integration/luprex/cpp/core/luastack.cpp

#include "luastack.hpp"
#include <cassert>
#include <cstdio>
#include <climits>
#include "wrap-string.hpp"
#include "wrap-set.hpp"
#include "wrap-sstream.hpp"

LuaSpecial LuaRegistry(LUA_REGISTRYINDEX);
LuaNilMarker LuaNil;
LuaNewTableMarker LuaNewTable;

LuaFunctionReg::LuaFunctionReg(const char *n, const char *a, const char *d, bool s, lua_CFunction f) {
    name_ = n;
    args_ = a;
    docs_ = d;
    func_ = f;
    sandbox_ = s;
    next_ = All;
    All = this;
}

LuaConstantReg::LuaConstantReg(const char *n, const char *d, LuaToken tokenvalue, lua_Number numbervalue) {
    name_ = n;
    docs_ = d;
    tokenvalue_ = tokenvalue;
    numbervalue_ = numbervalue;
    next_ = All;
    All = this;
}

const LuaFunctionReg *LuaFunctionReg::lookup(lua_CFunction fn) {
    for (const LuaFunctionReg *r = All; r != 0; r = r->next_) {
        if (r->func_ == fn) {
            return r;
        }
    }
    return nullptr;
}

LuaFunctionReg *LuaFunctionReg::All;
LuaConstantReg *LuaConstantReg::All;


eng::string LuaToken::str() const {
    uint64_t token = (uint64_t)value;
    char buffer[9];
    for (int i = 0; i < 8; i++) {
        unsigned char c = token;
        buffer[7-i] = c;
        token >>= 8;
    }
    buffer[8] = 0;
    return eng::string(buffer);
}

static int panicf(lua_State *L) {
    const char *p = lua_tostring(L, -1);
    fprintf(stderr, "PANIC: unprotected error in call to Lua API (%s)\n", p);
    fflush(stderr);
    exit(1);
}

// An allocator for lua states that uses system malloc and system free.
static void *l_alloc(void *ud, void *ptr, size_t osize, size_t nsize) {
    if (nsize == 0) {
        free(ptr);
        return NULL;
    } else {
        return realloc(ptr, nsize);
    }
}

lua_State *LuaCoreStack::newstate (lua_Alloc allocf) {
    if (allocf == nullptr) allocf = l_alloc;
    lua_State *L = lua_newstate(allocf, NULL);
    assert(L != nullptr);
    lua_atpanic(L, &panicf);

    // We want all states to have a classes table and
    // a tangibles table so that LS.makeclass and LS.maketan
    // work out-of-the-box.

    lua_pushstring(L, "classes");
    lua_newtable(L);
    lua_rawset(L, LUA_REGISTRYINDEX);
    lua_pushstring(L, "tangibles");
    lua_newtable(L);
    lua_rawset(L, LUA_REGISTRYINDEX);

    return L;
}

void LuaCoreStack::argerr(const char *nm, const char *tp) const {
    luaL_error(L_, "'%s' should be %s", nm, tp);
}

bool LuaCoreStack::isinteger(LuaSlot s) const {
    if (lua_type(L_, s) == LUA_TNUMBER) {
        lua_Number result = lua_tonumber(L_, s);
        if (lua_Integer(result) == result) return true;
    }
    return false;
}

bool LuaCoreStack::isint(LuaSlot s) const {
    if (lua_type(L_, s) == LUA_TNUMBER) {
        lua_Number result = lua_tonumber(L_, s);
        if (int(result) == result) return true;
    }
    return false;
}

bool LuaCoreStack::ckboolean(LuaSlot s) const {
    checkboolean(s, "value");
    return lua_toboolean(L_, s) ? true:false;
}

lua_Integer LuaCoreStack::ckinteger(LuaSlot s) const {
    checknumber(s, "value");
    luaL_checktype(L_, s, LUA_TNUMBER);
    lua_Number result = lua_tonumber(L_, s);
    lua_Integer iresult(result);
    if (iresult != result) {
        luaL_error(L_, "not a valid integer");
        return 0;
    }
    return iresult;
}

int LuaCoreStack::ckint(LuaSlot s) const {
    checknumber(s, "value");
    lua_Number result = lua_tonumber(L_, s);
    int iresult(result);
    if (iresult != result) {
        luaL_error(L_, "not a valid int");
        return 0;
    }
    return iresult;
}

lua_Number LuaCoreStack::cknumber(LuaSlot s) const {
    checknumber(s, "value");
    return lua_tonumber(L_, s);
}

eng::string LuaCoreStack::ckstring(LuaSlot s) const {
    checkstring(s, "value");
    size_t len;
    const char *str = lua_tolstring(L_, s, &len);
    return eng::string(str, len);
}

std::string_view LuaCoreStack::ckstringview(LuaSlot s) const {
    checkstring(s, "value");
    size_t len;
    const char *str = lua_tolstring(L_, s, &len);
    return std::string_view(str, len);
}

lua_State *LuaCoreStack::ckthread(LuaSlot s) const {
    checkthread(s, "value");
    return lua_tothread(L_, s);
}

LuaToken LuaCoreStack::cktoken(LuaSlot s) const {
    checktoken(s, "value");
    return LuaToken(lua_touserdata(L_, s));
}

void LuaCoreStack::clearmetatable(LuaSlot tab) const {
    lua_pushnil(L_);
    lua_setmetatable(L_, tab);
}

void LuaCoreStack::setmetatable(LuaSlot tab, LuaSlot mt) const {
    lua_pushvalue(L_, mt);
    lua_setmetatable(L_, tab);
}

bool LuaCoreStack::getmetatable(LuaSlot mt, LuaSlot tab) const {
    if (lua_getmetatable(L_, tab)) {
        lua_replace(L_, mt);
        return true;
    } else {
        lua_pushnil(L_);
        lua_replace(L_, mt);
        return false;
    }
}

int LuaCoreStack::next(LuaSlot tab, LuaSlot key, LuaSlot value) const {
    lua_pushvalue(L_, key);
    int ret = lua_next(L_, tab);
    if (ret != 0) {
        lua_replace(L_, value);
        lua_replace(L_, key);
    }
    return ret;
}

void LuaCoreStack::getglobaltable(LuaSlot target) const {
    lua_pushglobaltable(L_);
    lua_replace(L_, target);
}

void LuaCoreStack::newtable(LuaSlot target) const {
    lua_newtable(L_);
    lua_replace(L_, target);
}

void LuaCoreStack::createtable(LuaSlot target, int narr, int nrec) const {
    lua_createtable(L_, narr, nrec);
    lua_replace(L_, target);
}

lua_State *LuaCoreStack::newthread(LuaSlot target) const {
    lua_State *result = lua_newthread(L_);
    lua_replace(L_, target);
    return result;
}

bool LuaCoreStack::validclassname(std::string_view cname) {
    if (cname.empty()) return false;
    if (cname == "_G") return false;
    return true;
}

bool LuaCoreStack::validclassname(LuaSlot slot) const {
    if (!isstring(slot)) return false;
    return validclassname(ckstring(slot));
}

eng::string LuaCoreStack::classname(LuaSlot tab) const {
    eng::string result;
    if ((istable(tab)) && (gettabletype(tab) == LUA_TT_CLASS)) {
        LuaVar classes, name, dup;
        LuaExtStack LS(L_, classes, name, dup);
        // Get the classes table from the registry.
        LS.rawget(classes, LuaRegistry, "classes");

        // Try the efficient approach: get the class name from
        // the class, and confirm it by checking the classes table.
        LS.rawget(name, tab, "__class");
        if (LS.isstring(name)) {
            LS.rawget(dup, classes, name);
            if (LS.rawequal(dup, tab)) {
                return LS.ckstring(name);
            }
        }

        // Do it the brute force way: scan the classes table.
        LS.set(name, LuaNil);
        while (LS.next(classes, name, dup)) {
            if (LS.rawequal(dup, tab)) {
                return LS.ckstring(name);
            }
        }
    }
    return "";
}

eng::string LuaCoreStack::getclass(LuaSlot classtab, LuaSlot classname) const {
    lua_checkstack(L_, 20);
    LuaVar globtab, cname;
    LuaExtStack LS(L_, globtab, cname);
    LS.getglobaltable(globtab);

    if (LS.isstring(classname)) {
        if (!validclassname(LS.ckstring(classname))) {
            eng::string err = "invalid class name: " + LS.ckstring(classname);
            return err;
        }
        LS.rawget(classtab, globtab, classname);
        if (!LS.istable(classtab)) {
            eng::string err = "not a class: " + LS.ckstring(classname);
            return err;
        }
        LS.rawget(cname, classtab, "__class");
        if (!LS.rawequal(cname, classname)) {
            eng::string err = "not a valid class: " + LS.ckstring(classname);
            return err;
        }
        return "";
    } else if (LS.istable(classname)) {
        LS.rawget(cname, classname, "__class");
        if (!LS.isstring(cname)) {
            eng::string err = "table is not a class.";
            return err;
        }
        if (!validclassname(LS.ckstring(cname))) {
            eng::string err = "invalid class name: " + LS.ckstring(cname);
            return err;
        }
        LS.rawget(classtab, globtab, cname);
        if (!LS.rawequal(classtab, classname)) {
            eng::string err = "not a valid class: " + LS.ckstring(cname);
            return err;
        }
        return "";
    } else {
        eng::string err = "getclass expects a string or a classtab";
        return err;
    }
}

eng::string LuaCoreStack::getclass(LuaSlot tab, std::string_view name) const {
    push_any_value(name);
    LuaSpecial classname(lua_gettop(L_));
    eng::string err = getclass(tab, classname);
    lua_pop(L_, 1);
    return err;
}

void LuaCoreStack::makeclass(LuaSlot classtab, LuaSlot classname) const {
    LuaVar classes, globtab, cname;
    LuaExtStack LS(L_, classes, globtab, cname);

    // Validate the class name.
    assert(LS.validclassname(classname));
    
    // Fetch the classes table from the registry.
    LS.rawget(classes, LuaRegistry, "classes");
    assert(LS.istable(classes));

    // Fetch the global environment from the registry.
    LS.getglobaltable(globtab);
    
    // Get the classtab from the classes table.
    LS.rawget(classtab, classes, classname);

    // Make a new table if necessary.
    if (!LS.istable(classtab)) {
        LS.newtable(classtab);
        LS.rawset(classes, classname, classtab);
    }
    
    // Put the table into the global environment.
    LS.rawset(globtab, classname, classtab);

    // Repair the special fields.
    LS.settabletype(classtab, LUA_TT_CLASS);
    LS.rawset(classtab, "__class", classname);
    LS.rawset(classtab, "__index", classtab);
}

void LuaCoreStack::makeclass(LuaSlot tab, std::string_view name) const {
    push_any_value(name);
    LuaSpecial classname(lua_gettop(L_));
    makeclass(tab, classname);
    lua_pop(L_, 1);
}

void LuaCoreStack::maketan(LuaSlot tab, int64_t id) const {
    LuaVar tangibles, metatab;
    LuaExtStack LS(L_, tangibles, metatab);
    
    // Try to get the existing tangible.
    LS.rawget(tangibles, LuaRegistry, "tangibles");
    LS.rawget(tab, tangibles, id);

    // If we succeeded, return it.
    if (LS.istable(tab)) {
        return;
    }

    // Create the tangible's database and metatable.
    LS.set(tab, LuaNewTable);
    LS.set(metatab, LuaNewTable);
    LS.setmetatable(tab, metatab);

    // Mark the tangible using the tabletype field.
    LS.settabletype(tab, LUA_TT_TANGIBLE);
    LS.settabletype(metatab, LUA_TT_TANGIBLEMETA);

    // Store the tangible ID and lock the metatable.
    LS.rawset(metatab, "id", id);
    LS.rawset(metatab, "__metatable", false);

    // Store the database into the tangibles table.
    LS.rawset(tangibles, id, tab);
}


bool LuaCoreStack::tanblank(LuaSlot tab) const {
    bool result = true;
    if (istable(tab) && gettabletype(tab) == LUA_TT_TANGIBLE) {
        if (lua_getmetatable(L_, tab.index())) {
            lua_pushstring(L_, "threads");
            lua_rawget(L_, -2);
            if (lua_type(L_, -1) == LUA_TTABLE) {
                result = false;
            }
            lua_pop(L_, 2);
        }
    }
    return result;
}

int64_t LuaCoreStack::tanid(LuaSlot tab) const {
    int64_t result = 0;
    if (istable(tab) && gettabletype(tab) == LUA_TT_TANGIBLE) {
        if (lua_getmetatable(L_, tab.index())) {
            lua_pushstring(L_, "id");
            lua_rawget(L_, -2);
            if (lua_type(L_, -1) == LUA_TNUMBER) {
                result = int64_t(lua_tonumber(L_, -1));
            }
            lua_pop(L_, 2);
        }
    }
    return result;
}

bool LuaCoreStack::issortablekey(LuaSlot s) const {
    int type = lua_type(L_, s);
    return (type == LUA_TBOOLEAN) || (type == LUA_TNUMBER) || (type == LUA_TSTRING);
}

void LuaCoreStack::movesortablekey(LuaSlot key, LuaCoreStack &otherstack, LuaSlot otherslot) {
    int type = lua_type(L_, key);
    switch (type) {
    case LUA_TBOOLEAN:
        lua_pushboolean(otherstack.L_, lua_toboolean(L_, key));
        lua_replace(otherstack.L_, otherslot);
        break;
    case LUA_TNUMBER:
        lua_pushnumber(otherstack.L_, lua_tonumber(L_, key));
        lua_replace(otherstack.L_, otherslot);
        break;
    case LUA_TSTRING: {
        size_t len;
        const char *str = lua_tolstring(L_, key, &len);
        lua_pushlstring(otherstack.L_, str, len);
        lua_replace(otherstack.L_, otherslot);
        break;
    }
    default:
        assert(false && "movesortablekey: not a sortable key");
    }
}

void LuaCoreStack::cleartable(LuaSlot tab, bool clearmeta) const {
    assert(istable(tab));
    lua_pushnil(L_);
    while (lua_next(L_, tab.index()) != 0) {
        lua_pop(L_, 1); // Pop the old value.
        lua_pushvalue(L_, -1); // Clone the key
        lua_pushnil(L_); // Push the new value.
        lua_rawset(L_, tab.index());
    }
    if (clearmeta) {
        lua_pushnil(L_);
        lua_setmetatable(L_, tab.index());
    }
}

int LuaCoreStack::rawlen(LuaSlot obj) const {
    return lua_rawlen(L_, obj.index());
}

int LuaCoreStack::gettabletype(LuaSlot tab) const {
    uint16_t bits = lua_getflagbits(L_, tab.index());
    return LUA_TT_GENERAL + (bits & 0x000F);
}

void LuaCoreStack::settabletype(LuaSlot tab, int t) const {
    assert((t >= LUA_TT_GENERAL) && (t <= LUA_TT_CLASS));
    int offset = (t - LUA_TT_GENERAL);
    lua_modflagbits(L_, tab.index(), 0x000F, offset);
}

int LuaCoreStack::xtype(LuaSlot slot) const {
    int t = lua_type(L_, slot);
    if (t != LUA_TTABLE) return t;
    uint16_t bits = lua_getflagbits(L_, slot);
    return LUA_TT_GENERAL + (bits & 0x000F);
}

bool LuaCoreStack::getvisited(LuaSlot tab) const {
    uint16_t bits = lua_getflagbits(L_, tab.index());
    return (bits & 0x0010);
}

void LuaCoreStack::setvisited(LuaSlot tab, bool visited) const {
    lua_modflagbits(L_, tab.index(), 0x0010, visited ? 0x0010 : 0);
}

WorldType LuaCoreStack::world_type() const {
    lua_pushstring(L_, "worldtype");
    lua_rawget(L_, LUA_REGISTRYINDEX);
    lua_Integer n = lua_tointeger(L_, -1);
    lua_pop(L_, 1);
    assert(n != 0);
    return (WorldType)n;
}

void LuaCoreStack::guard_nopredict(const char *fn) {
    if (lua_isyieldable(L_)) {
        if (!is_authoritative()) {
            lua_yield(L_, 0);
            luaL_error(L_, "unexplained nopredict failure in %s", fn);
        }
    }
}

LuaKeywordParser::LuaKeywordParser(lua_State *L, int slot) {
    L_ = L;
    slot_ = slot;
    not_table_ = !lua_istable(L_, slot_);
    if (not_table_) {
        lua_newtable(L_);
        lua_replace(L_, slot_);
    }
}

bool LuaKeywordParser::parse(LuaSlot out, const char *kw) {
    lua_pushstring(L_, kw);
    lua_rawget(L_, slot_);
    lua_replace(L_, out.index());
    if (!lua_isnil(L_, out.index())) {
        parsed_.insert(kw);
        return true;
    } else {
        return false;
    }
};

eng::string LuaKeywordParser::final_check() {
    if (not_table_) {
        return "expected a keyword table";
    }
    if (lua_nkeys(L_, slot_) != int(parsed_.size())) {
        lua_pushnil(L_);
        while (lua_next(L_, slot_) != 0) {
            lua_pop(L_, 1); // Don't need the value.
            if (!lua_isstring(L_, -1)) {
                return "keyword table contains non-string key";
            }
            const char *kw = lua_tostring(L_, -1);
            if (parsed_.find(kw) == parsed_.end()) {
                eng::ostringstream oss;
                oss << "keyword " << kw << " not known";
                return oss.str();
            }
        }
        assert(false && "should never get here in check_unparsed_keywords");
    }
    return "";
}

void LuaKeywordParser::final_check_throw() {
    eng::string err = final_check();
    if (!err.empty()) {
        luaL_error(L_, "%s", err.c_str());
    }
}