Move the polymorphic/inheritance macros to a separate header

1 files changed, 108 insertions, 0 deletions

diff --git a/Alc/polymorphism.h b/Alc/polymorphism.h
new file mode 100644
index 00000000..b41ad64b
--- /dev/null
+++ b/Alc/polymorphism.h
@@ -0,0 +1,108 @@
+#ifndef POLYMORPHISM_H
+#define POLYMORPHISM_H
+
+/* Macros to declare inheriting types, and to (down-)cast and up-cast. */
+#define DERIVE_FROM_TYPE(t)          t t##_parent
+#define STATIC_CAST(to, obj)         (&(obj)->to##_parent)
+#ifdef __GNUC__
+#define STATIC_UPCAST(to, from, obj) __extension__({                          \
+    static_assert(__builtin_types_compatible_p(from, __typeof(*(obj))),       \
+                  "Invalid upcast object from type");                         \
+    (to*)((char*)(obj) - offsetof(to, from##_parent));                        \
+})
+#else
+#define STATIC_UPCAST(to, from, obj) ((to*)((char*)(obj) - offsetof(to, from##_parent)))
+#endif
+
+/* Defines method forwards, which call the given parent's (T2's) implementation. */
+#define DECLARE_FORWARD(T1, T2, rettype, func)                                \
+rettype T1##_##func(T1 *obj)                                                  \
+{ return T2##_##func(STATIC_CAST(T2, obj)); }
+
+#define DECLARE_FORWARD1(T1, T2, rettype, func, argtype1)                     \
+rettype T1##_##func(T1 *obj, argtype1 a)                                      \
+{ return T2##_##func(STATIC_CAST(T2, obj), a); }
+
+#define DECLARE_FORWARD2(T1, T2, rettype, func, argtype1, argtype2)           \
+rettype T1##_##func(T1 *obj, argtype1 a, argtype2 b)                          \
+{ return T2##_##func(STATIC_CAST(T2, obj), a, b); }
+
+#define DECLARE_FORWARD3(T1, T2, rettype, func, argtype1, argtype2, argtype3) \
+rettype T1##_##func(T1 *obj, argtype1 a, argtype2 b, argtype3 c)              \
+{ return T2##_##func(STATIC_CAST(T2, obj), a, b, c); }
+
+/* Defines method thunks, functions that call to the child's method. */
+#define DECLARE_THUNK(T1, T2, rettype, func)                                  \
+static rettype T1##_##T2##_##func(T2 *obj)                                    \
+{ return T1##_##func(STATIC_UPCAST(T1, T2, obj)); }
+
+#define DECLARE_THUNK1(T1, T2, rettype, func, argtype1)                       \
+static rettype T1##_##T2##_##func(T2 *obj, argtype1 a)                        \
+{ return T1##_##func(STATIC_UPCAST(T1, T2, obj), a); }
+
+#define DECLARE_THUNK2(T1, T2, rettype, func, argtype1, argtype2)             \
+static rettype T1##_##T2##_##func(T2 *obj, argtype1 a, argtype2 b)            \
+{ return T1##_##func(STATIC_UPCAST(T1, T2, obj), a, b); }
+
+#define DECLARE_THUNK3(T1, T2, rettype, func, argtype1, argtype2, argtype3)   \
+static rettype T1##_##T2##_##func(T2 *obj, argtype1 a, argtype2 b, argtype3 c) \
+{ return T1##_##func(STATIC_UPCAST(T1, T2, obj), a, b, c); }
+
+#define DECLARE_THUNK4(T1, T2, rettype, func, argtype1, argtype2, argtype3, argtype4) \
+static rettype T1##_##T2##_##func(T2 *obj, argtype1 a, argtype2 b, argtype3 c, argtype4 d) \
+{ return T1##_##func(STATIC_UPCAST(T1, T2, obj), a, b, c, d); }
+
+/* Defines the default functions used to (de)allocate a polymorphic object. */
+#define DECLARE_DEFAULT_ALLOCATORS(T)                                         \
+static void* T##_New(size_t size) { return al_malloc(16, size); }             \
+static void T##_Delete(void *ptr) { al_free(ptr); }
+
+
+/* Helper to extract an argument list for virtual method calls. */
+#define EXTRACT_VCALL_ARGS(...)  __VA_ARGS__))
+
+/* Call a "virtual" method on an object, with arguments. */
+#define V(obj, func)  ((obj)->vtbl->func((obj), EXTRACT_VCALL_ARGS
+/* Call a "virtual" method on an object, with no arguments. */
+#define V0(obj, func) ((obj)->vtbl->func((obj) EXTRACT_VCALL_ARGS
+
+
+/* Helper to extract an argument list for NEW_OBJ calls. */
+#define EXTRACT_NEW_ARGS(...)  __VA_ARGS__);                                  \
+    }                                                                         \
+} while(0)
+
+/* Allocate and construct an object, with arguments. */
+#define NEW_OBJ(_res, T) do {                                                 \
+    _res = T##_New(sizeof(T));                                                \
+    if(_res)                                                                  \
+    {                                                                         \
+        memset(_res, 0, sizeof(T));                                           \
+        T##_Construct(_res, EXTRACT_NEW_ARGS
+/* Allocate and construct an object, with no arguments. */
+#define NEW_OBJ0(_res, T) do {                                                \
+    _res = T##_New(sizeof(T));                                                \
+    if(_res)                                                                  \
+    {                                                                         \
+        memset(_res, 0, sizeof(T));                                           \
+        T##_Construct(_res EXTRACT_NEW_ARGS
+
+/* Destructs and deallocate an object. */
+#define DELETE_OBJ(obj) do {                                                  \
+    if((obj) != NULL)                                                         \
+    {                                                                         \
+        V0((obj),Destruct)();                                                 \
+        V0((obj),Delete)();                                                   \
+    }                                                                         \
+} while(0)
+
+
+/* Helper to get a type's vtable thunk for a child type. */
+#define GET_VTABLE2(T1, T2) (&(T1##_##T2##_vtable))
+/* Helper to set an object's vtable thunk for a child type. Used when constructing an object. */
+#define SET_VTABLE2(T1, T2, obj) (STATIC_CAST(T2, obj)->vtbl = GET_VTABLE2(T1, T2))
+
+/* Helper to set an object's vtable for a type. */
+#define SET_VTABLE1(T1, obj)     ((obj)->vtbl = &(T1##_vtable))
+
+#endif /* POLYMORPHISM_H */