143 lines
4.1 KiB
C
143 lines
4.1 KiB
C
/*
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* luaobject.c - useful functions for handling Lua objects
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*
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* Copyright © 2009 Julien Danjou <julien@danjou.info>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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*/
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#include "common/luaobject.h"
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/** Setup the object system at startup.
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* \param L The Lua VM state.
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*/
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void
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luaA_object_setup(lua_State *L)
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{
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/* Push identification string */
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lua_pushliteral(L, LUAA_OBJECT_REGISTRY_KEY);
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/* Create an empty table */
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lua_newtable(L);
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/* Create an empty metatable */
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lua_newtable(L);
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/* Set this empty table as the registry metatable.
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* It's used to store the number of reference on stored objects. */
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lua_setmetatable(L, -2);
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/* Register table inside registry */
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lua_rawset(L, LUA_REGISTRYINDEX);
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}
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/** Increment a object reference in its store table.
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* \param L The Lua VM state.
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* \param tud The table index on the stack.
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* \param oud The object index on the stack.
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* \return A pointer to the object.
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*/
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void *
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luaA_object_incref(lua_State *L, int tud, int oud)
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{
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/* Get pointer value of the item */
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void *pointer = (void *) lua_topointer(L, oud);
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/* Not referencable. */
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if(!pointer)
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{
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lua_remove(L, oud);
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return NULL;
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}
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/* Push the pointer (key) */
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lua_pushlightuserdata(L, pointer);
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/* Push the data (value) */
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lua_pushvalue(L, oud < 0 ? oud - 1 : oud);
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/* table.lightudata = data */
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lua_rawset(L, tud < 0 ? tud - 2 : tud);
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/* refcount++ */
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/* Get the metatable */
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lua_getmetatable(L, tud);
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/* Push the pointer (key) */
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lua_pushlightuserdata(L, pointer);
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/* Get the number of references */
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lua_rawget(L, -2);
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/* Get the number of references and increment it */
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int count = lua_tonumber(L, -1) + 1;
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lua_pop(L, 1);
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/* Push the pointer (key) */
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lua_pushlightuserdata(L, pointer);
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/* Push count (value) */
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lua_pushinteger(L, count);
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/* Set metatable[pointer] = count */
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lua_rawset(L, -3);
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/* Pop metatable */
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lua_pop(L, 1);
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/* Remove referenced item */
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lua_remove(L, oud);
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return pointer;
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}
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/** Decrement a object reference in its store table.
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* \param L The Lua VM state.
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* \param tud The table index on the stack.
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* \param oud The object index on the stack.
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* \return A pointer to the object.
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*/
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void
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luaA_object_decref(lua_State *L, int tud, void *pointer)
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{
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if(!pointer)
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return;
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/* First, refcount-- */
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/* Get the metatable */
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lua_getmetatable(L, tud);
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/* Push the pointer (key) */
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lua_pushlightuserdata(L, pointer);
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/* Get the number of references */
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lua_rawget(L, -2);
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/* Get the number of references and decrement it */
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int count = lua_tonumber(L, -1) - 1;
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lua_pop(L, 1);
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/* Push the pointer (key) */
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lua_pushlightuserdata(L, pointer);
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/* Hasn't the ref reached 0? */
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if(count)
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lua_pushinteger(L, count);
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else
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/* Yup, delete it, set nil as value */
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lua_pushnil(L);
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/* Set meta[pointer] = count/nil */
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lua_rawset(L, -3);
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/* Pop metatable */
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lua_pop(L, 1);
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/* Wait, no more ref? */
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if(!count)
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{
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/* Yes? So remove it from table */
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lua_pushlightuserdata(L, pointer);
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/* Push nil as value */
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lua_pushnil(L);
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/* table[pointer] = nil */
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lua_rawset(L, tud < 0 ? tud - 2 : tud);
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}
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}
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// vim: filetype=c:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=80
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