#1021 Add member function overload that takes pointer to member

- Added new pointer-to-member member function overload to untyped_component. - Added support for packed structs in flecs meta. - Removed unused size and alignment from EcsMetaType. - Fixed bug where member count was ignored if an explicit offset was provided.
SanderMertens · Aug 7, 2023 · c27c1da · c27c1da
1 parent f3424e4
commit c27c1da
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Showing 10 changed files with 289 additions and 90 deletions.
diff --git a/flecs.c b/flecs.c
@@ -55556,19 +55556,13 @@ int flecs_init_type(
                 ecs_err("computed size for '%s' matches with actual type but "
                     "alignment is different (%d vs. %d)", ecs_get_name(world, type),
                         alignment, comp->alignment);
-            } else {
-                /* If this is an existing type, the alignment can be larger but
-                 * not smaller than the computed alignment. */
-                alignment = comp->alignment;
             }
         }
 
         meta_type->partial = comp->size != size;
     }
 
     meta_type->kind = kind;
-    meta_type->size = size;
-    meta_type->alignment = alignment;
     ecs_modified(world, type, EcsMetaType);
 
     return 0;
@@ -55714,7 +55708,7 @@ int flecs_add_member_to_struct(
             /* Get component of member type to get its size & alignment */
             const EcsComponent *mbr_comp = ecs_get(world, elem->type, EcsComponent);
             if (!mbr_comp) {
-                char *path = ecs_get_fullpath(world, member);
+                char *path = ecs_get_fullpath(world, elem->type);
                 ecs_err("member '%s' is not a type", path);
                 ecs_os_free(path);
                 return -1;
@@ -55724,7 +55718,7 @@ int flecs_add_member_to_struct(
             ecs_size_t member_alignment = mbr_comp->alignment;
 
             if (!member_size || !member_alignment) {
-                char *path = ecs_get_fullpath(world, member);
+                char *path = ecs_get_fullpath(world, elem->type);
                 ecs_err("member '%s' has 0 size/alignment");
                 ecs_os_free(path);
                 return -1;
@@ -55751,14 +55745,42 @@ int flecs_add_member_to_struct(
         }
     } else {
         /* If members have explicit offsets, we can't rely on computed 
-         * size/alignment values. Grab size of just added member instead. It
-         * doesn't matter if the size doesn't correspond to the actual struct
-         * size. The flecs_init_type function compares computed size with actual
+         * size/alignment values. Calculate size as if this is the last member
+         * instead, since this will validate if the member fits in the struct.
+         * It doesn't matter if the size is smaller than the actual struct size
+         * because flecs_init_type function compares computed size with actual
          * (component) size to determine if the type is partial. */
-        const EcsComponent *cptr = ecs_get(world, m->type, EcsComponent);
-        ecs_assert(cptr != NULL, ECS_INTERNAL_ERROR, NULL);
-        size = cptr->size;
-        alignment = cptr->alignment;
+        ecs_member_t *elem = &members[i];
+
+        ecs_assert(elem->name != NULL, ECS_INTERNAL_ERROR, NULL);
+        ecs_assert(elem->type != 0, ECS_INTERNAL_ERROR, NULL);
+
+        /* Get component of member type to get its size & alignment */
+        const EcsComponent *mbr_comp = ecs_get(world, elem->type, EcsComponent);
+        if (!mbr_comp) {
+            char *path = ecs_get_fullpath(world, elem->type);
+            ecs_err("member '%s' is not a type", path);
+            ecs_os_free(path);
+            return -1;
+        }
+
+        ecs_size_t member_size = mbr_comp->size;
+        ecs_size_t member_alignment = mbr_comp->alignment;
+
+        if (!member_size || !member_alignment) {
+            char *path = ecs_get_fullpath(world, elem->type);
+            ecs_err("member '%s' has 0 size/alignment");
+            ecs_os_free(path);
+            return -1;
+        }
+
+        member_size *= elem->count;
+        elem->size = member_size;
+
+        size = elem->offset + member_size;
+
+        const EcsComponent* comp = ecs_get(world, type, EcsComponent);
+        alignment = comp->alignment;
     }
 
     if (size == 0) {

diff --git a/flecs.h b/flecs.h
@@ -13042,8 +13042,6 @@ typedef struct EcsMetaType {
     ecs_type_kind_t kind;
     bool existing;         /**< Did the type exist or is it populated from reflection */
     bool partial;          /**< Is the reflection data a partial type description */
-    ecs_size_t size;       /**< Computed size */
-    ecs_size_t alignment;  /**< Computed alignment */
 } EcsMetaType;
 
 /** Primitive type kinds supported by meta addon */
@@ -15864,7 +15862,7 @@ struct string {
         return m_const_str;
     }
 
-    std::size_t length() {
+    std::size_t length() const {
         return static_cast<std::size_t>(m_length);
     }
 
@@ -15873,7 +15871,7 @@ struct string {
         return N - 1;
     }
 
-    std::size_t size() {
+    std::size_t size() const {
         return length();
     }
 
@@ -24733,25 +24731,6 @@ struct untyped_component : entity {
  * @{
  */
 
-/** Add member. */
-untyped_component& member(flecs::entity_t type_id, const char *name, int32_t count = 0, size_t offset = 0) {
-    ecs_entity_desc_t desc = {};
-    desc.name = name;
-    desc.add[0] = ecs_pair(flecs::ChildOf, m_id);
-    ecs_entity_t eid = ecs_entity_init(m_world, &desc);
-    ecs_assert(eid != 0, ECS_INTERNAL_ERROR, NULL);
-
-    flecs::entity e(m_world, eid);
-
-    Member m = {};
-    m.type = type_id;
-    m.count = count;
-    m.offset = static_cast<int32_t>(offset);
-    e.set<Member>(m);
-
-    return *this;
-}
-
 /** Add member with unit. */
 untyped_component& member(flecs::entity_t type_id, flecs::entity_t unit, const char *name, int32_t count = 0, size_t offset = 0) {
     ecs_entity_desc_t desc = {};
@@ -24772,6 +24751,11 @@ untyped_component& member(flecs::entity_t type_id, flecs::entity_t unit, const c
     return *this;
 }
 
+/** Add member. */
+untyped_component& member(flecs::entity_t type_id, const char* name, int32_t count = 0, size_t offset = 0) {
+    return member(type_id, 0, name, count, offset);
+}
+
 /** Add member. */
 template <typename MemberType>
 untyped_component& member(const char *name, int32_t count = 0, size_t offset = 0) {
@@ -24794,6 +24778,31 @@ untyped_component& member(const char *name, int32_t count = 0, size_t offset = 0
     return member(type_id, unit_id, name, count, offset);
 }
 
+/** Add member using pointer-to-member. */
+template <typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, name, std::extent<MemberType>::value, offset);
+}
+
+/** Add member with unit using pointer-to-member. */
+template <typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(flecs::entity_t unit, const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, unit, name, std::extent<MemberType>::value, offset);
+}
+
+/** Add member with unit using pointer-to-member. */
+template <typename UnitType, typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    flecs::entity_t unit_id = _::cpp_type<UnitType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, unit_id, name, std::extent<MemberType>::value, offset);
+}
+
 /** Add constant. */
 untyped_component& constant(const char *name, int32_t value) {
     ecs_add_id(m_world, m_id, _::cpp_type<flecs::Enum>::id(m_world));

diff --git a/include/flecs/addons/cpp/mixins/meta/untyped_component.inl b/include/flecs/addons/cpp/mixins/meta/untyped_component.inl
@@ -10,25 +10,6 @@
  * @{
  */
 
-/** Add member. */
-untyped_component& member(flecs::entity_t type_id, const char *name, int32_t count = 0, size_t offset = 0) {
-    ecs_entity_desc_t desc = {};
-    desc.name = name;
-    desc.add[0] = ecs_pair(flecs::ChildOf, m_id);
-    ecs_entity_t eid = ecs_entity_init(m_world, &desc);
-    ecs_assert(eid != 0, ECS_INTERNAL_ERROR, NULL);
-
-    flecs::entity e(m_world, eid);
-
-    Member m = {};
-    m.type = type_id;
-    m.count = count;
-    m.offset = static_cast<int32_t>(offset);
-    e.set<Member>(m);
-
-    return *this;
-}
-
 /** Add member with unit. */
 untyped_component& member(flecs::entity_t type_id, flecs::entity_t unit, const char *name, int32_t count = 0, size_t offset = 0) {
     ecs_entity_desc_t desc = {};
@@ -49,6 +30,11 @@ untyped_component& member(flecs::entity_t type_id, flecs::entity_t unit, const c
     return *this;
 }
 
+/** Add member. */
+untyped_component& member(flecs::entity_t type_id, const char* name, int32_t count = 0, size_t offset = 0) {
+    return member(type_id, 0, name, count, offset);
+}
+
 /** Add member. */
 template <typename MemberType>
 untyped_component& member(const char *name, int32_t count = 0, size_t offset = 0) {
@@ -71,6 +57,31 @@ untyped_component& member(const char *name, int32_t count = 0, size_t offset = 0
     return member(type_id, unit_id, name, count, offset);
 }
 
+/** Add member using pointer-to-member. */
+template <typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, name, std::extent<MemberType>::value, offset);
+}
+
+/** Add member with unit using pointer-to-member. */
+template <typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(flecs::entity_t unit, const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, unit, name, std::extent<MemberType>::value, offset);
+}
+
+/** Add member with unit using pointer-to-member. */
+template <typename UnitType, typename MemberType, typename ComponentType, typename RealType = typename std::remove_extent<MemberType>::type>
+untyped_component& member(const char* name, const MemberType ComponentType::* ptr) {
+    flecs::entity_t type_id = _::cpp_type<RealType>::id(m_world);
+    flecs::entity_t unit_id = _::cpp_type<UnitType>::id(m_world);
+    size_t offset = reinterpret_cast<size_t>(&(static_cast<ComponentType*>(nullptr)->*ptr));
+    return member(type_id, unit_id, name, std::extent<MemberType>::value, offset);
+}
+
 /** Add constant. */
 untyped_component& constant(const char *name, int32_t value) {
     ecs_add_id(m_world, m_id, _::cpp_type<flecs::Enum>::id(m_world));

diff --git a/include/flecs/addons/meta.h b/include/flecs/addons/meta.h
@@ -154,8 +154,6 @@ typedef struct EcsMetaType {
     ecs_type_kind_t kind;
     bool existing;         /**< Did the type exist or is it populated from reflection */
     bool partial;          /**< Is the reflection data a partial type description */
-    ecs_size_t size;       /**< Computed size */
-    ecs_size_t alignment;  /**< Computed alignment */
 } EcsMetaType;
 
 /** Primitive type kinds supported by meta addon */

diff --git a/src/addons/meta/meta.c b/src/addons/meta/meta.c
@@ -299,19 +299,13 @@ int flecs_init_type(
                 ecs_err("computed size for '%s' matches with actual type but "
                     "alignment is different (%d vs. %d)", ecs_get_name(world, type),
                         alignment, comp->alignment);
-            } else {
-                /* If this is an existing type, the alignment can be larger but
-                 * not smaller than the computed alignment. */
-                alignment = comp->alignment;
             }
         }
 
         meta_type->partial = comp->size != size;
     }
 
     meta_type->kind = kind;
-    meta_type->size = size;
-    meta_type->alignment = alignment;
     ecs_modified(world, type, EcsMetaType);
 
     return 0;
@@ -457,7 +451,7 @@ int flecs_add_member_to_struct(
             /* Get component of member type to get its size & alignment */
             const EcsComponent *mbr_comp = ecs_get(world, elem->type, EcsComponent);
             if (!mbr_comp) {
-                char *path = ecs_get_fullpath(world, member);
+                char *path = ecs_get_fullpath(world, elem->type);
                 ecs_err("member '%s' is not a type", path);
                 ecs_os_free(path);
                 return -1;
@@ -467,7 +461,7 @@ int flecs_add_member_to_struct(
             ecs_size_t member_alignment = mbr_comp->alignment;
 
             if (!member_size || !member_alignment) {
-                char *path = ecs_get_fullpath(world, member);
+                char *path = ecs_get_fullpath(world, elem->type);
                 ecs_err("member '%s' has 0 size/alignment");
                 ecs_os_free(path);
                 return -1;
@@ -494,14 +488,42 @@ int flecs_add_member_to_struct(
         }
     } else {
         /* If members have explicit offsets, we can't rely on computed 
-         * size/alignment values. Grab size of just added member instead. It
-         * doesn't matter if the size doesn't correspond to the actual struct
-         * size. The flecs_init_type function compares computed size with actual
+         * size/alignment values. Calculate size as if this is the last member
+         * instead, since this will validate if the member fits in the struct.
+         * It doesn't matter if the size is smaller than the actual struct size
+         * because flecs_init_type function compares computed size with actual
          * (component) size to determine if the type is partial. */
-        const EcsComponent *cptr = ecs_get(world, m->type, EcsComponent);
-        ecs_assert(cptr != NULL, ECS_INTERNAL_ERROR, NULL);
-        size = cptr->size;
-        alignment = cptr->alignment;
+        ecs_member_t *elem = &members[i];
+
+        ecs_assert(elem->name != NULL, ECS_INTERNAL_ERROR, NULL);
+        ecs_assert(elem->type != 0, ECS_INTERNAL_ERROR, NULL);
+
+        /* Get component of member type to get its size & alignment */
+        const EcsComponent *mbr_comp = ecs_get(world, elem->type, EcsComponent);
+        if (!mbr_comp) {
+            char *path = ecs_get_fullpath(world, elem->type);
+            ecs_err("member '%s' is not a type", path);
+            ecs_os_free(path);
+            return -1;
+        }
+
+        ecs_size_t member_size = mbr_comp->size;
+        ecs_size_t member_alignment = mbr_comp->alignment;
+
+        if (!member_size || !member_alignment) {
+            char *path = ecs_get_fullpath(world, elem->type);
+            ecs_err("member '%s' has 0 size/alignment");
+            ecs_os_free(path);
+            return -1;
+        }
+
+        member_size *= elem->count;
+        elem->size = member_size;
+
+        size = elem->offset + member_size;
+
+        const EcsComponent* comp = ecs_get(world, type, EcsComponent);
+        alignment = comp->alignment;
     }
 
     if (size == 0) {

diff --git a/test/cpp_api/project.json b/test/cpp_api/project.json
@@ -1267,7 +1267,9 @@
                 "enum_w_bits",
                 "value_range",
                 "warning_range",
-                "error_range"
+                "error_range",
+                "struct_member_ptr",
+                "struct_member_ptr_packed_struct"
             ]
         }, {
             "id": "Table",