osci-render/Source/lua/LuaParser.cpp

#include "LuaParser.h"
#include "luaimport.h"


LuaParser::LuaParser(juce::String script) {
    // initialization
    L = luaL_newstate();
    luaL_openlibs(L);

    this->script = script;
	parse();
}

LuaParser::~LuaParser() {
    lua_close(L);
}

void LuaParser::parse() {
    const int ret = luaL_loadstring(L, script.toUTF8());
    if (ret != 0) {
        const char* error = lua_tostring(L, -1);
        DBG(error);
        lua_pop(L, 1);
        functionRef = -1;
    } else {
        functionRef = luaL_ref(L, LUA_REGISTRYINDEX);
    }
}

Vector2 LuaParser::draw() {
	Vector2 sample;
    
	if (functionRef == -1) {
		return sample;
	}
	
    lua_pushnumber(L, step);
    lua_setglobal(L, "step");
    
	lua_geti(L, LUA_REGISTRYINDEX, functionRef);
    
    const int ret = lua_pcall(L, 0, LUA_MULTRET, 0);
    if (ret != 0) {
        const char* error = lua_tostring(L, -1);
        DBG(error);
		functionRef = -1;
    } else if (lua_istable(L, -1)) {
        // get the first element of the table
        lua_pushinteger(L, 1);
        lua_gettable(L, -2);
        float x = lua_tonumber(L, -1);
        lua_pop(L, 1);

        // get the second element of the table
        lua_pushinteger(L, 2);
        lua_gettable(L, -2);
        float y = lua_tonumber(L, -1);
        lua_pop(L, 1);

        sample = Vector2(x, y);
    }

    lua_pop(L, 1);

	step++;
    
	return sample;
}