luasql.c

/*
** $Id: luasql.c,v 1.28 2009/02/11 12:08:50 tomas Exp $
** See Copyright Notice in license.html
*/

#include <string.h>

#include "lua.h"
#include "lauxlib.h"


#include "luasql.h"

#if !defined(lua_pushliteral)
#define lua_pushliteral(L, s) \
	lua_pushstring(L, "" s, (sizeof(s)/sizeof(char))-1)
#endif


/*
** Typical database error situation
*/
LUASQL_API int luasql_faildirect(lua_State *L, const char *err) {
	lua_pushnil(L);
	lua_pushliteral(L, LUASQL_PREFIX);
	lua_pushstring(L, err);
	lua_concat(L, 2);
	return 2;
}


/*
** Database error with LuaSQL message
** @param err LuaSQL error message.
** @param m Driver error message.
*/
LUASQL_API int luasql_failmsg(lua_State *L, const char *err, const char *m) {
	lua_pushnil(L);
	lua_pushliteral(L, LUASQL_PREFIX);
	lua_pushstring(L, err);
	lua_pushstring(L, m);
	lua_concat(L, 3);
	return 2;
}


typedef struct { short  closed; } pseudo_data;

/*
** Return the name of the object's metatable.
** This function is used by `tostring'.
*/
static int luasql_tostring (lua_State *L) {
	pseudo_data *obj = (pseudo_data *)lua_touserdata (L, 1);

	if (obj->closed) {
		lua_pushfstring (L, "%s (closed)", lua_tostring(L,lua_upvalueindex(1)));
	} else {
		lua_pushfstring (L, "%s (%p)", lua_tostring(L,lua_upvalueindex(1)), (void *)obj);
	}

	return 1;
}


#if !defined LUA_VERSION_NUM || LUA_VERSION_NUM==501
/*
** Adapted from Lua 5.2.0
*/
void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
	luaL_checkstack(L, nup+1, "too many upvalues");
	for (; l->name != NULL; l++) {	/* fill the table with given functions */
		int i;
		lua_pushstring(L, l->name);
		for (i = 0; i < nup; i++)	/* copy upvalues to the top */
			lua_pushvalue(L, -(nup + 1));
		lua_pushcclosure(L, l->func, nup);	/* closure with those upvalues */
		lua_settable(L, -(nup + 3));
	}
	lua_pop(L, nup);	/* remove upvalues */
}
#endif

/*
** Create a metatable and leave it on top of the stack.
*/
LUASQL_API int luasql_createmeta (lua_State *L, const char *name, const luaL_Reg *methods) {
	if (!luaL_newmetatable (L, name))
		return 0;

	/* define methods */
	luaL_setfuncs (L, methods, 0);

	/* define metamethods */
	lua_pushliteral (L, "__index");
	lua_pushvalue (L, -2);
	lua_settable (L, -3);

	lua_pushliteral (L, "__tostring");
	lua_pushstring (L, name);
	lua_pushcclosure (L, luasql_tostring, 1);
	lua_settable (L, -3);

	lua_pushliteral (L, "__metatable");
	lua_pushliteral (L, LUASQL_PREFIX"you're not allowed to get this metatable");
	lua_settable (L, -3);

	return 1;
}


/*
** Define the metatable for the object on top of the stack
*/
LUASQL_API void luasql_setmeta (lua_State *L, const char *name) {
	luaL_getmetatable (L, name);
	lua_setmetatable (L, -2);
}


/*
** Assumes the table is on top of the stack.
*/
LUASQL_API void luasql_set_info (lua_State *L) {
	lua_pushliteral (L, "_COPYRIGHT");
	lua_pushliteral (L, "Copyright (C) 2003-2015 Kepler Project");
	lua_settable (L, -3);
	lua_pushliteral (L, "_DESCRIPTION");
	lua_pushliteral (L, "LuaSQL is a simple interface from Lua to a DBMS");
	lua_settable (L, -3);
	lua_pushliteral (L, "_VERSION");
	lua_pushliteral (L, "LuaSQL 3.0.0");
	lua_settable (L, -3);
}

/*
** Finds a pre-existing LuaSQL table, or creates a new one.
*/
LUASQL_API void luasql_find_driver_table (lua_State *L) {
	lua_getglobal(L, "package");
	if(lua_istable(L, -1)) {
		lua_getfield(L, -1, "loaded");
		lua_remove(L, -2);

		lua_pushnil(L);
		while(lua_next(L, -2) != 0) {
			const char *key = lua_tostring(L, -2);
			if(strncmp(key, LUASQL_TABLENAME, strlen(LUASQL_TABLENAME)) == 0) {
				lua_remove(L, -2);
				lua_remove(L, -2);
				return;
			}

			lua_pop(L, 1);
		}
		lua_pop(L, 2);
	} else {
		lua_pop(L, 1);
	}

	lua_newtable (L);
}

/*
** registers a driver, taking account of the Lua version differences
** Lua Returns:
**   The new/existing 'luasql' driver table on the top of the stack
*/
LUASQL_API void luasql_reg_driver (lua_State *L, const luaL_Reg *driver)
{
#if LUA_VERSION_NUM<=501
	luaL_register (L, LUASQL_TABLENAME, driver);
#else
	luasql_find_driver_table (L);
	luaL_setfuncs (L, driver, 0);
#endif
	luasql_set_info (L);
}

/*
** Pulls an optional string value from the table at idx
*/
LUASQL_API const char* luasql_table_optstring(lua_State *L, int idx, const char* name, const char* def) {
	const char* res = NULL;

	lua_pushstring(L, name);
	lua_gettable(L, idx);

	res = lua_tostring(L, -1);
	lua_pop(L, 1);

	return (res != NULL) ? res : def;
}


/*
** Pulls an optional number value from the table at idx
*/
LUASQL_API lua_Number luasql_table_optnumber(lua_State *L, int idx, const char* name, lua_Number def) {
	lua_Number res = def;

	lua_pushstring(L, name);
	lua_gettable(L, idx);

	if(lua_isnumber(L, -1)) {
		res = lua_tonumber(L, -1);
	}
	lua_pop(L, 1);

	return res;
}

/*
** Registers a given C object in the registry to avoid GC
*/
void luasql_registerobj(lua_State *L, int index, void *obj)
{
	lua_pushvalue(L, index);
	lua_pushlightuserdata(L, obj);
	lua_pushvalue(L, -2);
	lua_settable(L, LUA_REGISTRYINDEX);
	lua_pop(L, 1);
}

/*
** Unregisters a given C object from the registry
*/
void luasql_unregisterobj(lua_State *L, void *obj)
{
	lua_pushlightuserdata(L, obj);
	lua_pushnil(L);
	lua_settable(L, LUA_REGISTRYINDEX);
}