path: root/lib/BLua.cc

/*
 *  Baltisot
 *  Copyright (C) 1999-2007 Nicolas "Pixel" Noble
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* $Id: BLua.cc,v 1.60 2008-05-20 18:11:51 pixel Exp $ */

#include <stdlib.h>
#include "BLua.h"
#include "Buffer.h"
#include <lualib.h>
#include <llimits.h>

#ifndef BUFFERSIZE
#define BUFFERSIZE	  2048
#endif

#undef isnumber

void LuaPrinter::puts(const char * msg) {
    fputs(msg, stdout);
}

LuaPrinter default_lua_printer;

extern "C" {
    void do_lua_lock(lua_State * __L) {
	Lua * L;
	try {
	    L = Lua::find(__L);
	} catch (GeneralException e) {
	    return;
	}
	L->lock();
    }
    
    void do_lua_unlock(lua_State * __L) {
	Lua * L;
	try {
    	    L = Lua::find(__L);
	} catch (GeneralException e) {
	    return;
	}
	L->unlock();
    }
}

class LuaStatics : public Base {
  public:
    static const char * getF(lua_State *, void *, size_t *);
    static int putF(lua_State *, const void *, size_t, void *);
    static int luapanic(lua_State *);
    static int trueluapanic(lua_State *) throw(GeneralException);
    static int luaerror(lua_State *);
    static int callwrap(lua_State *, lua_CFunction);
    static void createhook(lua_State *, lua_State *);
    static void destroyhook(lua_State *, lua_State *);
    static int collector(lua_State *);
    static int destructor(lua_State *);

    static int andB(lua_State *);
    static int orB(lua_State *);
    static int xorB(lua_State *);
    static int notB(lua_State *);
    static int hex(lua_State *);
    static int shl(lua_State *);
    static int shr(lua_State *);
    
    static int getglobal(lua_State *);
    static int dumpvars(lua_State *);

    static int iconv(lua_State *);
    static int mkdir(lua_State *);

    static int globalindex(lua_State *);
    
    static int print(lua_State *);
};

std::map<lua_State *, Lua *> Lua::lualist;

int LuaStatics::luaerror(lua_State * __L) {
    Lua * L = Lua::find(__L);
    L->lock();
    L->push_lua_context();
    L->showerror();
    L->unlock();
    return 0;
}

int LuaStatics::luapanic(lua_State * L) {
    return trueluapanic(L);
}

int LuaStatics::trueluapanic(lua_State * __L) throw (GeneralException) {
    Lua * L = Lua::find(__L);
    if (L->is_protected())
        return 0;  // luaerror will get it for us...
    L->lock();
    L->push_lua_context();
    L->showerror();
    L->unlock();
    throw LuaException("Unprotected error running Lua code, bailing out; expect unstable lua environment.");
}

int LuaStatics::andB(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 a, b;

    if ((n != 2) || !L->isnumber(1) || !L->isnumber(2)) {
	L->error("Incorrect arguments to function `andB'");
    }

    a = L->tonumber(1);
    b = L->tonumber(2);

    L->push((lua_Number) (a & b));

    return 1;
}

int LuaStatics::orB(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 a, b;

    if ((n != 2) || !L->isnumber(1) || !L->isnumber(2)) {
	L->error("Incorrect arguments to function `orB'");
    }

    a = L->tonumber(1);
    b = L->tonumber(2);

    L->push((lua_Number) (a | b));

    return 1;
}

int LuaStatics::xorB(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 a, b;

    if ((n != 2) || !L->isnumber(1) || !L->isnumber(2)) {
	L->error("Incorrect arguments to function `xorB'");
    }

    a = L->tonumber(1);
    b = L->tonumber(2);

    L->push((lua_Number) (a ^ b));

    return 1;
}

int LuaStatics::notB(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 x;

    if ((n != 1) || !L->isnumber()) {
	L->error("Incorrect arguments to function `notB'");
    }

    x = ~((Uint32) L->tonumber());

    L->push((lua_Number) x);

    return 1;
}

int LuaStatics::shl(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 a, b;

    if ((n > 2) || !L->isnumber(1) || ((n == 2) && !L->isnumber(2))) {
	L->error("Incorrect arguments to function `shl'");
    }

    a = L->tonumber(1);
    if (n == 2)
        b = L->tonumber(2);
    else
        b = 1;

    L->push((lua_Number) (a << b));

    return 1;
}

int LuaStatics::shr(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    Uint32 a, b;

    if ((n > 2) || !L->isnumber(1) || ((n == 2) && !L->isnumber(2))) {
	L->error("Incorrect arguments to function `shr'");
    }

    a = L->tonumber(1);
    if (n == 2)
        b = L->tonumber(2);
    else
        b = 1;

    L->push((lua_Number) (a >> b));

    return 1;
}

int LuaStatics::hex(lua_State * __L) {
    Lua * L = Lua::find(__L);
    int n = L->gettop();
    int x;
    String r;

    if (((n != 1) && (n != 2)) || !L->isnumber(1) || ((n == 2) && !L->isstring(2))) {
	L->error("Incorrect arguments to function `hex'");
    }

    x = L->tonumber(1);
    String fmt = n == 2 ? L->tostring() : "%02x";
    r.set(fmt.to_charp(), x);

    L->push(r);

    return 1;
}

int LuaStatics::getglobal(lua_State * _L) {
    Lua * L = Lua::find(_L);
    int n = L->gettop();
    
    if ((n != 1) || !L->isstring(1)) {
	L->error("Incorrect arguments to function `getglobal'");
    }

    Buffer b;
    b << "return " + L->tostring();
    
    L->lock();
    L->load(&b, false);
    L->call(0, 1);
    L->unlock();
    return 1;
}

int LuaStatics::dumpvars(lua_State * _L) {
    Lua * L = Lua::find(_L);
    int n = L->gettop();
    Handle * h;
    String prefix;
    String varname;
    
    if ((n > 3) || (n < 2) || !L->isobject(1) ||
        ((n == 2) && !L->isstring(2)) ||
	((n == 3) && !L->isstring(3) && !L->istable(2) && !L->isstring(2))) {
	L->error("Incorrect arguments to function `dumpvars'");
    }
    
    prefix = L->tostring(n);
    
    if (n == 3)
	L->pop();

    if (L->isstring(2))
	L->getglobal(L->tostring(2));
    
    h = (Handle *) LuaObject::getme(L);
    
    L->dumpvars(h, prefix);

    return 0;
}

int LuaStatics::iconv(lua_State * _L) {
    Lua * L = Lua::find(_L);
    int n = L->gettop();
    String str, from, to;

    if ((n != 3) || !L->isstring(1) || !L->isstring(2) || !L->isstring(3)) {
	L->error("Incorrect arguments to function `string.iconv'");
    }

    str = L->tostring(1);
    from = L->tostring(2);
    to = L->tostring(3);

    str.iconv(from, to);

    L->push(str);

    return 1;
}

int LuaStatics::mkdir(lua_State * _L) {
    Lua * L = Lua::find(_L);
    int n = L->gettop();
    String dirname;
    
    if (n != 1) {
	L->error("Incorrect arguments to function `mkdir'");
    }
    
    dirname = L->tostring(1);

    ::MKDIR(dirname.to_charp());
    
    return 0;
}

int LuaStatics::print(lua_State * _L) {
    Lua * L = Lua::find(_L);
    
    int n = L->gettop();  /* number of arguments */
    int i;
    for (i = 1; i <= n; i++) {
        const char *s;
        s = lua_tostring(_L, i);  /* get result */
        if (s == NULL)
            L->error("`tostring' must return a string to `print'");
        if (i > 1) L->puts("\t");
        L->puts(s);
        L->pop();  /* pop result */
    }
    L->puts("\n");
    return 0;
}

int LuaStatics::callwrap(lua_State * __L, lua_CFunction func) {
    Lua * L = Lua::find(__L);
    int n;

    try {
        n = func(__L);
    }
    catch (LuaException e) {
        L->error(String("LuaException: ") + e.GetMsg());
    }
    catch (GeneralException e) {
        L->error(String("GeneralException: ") + e.GetMsg());
    }

    return n;
}

int LuaStatics::collector(lua_State * __L) {
    Lua * L = Lua::find(__L);
    void ** u = (void **) L->touserdata();
    bool * obj = (bool *) (u + 1);
//    printm(M_INFO, "From LUA: collecting object\n");
    if (*obj) {
//        printm(M_INFO, "Is object at %p\n", *u);
        Base * b = (Base *) *u;
        delete b;
    } else {
//        printm(M_INFO, "Is struct at %p\n", *u);
        free(*u);
    }
    *u = 0;
    return 0;
}

int LuaStatics::destructor(lua_State * __L) {
    Lua * L = Lua::find(__L);
    L->push("__obj");
    L->gettable(-2, true);
    void ** u = (void **) L->touserdata();
    bool * obj = (bool *) (u + 1);
    if (*obj) {
        Base * b = (Base *) *u;
        delete b;
    } else {
        free(*u);
    }
    *u = 0;
    L->pop();
    return 0;
}

void LuaStatics::createhook(lua_State * __L, lua_State * L1) {
    Lua * L = Lua::find(__L);
    L->spawn_from_thread(L1);
}

void LuaStatics::destroyhook(lua_State * __L, lua_State * L1) {
    Lua * L = Lua::find(L1);
    delete L;
}

void Lua::setup_state(lua_State *) {
    lualist[L] = this;
    lua_atpanic(L, LuaStatics::luapanic);
    lua_setcallwrap(L, LuaStatics::callwrap);
    lua_setcreatehook(L, LuaStatics::createhook);
    lua_setdestroyhook(L, LuaStatics::destroyhook);
    
    lprinter = &default_lua_printer;
}

Lua::Lua() : L(lua_open()), _protected(false), _is_thread(false) {
    setup_state(L);
    declarefunc("andB", LuaStatics::andB);
    declarefunc("orB", LuaStatics::orB);
    declarefunc("xorB", LuaStatics::xorB);
    declarefunc("notB", LuaStatics::notB);
    declarefunc("shl", LuaStatics::shl);
    declarefunc("shr", LuaStatics::shr);
    declarefunc("hex", LuaStatics::hex);
    declarefunc("getglobal", LuaStatics::getglobal);
    declarefunc("dumpvars", LuaStatics::dumpvars);
    declarefunc("print", LuaStatics::print);
    push("BLUA_THREADS");
    newtable();
    settable(LUA_REGISTRYINDEX);
    
    father = 0;
}

Lua::Lua(lua_State * __L) : L(__L), _protected(false), _is_thread(true) {
    setup_state(L);

    // **TODO**
    // do we need to define global functions as well.. ?
    // I don't think so. Environment should be duplicated.

}

void Lua::SetPrinter(LuaPrinter * lp) {
    lprinter = lp;
}

void Lua::puts(const char * msg) {
    lprinter->puts(msg);
}

Lua * Lua::Father() {
    return father ? father : this;
}

Lua * Lua::spawn_from_thread(lua_State * __L) {
    Lua * L = new Lua(__L);
    L->father = Father();
}

void Lua::weaken() {
    if (_is_thread) {
        push();                               // -1 = nil
        push("BLUA_THREADS");                 // -2 = nil, -1 = "BLUA_THREADS"
        copy();                               // -3 = nil, -2 = "BLUA_THREADS", -1 = "BLUA_THREADS"
        gettable(LUA_REGISTRYINDEX);          // -3 = nil, -2 = "BLUA_THREADS", -1 = BLUA_THREADS
        push((lua_Number) IntPoint(L));       // -4 = nil, -3 = "BLUA_THREADS", -2 = BLUA_THREADS, -1 = key-Lt
        copy(-4);                             // -5 = nil, -4 = "BLUA_THREADS", -3 = BLUA_THREADS, -2 = key-Lt, -1 = thread
        settable();                           // -3 = nil, -2 = "BLUA_THREADS", -1 = BLUA_THREADS
        settable(LUA_REGISTRYINDEX);          // -1 = thread
        pop();
    }
}

Lua::~Lua() {
    weaken();
    if (!_is_thread)
        lua_close(L);
    L = 0;
}

bool Lua::is_protected() {
    return _protected;
}

Lua::Lua(const Lua & l) throw (GeneralException) {
    throw GeneralException("Error: can't duplicate a Lua object.");
}

void Lua::open_base() {
    lock();
    luaopen_base(L);
    push("mkdir");
    push(LuaStatics::mkdir);
    settable();
    lua_pop(L, 1);
    push("mkdir");
    push(LuaStatics::mkdir);
    settable(LUA_GLOBALSINDEX);
    unlock();
}

void Lua::open_table() {
    lock();
    luaopen_table(L);
    lua_pop(L, 1);
    unlock();
}

void Lua::open_io(bool safe) {
    lock();
    luaopen_io(L);
    lua_pop(L, 1);
    unlock();
}

void Lua::open_string() {
    lock();
    luaopen_string(L);
    push("iconv");
    push(LuaStatics::iconv);
    settable();
    lua_pop(L, 1);
    unlock();
}

void Lua::open_math() {
    lock();
    luaopen_math(L);
    lua_pop(L, 1);
    unlock();
}

void Lua::open_debug() {
    lock();
    luaopen_debug(L);
    lua_pop(L, 1);
    unlock();
}

void Lua::open_dir() {
    lock();
    luaopen_dir(L);
    lua_pop(L, 1);
    unlock();
}

void Lua::declarefunc(const String & name, lua_CFunction f, int i) {
    lock();
    lua_pushstring(L, name.to_charp());
    lua_pushcfunction(L, f);
    lua_settable(L, i);
    unlock();
}

void Lua::call(const String & f, int i, int nargs, int nresults) {
    lock();
    lua_pushstring(L, f.to_charp());
    lua_gettable(L, i);
    lua_insert(L, -1 - nargs - nresults);
    call(nargs, nresults);
    unlock();
}

void Lua::call(int nargs, int nresults) throw(GeneralException) {
    int r;

    lock();
    lua_pushcfunction(L, LuaStatics::luaerror);
    lua_insert(L, 1);
    _protected = true;
    r = lua_pcall(L, nargs, nresults, 1);
    _protected = false;
    lua_remove(L, 1);
    unlock();

    switch(r) {
    case 0:
        return;
    case LUA_ERRRUN:
        throw LuaException("Runtime error while running LUA code.");
    case LUA_ERRMEM:
        throw LuaException("Memory allocation error while running LUA code.");
    case LUA_ERRERR:
        throw LuaException("Error in Error function.");
    case LUA_ERRSYNTAX:
        throw LuaException("Syntax error in Lua code.");
    default:
        throw LuaException("Unknow error while running LUA code (err code: " + String(r) + ")");
    }
}

void Lua::push() {
    lua_pushnil(L);
}

void Lua::push(lua_Number n) {
    lua_pushnumber(L, n);
}

void Lua::push(const String & s) {
    lua_pushlstring(L, s.to_charp(), s.strlen());
}

void Lua::push(bool b) {
    lua_pushboolean(L, b);
}

void Lua::push(char * s, int size) {
    if (size < 0) {
        lua_pushstring(L, s);
    } else {
        lua_pushlstring(L, s, size);
    }
}

void Lua::push(void * p) {
    lua_pushlightuserdata(L, p);
}

void Lua::push(lua_CFunction f, int n) {
    lua_pushcclosure(L, f, n);
}

void Lua::pop(int n) {
    lua_pop(L, n);
}

int Lua::next(int t) {
    return lua_next(L, t);
}

void Lua::copy(int n) {
    lua_pushvalue(L, n);
}

void Lua::remove(int n) {
    lua_remove(L, n);
}

void Lua::insert(int n) {
    lua_insert(L, n);
}

void Lua::replace(int n) {
    lua_replace(L, n);
}

void Lua::newtable() {
    lua_newtable(L);
}

void * Lua::newuser(size_t s) {
    return lua_newuserdata(L, s);
}

void Lua::settable(int i, bool raw) {
    if (raw) {
        lua_rawset(L, i);
    } else {
        lua_settable(L, i);
    }
}

void Lua::gettable(int i, bool raw) {
    if (raw) {
        lua_rawget(L, i);
    } else {
        lua_gettable(L, i);
    }
}

void Lua::setvar() {
    lua_settable(L, LUA_GLOBALSINDEX);
}

int Lua::gettop() {
    return lua_gettop(L);
}

void Lua::getglobal(const String & name) throw (GeneralException) {
    Buffer b;
    b << "return " + name;
    
    try {
        lock();
	load(&b, false);
	call(0, 1);
        unlock();
    }
    catch (LuaException &) {
	throw LuaException("Error finding global variable `" + name + "'");
    }
}

void Lua::push_lua_context() {
    String whole_msg;
    struct lua_Debug ar;
    bool got_error = false;
    int level = 0;

    do {
        if (lua_getstack(L, level, &ar) == 1) {
            if (lua_getinfo(L, "nSl", &ar) != 0) {
                push(String("at ") + ar.source + ":" + ar.currentline + " (" + (ar.name ? ar.name : "[top]") + ")");
            } else {
                got_error = true;
            }
        } else {
            got_error = true;
        }
        level++;
    } while (!got_error);
}

void Lua::error(const String & msg) {
    push(msg);

    lua_error(L);
}

int Lua::status() {
    return 0;
}

int Lua::type(int i) {
    return lua_type(L, i);
}

bool Lua::isnil(int i) {
    return lua_isnil(L, i);
}

bool Lua::isboolean(int i) {
    return lua_isboolean(L, i);
}

bool Lua::isnumber(int i) {
    return lua_isnumber(L, i);
}

bool Lua::isstring(int i) {
    return lua_isstring(L, i);
}

bool Lua::istable(int i) {
    return lua_istable(L, i);
}

bool Lua::isfunction(int i) {
    return lua_isfunction(L, i);
}

bool Lua::iscfunction(int i) {
    return lua_iscfunction(L, i);
}

bool Lua::isuserdata(int i) {
    return lua_isuserdata(L, i);
}

bool Lua::islightuserdata(int i) {
    return lua_islightuserdata(L, i);
}

bool Lua::isobject(int i) {
    bool r = false;
    lock();
    if (istable(i)) {
        push("__obj");
        gettable(i);
        r = isuserdata();
        pop();
    } else {
        r = isnil(i);
    }
    unlock();
    return r;
}

bool Lua::toboolean(int i) {
    return lua_toboolean(L, i);
}

lua_Number Lua::tonumber(int i) {
    return lua_tonumber(L, i);
}

String Lua::tostring(int i) {
    const char * r = 0;
    size_t l = -1;
    switch (type(i)) {
    case LUA_TNIL:
        r = "(nil)";
        break;
    case LUA_TBOOLEAN:
	r = toboolean(i) ? "true" : "false";
	break;
    case LUA_TNUMBER:
        return String(tonumber(i));
        break;
    default:
        r = lua_tolstring(L, i, &l);
    }
    return String(r ? r : "<lua-NULL>", l);
}

lua_CFunction Lua::tocfunction(int i) {
    return lua_tocfunction(L, i);
}

void * Lua::touserdata(int i) {
    return lua_touserdata(L, i);
}

Lua * Lua::tothread(int i) {
    return find(lua_tothread(L, i));
}

struct LoadF {
    Handle * f;
    char buff[BUFFERSIZE];
};

const char * LuaStatics::getF(lua_State * L, void * ud, size_t * size) {
    LoadF *lf = (LoadF *)ud;
    (void)L;

    *size = lf->f->read(lf->buff, BUFFERSIZE);
    return (*size > 0) ? lf->buff : NULL;
}

struct DumpF {
    Handle * f;
};

int LuaStatics::putF(lua_State * L, const void * p, size_t size, void * ud) {
    DumpF *lf = (DumpF *)ud;
    (void)L;
    
    return (lf->f->write(p, size) != size) && (size != 0);
}

String Lua::escape_string(const String & s) {
    String r = "";
    int i;
    for (i = 0; i < s.strlen(); i++) {
        switch(s[i]) {
        case '"': case '\\':
            r += '\\';
            r += s[i];
            break;
        case '\n':
            r += "\\n";
            break;
        case '\r':
            r += "\\r";
            break;
        case '\0':
            r += "\\000";
            break;
        default:
            r += s[i];
        }
    }
    return r;
}

void Lua::load(Handle * h, bool docall) throw (GeneralException) {
    LoadF lf;
    int status;

    lf.f = h;

    if (docall)
        lock();
    status = lua_load(L, LuaStatics::getF, &lf, h->GetName().to_charp());

    if (status) {
        push_lua_context();
	showerror();
	throw LuaException("Error loading lua chunk from Handle `" + h->GetName() + "'");
    }

    if (docall) {
        call();
        unlock();
    }
}

void Lua::load(const String & s, bool docall) throw (GeneralException) {
    const char * buf = s.to_charp();
    int status;

    if (docall)
        lock();

    status = luaL_loadbuffer(L, buf, s.strlen(), buf);

    if (status) {
        push_lua_context();
	showerror();
	throw LuaException("Error loading lua string `" + s + "'");
    }

    if (docall) {
	call();
        unlock();
    }
}

extern "C" void luacmain(lua_State * L, int stripping, lua_Chunkwriter w, void * uD, int listing);

void Lua::dump(Handle * h, bool strip, int listing) {
    DumpF lf;

    lf.f = h;

    luacmain(L, strip, LuaStatics::putF, &lf, listing);
}

void Lua::dumpvars(Handle * h, const String & prefix, int i) {
    Buffer b;

    b << prefix << " = {\n";    
    dumpvars_r(&b, i);
    b << "}\n";
    
    b.copyto(h);
}

void Lua::dumpvars_r(Handle * h, int i, int depth) throw (GeneralException) {
    int j;
    String t;
    bool dump_value;
    
    if (lua_type(L, i) != LUA_TTABLE)
	throw LuaException("Error dumping variables: variable isn't a table.");

    push();
    
    if (i < 0)
	i--;

    depth++;

    while(lua_next(L, i) != 0) {
	for (j = 0; j < depth; j++) {
	    (*h) << "  ";
	}
	
	dump_value = true;
    
	// first, let's dump the key.
	switch(lua_type(L, -2)) {
	case LUA_TNONE:
	    throw LuaException("Internal error: got invalid index for key while dumpvars.");
	case LUA_TNIL:
	    throw LuaException("Internal error: got nil index for key while dumpvars.");
	case LUA_TNUMBER:
	    t.set("[%.14g] = ", lua_tonumber(L, -2));
	    break;
	case LUA_TBOOLEAN:
	    t = String("[") + (lua_toboolean(L, -2) ? "true" : "false") + "] = ";
	    break;
	case LUA_TSTRING:
	    t = "[\"" + escape_string(lua_tostring(L, -2)) + String("\"] = ");
	    break;
	case LUA_TTABLE:
	    t = "-- [a table]\n";
	    dump_value = false;
	    break;
	case LUA_TFUNCTION:
	    t = "-- [function() ... end]\n";
	    dump_value = false;
	    break;
	case LUA_TUSERDATA:
	    t = "-- [userdata]\n";
	    dump_value = false;
	    break;
	case LUA_TTHREAD:
	    t = "-- [thread]\n";
	    dump_value = false;
	    break;
	default:
	    throw LuaException("Internal error: got unknow index for key while dumpvars.");
	}
	
	// Seems that we can't dump that key.
	if (!dump_value) {
	    pop();
	    (*h) << t;
	    continue;
	}
	
	// let's look at the value: if it's a function, a userdata or a thread, we can't dump it.
	if ((lua_type(L, -1) == LUA_TFUNCTION) ||
 	    (lua_type(L, -1) == LUA_TUSERDATA) ||
 	    (lua_type(L, -1) == LUA_TTHREAD))
	    (*h) << "-- ";

	(*h) << t;
	
	// Finally, let's dump the value.
	switch(lua_type(L, -1)) {
	case LUA_TNONE:
	    throw LuaException("Internal error: got invalid index for value while dumpvars.");
	case LUA_TNIL:
	    (*h) << "nil,\n";
	case LUA_TNUMBER:
	    t.set("%.14g,\n", lua_tonumber(L, -1));
	    (*h) << t;
	    break;
	case LUA_TBOOLEAN:
	    (*h) << (lua_toboolean(L, -1) ? "true" : "false") << ",\n";
	    break;
	case LUA_TSTRING:
	    (*h) << "\"" << escape_string(lua_tostring(L, -1)) << "\",\n";
	    break;
	case LUA_TTABLE:
	    (*h) << "{\n";
	    dumpvars_r(h, -1, depth);
	    for (j = 0; j < depth; j++) {
		(*h) << "  ";
	    }
	    (*h) << "},\n";
	    break;
	case LUA_TFUNCTION:
	    (*h) << "function() ... end\n";
	    break;
        case LUA_TUSERDATA:
            (*h) << "userdata ...\n";
            break;
        case LUA_TTHREAD:
            (*h) << "thread ...\n";
            break;
	default:
	    throw LuaException("Internal error: got unknow index for value while dumpvars.");
	}
	
	pop();
    }
}

Lua * Lua::thread(bool saveit) {
    lua_State * L1 = lua_newthread(L);
    Lua * Lt = find(L1);
    if (saveit) {
        push("BLUA_THREADS");                 // -2 = thread, -1 = "BLUA_THREADS"
        copy();                               // -3 = thread, -2 = "BLUA_THREADS", -1 = "BLUA_THREADS"
        gettable(LUA_REGISTRYINDEX);          // -3 = thread, -2 = "BLUA_THREADS", -1 = BLUA_THREADS
        push((lua_Number) IntPoint(Lt));      // -4 = thread, -3 = "BLUA_THREADS", -2 = BLUA_THREADS, -1 = key-Lt
        copy(-4);                             // -5 = thread, -4 = "BLUA_THREADS", -3 = BLUA_THREADS, -2 = key-Lt, -1 = thread
        settable();                           // -3 = thread, -2 = "BLUA_THREADS", -1 = BLUA_THREADS
        settable(LUA_REGISTRYINDEX);          // -1 = thread
    }
    return Lt;
}

Lua * Lua::thread(const String & code, int nargs, bool saveit) {
    Lua * L1;
    L1 = thread(saveit);
    L1->resume(code, nargs);
    return L1;
}

Lua * Lua::thread(Handle * h, int nargs, bool saveit) {
    Lua * L1;
    L1 = thread(saveit);
    L1->resume(h, nargs);
    return L1;
}

int Lua::yield(int nresults) {
    return lua_yield(L, nresults);
}

bool Lua::resume(int nargs) throw (GeneralException) {
    int r;

    lock();
    _protected = true;
    r = lua_resume(L, nargs);
    _protected = false;

    if ((r != 0) && (r != LUA_YIELD)) {
        push_lua_context();
        showerror();
    }

    unlock();

    switch(r) {
    case 0:
        return false;
    case LUA_YIELD:
        return true;
    case LUA_ERRRUN:
        throw LuaException("Runtime error while running LUA code.");
    case LUA_ERRMEM:
        throw LuaException("Memory allocation error while running LUA code.");
    case LUA_ERRERR:
        throw LuaException("Error in Error function.");
    case LUA_ERRSYNTAX:
        throw LuaException("Syntax error in Lua code.");
    default:
        throw LuaException("Unknow error while running LUA code (err code: " + String(r) + ")");
    }
}

bool Lua::resume(Handle * h, int nargs) {
    bool r;
    
    lock();
    load(h, false);
    r = resume(nargs);
    unlock();
    
    return r;
}

bool Lua::resume(const String & s, int nargs) {
    bool r;
    
    lock();
    load(s, false);
    r = resume(nargs);
    unlock();
    
    return r;
}

Lua * Lua::find(lua_State * __L) throw (GeneralException) {
    std::map<lua_State *, Lua *>::iterator i;

    if ((i = lualist.find(__L)) == lualist.end()) {
	throw GeneralException("Unable to find the Lua object for this context");
    }

    return i->second;
}

void Lua::showstack(int level) {
    int n = lua_gettop(L);
    int i;
    String t;

    if (n == 0) {
	printm(level, "Stack empty\n");
	return;
    }

    for (i = 1; i <= n; i++) {
	switch(lua_type(L, i)) {
	case LUA_TNONE:
	    t = "Invalid";
	    break;
	case LUA_TNIL:
	    t = "(Nil)";
	    break;
	case LUA_TNUMBER:
	    t.set("(Number) %f", lua_tonumber(L, i));
	    break;
	case LUA_TBOOLEAN:
	    t = String("(Bool)   ") + (lua_toboolean(L, i) ? "true" : "false");
	    break;
	case LUA_TSTRING:
	    t = String("(String) ") + lua_tostring(L, i);
	    break;
	case LUA_TTABLE:
	    t = "(Table)";
	    break;
	case LUA_TFUNCTION:
	    t = "(Function)";
	    break;
	default:
	    t = "Unknown";
	}

	printr(level, String(i) + ": " + t + "\n");
    }
}

void Lua::showerror() {
    printm(M_ERROR, "Lua object: Got an LUA error, inspecting stack.\n");
    
    showstack(M_ERROR);
}

int Lua::getmetatable(int i) {
    return lua_getmetatable(L, i);
}

int Lua::setmetatable(int i) {
    return lua_setmetatable(L, i);
}

int Lua::sethook(lua_Hook func, int mask, int count) {
    return lua_sethook(L, func, mask, count);
}

void Lua::do_break() {
    lua_break(L);
}

void Lua::lock() {
}

void Lua::unlock() {
}

void Lua::openlib(const String & libname, const luaL_reg *l, int nup) {
    luaL_openlib(L, libname.to_charp(), l, nup);
}

void Lua::setgcthreshold(int newthreshold) {
//    lua_setgcthreshold(L, newthreshold);
}

int Lua::getgcthreshold() {
//    return lua_getgcthreshold(L);
}

int Lua::getgccount() {
    return lua_getgccount(L);
}

void LuaObject::push(Lua * L) throw (GeneralException) {
    if (pushed && wantdestruct) {
	throw GeneralException("Error: object is owned by the LUA script and can not be pushed.");
    }
    L->lock();
    L->newtable();
    pushmembers(L);
    L->unlock();
    pushed = true;
}

void LuaObject::pushme(Lua * L, void * o, const String & objname, bool obj) {
    void ** u;
    bool * b;
    L->lock();
    L->push("__obj");
    u = (void **) L->newuser(sizeof(o) + sizeof(bool));
    *u = o;
    b = (bool *) (u + 1);
    *b = obj;
    L->settable(-3, true);
    if (objname != "") {
        L->push("__objname");
        L->push(objname);
        L->settable(-3, true);
    }
    L->unlock();
}

void * LuaObject::getme(Lua * L, int i) {
    void ** r = 0;

    if (L->istable(i)) {
        L->push("__obj");
        L->gettable(i, true);
        if (!(r = (void **) L->touserdata()))
	    L->error("Table is not an object.");
	if (!*r)
	    L->error("Object already destroyed.");
        L->pop();
    } else if (L->isnil(i)) {
        r = 0;
    } else {
        L->error("Not an object (not even a table).");
    }
    
    return r ? *r : 0;
}

void LuaObject::pushit(Lua * L, const String & s, lua_CFunction f) {
    L->lock();
    L->push(s);
    L->push(f);
    L->settable(-3, true);
    L->unlock();
}

void LuaObject::pushmeta(Lua * L, const String & s, lua_CFunction f) {
    L->lock();
    if (!L->getmetatable()) {
	L->newtable();
    }
    L->push(s);
    L->push(f);
    L->settable();
    L->setmetatable();
    L->unlock();
}

void LuaObject::pushdestruct(Lua * L) throw (GeneralException) {
    if (pushed) {
	throw GeneralException("Error: can't push destructor, object already pushed");
    }
    L->lock();
    push(L);
    L->push("__obj");
    L->gettable(-2, true);
    pushmeta(L, "__gc", LuaStatics::collector);
    L->pop();
    pushit(L, "destroy", LuaStatics::destructor);
    L->unlock();

    wantdestruct = true;
}

LuaException::LuaException(String fn) : GeneralException(fn) { }

LuaException::LuaException() { }