RmlUi/Source/Core/Lua/GlobalLuaFunctions.cpp

/*
 * This source file is part of RmlUi, the HTML/CSS Interface Middleware
 *
 * For the latest information, see http://github.com/mikke89/RmlUi
 *
 * Copyright (c) 2008-2010 CodePoint Ltd, Shift Technology Ltd
 * Copyright (c) 2019 The RmlUi Team, and contributors
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */


#include "precompiled.h"
#include "GlobalLuaFunctions.h"
#include <RmlUi/Core/Lua/lua.hpp>

namespace Rml {
namespace Core {
namespace Lua {
/*
Below here are global functions and their helper functions that help overwrite the Lua global functions
*/

//__pairs should return two values.
//upvalue 1 is the __pairs function, upvalue 2 is the userdata created in rmlui_pairs
//[1] is the object implementing __pairs
//[2] is the key that was just read
int rmlui_pairsaux(lua_State* L)
{
    lua_pushvalue(L,lua_upvalueindex(1)); //push __pairs to top
    lua_insert(L,1); //move __pairs to the bottom
    lua_pushvalue(L,lua_upvalueindex(2)); //push userdata
    //stack looks like [1] = __pairs, [2] = object, [3] = latest key, [4] = userdata
    if(lua_pcall(L,lua_gettop(L)-1,LUA_MULTRET,0) != 0)
        Report(L,"__pairs");
    return lua_gettop(L);
}

//A version of paris that respects a __pairs metamethod.
//"next" function is upvalue 1
int rmlui_pairs(lua_State* L)
{
    luaL_checkany(L,1); //[1] is the object given to us by pairs(object)
    if(luaL_getmetafield(L,1,"__pairs"))
    {
        void* ud = lua_newuserdata(L,sizeof(void*)); //create a new block of memory to be used as upvalue 1
        (*(int*)(ud)) = -1;
        lua_pushcclosure(L,rmlui_pairsaux,2); //uv 1 is __pairs, uv 2 is ud
    }
    else
        lua_pushvalue(L,lua_upvalueindex(1)); //generator
    lua_pushvalue(L,1); //state
    lua_pushnil(L); //initial value
    return 3;
}

//copy + pasted from Lua's lbaselib.c
int ipairsaux (lua_State *L) {
    lua_Integer i = luaL_checkinteger(L, 2);
    luaL_checktype(L, 1, LUA_TTABLE);
    i++;  /* next value */
    lua_pushinteger(L, i);
    lua_rawgeti(L, 1, i);
    return (lua_isnil(L, -1)) ? 0 : 2;
}

//__ipairs should return two values
//upvalue 1 is the __ipairs function, upvalue 2 is the userdata created in rmlui_ipairs
//[1] is the object implementing __ipairs, [2] is the key last used
int rmlui_ipairsaux(lua_State* L)
{
    lua_pushvalue(L,lua_upvalueindex(1)); //push __ipairs
    lua_insert(L,1); //move __ipairs to the bottom
    lua_pushvalue(L,lua_upvalueindex(2)); //push userdata
    //stack looks like [1] = __ipairs, [2] = object, [3] = latest key, [4] = userdata
    if(lua_pcall(L,lua_gettop(L)-1,LUA_MULTRET,0) != 0)
        Report(L,"__ipairs");
    return lua_gettop(L);
}


//A version of paris that respects a __pairs metamethod.
//ipairsaux function is upvalue 1
int rmlui_ipairs(lua_State* L)
{
    luaL_checkany(L,1); //[1] is the object given to us by ipairs(object)
    if(luaL_getmetafield(L,1,"__ipairs"))
    {
        void* ud = lua_newuserdata(L,sizeof(void*)); //create a new block of memory to be used as upvalue 1
        (*(int*)(ud)) = -1;
        lua_pushcclosure(L,rmlui_pairsaux,2); //uv 1 is __ipairs, uv 2 is ud
    }
    else
        lua_pushvalue(L,lua_upvalueindex(1)); //generator
    lua_pushvalue(L,1); //state
    lua_pushnil(L); //initial value
    return 3;
}


//Based off of the luaB_print function from Lua's lbaselib.c
int LuaPrint(lua_State* L)
{
    int n = lua_gettop(L);  /* number of arguments */
    int i;
    lua_getglobal(L, "tostring");
    StringList string_list = StringList();
    String output = "";
    for (i=1; i<=n; i++) 
    {
        const char *s;
        lua_pushvalue(L, -1);  /* function to be called */
        lua_pushvalue(L, i);   /* value to print */
        lua_call(L, 1, 1);
        s = lua_tostring(L, -1);  /* get result */
        if (s == nullptr)
            return luaL_error(L, LUA_QL("tostring") " must return a string to "
                                 LUA_QL("print"));
        if (i>1) 
            output += "\t";
        output += String(s);
        lua_pop(L, 1);  /* pop result */
    }
    output += "\n";
    Log::Message(Log::LT_INFO, output.c_str());
    return 0;
}

void OverrideLuaGlobalFunctions(lua_State* L)
{
    lua_getglobal(L,"_G");

    lua_getglobal(L,"next");
    lua_pushcclosure(L,rmlui_pairs,1);
    lua_setfield(L,-2,"pairs");

    lua_pushcfunction(L,ipairsaux);
    lua_pushcclosure(L,rmlui_ipairs,1);
    lua_setfield(L,-2,"ipairs");

    lua_pushcfunction(L,LuaPrint);
    lua_setfield(L,-2,"print");

    lua_pop(L,1); //pop _G
}

}
}
}