added 'class_push_exit'

enhanced the compiler to produce 'pop_stacktop' at the end of the class if the class body is not empty

lib/comp.c

@@ -757,7 +757,7 @@ static HCL_INLINE void patch_double_long_params_with_oow (hcl_t* hcl, hcl_ooi_t
 
 static int emit_variable_access (hcl_t* hcl, int mode, const hcl_var_info_t* vi, const hcl_ioloc_t* srcloc)
 {
-	static hcl_oob_t inst_map[2][3] =
+	static hcl_oob_t inst_map[][3] =
 	{
 		{ HCL_CODE_PUSH_CTXTEMPVAR_0, HCL_CODE_POP_INTO_CTXTEMPVAR_0, HCL_CODE_STORE_INTO_CTXTEMPVAR_0 },
 		{ HCL_CODE_PUSH_INSTVAR_0,    HCL_CODE_POP_INTO_INSTVAR_0,    HCL_CODE_STORE_INTO_INSTVAR_0    },
@@ -858,15 +858,15 @@ static int push_clsblk (hcl_t* hcl, const hcl_ioloc_t* errloc, hcl_oow_t nivars,
 	ci->nivars = nivars;
 	ci->ncvars = ncvars;
 
-	if (ivars_str)
+	if (nivars > 0)
 	{
-		HCL_ASSERT (hcl, ci->nivars > 0);
+		HCL_ASSERT (hcl, ivars_str != HCL_NULL);
 		ci->ivars_str = hcl_dupoocstr(hcl, ivars_str, HCL_NULL);
 		if (HCL_UNLIKELY(!ci->ivars_str)) return -1;
 	}
-	if (cvars_str)
+	if (ncvars > 0)
 	{
-		HCL_ASSERT (hcl, ci->ncvars > 0);
+		HCL_ASSERT (hcl, cvars_str != HCL_NULL);
 		ci->cvars_str = hcl_dupoocstr(hcl, cvars_str, HCL_NULL);
 		if (HCL_UNLIKELY(!ci->cvars_str))
 		{
@@ -2056,7 +2056,12 @@ static HCL_INLINE int compile_class_p1 (hcl_t* hcl)
 	if (emit_long_param(hcl, nivars) <= -1) goto oops;
 	if (emit_long_param(hcl, ncvars) <= -1) goto oops;
 
-	SWITCH_TOP_CFRAME (hcl, COP_COMPILE_OBJECT_LIST, obj); /* 1 */
+	/* remember the first byte code position to be emitted for the body of 
+	 * this class. this posistion is used for empty class body check at the
+	 * end of the class before 'class_exit' is generated */
+	hcl->c->clsblk.info[hcl->c->clsblk.depth].class_start_inst_pos = hcl->code.bc.len;
+
+	SWITCH_TOP_CFRAME (hcl, COP_COMPILE_OBJECT_LIST, obj);
 
 	return 0;
 
@@ -2077,7 +2082,7 @@ static HCL_INLINE int compile_class_p3 (hcl_t* hcl)
 /* TODO: emit instruction to store into the class name...? */
 /* TODO: NEED TO EMIT POP_STACKTOP???? IN THIS CASE CLASS_EXIT MUST PUSH SOMETHING? */
 	if (emit_byte_instruction(hcl, HCL_CODE_CLASS_EXIT, HCL_CNODE_GET_LOC(cf->operand)) <= -1) return -1;
-	printf ("end of CLASS DEFINITION\n");
+
 	POP_CFRAME (hcl);
 	return 0;
 }
@@ -2090,10 +2095,16 @@ static HCL_INLINE int compile_class_p2 (hcl_t* hcl)
 	HCL_ASSERT (hcl, cf->opcode == COP_COMPILE_CLASS_P2);
 	HCL_ASSERT (hcl, cf->operand != HCL_NULL);
 
+	if (hcl->code.bc.len > hcl->c->clsblk.info[hcl->c->clsblk.depth].class_start_inst_pos)
+	{
+		/* no instructions generated after the class_enter instruction */
+		if (emit_byte_instruction(hcl, HCL_CODE_POP_STACKTOP, HCL_CNODE_GET_LOC(cf->operand)) <= -1) return -1;
+	}
+
 	pop_clsblk (hcl);  /* end of the class block */
 
-	if (emit_byte_instruction(hcl, HCL_CODE_CLASS_EXIT, HCL_CNODE_GET_LOC(cf->operand)) <= -1) return -1;
+
-	printf ("end of CLASS DEFINITION\n");
+	if (emit_byte_instruction(hcl, HCL_CODE_CLASS_PUSH_EXIT, HCL_CNODE_GET_LOC(cf->operand)) <= -1) return -1;
 
 //	if (cf->operand)
 	{
@@ -2863,7 +2874,7 @@ static HCL_INLINE int post_catch (hcl_t* hcl)
 static int compile_throw (hcl_t* hcl, hcl_cnode_t* src)
 {
 	hcl_cnode_t* obj, * val;
-	hcl_cframe_t* cf;
+	/*hcl_cframe_t* cf;*/
 
 	HCL_ASSERT (hcl, HCL_CNODE_IS_CONS(src));
 	HCL_ASSERT (hcl, HCL_CNODE_IS_SYMBOL_SYNCODED(HCL_CNODE_CONS_CAR(src), HCL_SYNCODE_THROW));
@@ -4631,7 +4642,6 @@ int hcl_compile (hcl_t* hcl, hcl_cnode_t* obj, int flags)
 				break;
 
 
-
 			case COP_COMPILE_AND_P1:
 				if (compile_and_p1(hcl) <= -1) goto oops;
 				break;

lib/debug.c

@@ -32,7 +32,7 @@ void hcl_dumpsymtab (hcl_t* hcl)
 	hcl_oop_char_t symbol;
 
 	HCL_DEBUG0 (hcl, "--------------------------------------------\n");
-	HCL_DEBUG1 (hcl, "Stix Symbol Table %zu\n", HCL_OBJ_GET_SIZE(hcl->symtab->bucket));
+	HCL_DEBUG1 (hcl, "HCL Symbol Table %zu\n", HCL_OBJ_GET_SIZE(hcl->symtab->bucket));
 	HCL_DEBUG0 (hcl, "--------------------------------------------\n");
 
 	for (i = 0; i < HCL_OBJ_GET_SIZE(hcl->symtab->bucket); i++)

lib/decode.c

@@ -381,6 +381,10 @@ int hcl_decode (hcl_t* hcl, hcl_oow_t start, hcl_oow_t end)
 			case HCL_CODE_CLASS_EXIT:
 				LOG_INST_0 (hcl, "class_exit");
 				break;
+
+			case HCL_CODE_CLASS_PUSH_EXIT:
+				LOG_INST_0 (hcl, "class_push_exit");
+				break;
 			/* -------------------------------------------------------- */
 
 			case HCL_CODE_PUSH_CTXTEMPVAR_X:

lib/exec.c

@@ -3367,16 +3367,21 @@ if (do_throw(hcl, hcl->_nil, fetched_instruction_pointer) <= -1)
 
 			case HCL_CODE_CLASS_EXIT:
 			{
-				hcl_oop_t c;
-
 				LOG_INST_0 (hcl, "class_exit");
 				/* TODO: stack underflow check? */
-			#if 0
+				HCL_CLSTACK_POP (hcl);
+				break;
+			}
+
+			case HCL_CODE_CLASS_PUSH_EXIT:
+			{
+				hcl_oop_t c;
+
+				LOG_INST_0 (hcl, "class_push_exit");
+				/* TODO: stack underflow check? */
 				HCL_CLSTACK_POP_TO (hcl, c);
 				HCL_STACK_PUSH (hcl, c);
-			#else
+
-				HCL_CLSTACK_POP (hcl);
-			#endif
 				break;
 			}
 			/* -------------------------------------------------------- */

lib/hcl-prv.h

@@ -454,6 +454,7 @@ struct hcl_clsblk_info_t
 	hcl_oow_t spec; /* TODO: byte indexed, word indexed? */
 
 	hcl_ooi_t fnblk_base;
+	hcl_ooi_t class_start_inst_pos; /* the position of the first instruction in the class body after CLASS_ENTER */
 };
 typedef struct hcl_clsblk_info_t hcl_clsblk_info_t;
 
@@ -903,7 +904,7 @@ enum hcl_bcode_t
 	HCL_CODE_PUSH_CTXTEMPVAR_X        = 0xE0, /* 224 ## */
 	HCL_CODE_CLASS_ENTER              = 0xE1, /* 225 ## */
 	HCL_CODE_CLASS_EXIT               = 0xE2, /* 226 */
-	/* UNUSED - 0xE3 */
+	HCL_CODE_CLASS_PUSH_EXIT          = 0xE3, /* 227 */
 
 	HCL_CODE_PUSH_OBJVAR_X            = 0xE4, /* 228 ## */
 	/* UNUSED - 0xE5 - 0xE7 */