Kayne Ruse
113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/* Copyright: (c) Kayne Ruse 2013-2015
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*
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* This software is provided 'as-is', without any express or implied
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* warranty. In no event will the authors be held liable for any damages
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* arising from the use of this software.
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*
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* Permission is granted to anyone to use this software for any purpose,
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* including commercial applications, and to alter it and redistribute it
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* freely, subject to the following restrictions:
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*
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* 1. The origin of this software must not be misrepresented; you must not
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* claim that you wrote the original software. If you use this software
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* in a product, an acknowledgment in the product documentation would be
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* appreciated but is not required.
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*
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* 2. Altered source versions must be plainly marked as such, and must not be
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* misrepresented as being the original software.
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*
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* 3. This notice may not be removed or altered from any source
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* distribution.
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*/
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#include "userdata.hpp"
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#define METAMETA "__metameta"
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static int index(lua_State* L) {
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//get __metameta
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lua_getmetatable(L, 1); //get the userdata metatable
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lua_pushstring(L, METAMETA); //push the __metameta name
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lua_gettable(L, -2); //get the __metameta field from the metatable
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//get __metameta[userdata]
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lua_pushvalue(L, 1); //copy of the userdata
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lua_gettable(L, -2); //get the table at __metameta[userdata]
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//table doesn't exist yet
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if (lua_isnil(L, -1)) {
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return 1;
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}
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//get the value at __metameta[userdata][key]
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lua_pushvalue(L, 2); //copy the key
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lua_gettable(L, -2); //get value from the deepest table
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//return
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return 1;
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}
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static int newindex(lua_State* L) {
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//get __metameta
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lua_getmetatable(L, 1); //get the userdata metatable
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lua_pushstring(L, METAMETA); //push the __metameta name
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lua_gettable(L, -2); //get the __metameta field from the metatable
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//get __metameta[userdata]
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lua_pushvalue(L, 1); //copy of the userdata
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lua_gettable(L, -2); //get the table at __metameta[userdata]
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//if this table doesn't exist yet
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if (lua_isnil(L, -1)) {
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lua_pop(L, 1); //pop nil
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lua_pushvalue(L, 1); //copy userdata (key)
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lua_createtable(L, 0, 0); //new table (value)
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lua_settable(L, -3); //create the new table in __metameta
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lua_pushvalue(L, 1); //copy userdata (key)
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lua_gettable(L, -2); //get the newly created table
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}
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//set the value at __metameta[userdata][key] = value
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lua_pushvalue(L, 2); //copy the key
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lua_pushvalue(L, 3); //copy the value
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lua_settable(L, -3); //set value in the deepest table
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//return
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return 0;
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}
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static luaL_Reg metatable[] = {
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{"__index", index},
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{"__newindex", newindex},
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{nullptr, nullptr}
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};
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int createUserdataMetatable(lua_State* L) {
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//create the userdata metatable
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lua_pushlightuserdata(L, nullptr); //anon userdata
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lua_createtable(L, 0, 0); //table
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//insert meta-metatable
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lua_pushstring(L, METAMETA);
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lua_createtable(L, 0, 0);
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lua_settable(L, -3);
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//insert metatable blocker
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lua_pushstring(L, "__metatable");
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lua_createtable(L, 0, 0);
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lua_settable(L, -3);
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//insert metamethods
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for (luaL_Reg* it = metatable; it->name; it++) {
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lua_pushstring(L, it->name);
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lua_pushcfunction(L, it->func);
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lua_settable(L, -3);
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}
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//set in the object & pop the anon userdata
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lua_setmetatable(L, -2); //set the metatable for userdata
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lua_pop(L, 1); //pop the anon userdata
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return 0;
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} |