Add Lua fallback script if it doesn't run correctly

Source/lua/LuaParser.cpp

@@ -2,18 +2,27 @@
 #include "luaimport.h"
 
 
-LuaParser::LuaParser(juce::String script) {
+LuaParser::LuaParser(juce::String script, juce::String fallbackScript) : fallbackScript(fallbackScript) {
-    // initialization
+    reset(script);
+}
+
+LuaParser::~LuaParser() {
+    lua_close(L);
+}
+
+void LuaParser::reset(juce::String script) {
+    functionRef = -1;
+
+    if (L != nullptr) {
+        lua_close(L);
+    }
+    
     L = luaL_newstate();
     lua_atpanic(L, panic);
     luaL_openlibs(L);
 
     this->script = script;
-	parse();
+    parse();
-}
-
-LuaParser::~LuaParser() {
-    lua_close(L);
 }
 
 void LuaParser::parse() {
@@ -23,6 +32,9 @@ void LuaParser::parse() {
         DBG(error);
         lua_pop(L, 1);
         functionRef = -1;
+        if (script != fallbackScript) {
+            reset(fallbackScript);
+        }
     } else {
         functionRef = luaL_ref(L, LUA_REGISTRYINDEX);
     }
@@ -31,10 +43,6 @@ void LuaParser::parse() {
 // only the audio thread runs this fuction
 std::vector<float> LuaParser::run() {
     std::vector<float> values;
-    
-	if (functionRef == -1) {
-		return values;
-	}
 	
     lua_pushnumber(L, step);
     lua_setglobal(L, "step");
@@ -61,6 +69,9 @@ std::vector<float> LuaParser::run() {
             const char* error = lua_tostring(L, -1);
             DBG(error);
             functionRef = -1;
+            if (script != fallbackScript) {
+                reset(fallbackScript);
+            }
         } else if (lua_istable(L, -1)) {
             auto length = lua_rawlen(L, -1);
 
@@ -73,8 +84,10 @@ std::vector<float> LuaParser::run() {
             }
         }
     } else {
-        DBG("functionRef is not a function");
         functionRef = -1;
+        if (script != fallbackScript) {
+            reset(fallbackScript);
+        }
     }
 
     // clear stack
@@ -94,6 +107,14 @@ void LuaParser::setVariable(juce::String variableName, double value) {
     updateVariables = true;
 }
 
+bool LuaParser::isFunctionValid() {
+    return functionRef != -1;
+}
+
+juce::String LuaParser::getScript() {
+    return script;
+}
+
 
 int LuaParser::panic(lua_State *L) {
     const char *msg = lua_tostring(L, -1);

Source/lua/LuaParser.h

@@ -5,21 +5,25 @@
 struct lua_State;
 class LuaParser {
 public:
-	LuaParser(juce::String script);
+	LuaParser(juce::String script, juce::String LuaParser = "return { 0.0, 0.0 }");
 	~LuaParser();
 
 	std::vector<float> run();
 	void setVariable(juce::String variableName, double value);
+	bool isFunctionValid();
+	juce::String getScript();
 
 private:
+	void reset(juce::String script);
 	void parse();
 
 	static int panic(lua_State* L);
 
 	int functionRef = -1;
 	long step = 1;
-	lua_State* L;
+	lua_State* L = nullptr;
 	juce::String script;
+	juce::String fallbackScript;
 	std::atomic<bool> updateVariables = false;
 	juce::SpinLock variableLock;
 	std::vector<juce::String> variableNames;

Source/parser/FileParser.cpp

@@ -8,6 +8,10 @@ FileParser::FileParser() {}
 void FileParser::parse(juce::String extension, std::unique_ptr<juce::InputStream> stream, juce::Font font) {
 	juce::SpinLock::ScopedLockType scope(lock);
 
+	if (extension == ".lua" && lua != nullptr && lua->isFunctionValid()) {
+		fallbackLuaScript = lua->getScript();
+	}
+
 	object = nullptr;
 	camera = nullptr;
 	svg = nullptr;
@@ -23,7 +27,7 @@ void FileParser::parse(juce::String extension, std::unique_ptr<juce::InputStream
 	} else if (extension == ".txt") {
 		text = std::make_shared<TextParser>(stream->readEntireStreamAsString(), font);
 	} else if (extension == ".lua") {
-		lua = std::make_shared<LuaParser>(stream->readEntireStreamAsString());
+		lua = std::make_shared<LuaParser>(stream->readEntireStreamAsString(), fallbackLuaScript);
 	}
 
 	sampleSource = lua != nullptr;

Source/parser/FileParser.h

@@ -37,4 +37,6 @@ private:
 	std::shared_ptr<SvgParser> svg;
 	std::shared_ptr<TextParser> text;
 	std::shared_ptr<LuaParser> lua;
+
+	juce::String fallbackLuaScript = "return { 0.0, 0.0 }";
 };