/*=========================================================================*\
* Simple exception support
* LuaSocket toolkit
*
* RCS ID: $Id$
\*=========================================================================*/
#include <lauxlib.h>
#include <stdio.h>

#include "except.h"

/*=========================================================================*\
* Internal function prototypes.
\*=========================================================================*/
static int global_protect(lua_State *L);
static int global_newtry(lua_State *L);
static int protected(lua_State *L);
static int finalize(lua_State *L);
static int do_nothing(lua_State *L);

/* except functions */
static luaL_reg func[] = {
    {"newtry",    global_newtry},
    {"protect",   global_protect},
    {NULL,        NULL}
};

/*-------------------------------------------------------------------------*\
* Try factory
\*-------------------------------------------------------------------------*/
static int finalize(lua_State *L) {
    if (lua_isnil(L, 1) || (lua_isboolean(L, 1) && !lua_toboolean(L, 1))) {
        lua_pushvalue(L, lua_upvalueindex(1));
        lua_pcall(L, 0, 0, 0);
        lua_settop(L, 2);
        lua_error(L);
        return 0;
    } else return lua_gettop(L);
}

static int do_nothing(lua_State *L) { 
    (void) L;
    return 0; 
}

static int global_newtry(lua_State *L) {
    lua_settop(L, 1);
    if (lua_isnil(L, 1)) lua_pushcfunction(L, do_nothing);
    lua_pushcclosure(L, finalize, 1);
    return 1;
}

/*-------------------------------------------------------------------------*\
* Protect factory
\*-------------------------------------------------------------------------*/
static int protected(lua_State *L) {
    lua_pushvalue(L, lua_upvalueindex(1));
    lua_insert(L, 1);
    if (lua_pcall(L, lua_gettop(L) - 1, LUA_MULTRET, 0) != 0) {
        lua_pushnil(L);
        lua_insert(L, 1);
        return 2;
    } else return lua_gettop(L);
}

static int global_protect(lua_State *L) {
    lua_pushcclosure(L, protected, 1);
    return 1;
}

/*-------------------------------------------------------------------------*\
* Init module
\*-------------------------------------------------------------------------*/
int except_open(lua_State *L) {
    luaL_openlib(L, NULL, func, 0);
    return 0;
}