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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
// FIXME: it'd probably be faster overall to have a Script.NewSyncTable()
// available to the synced side, that checks data assignments in a
// __newindex call. This could be used in conjunction with the
// current setup to avoid table creation in WrapTable().
#include "System/mmgr.h"
#include "LuaSyncedTable.h"
#include "LuaInclude.h"
#include "LuaHashString.h"
#include "LuaUtils.h"
// replace a normal table with a read-only proxy
static bool WrapTable(lua_State* L);
// iteration routines
static int Next(lua_State* L);
static int Pairs(lua_State* L);
static int IPairs(lua_State* L);
// meta-table calls
static int SyncTableIndex(lua_State* L);
static int SyncTableNewIndex(lua_State* L);
static int SyncTableMetatable(lua_State* L);
/******************************************************************************/
/******************************************************************************/
bool LuaSyncedTable::PushEntries(lua_State* L)
{
HSTR_PUSH(L, "SYNCED");
lua_pushvalue(L, LUA_GLOBALSINDEX);
WrapTable(L); // replace the GLOBAL table with a proxy
lua_rawset(L, -3);
LuaPushNamedCFunc(L, "snext", Next);
LuaPushNamedCFunc(L, "spairs", Pairs);
LuaPushNamedCFunc(L, "sipairs", IPairs);
return true;
}
static bool WrapTable(lua_State* L)
{
const int realTable = lua_gettop(L);
lua_newtable(L); { // the proxy table
lua_newtable(L); { // the metatable
HSTR_PUSH(L, "__index");
lua_pushvalue(L, realTable);
lua_pushcclosure(L, SyncTableIndex, 1);
lua_rawset(L, -3); // closure
HSTR_PUSH(L, "__newindex");
lua_pushcfunction(L, SyncTableNewIndex);
lua_rawset(L, -3);
HSTR_PUSH(L, "__metatable");
lua_pushcfunction(L, SyncTableMetatable);
lua_rawset(L, -3);
HSTR_PUSH(L, "realTable");
lua_pushvalue(L, realTable);
lua_rawset(L, -3);
}
lua_setmetatable(L, -2);
}
lua_remove(L, realTable);
return true;
}
/******************************************************************************/
inline static bool SafeType(lua_State* L, const int& index)
{
const int t = lua_type(L, index);
return (
(t == LUA_TSTRING)
|| (t == LUA_TNUMBER)
|| (t == LUA_TBOOLEAN)
|| (t == LUA_TTABLE)
);
}
/******************************************************************************/
static int SyncTableIndex(lua_State* L)
{
lua_gettable(L, lua_upvalueindex(1));
if (lua_isstring(L, -1) ||
lua_isnumber(L, -1) ||
lua_isboolean(L, -1)) {
return 1;
}
if (lua_istable(L, -1)) {
if (WrapTable(L)) {
return 1;
} else {
return 0;
}
}
return 0; // functions, userdata, etc...
}
static int SyncTableNewIndex(lua_State* L)
{
luaL_error(L, "Attempt to write to SYNCED table");
return 0;
}
static int SyncTableMetatable(lua_State* L)
{
luaL_error(L, "Attempt to access SYNCED metatable");
return 0;
}
/******************************************************************************/
static inline void PushRealTable(lua_State* L, int index, const char* name)
{
if (lua_getmetatable(L, 1) == 0) {
luaL_error(L, "Error: using %s() with an invalid table", name);
}
HSTR_PUSH(L, "realTable");
lua_rawget(L, -2);
if (!lua_istable(L, -1)) {
luaL_error(L, "Error: using %s() with an invalid table", name);
}
return;
}
static int Next(lua_State* L)
{
luaL_checktype(L, 1, LUA_TTABLE);
lua_settop(L, 2); // create a 2nd argument if there isn't one
PushRealTable(L, 1, "snext");
const int realTable = lua_gettop(L);
lua_pushvalue(L, 2); // push the key to the top
lua_pushnil(L); // gets removed by lua_pop beneath!
do {
lua_pop(L, 1); // remove the value
if (!lua_next(L, realTable)) {
lua_pushnil(L);
return 1;
}
} while (lua_istable(L, -2) || !SafeType(L, -1));
if (lua_istable(L, -1)) {
WrapTable(L);
}
return 2;
}
static int Pairs(lua_State* L)
{
luaL_checktype(L, 1, LUA_TTABLE);
lua_pushcfunction(L, Next); // iterator
lua_pushvalue(L, 1); // state (table)
lua_pushnil(L); // initial value
return 3;
}
static int IPairs(lua_State* L)
{
lua_Number i = lua_tonumber(L, 2);
luaL_checktype(L, 1, LUA_TTABLE);
// initializing
if ((i == 0) && lua_isnone(L, 2)) {
PushRealTable(L, 1, "sipairs");
lua_pushcclosure(L, IPairs, 1); // iterator
lua_pushvalue(L, 1); // state (table)
lua_pushnumber(L, 0); // initial value
return 3;
}
lua_pushnil(L);
lua_pushnil(L); // gets removed by lua_pop beneath!
do {
lua_pop(L, 2); // remove old i,v pair
// incrementing
i++;
lua_pushnumber(L, i); // key (i)
lua_rawgeti(L, lua_upvalueindex(1), (int)i); // value (v)
// no more elements left in the table
if (lua_isnil(L, -1)) {
return 1;
}
} while (!SafeType(L, -1));
// wrap tables
if (lua_istable(L, -1)) {
WrapTable(L);
}
return 2;
}
/******************************************************************************/
/******************************************************************************/
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