libmisc: obj.h: Use LM_DEFAPPEND() to implement magic LO_BOX()

2 files changed, 67 insertions, 57 deletions

diff --git a/libmisc/include/libmisc/fmt.h b/libmisc/include/libmisc/fmt.h
index 6c04d99..135e48b 100644
--- a/libmisc/include/libmisc/fmt.h
+++ b/libmisc/include/libmisc/fmt.h
@@ -113,27 +113,27 @@ struct fmt_buf {
 };
 LO_IMPLEMENTATION_H(fmt_dest, struct fmt_buf, fmt_buf);
 
-#define fmt_snprint(buf, n, ...) ({                                \
-	struct fmt_buf _w = { .dat = buf, .cap = n };              \
-	lo_interface fmt_dest w = lo_box_fmt_buf_as_fmt_dest(&_w); \
-	fmt_print(w, __VA_ARGS__);                                 \
-	if (_w.len < _w.cap)                                       \
-		((char *)_w.dat)[_w.len] = '\0';                   \
-	_w.len;                                                    \
+#define fmt_snprint(buf, n, ...) ({                      \
+	struct fmt_buf _w = { .dat = buf, .cap = n };    \
+	lo_interface fmt_dest w = LO_BOX(fmt_dest, &_w); \
+	fmt_print(w, __VA_ARGS__);                       \
+	if (_w.len < _w.cap)                             \
+		((char *)_w.dat)[_w.len] = '\0';         \
+	_w.len;                                          \
 })
 
-#define fmt_asprint(...) ({                                        \
-	struct fmt_buf _w = {};                                    \
-	lo_interface fmt_dest w = lo_box_fmt_buf_as_fmt_dest(&_w); \
-	fmt_print(w, __VA_ARGS__);                                 \
-	while (_w.cap <= _w.len) {                                 \
-		_w.cap = _w.len + 1;                               \
-		_w.len = 0;                                        \
-		_w.dat = realloc(_w.dat, _w.cap);                  \
-		fmt_print(w, __VA_ARGS__);                         \
-	}                                                          \
-	((char *)_w.dat)[_w.len] = '\0';                           \
-	_w.dat;                                                    \
+#define fmt_asprint(...) ({                              \
+	struct fmt_buf _w = {};                          \
+	lo_interface fmt_dest w = LO_BOX(fmt_dest, &_w); \
+	fmt_print(w, __VA_ARGS__);                       \
+	while (_w.cap <= _w.len) {                       \
+		_w.cap = _w.len + 1;                     \
+		_w.len = 0;                              \
+		_w.dat = realloc(_w.dat, _w.cap);        \
+		fmt_print(w, __VA_ARGS__);               \
+	}                                                \
+	((char *)_w.dat)[_w.len] = '\0';                 \
+	_w.dat;                                          \
 })
 
 /* justify ********************************************************************/
@@ -145,13 +145,13 @@ LO_IMPLEMENTATION_H(fmt_dest, struct fmt_buf, fmt_buf);
 		fmt_print_byte(w, fillchar);          \
 } while (0)
 
-#define fmt_print_rjust(w, width, fillchar, ...) do {                          \
-	struct fmt_buf _discard = {};                                          \
-	lo_interface fmt_dest discard = lo_box_fmt_buf_as_fmt_dest(&_discard); \
-	fmt_print2(discard, __VA_ARGS__);                                      \
-	while (_discard.len++ < width)                                         \
-		fmt_print_byte(w, fillchar);                                   \
-	fmt_print2(w, __VA_ARGS__);                                            \
+#define fmt_print_rjust(w, width, fillchar, ...) do {                 \
+	struct fmt_buf _discard = {};                                 \
+	lo_interface fmt_dest discard = LO_BOX2(fmt_dest, &_discard); \
+	fmt_print2(discard, __VA_ARGS__);                             \
+	while (_discard.len++ < width)                                \
+		fmt_print_byte(w, fillchar);                          \
+	fmt_print2(w, __VA_ARGS__);                                   \
 } while (0)
 
 void fmt_print_base16_u8_(lo_interface fmt_dest w, uint8_t x);
diff --git a/libmisc/include/libmisc/obj.h b/libmisc/include/libmisc/obj.h
index 48695af..6afa391 100644
--- a/libmisc/include/libmisc/obj.h
+++ b/libmisc/include/libmisc/obj.h
@@ -30,10 +30,6 @@
  *
  * Use `lo_interface {iface_name}` as the type of this interface; it
  * should not be a pointer type.
- *
- * If there are any LO_NEST interfaces, this will define a
- * `lo_box_{iface_name}_as_{wrapped_iface_name}(obj)` function for
- * each.
  */
 #define LO_NEST(_ARG_child_iface_name) \
 	(lo_nest, _ARG_child_iface_name)
@@ -52,26 +48,46 @@
 	                 _LO_IFACE_PROTO, _ARG_iface_name)           \
 	LM_FORCE_SEMICOLON
 
-#define _LO_IFACE_VTABLE(_tuple_typ, ...)                             _LO_IFACE_VTABLE_##_tuple_typ(__VA_ARGS__)
-#define _LO_IFACE_VTABLE_lo_nest(_ARG_child_iface_name)               const struct _lo_##_ARG_child_iface_name##_vtable *_lo_##_ARG_child_iface_name##_vtable; LM_FOREACH_TUPLE2(_ARG_child_iface_name##_LO_IFACE, _LO_IFACE_VTABLE2)
-#define _LO_IFACE_VTABLE_lo_func(_ARG_ret_type, _ARG_func_name, ...)  _ARG_ret_type (*_ARG_func_name)(void * __VA_OPT__(,) __VA_ARGS__);
+#define _LO_IFACE_VTABLE(_tuple_typ, ...) _LO_IFACE_VTABLE_##_tuple_typ(__VA_ARGS__)
+#define _LO_IFACE_VTABLE_lo_nest(_ARG_child_iface_name)                                          \
+	const struct _lo_##_ARG_child_iface_name##_vtable *_lo_##_ARG_child_iface_name##_vtable; \
+	LM_FOREACH_TUPLE2(_ARG_child_iface_name##_LO_IFACE, _LO_IFACE_VTABLE2)
+#define _LO_IFACE_VTABLE_lo_func(_ARG_ret_type, _ARG_func_name, ...)  \
+	_ARG_ret_type (*_ARG_func_name)(void * __VA_OPT__(,) __VA_ARGS__);
 
 #define _LO_IFACE_VTABLE_indirect() _LO_IFACE_VTABLE
 #define _LO_IFACE_VTABLE2(...) _LM_DEFER2(_LO_IFACE_VTABLE_indirect)()(__VA_ARGS__)
 
-#define _LO_IFACE_PROTO(_ARG_iface_name, _tuple_typ, ...)  _LO_IFACE_PROTO_##_tuple_typ(_ARG_iface_name, __VA_ARGS__)
-#define _LO_IFACE_PROTO_lo_nest(_ARG_iface_name, _ARG_child_iface_name)                        \
-	LM_ALWAYS_INLINE static lo_interface _ARG_child_iface_name                             \
-	box_##_ARG_iface_name##_as_##_ARG_child_iface_name(lo_interface _ARG_iface_name obj) { \
-		return (lo_interface _ARG_child_iface_name){                                   \
-			.self = obj.self,                                                      \
-			.vtable = obj.vtable->_lo_##_ARG_child_iface_name##_vtable,            \
-		};                                                                             \
-	}
+#define _LO_IFACE_PROTO(_ARG_iface_name, _tuple_typ, ...) _LO_IFACE_PROTO_##_tuple_typ(_ARG_iface_name, __VA_ARGS__)
+#define _LO_IFACE_PROTO_lo_nest(_ARG_iface_name, _ARG_child_iface_name)                                       \
+	LM_DEFAPPEND(_LO_REGISTRY_##_ARG_child_iface_name,                                                    \
+	             (lo_interface _ARG_iface_name, _LO_BOX_##_ARG_iface_name##_as_##_ARG_child_iface_name)); \
+	LM_DEFAPPEND(_LO_BOX_##_ARG_iface_name##_as_##_ARG_child_iface_name(obj),                             \
+	             { .self = obj.self, .vtable = obj.vtable->_lo_##_ARG_child_iface_name##_vtable });
 #define _LO_IFACE_PROTO_lo_func(_ARG_iface_name, _ARG_ret_type, _ARG_func_name, ...) \
 	/* empty */
 
 /**
+ * `LO_BOX(iface_name, obj)` boxes `obj` as a `lo_interface
+ * iface_name`.  `obj` must be one of:
+ *
+ *  - A pointer to a value that implements `lo_interface iface_name`
+ *  - An already-boxed instance of `lo_interface iface_name`
+ *  - An already-boxed instance of another interface that
+ *    `iface_name` inherits from.
+ */
+#define LO_BOX(_ARG_iface_name, obj) _Generic((obj),     \
+	lo_interface _ARG_iface_name: obj                \
+	LM_FOREACH_TUPLE(_LO_REGISTRY_##_ARG_iface_name, \
+	                 _LO_BOX, _ARG_iface_name, obj))
+#define LO_BOX2(_ARG_iface_name, obj) _Generic((obj),     \
+	lo_interface _ARG_iface_name: obj                 \
+	LM_FOREACH_TUPLE2(_LO_REGISTRY_##_ARG_iface_name, \
+	                  _LO_BOX, _ARG_iface_name, obj))
+#define _LO_BOX(_ARG_iface_name, obj, typ, boxfn) \
+	, typ: (lo_interface _ARG_iface_name)boxfn(obj)
+
+/**
  * `LO_NULL(iface_name)` is the null/nil/zero value for `lo_interface {iface_name}`.
  */
 #define LO_NULL(_ARG_iface_name) ((lo_interface _ARG_iface_name){})
@@ -99,23 +115,17 @@
  * file to declare that `{impl_type}` implements the `{iface_name}`
  * interface with functions named `{impl_name}_{method_name}`.
  *
- * This will also define a `lo_box_{impl_name}_as_{iface_name}(obj)`
- * function.
- *
  * You must also call the LO_IMPLEMENTATION_C in a single .c file.
  */
-#define LO_IMPLEMENTATION_H(_ARG_iface_name, _ARG_impl_type, _ARG_impl_name)          \
-	/* Vtable.  */                                                                \
-	extern const struct _lo_##_ARG_iface_name##_vtable                            \
-	_lo_##_ARG_impl_name##_##_ARG_iface_name##_vtable;                            \
-	/* Boxing.  */                                                                \
-	LM_ALWAYS_INLINE static lo_interface _ARG_iface_name                          \
-	lo_box_##_ARG_impl_name##_as_##_ARG_iface_name(_ARG_impl_type *self) {        \
-		return (lo_interface _ARG_iface_name){                                \
-			.self = self,                                                 \
-			.vtable = &_lo_##_ARG_impl_name##_##_ARG_iface_name##_vtable, \
-		};                                                                    \
-	}                                                                             \
+#define LO_IMPLEMENTATION_H(_ARG_iface_name, _ARG_impl_type, _ARG_impl_name)                         \
+	/* Vtable.  */                                                                               \
+	extern const struct _lo_##_ARG_iface_name##_vtable                                           \
+	_lo_##_ARG_impl_name##_##_ARG_iface_name##_vtable;                                           \
+	/* Boxing.  */                                                                               \
+	LM_DEFAPPEND(_LO_REGISTRY_##_ARG_iface_name,                                                 \
+	             (_ARG_impl_type *, _LO_BOX_##_ARG_impl_name##_as_##_ARG_iface_name));           \
+	LM_DEFAPPEND(_LO_BOX_##_ARG_impl_name##_as_##_ARG_iface_name(obj),                           \
+	             { .self = obj, .vtable = &_lo_##_ARG_impl_name##_##_ARG_iface_name##_vtable }); \
 	LM_FORCE_SEMICOLON
 
 /**