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TFS 1.X+ Reading 2D table from lua in sources

Snavy

Snavy

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I have been trying to read a 2D lua-table in sources and I am not sure how to debug this.
The error msg that shows up is "attemp to index a boolean value".

What is going on here?

Lua: 
myLuaFunction({
    { a = 0, b = 123, c = "string", d = true, e = true, f = true },
    { a = 0, b = 123, c = "string", d = true, e = true, f = true }
})

C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if(!isTable(L, -1)) {
        printf("not a table.");
        return 1;
    }

    lua_pushnil(L);
    while (lua_next(L, lua_gettop(L)) != 0) {
        auto index = lua_gettop(L);
        auto a = getField<int>(L, index, "a");
        auto b = getField<int>(L, index, "b");
        auto c = getFieldString(L, index, "c");
        bool d = getField<bool>(L, index, "d");
        bool e = getField<bool>(L, index, "e");
        bool f = getField<bool>(L, index, "f");
        lua_pop(L, 7);
    }
    lua_pop(L, 1);
    return 1;
}

error msg on startup:
Code: 
Lua Script Error: [Scripts Interface]
/Users/snavy/forgottenserver/data/scripts/test.lua
attempt to index a boolean value
stack traceback:
    [C]: at 0x01093ec710
    [C]: in function 'myLuaFunction'
    ...snavy/forgottenserver/data/scripts/test.lua:1: in main chunk
> test.lua [error]
 
Solution
oen432
I'm pretty sure there is a better way to do this but getField didn't work for me either when I had to work with similar table...
C++: 
lua_pushnil(L);
while (lua_next(L, -2) != 0)
{
    int32_t a;
    int32_t b;
    std::string c;
    bool d;
    bool e;
    bool f;
    lua_pushnil(L);
    while (lua_next(L, -2) != 0)
    {
        if (getString(L, -2) == "a")
            a = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "b")
            b = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "c")
            c = getString(L, -1);
        else if (getString(L, -2) == "d")
            d = getBoolean(L, -1);
        else if (getString(L, -2) == "e")
            e = getBoolean(L, -1);
        else if...
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I'm pretty sure there is a better way to do this but getField didn't work for me either when I had to work with similar table...
C++: 
lua_pushnil(L);
while (lua_next(L, -2) != 0)
{
    int32_t a;
    int32_t b;
    std::string c;
    bool d;
    bool e;
    bool f;
    lua_pushnil(L);
    while (lua_next(L, -2) != 0)
    {
        if (getString(L, -2) == "a")
            a = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "b")
            b = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "c")
            c = getString(L, -1);
        else if (getString(L, -2) == "d")
            d = getBoolean(L, -1);
        else if (getString(L, -2) == "e")
            e = getBoolean(L, -1);
        else if (getString(L, -2) == "f")
            f = getBoolean(L, -1);
        lua_pop(L, 1);
    }
    lua_pop(L, 1);
}
 
Upvote 1 Downvote
Solution
This is bad use this Example is better...

¡bad example!
C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if (!isTable(L, -1)) {
        lua_pushnil(L);
        return 1;
    }

    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        if (!isTable(L, -1)) {
            pushBoolean(L, false);
            return 1;
        }
        int32_t a = getField<int32_t>(L, -1, "a");
        int32_t b = getField<int32_t>(L, -1, "b");
        const std::string& c = getFieldString(L, -1, "c");
        bool d = getField<int32_t>(L, -1, "d") != 0;
        bool e = getField<int32_t>(L, -1, "e") != 0;
        bool f = getField<int32_t>(L, -1, "f") != 0;
        lua_pop(L, 1);
    }

    lua_pop(L, 1);
    pushBoolean(L, true);
    return 1;
}
 
Last edited:
Upvote 0 Downvote
Sarah Wesker said:
C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if (!isTable(L, -1)) {
        lua_pushnil(L);
        return 1;
    }

    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        if (!isTable(L, -1)) {
            pushBoolean(L, false);
            return 1;
        }
        int32_t a = getField<int32_t>(L, -1, "a");
        int32_t b = getField<int32_t>(L, -1, "b");
        const std::string& c = getFieldString(L, -1, "c");
        bool d = getField<int32_t>(L, -1, "d") != 0;
        bool e = getField<int32_t>(L, -1, "e") != 0;
        bool f = getField<int32_t>(L, -1, "f") != 0;
        lua_pop(L, 1);
    }

    lua_pop(L, 1);
    pushBoolean(L, true);
    return 1;
}
Click to expand...
That's the thing, getField doesn't work here. So this code is not working either.
 
Upvote 0 Downvote
oen432 said:
I'm pretty sure there is a better way to do this but getField didn't work for me either when I had to work with similar table...
C++: 
lua_pushnil(L);
while (lua_next(L, -2) != 0)
{
    int32_t a;
    int32_t b;
    std::string c;
    bool d;
    bool e;
    bool f;
    lua_pushnil(L);
    while (lua_next(L, -2) != 0)
    {
        if (getString(L, -2) == "a")
            a = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "b")
            b = getNumber<int32_t>(L, -1);
        else if (getString(L, -2) == "c")
            c = getString(L, -1);
        else if (getString(L, -2) == "d")
            d = getBoolean(L, -1);
        else if (getString(L, -2) == "e")
            e = getBoolean(L, -1);
        else if (getString(L, -2) == "f")
            f = getBoolean(L, -1);
        lua_pop(L, 1);
    }
    lua_pop(L, 1);
}
Click to expand...
Sarah Wesker said:
C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if (!isTable(L, -1)) {
        lua_pushnil(L);
        return 1;
    }

    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        if (!isTable(L, -1)) {
            pushBoolean(L, false);
            return 1;
        }
        int32_t a = getField<int32_t>(L, -1, "a");
        int32_t b = getField<int32_t>(L, -1, "b");
        const std::string& c = getFieldString(L, -1, "c");
        bool d = getField<int32_t>(L, -1, "d") != 0;
        bool e = getField<int32_t>(L, -1, "e") != 0;
        bool f = getField<int32_t>(L, -1, "f") != 0;
        lua_pop(L, 1);
    }

    lua_pop(L, 1);
    pushBoolean(L, true);
    return 1;
}
Click to expand...
Oen, your code gave the expected results and the error message is gone. 👍
However I am a bit confused because experienceStages from config.lua is also a 2D table and only 1 while loop is used 🤔
github.com

forgottenserver/src/configmanager.cpp at master · otland/forgottenserver

A free and open-source MMORPG server emulator written in C++ - otland/forgottenserver
github.com github.com

Sarah, your code did not produce the expected results and the error remains.
 
Upvote 0 Downvote
Snavy said:
Oen, your code gave the expected results and the error message is gone. 👍
However I am a bit confused because experienceStages from config.lua is also a 2D table and only 1 while loop is used 🤔
github.com

forgottenserver/src/configmanager.cpp at master · otland/forgottenserver

A free and open-source MMORPG server emulator written in C++ - otland/forgottenserver
github.com github.com

Sarah, your code did not produce the expected results and the error remains.
Click to expand...
Oh wow, if only this was a thing when I needed it the most... And looks like all I was missing is lua_pop having +1 number. I'm so disappointed right now...

This works (except bool, somehow not returning proper value).
Lua: 
{
    {a = 123, b = "str", c = true},
    {a = 456, b = "ing", c = false},
}
C++: 
    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        const auto tableIndex = lua_gettop(L);
        auto a = getField<uint32_t>(L, tableIndex, "a");
        auto b = getFieldString(L, tableIndex, "b");
        auto c = getField<bool>(L, tableIndex, "c");
        std::cout << "a " << a << std::endl;
        std::cout << "b " << b << std::endl;
        std::cout << "c " << c << std::endl;
        lua_pop(L, 4);
    }
    lua_pop(L, 1);

Code: 
a 123
b str
c 0
a 456
b ing
c 0
 
Upvote 0 Downvote
oen432 said:
Oh wow, if only this was a thing when I needed it the most... And looks like all I was missing is lua_pop having +1 number. I'm so disappointed right now...

This works (except bool, somehow not returning proper value).
Lua: 
{
    {a = 123, b = "str", c = true},
    {a = 456, b = "ing", c = false},
}
C++: 
    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        const auto tableIndex = lua_gettop(L);
        auto a = getField<uint32_t>(L, tableIndex, "a");
        auto b = getFieldString(L, tableIndex, "b");
        auto c = getField<bool>(L, tableIndex, "c");
        std::cout << "a " << a << std::endl;
        std::cout << "b " << b << std::endl;
        std::cout << "c " << c << std::endl;
        lua_pop(L, 4);
    }
    lua_pop(L, 1);

Code: 
a 123
b str
c 0
a 456
b ing
c 0
Click to expand...
This gave 0 on both bool values (true or false) and caused Seg fault 11 🤔
 
Upvote 0 Downvote
Snavy said:
This gave 0 on both bool values (true or false) and caused Seg fault 11 🤔
Click to expand...
Yup, thought it's because I used that code in global.lua but even after server starts it just crashes. Eh, I'm over it, sorry, you will have to use the longer version.
 
Upvote 0 Downvote
Here is an example without using the TFS interface

only lua api
C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if (lua_istable(L, -1) == 0) {
        return 0;
    }

    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        if (lua_istable(L, -1) == 0) {
            return 0;
        }
        lua_getfield(L, -1, "a");
        int32_t a = lua_tonumber(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "b");
        int32_t b = lua_tonumber(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "c");
        const std::string& c = lua_tostring(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "d");
        bool d = lua_toboolean(L, -1) != 0;
        lua_pop(L, 1);
        lua_getfield(L, -1, "e");
        bool e = lua_toboolean(L, -1) != 0;
        lua_pop(L, 1);
        lua_getfield(L, -1, "f");
        bool f = lua_toboolean(L, -1) != 0;
        lua_pop(L, 2);
    }

    lua_pop(L, 1);
    return 0;
}
 
Upvote 0 Downvote
oen432 said:
Eh, I'm over it, sorry, you will have to use the longer version.
Click to expand...
Understandable xD
Thank you for saving me from the confusion I've been having for over 24h.
Post automatically merged:

Sarah Wesker said:
Here is an example without using the TFS interface

only lua api
C++: 
int LuaScriptInterface::luaMyLuaFunction(lua_State* L)
{
    if (lua_istable(L, -1) == 0) {
        return 0;
    }

    lua_pushnil(L);
    while (lua_next(L, -2) != 0) {
        if (lua_istable(L, -1) == 0) {
            return 0;
        }
        lua_getfield(L, -1, "a");
        int32_t a = lua_tonumber(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "b");
        int32_t b = lua_tonumber(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "c");
        const std::string& c = lua_tostring(L, -1);
        lua_pop(L, 1);
        lua_getfield(L, -1, "d");
        bool d = lua_toboolean(L, -1) != 0;
        lua_pop(L, 1);
        lua_getfield(L, -1, "e");
        bool e = lua_toboolean(L, -1) != 0;
        lua_pop(L, 1);
        lua_getfield(L, -1, "f");
        bool f = lua_toboolean(L, -1) != 0;
        lua_pop(L, 2);
    }

    lua_pop(L, 1);
    return 0;
}
Click to expand...

Thank you sarah, I will have to stick to Oen's previous solution for now and keep digging into the next problem I have at hand xD
 
Upvote 0 Downvote
Snavy said:
Understandable xD
Thank you for saving me from the confusion I've been having for over 24h.
Post automatically merged:



Thank you sarah, I will have to stick to Oen's previous solution for now and keep digging into the next problem I have at hand xD
Click to expand...
The problem you have is that the TFS lua interface does not have a method to obtain booleans from a table, and you must handle this case manually with the original lua api or else create this new method, it should have the name: getFieldBoolean ;)

And if you wonder why this method does not exist, the answer is simple, so far it has no use and therefore does not exist

here an example of what the function looks like:
C++: 
static bool getFieldBoolean(lua_State* L, int32_t arg, const std::string& key)
{
    lua_getfield(L, arg, key.c_str());
    return getBoolean(L, -1);
}
 
Upvote 0 Downvote
Sarah Wesker said:
The problem you have is that the TFS lua interface does not have a method to obtain booleans from a table, and you must handle this case manually with the original lua api or else create this new method, it should have the name: getFieldBoolean ;)
Click to expand...

I see. Once I have (hopefully) fixed the next problem I will try to do that and see how that works out.
 
Upvote 0 Downvote

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