added state options

include/frame.h

@@ -41,12 +41,27 @@ struct _sm_frame {
 	_sm_frame* prev;
 };
 
+/// Options for `state`.
+struct _sm_state_opt
+{
+	/// Set the return value within a generator at every yield point, instead of just at the end of the function.
+	///  (default: true)
+	bool _opt_INTERMEDIATE_RETURNS;
+};
+
+extern const _sm_state_opt _sm_state_opt_default;
+ 
 struct sm_state {
 
+	_sm_state_opt opt;
 
 	_sm_frame* current;
 };
 
+#define sm_state_setopt(state, name, value) ((state)->opt._opt_ ## name = (value))
+#define sm_state_getopt(state, name) ((state)->opt._opt_ ## name)
+
+
 template<typename T>
 inline T* _sm_init(_sm_user* frame, T init)
 {

src/gen.cpp

@@ -28,9 +28,11 @@ bool sm_next(sm_generator** gen, sm_state* state, _sm_user* output)
 
 	sm_yield next = (*gen)->current(state);
 
-	// Set the return value to `output`.
+	if(sm_state_getopt(state, INTERMEDIATE_RETURNS) || next == nullptr) {
-	if(output && state->current->rval) *output = *state->current->rval;
+		// Set the return value to `output`.
-	else if(output) output->set = false;
+		if(output && state->current->rval) *output = *state->current->rval;
+		else if(output) output->set = false;
+	}
 
 	switch((uintptr_t)next)
 	{

src/main.cpp

@@ -50,14 +50,17 @@ int main()
 	auto state = sm_new_state();
 	auto gen = sm_generate(&sm_test);
 
+	sm_state_setopt(state, INTERMEDIATE_RETURNS, false);
+
 	sm_output output;
+	int out_int;
 	while(sm_next(&gen, state, &output)) {
-		int out_int;
 		if(!sm_output_value(output, &out_int))
 			continue;
-		printf("OUT \t\ta = %d\n", out_int);
+		printf("OUT \t\ta = %d\n", out_int); // prints the last one, is this a good or bad thing?
 	}
 
+	printf("\n\nFinal output: %d\n", out_int);
 	sm_free_output(&output);
 
 	sm_free_generator(gen);

src/state.cpp

@@ -1,6 +1,10 @@
 #include <state.h>
 #include "dev.h"
 
+const _sm_state_opt _sm_state_opt_default = {
+	._opt_INTERMEDIATE_RETURNS = true,
+};
+
 /// A generator that just returns `nullptr` (end). Used for yielding without calling in to another generator. 
 ///
 /// NOTE: To avoid uselessly creating a stack frame for calls to this generator, its address is (TODO) directly compared to when switching into a deeper generator, and then skipped entirely.
@@ -13,6 +17,7 @@ sm_state* sm_new_state()
 {
 	auto state = box<sm_state>();
 	state->current = box<_sm_frame, true>();
+	state->opt = _sm_state_opt_default;
 	return state;
 }