Step support.

Ability to step to the next line which will force the debugger to break after execution even if that line doesn't have a breakpoint.

Author: mdavisprog

Assets/Scripts/Language/Debugger.gd

@@ -38,6 +38,7 @@ enum MESSAGE {
 	SNIPPET_END,
 	BREAK,
 	RESUME,
+	STEP,
 	STOP
 }
 
@@ -223,6 +224,8 @@ func OnServerDataReceived(Data: String) -> void:
 	match (Type):
 		MESSAGE.RESUME:
 			Runtime.Resume()
+		MESSAGE.STEP:
+			Runtime.Step()
 		MESSAGE.STOP:
 			Runtime.Stop()
 
@@ -276,6 +279,10 @@ func Resume() -> void:
 	DispatchToServer(MESSAGE.RESUME, "")
 
 
+func Step() -> void:
+	DispatchToServer(MESSAGE.STEP, "")
+	
+
 func Stop() -> void:
 	DispatchToServer(MESSAGE.STOP, "")
 

Assets/Scripts/Language/Runtime.gd

@@ -205,6 +205,10 @@ func Resume() -> void:
 	Code.Resume()
 
 
+func Step() -> void:
+	Code.Step()
+	
+
 func Compile(InSnippet: SnippetData) -> Reference:
 	if not InSnippet:
 		return null

Assets/Scripts/Language/VirtualMachine.gd

@@ -63,8 +63,8 @@ func _process(_delta: float) -> void:
 		Guard.unlock()
 
 	if State == STATE.BREAK:
-		emit_signal("OnBreak", LineBreak)
 		State = STATE.PAUSED
+		emit_signal("OnBreak", LineBreak)
 
 
 func ToLua(Code: String) -> ParserResult:
@@ -142,6 +142,19 @@ func Resume() -> void:
 	Guard.unlock()
 
 
+func Step() -> void:
+	if not ActiveVM:
+		return
+	
+	if State != STATE.PAUSED:
+		return
+	
+	Guard.lock()
+	ActiveVM.Step()
+	State = STATE.RUNNING
+	Guard.unlock()
+	
+
 func UpdateBreakpoints(Breakpoints: Array) -> void:
 	if not ActiveVM:
 		return

Native/Snippet/Lua/LuaVM.cpp

@@ -77,6 +77,7 @@ void LuaVM::_register_methods()
 	register_method((char*)"Reset", &LuaVM::Reset);
 	register_method((char*)"Resume", &LuaVM::Resume);
 	register_method((char*)"Stop", &LuaVM::Stop);
+	register_method((char*)"Step", &LuaVM::Step);
 	register_method((char*)"AttachDebugger", &LuaVM::AttachDebugger);
 	register_method((char*)"GetDebugger", &LuaVM::GetDebugger);
 	register_signal<LuaVM>((char*)"OnPrint", "Contents", GODOT_VARIANT_TYPE_STRING);
@@ -321,6 +322,17 @@ void LuaVM::Stop()
 	// Owning thread object must call wait_to_finish().
 }
 
+void LuaVM::Step()
+{
+	if (!Debugger.is_valid())
+	{
+		return;
+	}
+
+	Debugger->SetStep(true);
+	Resume();
+}
+
 void LuaVM::AttachDebugger()
 {
 	if (State == nullptr)

Native/Snippet/Lua/LuaVM.h

@@ -72,6 +72,7 @@ class LuaVM : public Reference
 	void Reset();
 	void Resume();
 	void Stop();
+	void Step();
 	void AttachDebugger();
 	Ref<LuaVMDebugger> GetDebugger() const;
 

Native/Snippet/Lua/LuaVMDebugger.cpp

@@ -149,8 +149,10 @@ void LuaVMDebugger::OnHook(lua_State *State, lua_Debug *Ar)
 			int Index = Ar->currentline - 1;
 
 			// If we hit a breakpoint, grab all needed data.
-			if (Breakpoints.has(Index))
+			if (Breakpoints.has(Index) || VM->GetDebugger()->ShouldStep())
 			{
+				VM->GetDebugger()->SetStep(false);
+
 				// Grab all valid local variables.
 				VM->GetDebugger()->ClearVariables();
 				const char *Name = nullptr;
@@ -250,6 +252,7 @@ LuaVMDebugger::~LuaVMDebugger()
 
 void LuaVMDebugger::_init()
 {
+	Step = false;
 }
 
 void LuaVMDebugger::SetBreakpoints(Array InBreakpoints)
@@ -297,4 +300,14 @@ void LuaVMDebugger::Unhook(lua_State *State)
 	lua_sethook(State, nullptr, 0, 0);
 }
 
+void LuaVMDebugger::SetStep(bool InStep)
+{
+	Step = InStep;
+}
+
+bool LuaVMDebugger::ShouldStep() const
+{
+	return Step;
+}
+
 }

Native/Snippet/Lua/LuaVMDebugger.h

@@ -41,6 +41,7 @@ class LuaVMDebugger : public Reference
 private:
 	Array Breakpoints;
 	Dictionary Variables;
+	bool Step;
 
 	static void OnHook(lua_State *State, lua_Debug *Ar);
 
@@ -60,6 +61,8 @@ class LuaVMDebugger : public Reference
 	void ClearVariables();
 	void Hook(lua_State *State);
 	void Unhook(lua_State *State);
+	void SetStep(bool InStep);
+	bool ShouldStep() const;
 };
 
 }