Merge libobj into libmisc

4 files changed, 309 insertions, 0 deletions

diff --git a/libmisc/CMakeLists.txt b/libmisc/CMakeLists.txt
index 1bce759..8c9fa57 100644
--- a/libmisc/CMakeLists.txt
+++ b/libmisc/CMakeLists.txt
@@ -20,5 +20,7 @@ add_lib_test(libmisc test_hash)
 add_lib_test(libmisc test_log)
 add_lib_test(libmisc test_macro)
 add_lib_test(libmisc test_map)
+add_lib_test(libmisc test_obj)
+add_lib_test(libmisc test_obj_nest)
 add_lib_test(libmisc test_private)
 add_lib_test(libmisc test_rand)
diff --git a/libmisc/include/libmisc/obj.h b/libmisc/include/libmisc/obj.h
new file mode 100644
index 0000000..76dde91
--- /dev/null
+++ b/libmisc/include/libmisc/obj.h
@@ -0,0 +1,173 @@
+/* libmisc/obj.h - A simple Go-ish object system
+ *
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBMISC_OBJ_H_
+#define _LIBMISC_OBJ_H_
+
+#include <libmisc/macro.h>
+
+/**
+ * Use `lo_interface` similarly to how you would use
+ * `struct`/`enum`/`union` when writing the type of an interface
+ * value.
+ */
+#define lo_interface struct
+
+/**
+ * Use `LO_INTERFACE` in a .h file to define an interface.
+ *
+ * First define a macro named `{iface_name}_LO_IFACE` consisting of a
+ * series of calls to LO_NEST and/or LO_FUNC, then call
+ * `LO_INTERFACE({iface_name})`:
+ *
+ *     #define myiface_LO_IFACE                  \
+ *         LO_NEST(wrapped_iface_name)           \
+ *         LO_FUNC(ret_type, func_name, args...)
+ *     LO_INTERFACE(myiface)
+ *
+ * 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)
+#define LO_FUNC(_ARG_ret_type, _ARG_func_name, ...) \
+	(lo_func, _ARG_ret_type, _ARG_func_name __VA_OPT__(,) __VA_ARGS__)
+#define LO_INTERFACE(_ARG_iface_name)                                \
+	struct _lo_##_ARG_iface_name##_vtable {                      \
+		LM_FOREACH_TUPLE(_ARG_iface_name##_LO_IFACE,         \
+		                 _LO_IFACE_VTABLE)                   \
+	};                                                           \
+	struct _ARG_iface_name {                                     \
+		void                                 *self;          \
+		const struct _lo_##_ARG_iface_name##_vtable *vtable; \
+	};                                                           \
+	LM_FOREACH_TUPLE(_ARG_iface_name##_LO_IFACE,                 \
+	                 _LO_IFACE_PROTO, _ARG_iface_name)           \
+	extern int LM_CAT2_(_HIDDEN_BOGUS_, __COUNTER__)
+
+#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_VTABLE2(_tuple_typ, ...)                            _LO_IFACE_VTABLE2_##_tuple_typ(__VA_ARGS__)
+#define _LO_IFACE_VTABLE2_lo_nest(_ARG_child_iface_name)              const struct _lo_##_ARG_child_iface_name##_vtable *_lo_##_ARG_child_iface_name##_vtable; LM_FOREACH_TUPLE3(_ARG_child_iface_name##_LO_IFACE, _LO_IFACE_VTABLE3)
+#define _LO_IFACE_VTABLE2_lo_func(_ARG_ret_type, _ARG_func_name, ...) _ARG_ret_type (*_ARG_func_name)(void * __VA_OPT__(,) __VA_ARGS__);
+
+#define _LO_IFACE_VTABLE3(_tuple_typ, ...)                            _LO_IFACE_VTABLE3_##_tuple_typ(__VA_ARGS__)
+#define _LO_IFACE_VTABLE3_lo_nest(_ARG_child_iface_name)              const struct _lo_##_ARG_child_iface_name##_vtable *_lo_##_ARG_child_iface_name##_vtable; LM_FOREACH_TUPLE4(_ARG_child_iface_name##_LO_IFACE, _LO_IFACE_VTABLE4)
+#define _LO_IFACE_VTABLE3_lo_func(_ARG_ret_type, _ARG_func_name, ...) _ARG_ret_type (*_ARG_func_name)(void * __VA_OPT__(,) __VA_ARGS__);
+
+#define _LO_IFACE_VTABLE4(_tuple_typ, ...)                            _LO_IFACE_VTABLE4_##_tuple_typ(__VA_ARGS__)
+#define _LO_IFACE_VTABLE4_lo_nest(_ARG_child_iface_name)              static_assert(0, "BUG: libmisc/obj.h cannot nest interfaces more than 4 deep");
+#define _LO_IFACE_VTABLE4_lo_func(_ARG_ret_type, _ARG_func_name, ...) _ARG_ret_type (*_ARG_func_name)(void * __VA_OPT__(,) __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_lo_func(_ARG_iface_name, _ARG_ret_type, _ARG_func_name, ...) \
+	/* empty */
+
+/**
+ * `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){0})
+
+/**
+ * `LO_IS_NULL(iface_val)` returns whether `iface_val` is LO_NULL.
+ */
+#define LO_IS_NULL(_ARG_iface_val) ((_ARG_iface_val).vtable == NULL)
+
+/**
+ * `LO_IFACE_EQ(a, b)` returns whether the interface values `a` and
+ * `b` are the same object.
+ */
+#define LO_EQ(_ARG_iface_val_a, _ARG_iface_val_b) \
+	((_ARG_iface_val_a).self == (_ARG_iface_val_b).self)
+
+/**
+ * Use LO_CALL(obj, method_name, args...) to call a method on an `lo_interface`.
+ */
+#define LO_CALL(_ARG_obj, _ARG_meth, ...) \
+	(_ARG_obj).vtable->_ARG_meth((_ARG_obj).self __VA_OPT__(,) __VA_ARGS__)
+
+/**
+ * Use `LO_IMPLEMENTATION_H(iface_name, impl_type, impl_name)` in a .h
+ * 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, \
+		};                                                                    \
+	}                                                                             \
+	LM_FORCE_SEMICOLON
+
+/**
+ * Use `LO_IMPLEMENTATION_C(iface_name, impl_type, impl_name[, static])` in a .c
+ * file to declare that `{impl_type}` implements the `{iface_name}` interface
+ * with functions named `{impl_name}_{method_name}`.
+ *
+ * You must also call the LO_IMPLEMENTATION_H in the corresponding .h file.
+ *
+ * If `iface_name` contains a nested interface, then the
+ * implementation of the nested interfaces must be declared with
+ * `LO_IMPLEMENTATION_C` first.
+ */
+#define LO_IMPLEMENTATION_C(_ARG_iface_name, _ARG_impl_type, _ARG_impl_name, ...)     \
+	/* Method prototypes.  */                                                     \
+	LM_FOREACH_TUPLE(_ARG_iface_name##_LO_IFACE,                                  \
+	                 _LO_IMPL_PROTO, _ARG_impl_type, _ARG_impl_name, __VA_ARGS__) \
+	/* Vtable.  */                                                                \
+	const struct _lo_##_ARG_iface_name##_vtable                                   \
+	_lo_##_ARG_impl_name##_##_ARG_iface_name##_vtable = {                         \
+		LM_FOREACH_TUPLE(_ARG_iface_name##_LO_IFACE,                          \
+		                 _LO_IMPL_VTABLE, _ARG_impl_name)                     \
+	}
+
+#define _LO_IMPL_PROTO(        _ARG_impl_type, _ARG_impl_name, _ARG_quals, _tuple_typ, ...)                     _LO_IMPL_PROTO_##_tuple_typ(_ARG_impl_type, _ARG_impl_name, _ARG_quals, __VA_ARGS__)
+#define _LO_IMPL_PROTO_lo_nest(_ARG_impl_type, _ARG_impl_name, _ARG_quals, _ARG_child_iface_name)               /* empty */
+#define _LO_IMPL_PROTO_lo_func(_ARG_impl_type, _ARG_impl_name, _ARG_quals, _ARG_ret_type, _ARG_func_name, ...)  _ARG_quals _ARG_ret_type _ARG_impl_name##_##_ARG_func_name(_ARG_impl_type * __VA_OPT__(,) __VA_ARGS__);
+
+#define _LO_IMPL_VTABLE(_ARG_impl_name, _tuple_typ, ...)                             _LO_IMPL_VTABLE_##_tuple_typ(_ARG_impl_name, __VA_ARGS__)
+#define _LO_IMPL_VTABLE_lo_nest(_ARG_impl_name, _ARG_child_iface_name)               ._lo_##_ARG_child_iface_name##_vtable = &_lo_##_ARG_impl_name##_##_ARG_child_iface_name##_vtable, LM_FOREACH_TUPLE2(_ARG_child_iface_name##_LO_IFACE, _LO_IMPL_VTABLE2, _ARG_impl_name)
+#define _LO_IMPL_VTABLE_lo_func(_ARG_impl_name, _ARG_ret_type, _ARG_func_name, ...)  ._ARG_func_name                       = (void*)_ARG_impl_name##_##_ARG_func_name,
+
+#define _LO_IMPL_VTABLE2(_ARG_impl_name, _tuple_typ, ...)                            _LO_IMPL_VTABLE2_##_tuple_typ(_ARG_impl_name, __VA_ARGS__)
+#define _LO_IMPL_VTABLE2_lo_nest(_ARG_impl_name, _ARG_child_iface_name)              ._lo_##_ARG_child_iface_name##_vtable = &_lo_##_ARG_impl_name##_##_ARG_child_iface_name##_vtable, LM_FOREACH_TUPLE3(_ARG_child_iface_name##_LO_IFACE, _LO_IMPL_VTABLE3, _ARG_impl_name)
+#define _LO_IMPL_VTABLE2_lo_func(_ARG_impl_name, _ARG_ret_type, _ARG_func_name, ...) ._ARG_func_name                       = (void*)_ARG_impl_name##_##_ARG_func_name,
+
+#define _LO_IMPL_VTABLE3(_ARG_impl_name, _tuple_typ, ...)                            _LO_IMPL_VTABLE3_##_tuple_typ(_ARG_impl_name, __VA_ARGS__)
+#define _LO_IMPL_VTABLE3_lo_nest(_ARG_impl_name, _ARG_child_iface_name)              ._lo_##_ARG_child_iface_name##_vtable = &_lo_##_ARG_impl_name##_##_ARG_child_iface_name##_vtable, LM_FOREACH_TUPLE4(_ARG_child_iface_name##_LO_IFACE, _LO_IMPL_VTABLE4, _ARG_impl_name)
+#define _LO_IMPL_VTABLE3_lo_func(_ARG_impl_name, _ARG_ret_type, _ARG_func_name, ...) ._ARG_func_name                       = (void*)_ARG_impl_name##_##_ARG_func_name,
+
+#define _LO_IMPL_VTABLE4(_ARG_impl_name, _tuple_typ, ...)                            _LO_IMPL_VTABLE4_##_tuple_typ(_ARG_impl_name, __VA_ARGS__)
+#define _LO_IMPL_VTABLE4_lo_nest(_ARG_impl_name, _ARG_child_iface_name)              static_assert(0, "BUG: libmisc/obj.h cannot nest interfaces more than 4 deep");
+#define _LO_IMPL_VTABLE4_lo_func(_ARG_impl_name, _ARG_ret_type, _ARG_func_name, ...) ._ARG_func_name                       = (void*)_ARG_impl_name##_##_ARG_func_name,
+
+
+#endif /* _LIBMISC_OBJ_H_ */
diff --git a/libmisc/tests/test_obj.c b/libmisc/tests/test_obj.c
new file mode 100644
index 0000000..687ad4e
--- /dev/null
+++ b/libmisc/tests/test_obj.c
@@ -0,0 +1,61 @@
+/* libmisc/tests/test_obj.c - Tests for <libmisc/obj.h>
+ *
+ * Copyright (C) 2024-2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#include <libmisc/obj.h>
+
+#include "test.h"
+
+/* `lo_inteface frobber` header ***********************************************/
+
+#define frobber_LO_IFACE                        \
+	/** Basic function.  */                 \
+	LO_FUNC(int, frob)                      \
+	/** Function that takes 1 argument.  */ \
+	LO_FUNC(int, frob1, int)                \
+	/** Function that returns nothing.  */  \
+	LO_FUNC(void, frob0)
+LO_INTERFACE(frobber);
+
+/* `struct myclass` header ****************************************************/
+
+struct myclass {
+	int a;
+};
+LO_IMPLEMENTATION_H(frobber, struct myclass, myclass);
+
+/* `struct myclass` implementation ********************************************/
+
+LO_IMPLEMENTATION_C(frobber, struct myclass, myclass, static);
+
+static int myclass_frob(struct myclass *self) {
+	test_assert(self);
+	return self->a;
+}
+
+static int myclass_frob1(struct myclass *self, int arg) {
+	test_assert(self);
+	return arg;
+}
+
+static void myclass_frob0(struct myclass *self) {
+	test_assert(self);
+}
+
+/* main test body *************************************************************/
+
+#define MAGIC1 909837
+#define MAGIC2 657441
+
+int main() {
+	struct myclass obj = {
+		.a = MAGIC1,
+	};
+	lo_interface frobber iface = lo_box_myclass_as_frobber(&obj);
+	test_assert(LO_CALL(iface, frob) == MAGIC1);
+	test_assert(LO_CALL(iface, frob1, MAGIC2) == MAGIC2);
+	LO_CALL(iface, frob0);
+	return 0;
+}
diff --git a/libmisc/tests/test_obj_nest.c b/libmisc/tests/test_obj_nest.c
new file mode 100644
index 0000000..bb9d6de
--- /dev/null
+++ b/libmisc/tests/test_obj_nest.c
@@ -0,0 +1,73 @@
+/* libmisc/tests/test_obj_nest.c - Tests for <libmisc/obj.h> nesting
+ *
+ * Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#include <string.h> /* for memcpy() */
+
+#include <libmisc/obj.h>
+
+#include "test.h"
+
+/* interfaces *****************************************************************/
+
+#define reader_LO_IFACE \
+	LO_FUNC(ssize_t, read, void *, size_t)
+LO_INTERFACE(reader);
+
+#define writer_LO_IFACE \
+	LO_FUNC(ssize_t, write, void *, size_t)
+LO_INTERFACE(writer);
+
+#define read_writer_LO_IFACE \
+	LO_NEST(reader) \
+	LO_NEST(writer)
+LO_INTERFACE(read_writer);
+
+/* implementation header ******************************************************/
+
+struct myclass {
+	size_t len;
+	char   buf[512];
+};
+LO_IMPLEMENTATION_H(reader, struct myclass, myclass);
+LO_IMPLEMENTATION_H(writer, struct myclass, myclass);
+LO_IMPLEMENTATION_H(read_writer, struct myclass, myclass);
+
+/* implementation main ********************************************************/
+
+LO_IMPLEMENTATION_C(reader, struct myclass, myclass, static);
+LO_IMPLEMENTATION_C(writer, struct myclass, myclass, static);
+LO_IMPLEMENTATION_C(read_writer, struct myclass, myclass, static);
+
+static ssize_t myclass_read(struct myclass *self, void *buf, size_t count) {
+	test_assert(self);
+	if (count > self->len)
+		count = self->len;
+	memcpy(buf, self->buf, count);
+	return count;
+}
+
+static ssize_t myclass_write(struct myclass *self, void *buf, size_t count) {
+	test_assert(self);
+	if (self->len)
+		return -1;
+	if (count > sizeof(self->buf))
+		count = sizeof(self->buf);
+	memcpy(self->buf, buf, count);
+	self->len = count;
+	return count;
+}
+
+/* main test body *************************************************************/
+
+int main() {
+	struct myclass _obj = {0};
+	lo_interface read_writer obj = lo_box_myclass_as_read_writer(&_obj);
+	test_assert(LO_CALL(obj, write, "Hello", 6) == 6);
+	char buf[6] = {0};
+	test_assert(LO_CALL(obj, read, buf, 3) == 3);
+	test_assert(memcmp(buf, "Hel\0\0\0", 6) == 0);
+	return 0;
+}