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Rewrote `thinkers.iterate` to handle invalid pointers elegantly.

This commit is contained in:
Yukita Mayako 2017-05-27 14:03:27 -05:00
parent 11d57fba1b
commit c44a935b04
1 changed files with 84 additions and 50 deletions
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134
src/lua_thinkerlib.c
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@ -16,84 +16,118 @@
#include "lua_script.h"
#include "lua_libs.h"
#define META_ITERATIONSTATE "iteration state"
static const char *const iter_opt[] = {
"all",
"mobj",
NULL};
static const actionf_p1 iter_funcs[] = {
NULL,
(actionf_p1)P_MobjThinker
};
struct iterationState {
actionf_p1 filter;
int next;
};
static int iterationState_gc(lua_State *L)
{
struct iterationState *it = luaL_checkudata(L, -1, META_ITERATIONSTATE);
if (it->next != LUA_REFNIL)
{
luaL_unref(L, LUA_REGISTRYINDEX, it->next);
it->next = LUA_REFNIL;
}
return 0;
}
#define push_thinker(th) {\
if ((th)->function.acp1 == (actionf_p1)P_MobjThinker) \
LUA_PushUserdata(L, (th), META_MOBJ); \
else \
lua_pushlightuserdata(L, (th)); \
}
static int lib_iterateThinkers(lua_State *L)
{
int state = luaL_checkoption(L, 1, "mobj", iter_opt);
thinker_t *th = NULL;
actionf_p1 searchFunc;
const char *searchMeta;
thinker_t *th = NULL, *next = NULL;
struct iterationState *it = luaL_checkudata(L, 1, META_ITERATIONSTATE);
lua_settop(L, 2);
lua_remove(L, 1); // remove state now.
switch(state)
if (lua_isnil(L, 2))
th = &thinkercap;
else if (lua_isuserdata(L, 2))
{
case 0:
searchFunc = NULL;
searchMeta = NULL;
break;
case 1:
default:
searchFunc = (actionf_p1)P_MobjThinker;
searchMeta = META_MOBJ;
break;
if (lua_islightuserdata(L, 2))
th = lua_touserdata(L, 2);
else
{
th = *(thinker_t **)lua_touserdata(L, -1);
if (!th)
{
if (it->next == LUA_REFNIL)
return 0;
lua_rawgeti(L, LUA_REGISTRYINDEX, it->next);
if (lua_islightuserdata(L, -1))
next = lua_touserdata(L, -1);
else
next = *(thinker_t **)lua_touserdata(L, -1);
}
}
}
if (!lua_isnil(L, 1)) {
if (lua_islightuserdata(L, 1))
th = (thinker_t *)lua_touserdata(L, 1);
else if (searchMeta)
th = *((thinker_t **)luaL_checkudata(L, 1, searchMeta));
else
th = *((thinker_t **)lua_touserdata(L, 1));
} else
th = &thinkercap;
luaL_unref(L, LUA_REGISTRYINDEX, it->next);
it->next = LUA_REFNIL;
if (!th) // something got our userdata invalidated!
return 0;
if (th && !next)
next = th->next;
if (!next)
return luaL_error(L, "next thinker invalidated during iteration");
if (searchFunc == NULL)
{
if ((th = th->next) != &thinkercap)
for (; next != &thinkercap; next = next->next)
if (!it->filter || next->function.acp1 == it->filter)
{
if (th->function.acp1 == (actionf_p1)P_MobjThinker)
LUA_PushUserdata(L, th, META_MOBJ);
else
lua_pushlightuserdata(L, th);
push_thinker(next);
if (next->next != &thinkercap)
{
push_thinker(next->next);
it->next = luaL_ref(L, LUA_REGISTRYINDEX);
}
return 1;
}
return 0;
}
for (th = th->next; th != &thinkercap; th = th->next)
{
if (th->function.acp1 != searchFunc)
continue;
LUA_PushUserdata(L, th, searchMeta);
return 1;
}
return 0;
}
static int lib_startIterate(lua_State *L)
{
luaL_checkoption(L, 1, iter_opt[0], iter_opt);
lua_pushcfunction(L, lib_iterateThinkers);
lua_pushvalue(L, 1);
struct iterationState *it;
lua_pushvalue(L, lua_upvalueindex(1));
it = lua_newuserdata(L, sizeof(struct iterationState));
luaL_getmetatable(L, META_ITERATIONSTATE);
lua_setmetatable(L, -2);
it->filter = iter_funcs[luaL_checkoption(L, 1, "mobj", iter_opt)];
it->next = LUA_REFNIL;
return 2;
}
#undef push_thinker
int LUA_ThinkerLib(lua_State *L)
{
luaL_newmetatable(L, META_ITERATIONSTATE);
lua_pushcfunction(L, iterationState_gc);
lua_setfield(L, -2, "__gc");
lua_pop(L, 1);
lua_createtable(L, 0, 1);
lua_pushcfunction(L, lib_startIterate);
lua_pushcfunction(L, lib_iterateThinkers);
lua_pushcclosure(L, lib_startIterate, 1);
lua_setfield(L, -2, "iterate");
lua_setglobal(L, "thinkers");
return 0;