *c = &w->c[cid];
	assert(index >= 0 && index < c->n);
	unsigned int eid = c->id[index];
	insert_id((lua_State *)L, world_index, w, tag_id, eid);
}

static int
binary_search(unsigned int *a, int from, int to, unsigned int v)
{
	while (from < to)
	{
		int mid = (from + to) / 2;
		int aa = a[mid];
		if (aa == v)
			return mid;
		else if (aa < v)
		{
			from = mid + 1;
		}
		else
		{
			to = mid;
		}
	}
	return -1;
}

#define GUESS_RANGE 64

static inline int
lookup_component(struct component_pool *pool, unsigned int eid, int guess_index)
{
	int n = pool->n;
	if (n == 0)
		return -1;
	if (guess_index + GUESS_RANGE >= n)
		return binary_search(pool->id, 0, pool->n, eid);
	unsigned int *a = pool->id;
	int higher = a[guess_index + GUESS_RANGE];
	if (eid > higher)
	{
		return binary_search(a, guess_index + GUESS_RANGE + 1, pool->n, eid);
	}
	int lower = a[guess_index];
	if (eid < lower)
	{
		return binary_search(a, 0, guess_index, eid);
	}
	return binary_search(a, guess_index, guess_index + GUESS_RANGE, eid);
}

static inline void
replace_id(struct component_pool *c, int index, unsigned int eid)
{
	unsigned int rid = c->id[index];
	c->id[index] = eid;
	int i;
	for (i = index + 1; i < c->n && c->id[i] == rid; i++)
	{
		c->id[i] = eid;
	}
}

static void
entity_disable_tag_(struct entity_world *w, int cid, int index, int tag_id)
{
	struct component_pool *c = &w->c[cid];
	assert(index >= 0 && index < c->n);
	unsigned int eid = c->id[index];
	if (cid != tag_id)
	{
		c = &w->c[tag_id];
		index = lookup_component(c, eid, c->last_lookup);
		if (index < 0)
			return;
	}
	int i;
	for (i = index - 1; i >= 0; i--)
	{
		if (c->id[i] != eid)
		{
			replace_id(c, i + 1, c->id[i]);
			return;
		}
	}
	for (i = index + 1; i < c->n; i++)
	{
		if (c->id[i] != eid)
		{
			replace_id(c, index, c->id[i]);
			return;
		}
	}
	c->n = 0;
}

static void
entity_remove_(struct entity_world *w, int cid, int index, void *L, int world_index)
{
	entity_enable_tag_(w, cid, index, ENTITY_REMOVED, L, world_index);
}

struct rearrange_context
{
	struct entity_world *w;
	unsigned int ptr[MAX_COMPONENT - 1];
};

static int
find_min(struct rearrange_context *ctx)
{
	unsigned int m = ~0;
	int i;
	int r = -1;
	struct entity_world *w = ctx->w;
	for (i = 1; i < MAX_COMPONENT; i++)
	{
		int index = ctx->ptr[i - 1];
		if (index < w->c[i].n)
		{
			if (w->c[i].id[index] <= m)
			{
				m = w->c[i].id[index];
				r = i;
			}
		}
	}
	return r;
}

static void
rearrange(struct entity_world *w)
{
	struct rearrange_context ctx;
	memset(&ctx, 0, sizeof(ctx));
	ctx.w = w;
	int cid;
	unsigned int new_id = 1;
	unsigned int last_id = 0;
	while ((cid = find_min(&ctx)) >= 0)
	{
		int index = ctx.ptr[cid - 1];
		unsigned int current_id = w->c[cid].id[index];
		//		printf("arrange %d <- %d\n", new_id, w->c[cid].id[index]);
		w->c[cid].id[index] = new_id;
		if (current_id != last_id)
		{
			++new_id;
			last_id = current_id;
		}
		++ctx.ptr[cid - 1];
	}
	w->max_id = new_id;
}

static inline void
move_tag(struct component_pool *pool, int from, int to)
{
	if (from != to)
	{
		pool->id[to] = pool->id[from];
	}
}

static inline void
move_item(struct component_pool *pool, int from, int to)
{
	if (from != to)
	{
		pool->id[to] = pool->id[from];
		int stride = pool->stride;
		memcpy((char *)pool->buffer + to * stride, (char *)pool->buffer + from * stride, stride);
	}
}

static void
move_object(lua_State *L, struct component_pool *pool, int from, int to)
{
	if (from != to)
	{
		pool->id[to] = pool->id[from];
		lua_rawgeti(L, -1, from + 1);
		lua_rawseti(L, -2, to + 1);
	}
}

static void
remove_all(lua_State *L, struct component_pool *pool, struct component_pool *removed, int cid)
{
	int index = 0;
	int count = 0;
	int i;
	if (pool->stride != STRIDE_ORDER)
	{
		unsigned int *id = removed->id;
		unsigned int last_id = 0;
		for (i = 0; i < removed->n; i++)
		{
			if (id[i] != last_id)
			{
				// todo : order
				int r = lookup_component(pool, id[i], index);
				if (r >= 0)
				{
					index = r;
					pool->id[r] = 0;
					++count;
				}
			}
		}
	}
	else
	{
		unsigned int *id = pool->id;
		for (i = 0; i < pool->n; i++)
		{
			int r = lookup_component(removed, id[i], 0);
			if (r >= 0)
			{
				id[i] = 0;
				++count;
			}
		}
	}
	if (count > 0)
	{
		index = 0;
		switch (pool->stride)
		{
		case STRIDE_LUA:
			if (lua_getiuservalue(L, 1, cid * 2 + 2) != LUA_TTABLE)
			{
				luaL_error(L, "Missing lua object table for type %d", cid);
			}
			for (i = 0; i < pool->n; i++)
			{
				if (pool->id[i] != 0)
				{
					move_object(L, pool, i, index);
					++index;
				}
			}
			lua_pop(L, 1); // pop lua object table
			break;
		case STRIDE_TAG:
		case STRIDE_ORDER:
			for (i = 0; i < pool->n; i++)
			{
				if (pool->id[i] != 0)
				{
					move_tag(pool, i, index);
					++index;
				}
			}
			break;
		default:
			for (i = 0; i < pool->n; i++)
			{
				if (pool->id[i] != 0)
				{
					move_item(pool, i, index);
					++index;
				}
			}
			break;
		}
		pool->n -= count;
	}
}

static int
lupdate(lua_State *L)
{
	struct entity_world *w = getW(L);
	struct component_pool *removed = &w->c[ENTITY_REMOVED];
	int i;
	if (removed->n > 0)
	{
		// mark removed
		assert(ENTITY_REMOVED == 0);
		for (i = 1; i < MAX_COMPONENT; i++)
		{
			struct component_pool *pool = &w->c[i];
			if (pool->n > 0)
				remove_all(L, pool, removed, i);
		}
		removed->n = 0;
	}

	if (w->max_id > REARRANGE_THRESHOLD)
	{
		rearrange(w);
	}

	return 0;
}

static void
remove_dup(struct component_pool *c, int index)
{
	int i;
	unsigned int eid = c->id[index];
	int to = index;
	for (i = index + 1; i < c->n; i++)
	{
		if (c->id[i] != eid)
		{
			eid = c->id[i];
			c->id[to] = eid;
			++to;
		}
	}
	c->n = to;
}

static void *
entity_iter_(struct entity_world *w, int cid, int index)
{
	struct component_pool *c = &w->c[cid];
	assert(index >= 0);
	if (index >= c->n)
		return NULL;
	if (c->stride == STRIDE_TAG)
	{
		// it's a tag
		unsigned int eid = c->id[index];
		if (index > 0 && eid == c->id[index - 1])
		{
			remove_dup(c, index);
			if (index >= c->n)
				return NULL;
		}
		return DUMMY_PTR;
	}
	return get_ptr(c, index);
}

static void *
entity_iter_lua_(struct entity_world *w, int cid, int index, void *L)
{
	void *ret = entity_iter_(w, cid, index);
	if (ret != DUMMY_PTR)
		return ret;
	if (lua_getiuservalue(L, 1, cid * 2 + 2) != LUA_TTABLE)
	{
		lua_pop(L, 1);
		return 0;
	}
	int t = lua_rawgeti(L, -1, index + 1);
	switch (t)
	{
	case LUA_TSTRING:
		ret = (void *)lua_tostring(L, -1);
		break;
	case LUA_TUSERDATA:
	case LUA_TLIGHTUSERDATA:
		ret = (void *)lua_touserdata(L, -1);
		break;
	default:
		ret = NULL;
		break;
	}
	lua_pop(L, 2);
	return ret;
}

static void
entity_clear_type_(struct entity_world *w, int cid)
{
	struct component_pool *c = &w->c[cid];
	c->n = 0;
}

static int
lclear_type(lua_State *L)
{
	struct entity_world *w = getW(L);
	int cid = check_cid(L, w, 2);
	entity_clear_type_(w, cid);
	return 0;
}

static void *
entity_sibling_(struct entity_world *w, int cid, int index, int slibling_id)
{
	struct component_pool *c = &w->c[cid];
	if (index < 0 || index >= c->n)
		return NULL;
	unsigned int eid = c->id[index];
	c = &w->c[slibling_id];
	assert(c->stride != STRIDE_ORDER);
	int result_index = lookup_component(c, eid, c->last_lookup);
	if (result_index >= 0)
	{
		c->last_lookup = result_index;
		return get_ptr(c, result_index);
	}
	return NULL;
}

static int
entity_sibling_index_(struct entity_world *w, int cid, int index, int slibling_id)
{
	struct component_pool *c = &w->c[cid];
	if (index < 0 || index >= c->n)
		return 0;
	unsigned int eid = c->id[index];
	c = &w->c[slibling_id];
	assert(c->stride != STRIDE_ORDER);
	int result_index = lookup_component(c, eid, c->last_lookup);
	if (result_index >= 0)
	{
		c->last_lookup = result_index;
		return result_index + 1;
	}
	return 0;
}

static void *
entity_add_sibling_(struct entity_world *w, int cid, int index, int slibling_id, const void *buffer, void *L, int world_index)
{
	struct component_pool *c = &w->c[cid];
	assert(index >= 0 && index < c->n);
	unsigned int eid = c->id[index];
	// todo: pcall add_component_
	assert(c->stride >= 0);
	void *ret = add_component_((lua_State *)L, world_index, w, slibling_id, eid, buffer);
	c = &w->c[slibling_id];
	return ret;
}

static int
entity_add_sibling_index_(lua_State *L, int world_index, struct entity_world *w, int cid, int index, int slibling_id)
{
	struct component_pool *c = &w->c[cid];
	assert(index >= 0 && index < c->n);
	unsigned int eid = c->id[index];
	// todo: pcall add_component_
	assert(c->stride == STRIDE_LUA);
	int ret = add_component_id_(L, world_index, w, slibling_id, eid);
	return ret;
}

static int
comp_index(void *v, const void *a, const void *b)
{
	const unsigned int *aa = (const unsigned int *)a;
	const unsigned int *bb = (const unsigned int *)b;
	int *vv = (int *)v;
	return vv[*aa] - vv[*bb];
}

static void
entity_sort_key_(struct entity_world *w, int orderid, int cid, void *L, int world_index)
{
	struct component_pool *c = &w->c[cid];
	assert(c->stride == sizeof(int));
	struct component_pool *order = &w->c[orderid];
	assert(order->stride == STRIDE_ORDER);

	if (order->id == NULL || order->cap < c->cap)
	{
		order->cap = c->cap;
		order->id = (unsigned int *)lua_newuserdatauv(L, c->cap * sizeof(unsigned int), 0);
		lua_setiuservalue(L, world_index, orderid * 2 + 1);
	}
	int i;
	for (i = 0; i < c->n; i++)
	{
		order->id[i] = i;
	}
	qsort_s(order->id, c->n, sizeof(unsigned int), comp_index, c->buffer);
	for (i = 0; i < c->n; i++)
	{
		order->id[i] = c->id[order->id[i]];
	}
	order->n = c->n;
}

static int
lcontext(lua_State *L)
{
	struct entity_world *w = getW(L);
	luaL_checktype(L, 2, LUA_TTABLE);
	lua_len(L, 2);
	int n = lua_tointeger(L, -1);
	lua_pop(L, 1);
	if (n <= 0)
	{
		return luaL_error(L, "Invalid length %d of table", n);
	}
	size_t sz = sizeof(struct ecs_context) + sizeof(int) * n;
	struct ecs_context *ctx = (struct ecs_context *)lua_newuserdatauv(L, sz, 1);
	ctx->L = (void *)lua_newthread(L);
	lua_pushvalue(L, 1);
	lua_xmove(L, ctx->L, 1); // put world in the index 1 of newthread
	lua_setiuservalue(L, -2, 1);
	ctx->max_id = n;
	ctx->world = w;
	static struct ecs_capi c_api = {
		entity_iter_,
		entity_clear_type_,
		entity_sibling_,
		entity_add_sibling_,
		entity_remove_,
		entity_enable_tag_,
		entity_disable_tag_,
		entity_sort_key_,
		entity_iter_lua_,
	};
	ctx->api = &c_api;
	ctx->cid[0] = ENTITY_REMOVED;
	int i;
	for (i = 1; i <= n; i++)
	{
		if (lua_geti(L, 2, i) != LUA_TNUMBER)
		{
			return luaL_error(L, "Invalid id at index %d", i);
		}
		ctx->cid[i] = lua_tointeger(L, -1);
		lua_pop(L, 1);
		int cid = ctx->cid[i];
		if (cid == ENTITY_REMOVED || cid < 0 || cid >= MAX_COMPONENT)
			return luaL_error(L, "Invalid id (%d) at index %d", cid, i);
	}
	return 1;
}

static int
lnew_world(lua_State *L)
{
	size_t sz = sizeof(struct entity_world);
	struct entity_world *w = (struct entity_world *)lua_newuserdatauv(L, sz, MAX_COMPONENT * 2);
	memset(w, 0, sz);
	// removed set
	entity_new_type(L, w, ENTITY_REMOVED, 0, 0);
	luaL_getmetatable(L, "ENTITY_WORLD");
	lua_setmetatable(L, -2);
	return 1;
}

#define TYPE_INT 0
#define TYPE_FLOAT 1
#define TYPE_BOOL 2

struct field
{
	const char *key;
	int offset;
	int type;
};

static int
check_type(lua_State *L)
{
	int type = lua_tointeger(L, -1);
	if (type != TYPE_INT &&
		type != TYPE_FLOAT &&
		type != TYPE_BOOL)
	{
		luaL_error(L, "Invalid field type(%d)", type);
	}
	lua_pop(L, 1);
	return type;
}

static void
get_field(lua_State *L, int i, struct field *f)
{
	if (lua_geti(L, -1, 1) != LUA_TNUMBER)
	{
		luaL_error(L, "Invalid field %d [1] type", i);
	}
	f->type = check_type(L);

	if (lua_geti(L, -1, 2) != LUA_TSTRING)
	{
		luaL_error(L, "Invalid field %d [2] key", i);
	}
	f->key = lua_tostring(L, -1);
	lua_pop(L, 1);

	if (lua_geti(L, -1, 3) != LUA_TNUMBER)
	{
		luaL_error(L, "Invalid field %d [3] offset", i);
	}
	f->offset = lua_tointeger(L, -1);
	lua_pop(L, 1);

	lua_pop(L, 1);
}

static void
write_value(lua_State *L, struct field *f, char *buffer)
{
	int luat = lua_type(L, -1);
	char *ptr = buffer + f->offset;
	switch (f->type)
	{
	case TYPE_INT:
		if (!lua_isinteger(L, -1))
			luaL_error(L, "Invalid .%s type %s (int)", f->key ? f->key : "*", lua_typename(L, luat));
		*(int *)ptr = lua_tointeger(L, -1);
		break;
	case TYPE_FLOAT:
		if (luat != LUA_TNUMBER)
			luaL_error(L, "Invalid .%s type %s (float)", f->key ? f->key : "*", lua_typename(L, luat));
		*(float *)ptr = lua_tonumber(L, -1);
		break;
	case TYPE_BOOL:
		if (luat != LUA_TBOOLEAN)
			luaL_error(L, "Invalid .%s type %s (bool)", f->key ? f->key : "*", lua_typename(L, luat));
		*(unsigned char *)ptr = lua_toboolean(L, -1);
		break;
	}
	lua_pop(L, 1);
}

static inline void
write_component(lua_State *L, int field_n, struct field *f, int index, char *buffer)
{
	int i;
	for (i = 0; i < field_n; i++)
	{
		lua_getfield(L, index, f[i].key);
		write_value(L, &f[i], buffer);
	}
}

static void
read_value(lua_State *L, struct field *f, const char *buffer)
{
	const char *ptr = buffer + f->offset;
	switch (f->type)
	{
	case TYPE_INT:
		lua_pushinteger(L, *(const int *)ptr);
		break;
	case TYPE_FLOAT:
		lua_pushnumber(L, *(const float *)ptr);
		break;
	case TYPE_BOOL:
		lua_pushboolean(L, *ptr);
		break;
	default:
		// never here
		luaL_error(L, "Invalid field type %d", f->type);
		break;
	}
}

static void
read_component(lua_State *L, int field_n, struct field *f, int index, const char *buffer)
{
	int i;
	for (i = 0; i < field_n; i++)
	{
		read_value(L, &f[i], buffer);
		lua_setfield(L, index, f[i].key);
	}
}

static int
get_len(lua_State *L, int index)
{
	lua_len(L, index);
	if (lua_type(L, -1) != LUA_TNUMBER)
	{
		return luaL_error(L, "Invalid table length");
	}
	int n = lua_tointeger(L, -1);
	if (n < 0)
	{
		return luaL_error(L, "Invalid table length %d", n);
	}
	lua_pop(L, 1);
	return n;
}

#define COMPONENT_IN 1
#define COMPONENT_OUT 2
#define COMPONENT_OPTIONAL 4
#define COMPONENT_OBJECT 8
#define COMPONENT_EXIST 16

struct group_key
{
	const char *name;
	int id;
	int field_n;
	int attrib;
};

static inline int
is_temporary(int attrib)
{
	if (attrib & COMPONENT_EXIST)
		return 0;
	return (attrib & COMPONENT_IN) == 0 && (attrib & COMPONENT_OUT) == 0;
}

struct group_iter
{
	struct entity_world *world;
	struct field *f;
	int nkey;
	int readonly;
	struct group_key k[1];
};

static int
get_write_component(lua_State *L, int lua_index, const char *name, struct field *f, struct component_pool *c)
{
	switch (lua_getfield(L, lua_index, name))
	{
	case LUA_TNIL:
		lua_pop(L, 1);
		// restore cache (metatable can be absent during sync)
		if (lua_getmetatable(L, lua_index))
		{
			lua_getfield(L, -1, name);
			lua_setfield(L, lua_index, name);
			lua_pop(L, 1); // pop metatable
		}
		return 0;
	case LUA_TTABLE:
		return 1;
	default:
		if (c->stride == STRIDE_LUA)
		{
			// lua object
			return 1;
		}
		if (f->key == NULL)
		{
			// value type
			return 1;
		}
		return luaL_error(L, "Invalid iterator type %s", lua_typename(L, lua_type(L, -1)));
	}
}

static void
write_component_object(lua_State *L, int n, struct field *f, void *buffer)
{
	if (f->key == NULL)
	{
		write_value(L, f, buffer);
	}
	else
	{
		write_component(L, n, f, -1, (char *)buffer);
		lua_pop(L, 1);
	}
}

static int
remove_tag(lua_State *L, int lua_index, const char *name)
{
	int r = 0;
	switch (lua_getfield(L, lua_index, name))
	{
	case LUA_TNIL:
		r = 1;
		break;
	case LUA_TBOOLEAN:
		r = !lua_toboolean(L, -1);
		break;
	default:
		return luaL_error(L, "Invalid tag type %s", lua_typename(L, lua_type(L, -1)));
	}
	return r;
}

static void
update_last_index(lua_State *L, int world_index, int lua_index, struct group_iter *iter, int idx)
{
	int i;
	int mainkey = iter->k[0].id;
	struct component_pool *c = &iter->world->c[mainkey];
	if (!(iter->k[0].attrib & COMPONENT_EXIST))
	{
		if (c->stride == STRIDE_TAG)
		{
			// It's a tag
			if ((iter->k[0].attrib & COMPONENT_OUT) && remove_tag(L, lua_index, iter->k[0].name))
			{
				entity_disable_tag_(iter->world, mainkey, idx, mainkey);
			}
		}
		else if ((iter->k[0].attrib & COMPONENT_OUT) && get_write_component(L, lua_index, iter->k[0].name, iter->f, c))
		{
			struct component_pool *c = &iter->world->c[mainkey];
			if (c->n <= idx)
			{
				luaL_error(L, "Can't find component %s for index %d", iter->k[0].name, idx);
			}
			if (c->stride == STRIDE_LUA)
			{
				if (lua_getiuservalue(L, world_index, mainkey * 2 + 2) != LUA_TTABLE)
				{
					luaL_error(L, "Missing lua table for %d", mainkey);
				}
				lua_insert(L, -2);
				lua_rawseti(L, -2, idx + 1);
			}
			else
			{
				void *buffer = get_ptr(c, idx);
				write_component_object(L, iter->k[0].field_n, iter->f, buffer);
			}
		}
	}

	struct field *f = iter->f + iter->k[0].field_n;

	for (i = 1; i < iter->nkey; i++)
	{
		struct group_key *k = &iter->k[i];
		if (!(k->attrib & COMPONENT_EXIST))
		{
			struct component_pool *c = &iter->world->c[k->id];
			if (c->stride == STRIDE_TAG)
			{
				// It's a tag
				if ((k->attrib & COMPONENT_OUT) || is_temporary(k->attrib))
				{
					switch (lua_getfield(L, lua_index, k->name))
					{
					case LUA_TNIL:
						break;
					case LUA_TBOOLEAN:
						if (lua_toboolean(L, -1))
						{
							entity_enable_tag_(iter->world, mainkey, idx, k->id, L, world_index);
						}
						else
						{
							entity_disable_tag_(iter->world, mainkey, idx, k->id);
						}
						break;
					default:
						luaL_error(L, ".%s is a tag , should be a boolean or nil. It's %s", k->name, lua_typename(L, lua_type(L, -1)));
					}
					lua_pop(L, 1);
				}
			}
			else if ((k->attrib & COMPONENT_OUT) && get_write_component(L, lua_index, k->name, f, c))
			{
				int index = entity_sibling_index_(iter->world, mainkey, idx, k->id);
				if (index == 0)
				{
					luaL_error(L, "Can't find sibling %s of %s", k->name, iter->k[0].name);
				}
				if (c->stride == STRIDE_LUA)
				{
					if (lua_getiuservalue(L, world_index, k->id * 2 + 2) != LUA_TTABLE)
					{
						luaL_error(L, "Missing lua table for %d", k->id);
					}
					lua_insert(L, -2);
					lua_rawseti(L, -2, index);
				}
				else
				{
					void *buffer = get_ptr(c, index - 1);
					write_component_object(L, k->field_n, f, buffer);
				}
			}
			else if (is_temporary(k->attrib) && get_write_component(L, lua_index, k->name, f, c))
			{
				if (c->stride == STRIDE_LUA)
				{
					int index = entity_add_sibling_index_(L, world_index, iter->world, mainkey, idx, k->id);
					if (lua_getiuservalue(L, world_index, k->id * 2 + 2) != LUA_TTABLE)
					{
						luaL_error(L, "Missing lua table for %d", k->id);
					}
					lua_insert(L, -2);
					lua_rawseti(L, -2, index);
				}
				else
				{
					void *buffer = entity_add_sibling_(iter->world, mainkey, idx, k->id, NULL, L, world_index);
					write_component_object(L, k->field_n, f, buffer);
				}
			}
		}
		f += k->field_n;
	}
}

static void
read_component_in_field(lua_State *L, int lua_index, const char *name, int n, struct field *f, void *buffer)
{
	if (n == 0)
	{
		// It's tag
		lua_pushboolean(L, buffer ? 1 : 0);
		lua_setfield(L, lua_index, name);
		return;
	}
	if (f->key == NULL)
	{
		// value type
		read_value(L, f, buffer);
		lua_setfield(L, lua_index, name);
		return;
	}
	if (lua_getfield(L, lua_index, name) != LUA_TTABLE)
	{
		luaL_error(L, ".%s is missing", name);
	}
	read_component(L, n, f, lua_gettop(L), buffer);
	lua_pop(L, 1);
}

// -1 : end ; 0 : next ; 1 : succ
static int
query_index(struct group_iter *iter, int mainkey, int idx, unsigned int index[MAX_COMPONENT])
{
	if (entity_iter_(iter->world, mainkey, idx) == NULL)
	{
		return -1;
	}
	index[0] = idx + 1;
	int j;
	for (j = 1; j < iter->nkey; j++)
	{
		struct group_key *k = &iter->k[j];
		if (!is_temporary(k->attrib))
		{
			index[j] = entity_sibling_index_(iter->world, mainkey, idx, k->id);
			if (index[j] == 0)
			{
				if (!(k->attrib & COMPONENT_OPTIONAL))
				{
					// required. try next
					return 0;
				}
			}
		}
		else
		{
			index[j] = 0;
		}
	}
	return 1;
}

static void
read_iter(lua_State *L, int world_index, int obj_index, struct group_iter *iter, unsigned int index[MAX_COMPONENT])
{
	struct field *f = iter->f;
	int i;
	for (i = 0; i < iter->nkey; i++)
	{
		struct group_key *k = &iter->k[i];
		struct component_pool *c = &iter->world->c[k->id];
		if (c->stride == STRIDE_LUA)
		{
			// lua object component
			if (index[i])
			{
				if (lua_getiuservalue(L, world_index, k->id * 2 + 2) != LUA_TTABLE)
				{
					luaL_error(L, "Missing lua table for %d", k->id);
				}

				lua_rawgeti(L, -1, index[i]);
				lua_setfield(L, obj_index, k->name);
				lua_pop(L, 1);
			}
			else
			{
				lua_pushnil(L);
				lua_setfield(L, obj_index, k->name);
			}
		}
		else if (c->stride != STRIDE_ORDER)
		{
			if (!(k->attrib & COMPONENT_EXIST))
			{
				if (k->attrib & COMPONENT_IN)
				{
					if (index[i])
					{
						void *ptr = get_ptr(c, index[i] - 1);
						read_component_in_field(L, obj_index, k->name, k->field_n, f, ptr);
					}
					else
					{
						lua_pushnil(L);
						lua_setfield(L, obj_index, k->name);
					}
				}
				else if (index[i] == 0 && !is_temporary(k->attrib))
				{
					lua_pushnil(L);
					lua_setfield(L, obj_index, k->name);
				}
			}
			f += k->field_n;
		}
	}
}

static int
lsync(lua_State *L)
{
	struct group_iter *iter = luaL_checkudata(L, 2, "ENTITY_GROUPITER");
	luaL_checktype(L, 3, LUA_TTABLE);
	if (lua_rawgeti(L, 3, 1) != LUA_TNUMBER)
	{
		return luaL_error(L, "Invalid iterator");
	}
	int idx = lua_tointeger(L, -1) - 1;
	if (idx < 0)
		return luaL_error(L, "Invalid iterator index %d", idx);
	lua_pop(L, 1);

	if (!iter->readonly)
	{
		update_last_index(L, 1, 3, iter, idx);
	}

	unsigned int index[MAX_COMPONENT];
	if (query_index(iter, iter->k[0].id, idx, index) <= 0)
	{
		return luaL_error(L, "Read pattern fail");
	}
	read_iter(L, 1, 3, iter, index);
	return 0;
}

static int
leach_group(lua_State *L)
{
	struct group_iter *iter = lua_touserdata(L, 1);
	if (lua_rawgeti(L, 2, 1) != LUA_TNUMBER)
	{
		return luaL_error(L, "Invalid group iterator");
	}
	int i = lua_tointeger(L, -1);
	if (i < 0)
		return luaL_error(L, "Invalid iterator index %d", i);
	lua_pop(L, 1);

	if (lua_getiuservalue(L, 1, 1) != LUA_TUSERDATA)
	{
		return luaL_error(L, "Missing world object for iterator");
	}

	int world_index = lua_gettop(L);

	if (i > 0 && !iter->readonly)
	{
		update_last_index(L, world_index, 2, iter, i - 1);
	}
	int mainkey = iter->k[0].id;
	unsigned int index[MAX_COMPONENT];
	for (;;)
	{
		int ret = query_index(iter, mainkey, i++, index);
		if (ret < 0)
			return 0;
		if (ret > 0)
			break;
	}

	lua_pushinteger(L, i);
	lua_rawseti(L, 2, 1);

	read_iter(L, world_index, 2, iter, index);

	lua_settop(L, 2);
	return 1;
}

static void
create_key_cache(lua_State *L, struct group_key *k, struct field *f)
{
	if (k->field_n == 0 // is tag or object?
		|| (k->attrib & COMPONENT_EXIST))
	{ // only existence
		return;
	}
	if (k->field_n == 1 && f[0].key == NULL)
	{
		// value type
		switch (f[0].type)
		{
		case TYPE_INT:
			lua_pushinteger(L, 0);
			break;
		case TYPE_FLOAT:
			lua_pushnumber(L, 0);
			break;
		case TYPE_BOOL:
			lua_pushboolean(L, 0);
			break;
		default:
			lua_pushnil(L);
			break;
		}
	}
	else
	{
		lua_createtable(L, 0, k->field_n);
	}
	lua_setfield(L, -2, k->name);
}

static int
lpairs_group(lua_State *L)
{
	struct group_iter *iter = lua_touserdata(L, 1);
	lua_pushcfunction(L, leach_group);
	lua_pushvalue(L, 1);
	lua_createtable(L, 2, iter->nkey);
	int i;
	int opt = 0;
	struct field *f = iter->f;
	for (i = 0; i < iter->nkey; i++)
	{
		struct group_key *k = &iter->k[i];
		create_key_cache(L, k, f);
		f += k->field_n;
		if (k->attrib & COMPONENT_OPTIONAL)
			++opt;
	}
	if (opt)
	{
		// create backup table in metatable
		lua_createtable(L, 0, opt);
		for (i = 0; i < iter->nkey; i++)
		{
			struct group_key *k = &iter->k[i];
			if (k->attrib & COMPONENT_OPTIONAL)
			{
				lua_getfield(L, -2, k->name);
				lua_setfield(L, -2, k->name);
			}
		}
		lua_setmetatable(L, -2);
	}
	lua_pushinteger(L, 0);
	lua_rawseti(L, -2, 1);
	lua_pushinteger(L, iter->k[0].id); // mainkey
	lua_rawseti(L, -2, 2);
	return 3;
}

static int
check_boolean(lua_State *L, const char *key)
{
	int r = 0;
	switch (lua_getfield(L, -1, key))
	{
	case LUA_TNIL:
		break;
	case LUA_TBOOLEAN:
		r = lua_toboolean(L, -1);
		break;
	default:
		return luaL_error(L, "Invalid boolean type %s", lua_typename(L, lua_type(L, -1)));
	}
	lua_pop(L, 1);
	return r;
}

static int
is_value(lua_State *L, struct field *f)
{
	switch (lua_getfield(L, -1, "type"))
	{
	case LUA_TNIL:
		lua_pop(L, 1);
		return 0;
	case LUA_TNUMBER:
		f->key = NULL;
		f->offset = 0;
		f->type = check_type(L);
		return 1;
	default:
		return luaL_error(L, "Invalid value type %s", lua_typename(L, lua_type(L, -1)));
	}
}

static int
get_key(struct entity_world *w, lua_State *L, struct group_key *key, struct field *f)
{
	if (lua_getfield(L, -1, "id") != LUA_TNUMBER)
	{
		return luaL_error(L, "Invalid id");
	}
	key->id = lua_tointeger(L, -1);
	lua_pop(L, 1);
	if (key->id < 0 || key->id >= MAX_COMPONENT || w->c[key->id].cap == 0)
	{
		return luaL_error(L, "Invalid id %d", key->id);
	}
	if (lua_getfield(L, -1, "name") != LUA_TSTRING)
	{
		return luaL_error(L, "Invalid component name");
	}
	key->name = lua_tostring(L, -1);
	lua_pop(L, 1);
	int attrib = 0;
	if (check_boolean(L, "r"))
	{
		attrib |= COMPONENT_IN;
	}
	if (check_boolean(L, "w"))
	{
		attrib |= COMPONENT_OUT;
	}
	if (check_boolean(L, "opt"))
	{
		attrib |= COMPONENT_OPTIONAL;
	}
	if (check_boolean(L, "exist"))
	{
		attrib |= COMPONENT_EXIST;
	}
	key->attrib = attrib;
	if (is_value(L, f))
	{
		key->field_n = 1;
		return 1;
	}
	else
	{
		int i = 0;
		int ttype;
		while ((ttype = lua_geti(L, -1, i + 1)) != LUA_TNIL)
		{
			if (ttype != LUA_TTABLE)
			{
				return luaL_error(L, "Invalid field %d", i + 1);
			}
			get_field(L, i + 1, &f[i]);
			++i;
		}
		key->field_n = i;
		lua_pop(L, 1);
		return i;
	}
}

static int
lgroupiter(lua_State *L)
{
	struct entity_world *w = getW(L);
	luaL_checktype(L, 2, LUA_TTABLE);
	int nkey = get_len(L, 2);
	int field_n = 0;
	int i;
	if (nkey == 0)
	{
		return luaL_error(L, "At least one key");
	}
	if (nkey > MAX_COMPONENT)
	{
		return luaL_error(L, "Too many keys");
	}
	for (i = 0; i < nkey; i++)
	{
		if (lua_geti(L, 2, i + 1) != LUA_TTABLE)
		{
			return luaL_error(L, "index %d is not a table", i);
		}
		field_n += get_len(L, -1);
		lua_pop(L, 1);
	}
	size_t header_size = sizeof(struct group_iter) + sizeof(struct group_key) * (nkey - 1);
	const int align_size = sizeof(void *);
	// align
	header_size = (header_size + align_size - 1) & ~(align_size - 1);
	size_t size = header_size + field_n * sizeof(struct field);
	struct group_iter *iter = (struct group_iter *)lua_newuserdatauv(L, size, 1);
	// refer world
	lua_pushvalue(L, 1);
	lua_setiuservalue(L, -2, 1);
	iter->nkey = nkey;
	iter->world = w;
	iter->readonly = 1;
	struct field *f = (struct field *)((char *)iter + header_size);
	iter->f = f;
	for (i = 0; i < nkey; i++)
	{
		lua_geti(L, 2, i + 1);
		int n = get_key(w, L, &iter->k[i], f);
		struct component_pool *c = &w->c[iter->k[i].id];
		f += n;
		lua_pop(L, 1);
		if (c->stride == STRIDE_LUA)
		{
			if (n != 0)
				return luaL_error(L, ".%s is object component, no fields needed", iter->k[i].name);
			iter->k[i].attrib |= COMPONENT_OBJECT;
		}
		else if (c->stride == STRIDE_ORDER)
		{
			if (i != 0)
			{
				return luaL_error(L, ".%s is an order key, must be main key", iter->k[i].name);
			}
			else if (iter->k[0].attrib & COMPONENT_OUT)
			{
				return luaL_error(L, ".%s is an order key, it should be readonly", iter->k[0].name);
			}
		}
		int attrib = iter->k[i].attrib;
		int readonly;
		if (attrib & COMPONENT_EXIST)
			readonly = 0;
		else
			readonly = (attrib & COMPONENT_IN) && !(attrib & COMPONENT_OUT);
		if (!readonly)
			iter->readonly = 0;
	}
	if (iter->k[0].attrib & COMPONENT_OPTIONAL)
	{
		return luaL_error(L, "The main key should not be optional");
	}
	if (is_temporary(iter->k[0].attrib))
	{
		return luaL_error(L, "The main key can't be temporary");
	}
	if (luaL_newmetatable(L, "ENTITY_GROUPITER"))
	{
		lua_pushcfunction(L, lpairs_group);
		lua_setfield(L, -2, "__call");
	}
	lua_setmetatable(L, -2);
	return 1;
}

static int
get_integer(lua_State *L, int index, int i, const char *key)
{
	if (lua_rawgeti(L, index, i) != LUA_TNUMBER)
	{
		return luaL_error(L, "Can't find %s in iterator", key);
	}
	int r = lua_tointeger(L, -1);
	lua_pop(L, 1);
	if (r <= 0)
		return luaL_error(L, "Invalid %s (%d)", key, r);
	return r;
}

static int
lremove(lua_State *L)
{
	struct entity_world *w = getW(L);
	luaL_checktype(L, 2, LUA_TTABLE);
	int iter = get_integer(L, 2, 1, "index") - 1;
	int mainkey = get_integer(L, 2, 2, "mainkey");
	entity_remove_(w, mainkey, iter, L, 1);
	return 0;
}

static int
lsortkey(lua_State *L)
{
	struct entity_world *w = getW(L);
	int oid = luaL_checkinteger(L, 2);
	int cid = luaL_checkinteger(L, 3);
	entity_sort_key_(w, oid, cid, L, 1);
	return 0;
}

static int
lsingleton(lua_State *L)
{
	struct group_iter *iter = luaL_checkudata(L, 1, "ENTITY_GROUPITER");
	int cid = iter->k[0].id;
	struct entity_world *w = iter->world;
	if (cid < 0 || cid >= MAX_COMPONENT)
	{
		return luaL_error(L, "Invalid singleton %d", cid);
	}
	struct component_pool *c = &w->c[cid];
	if (c->n == 0)
	{
		return luaL_error(L, "No singleton %d", cid);
	}
	if (c->stride == STRIDE_LUA)
	{
		// lua singleton
		lua_settop(L, 2);
		if (lua_getiuservalue(L, 1, 1) != LUA_TUSERDATA)
		{
			return luaL_error(L, "No world");
		}
		if (lua_getiuservalue(L, -1, cid * 2 + 2) != LUA_TTABLE)
		{
			return luaL_error(L, "Missing lua table for %d", cid);
		}
		if (lua_isnil(L, 2))
		{
			lua_rawgeti(L, -1, 1);
		}
		else
		{
			lua_pushvalue(L, 2);
			lua_rawseti(L, -2, 1);
			lua_settop(L, 2);
		}
		return 1;
	}
	else if (c->stride <= 0)
	{
		return luaL_error(L, "Invalid singleton %d", cid);
	}
	struct field *f = iter->f;
	void *buffer = get_ptr(c, 0);
	if (lua_isnoneornil(L, 2))
	{
		// read singleton
		lua_createtable(L, 0, iter->k[0].field_n);
		if (f->key == NULL)
		{
			// value type
			read_value(L, f, buffer);
		}
		else
		{
			int index = lua_gettop(L);
			read_component(L, iter->k[0].field_n, f, index, buffer);
		}
	}
	else
	{
		// write singleton
		lua_pushvalue(L, 2);
		write_component_object(L, iter->k[0].field_n, f, buffer);
	}
	return 1;
}

// reference object

struct ecs_ref
{
	struct ecs_ref_i interface;
	void *data;
	lua_State *L;
	int n;
	int cap;
	int stride;
	int nkey;
	int freelist;
	struct field f[1];
};

struct ref_freenode
{
	int freelist;
};

static void
init_fields(struct ecs_ref *R, lua_State *L, int index, int nkey)
{
	if (nkey == 0)
	{
		// lua object
		R->stride = 0;
		lua_newtable(R->L);
		if (lua_gettop(R->L) != 1)
		{
			luaL_error(L, "Invalid ref context");
		}
	}
	else
	{
		if (lua_getfield(L, index, "size") != LUA_TNUMBER)
		{
			luaL_error(L, "need .size");
		}
		R->stride = lua_tointeger(L, -1);
		lua_pop(L, 1);
		int i;
		for (i = 0; i < nkey; i++)
		{
			struct field *f = &R->f[i];
			if (lua_geti(L, index, i + 1) != LUA_TTABLE)
			{
				luaL_error(L, "Invalid field %d, need table, it's %s", i + 1, lua_typename(L, lua_type(L, -1)));
			}
			if (lua_geti(L, -1, 1) != LUA_TNUMBER)
			{
				luaL_error(L, "Invalid type id in [%d]", i + 1);
			}
			f->type = lua_tointeger(L, -1);
			lua_pop(L, 1);
			if (lua_geti(L, -1, 2) != LUA_TSTRING)
			{
				if (lua_type(L, -1) == LUA_TNIL && i == 0)
				{
					f->key = NULL;
				}
				else
				{
					luaL_error(L, "Invalid key name in [%d]", i + 1);
				}
			}
			else
			{
				f->key = lua_tostring(L, -1);
			}
			lua_pop(L, 1);
			if (lua_geti(L, -1, 3) != LUA_TNUMBER)
			{
				luaL_error(L, "Invalid offset in [%d]", i + 1);
			}
			f->offset = lua_tointeger(L, -1);
			if (f->offset >= R->stride)
			{
				luaL_error(L, "Invalid offset (%d/%d) in [%d]", f->offset, R->stride, i + 1);
			}
			lua_pop(L, 2);
		}
	}
}

static inline void *
ref_index_ptr(struct ecs_ref *R, int index)
{
	return (void *)((char *)R->data + R->stride * index);
}

static int
alloc_id(struct ecs_ref *R)
{
	if (R->data == NULL)
	{
		lua_settop(R->L, 0);
		R->data = lua_newuserdata(R->L, R->stride * R->cap);
		R->n = 1;
		return 1;
	}
	if (R->freelist)
	{
		int r = R->freelist - 1;
		struct ref_freenode *node = (struct ref_freenode *)ref_index_ptr(R, r);
		R->freelist = node->freelist;
		return r;
	}
	if (R->n >= R->cap)
	{
		int newcap = R->cap * 3 / 2;
		void *data = lua_newuserdata(R->L, R->stride * newcap);
		memcpy(R->data, data, R->stride * R->n);
		lua_replace(R->L, 1);
		R->data = data;
		R->cap = newcap;
	}
	return ++R->n;
}

static int
lnew_object(lua_State *L)
{
	struct ecs_ref *R = (struct ecs_ref *)luaL_checkudata(L, 1, "ENTITY_REFOBJECT");
	int n;
	if (R->stride == 0)
	{
		// lua object
		if (!lua_istable(R->L, 1))
		{
			return luaL_error(L, "Invalid ref context");
		}
		n = lua_rawlen(R->L, 1);
		lua_settop(L, 2);
		lua_xmove(L, R->L, 1);
		lua_rawseti(R->L, 1, n + 1);
		lua_pushinteger(L, n + 1);
	}
	else
	{
		n = alloc_id(R);
		void *buffer = ref_index_ptr(R, n - 1);
		if (R->f[0].key == NULL)
		{
			write_value(L, R->f, buffer);
		}
		else
		{
			write_component(L, R->nkey, R->f, 2, buffer);
		}
		lua_pushinteger(L, n);
	}
	return 1;
}

static void
release_object(struct ecs_ref *R, int id)
{
	if (R->stride == 0)
	{
		// lua object
		if (!lua_istable(R->L, 1))
		{
			luaL_error(R->L, "Invalid ref context");
		}
		lua_pushnil(R->L);
		lua_rawseti(R->L, 1, id);
	}
	else
	{
		if (id <= 0 || id > R->n)
			luaL_error(R->L, "Invalid id %d", id);
		if (id == R->n)
		{
			--R->n;
		}
		else
		{
			struct ref_freenode *node = (struct ref_freenode *)ref_index_ptr(R, id - 1);
			node->freelist = R->freelist;
			R->freelist = id;
		}
	}
}

static void *
index_object(struct ecs_ref *R, int id)
{
	if (R->stride == 0)
	{
		luaL_error(R->L, "Can't index lua object");
	}
	else if (id <= 0 || id > R->n)
	{
		luaL_error(R->L, "Invalid id %d", id);
	}
	return ref_index_ptr(R, id - 1);
}

static int
ldelete_object(lua_State *L)
{
	struct ecs_ref *R = (struct ecs_ref *)luaL_checkudata(L, 1, "ENTITY_REFOBJECT");
	int id = luaL_checkinteger(L, 2);
	release_object(R, id);
	return 0;
}

#define KEY(s) s, sizeof(""s)

static int
iskey(const char *name, size_t sz, const char *keyname, size_t keysize)
{
	return (sz + 1 == keysize) && memcmp(name, keyname, sz) == 0;
}

static inline int
method(lua_State *L, int index)
{
	size_t sz;
	const char *name = lua_tolstring(L, index, &sz);
	if (iskey(name, sz, KEY("new")))
	{
		lua_pushcfunction(L, lnew_object);
	}
	else if (iskey(name, sz, KEY("delete")))
	{
		lua_pushcfunction(L, ldelete_object);
	}
	else
	{
		return luaL_error(L, "Invalid method %s", name);
	}
	return 1;
}

static inline int
index_ref(lua_State *L, int index)
{
	int id = lua_tointeger(L, index);
	if (id <= 0)
	{
		return luaL_error(L, "Invalid index %d", id);
	}
	struct ecs_ref *R = (struct ecs_ref *)lua_touserdata(L, 1);
	if (R->stride == 0)
	{
		// lua object
		if (!lua_istable(R->L, 1))
		{
			return luaL_error(L, "Invalid ref context");
		}
		lua_rawgeti(R->L, 1, id);
		lua_xmove(R->L, L, 1);
	}
	else
	{
		if (id <= 0 || id > R->n)
		{
			return luaL_error(L, "Invalid id %d\n", id);
		}
		void *buffer = ref_index_ptr(R, id - 1);
		if (R->f->key == NULL)
		{
			read_value(L, R->f, buffer);
		}
		else
		{
			lua_createtable(L, 0, R->nkey);
			int index = lua_gettop(L);
			read_component(L, R->nkey, R->f, index, buffer);
		}
	}
	return 1;
}

static int
lread_ref(lua_State *L)
{
	switch (lua_type(L, 2))
	{
	case LUA_TSTRING:
		return method(L, 2);
	case LUA_TNUMBER:
		return index_ref(L, 2);
	default:
		return luaL_error(L, "Invalid key type %s", lua_typename(L, lua_type(L, -1)));
	}
}

static int
lwrite_ref(lua_State *L)
{
	struct ecs_ref *R = (struct ecs_ref *)lua_touserdata(L, 1);
	int id = luaL_checkinteger(L, 2);
	if (R->stride == 0)
	{
		// lua object
		if (!lua_istable(R->L, 1))
		{
			return luaL_error(L, "Invalid ref context");
		}
		lua_xmove(L, R->L, 1);
		lua_rawseti(R->L, 1, id);
	}
	if (id <= 0 && id > R->n)
		return luaL_error(L, "Invalid id %d", id);
	void *buffer = ref_index_ptr(R, id - 1);
	write_component_object(L, R->nkey, R->f, buffer);
	return 0;
}

static int
lnew_ref(lua_State *L)
{
	size_t sz;
	int nkey;
	if (lua_isnoneornil(L, 1))
	{
		sz = offsetof(struct ecs_ref, f);
		nkey = 0;
	}
	else
	{
		luaL_checktype(L, 1, LUA_TTABLE);
		nkey = get_len(L, 1);
		sz = sizeof(struct ecs_ref) + (nkey - 1) * sizeof(struct field);
	}
	struct ecs_ref *R = (struct ecs_ref *)lua_newuserdatauv(L, sz, 1);
	static struct ecs_capi_ref apis = {
		alloc_id,
		release_object,
		index_object,
	};
	R->interface.api = &apis;
	R->data = NULL;
	R->n = 0;
	R->cap = DEFAULT_SIZE;
	R->nkey = nkey;
	R->freelist = 0;
	R->L = lua_newthread(L);
	lua_setiuservalue(L, -2, 1);
	init_fields(R, L, 1, nkey);
	if (luaL_newmetatable(L, "ENTITY_REFOBJECT"))
	{
		luaL_Reg l[] = {
			{"__index", lread_ref},
			{"__newindex", lwrite_ref},
			{NULL, NULL},
		};
		luaL_setfuncs(L, l, 0);
	}
	lua_setmetatable(L, -2);
	return 1;
}

LUAMOD_API int
luaopen_ecs_core(lua_State *L)
{
	luaL_checkversion(L);
	luaL_Reg l[] = {
		{"_world", lnew_world},
		{"_ref", lnew_ref},
		{"_MAXTYPE", NULL},
		{"_METHODS", NULL},
		{"_TYPEINT", NULL},
		{"_TYPEFLOAT", NULL},
		{"_TYPEBOOL", NULL},
		{NULL, NULL},
	};
	luaL_newlib(L, l);
	lua_pushinteger(L, MAX_COMPONENT - 1);
	lua_setfield(L, -2, "_MAXTYPE");
	if (luaL_newmetatable(L, "ENTITY_WORLD"))
	{
		luaL_Reg l[] = {
			{"__index", NULL},
			{"memory", lcount_memory},
			{"collect", lcollect_memory},
			{"_newtype", lnew_type},
			{"_newentity", lnew_entity},
			{"_addcomponent", ladd_component},
			{"update", lupdate},
			{"_clear", lclear_type},
			{"_context", lcontext},
			{"_groupiter", lgroupiter},
			{"remove", lremove},
			{"_sortkey", lsortkey},
			{"_singleton", lsingleton},
			{"_sync", lsync},
			{NULL, NULL},
		};
		luaL_setfuncs(L, l, 0);
		lua_pushvalue(L, -1);
		lua_setfield(L, -2, "__index");
	}
	else
	{
		return luaL_error(L, "ENTITY_WORLD exist");
	}
	lua_setfield(L, -2, "_METHODS");
	lua_pushinteger(L, TYPE_INT);
	lua_setfield(L, -2, "_TYPEINT");
	lua_pushinteger(L, TYPE_FLOAT);
	lua_setfield(L, -2, "_TYPEFLOAT");
	lua_pushinteger(L, TYPE_BOOL);
	lua_setfield(L, -2, "_TYPEBOOL");
	lua_pushinteger(L, STRIDE_LUA);
	lua_setfield(L, -2, "_LUAOBJECT");
	lua_pushinteger(L, ENTITY_REMOVED);
	lua_setfield(L, -2, "_REMOVED");
	lua_pushinteger(L, STRIDE_ORDER);
	lua_setfield(L, -2, "_ORDERKEY");

	return 1;
}

#ifdef TEST_LUAECS

#include <stdio.h>

#define COMPONENT_VECTOR2 1
#define TAG_MARK 2
#define COMPONENT_ID 3
#define SINGLETON_STRING 4

struct vector2
{
	float x;
	float y;
};

struct id
{
	int v;
};

static int
ltest(lua_State *L)
{
	struct ecs_context *ctx = lua_touserdata(L, 1);
	struct vector2 *v;
	int i;
	for (i = 0; (v = (struct vector2 *)entity_iter(ctx, COMPONENT_VECTOR2, i)); i++)
	{
		printf("vector2 %d: x=%f y=%f\n", i, v->x, v->y);
		struct id *id = (struct id *)entity_sibling(ctx, COMPONENT_VECTOR2, i, COMPONENT_ID);
		if (id)
		{
			printf("\tid = %d\n", id->v);
		}
		void *mark = entity_sibling(ctx, COMPONENT_VECTOR2, i, TAG_MARK);
		if (mark)
		{
			printf("\tMARK\n");
		}
	}

	return 0;
}

static int
lsum(lua_State *L)
{
	struct ecs_context *ctx = lua_touserdata(L, 1);
	struct vector2 *v;
	int i;
	float s = 0;
	for (i = 0; (v = (struct vector2 *)entity_iter(ctx, COMPONENT_VECTOR2, i)); i++)
	{
		s += v->x + v->y;
	}
	lua_pushnumber(L, s);
	return 1;
}

static int
lget(lua_State *L)
{
	struct ecs_context *ctx = lua_touserdata(L, 1);
	const char *ret = (const char *)entity_iter_lua(ctx, SINGLETON_STRING, 0);
	if (ret)
	{
		lua_pushfstring(L, "[string:%s]", ret);
	}
	return 1;
}

static int
ltestref(lua_State *L)
{
	struct ecs_ref_i *R = (struct ecs_ref_i *)lua_touserdata(L, 1);
	int id = robject_create(R);
	printf("create id = %d\n", id);
	struct vector2 *vec = robject_index(R, id);
	vec->x = 42.0f;
	vec->y = 24.0f;
	lua_pushinteger(L, id);
	return 1;
}

LUAMOD_API int
luaopen_ecs_ctest(lua_State *L)
{
	luaL_checkversion(L);
	luaL_Reg l[] = {
		{"test", ltest},
		{"sum", lsum},
		{"get", lget},
		{"testref", ltestref},
		{NULL, NULL},
	};
	luaL_newlib(L, l);
	return 1;
}

#endif