py: implement some basic exception matching.

py/obj.h

@@ -176,6 +176,10 @@ extern const mp_obj_type_t bool_type;
 mp_obj_t mp_obj_cell_get(mp_obj_t self_in);
 void mp_obj_cell_set(mp_obj_t self_in, mp_obj_t obj);
 
+// exception
+extern const mp_obj_type_t exception_type;
+qstr mp_obj_exception_get_type(mp_obj_t self_in);
+
 // str
 extern const mp_obj_type_t str_type;
 qstr mp_obj_str_get(mp_obj_t self_in);

py/objexcept.c

@@ -84,3 +84,9 @@ mp_obj_t mp_obj_new_exception_msg_2_args(qstr id, const char *fmt, const char *a
     o->args[2] = a2;
     return o;
 }
+
+qstr mp_obj_exception_get_type(mp_obj_t self_in) {
+    assert(MP_OBJ_IS_TYPE(self_in, &exception_type));
+    mp_obj_exception_t *self = self_in;
+    return self->id;
+}

py/runtime.c

@@ -103,9 +103,23 @@ void rt_init(void) {
     map_locals = map_globals = mp_map_new(MP_MAP_QSTR, 1);
     mp_qstr_map_lookup(map_globals, qstr_from_str_static("__name__"), true)->value = mp_obj_new_str(qstr_from_str_static("__main__"));
 
+    // init built-in hash table
     mp_map_init(&map_builtins, MP_MAP_QSTR, 3);
+
+    // built-in exceptions (TODO, make these proper classes)
+    mp_qstr_map_lookup(&map_builtins, rt_q_AttributeError, true)->value = mp_obj_new_exception(rt_q_AttributeError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_IndexError, true)->value = mp_obj_new_exception(rt_q_IndexError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_KeyError, true)->value = mp_obj_new_exception(rt_q_KeyError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_NameError, true)->value = mp_obj_new_exception(rt_q_NameError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_TypeError, true)->value = mp_obj_new_exception(rt_q_TypeError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_SyntaxError, true)->value = mp_obj_new_exception(rt_q_SyntaxError);
+    mp_qstr_map_lookup(&map_builtins, rt_q_ValueError, true)->value = mp_obj_new_exception(rt_q_ValueError);
+
+    // built-in core functions
     mp_qstr_map_lookup(&map_builtins, rt_q___build_class__, true)->value = rt_make_function_2(mp_builtin___build_class__);
     mp_qstr_map_lookup(&map_builtins, qstr_from_str_static("__repl_print__"), true)->value = rt_make_function_1(mp_builtin___repl_print__);
+
+    // built-in user functions
     mp_qstr_map_lookup(&map_builtins, qstr_from_str_static("abs"), true)->value = rt_make_function_1(mp_builtin_abs);
     mp_qstr_map_lookup(&map_builtins, qstr_from_str_static("all"), true)->value = rt_make_function_1(mp_builtin_all);
     mp_qstr_map_lookup(&map_builtins, qstr_from_str_static("any"), true)->value = rt_make_function_1(mp_builtin_any);
@@ -550,6 +564,18 @@ mp_obj_t rt_compare_op(int op, mp_obj_t lhs, mp_obj_t rhs) {
         }
     }
 
+    // deal with exception_match
+    if (op == RT_COMPARE_OP_EXCEPTION_MATCH) {
+        // TODO properly! at the moment it just compares the exception identifier for equality
+        if (MP_OBJ_IS_TYPE(lhs, &exception_type) && MP_OBJ_IS_TYPE(rhs, &exception_type)) {
+            if (mp_obj_exception_get_type(lhs) == mp_obj_exception_get_type(rhs)) {
+                return mp_const_true;
+            } else {
+                return mp_const_false;
+            }
+        }
+    }
+
     // deal with small ints
     if (MP_OBJ_IS_SMALL_INT(lhs) && MP_OBJ_IS_SMALL_INT(rhs)) {
         mp_small_int_t lhs_val = MP_OBJ_SMALL_INT_VALUE(lhs);

py/vm.c

@@ -491,7 +491,7 @@ bool mp_execute_byte_code_2(const byte **ip_in_out, mp_obj_t *fastn, mp_obj_t **
                 // push(traceback, exc-val, exc-type)
                 PUSH(mp_const_none);
                 PUSH(nlr.ret_val);
-                PUSH(mp_const_none);
+                PUSH(nlr.ret_val); // TODO should be type(nlr.ret_val), I think...
 
             } else {
                 // re-raise exception to higher level

unix/main.c

@@ -115,14 +115,10 @@ void do_file(const char *file) {
                 if (module_fun != mp_const_none) {
                     nlr_buf_t nlr;
                     if (nlr_push(&nlr) == 0) {
-                        mp_obj_t ret = rt_call_function_0(module_fun);
-                        printf("done! got: ");
-                        mp_obj_print(ret);
-                        printf("\n");
+                        rt_call_function_0(module_fun);
                         nlr_pop();
                     } else {
                         // uncaught exception
-                        printf("exception: ");
                         mp_obj_print((mp_obj_t)nlr.ret_val);
                         printf("\n");
                     }