Castable: factor out Is and As to free standing functions
These can now also be called with nullptr and will return false or
nullptr respectively.
Change-Id: I5fcf292503dd718f8d3771c7c39c204ce03ff4f7
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/44461
Reviewed-by: Ben Clayton <bclayton@google.com>
Commit-Queue: Antonio Maiorano <amaiorano@google.com>
diff --git a/src/castable.h b/src/castable.h
index 956f4f6..072872a 100644
--- a/src/castable.h
+++ b/src/castable.h
@@ -83,9 +83,37 @@
/// The unique TypeInfo for the type T.
static const TypeInfo info;
};
-
} // namespace detail
+/// @returns true if `obj` is a valid pointer, and is of, or derives from the
+/// class `TO`
+/// @param obj the object to test from
+template <typename TO, typename FROM>
+bool Is(FROM* obj) {
+ constexpr const bool downcast = std::is_base_of<FROM, TO>::value;
+ constexpr const bool upcast = std::is_base_of<TO, FROM>::value;
+ constexpr const bool nocast = std::is_same<FROM, TO>::value;
+ static_assert(upcast || downcast || nocast, "impossible cast");
+
+ if (obj == nullptr) {
+ return false;
+ }
+
+ if (upcast || nocast) {
+ return true;
+ }
+
+ return obj->TypeInfo().Is(TypeInfo::Of<std::remove_const_t<TO>>());
+}
+
+/// @returns obj dynamically cast to the type `TO` or `nullptr` if
+/// this object does not derive from `TO`.
+/// @param obj the object to cast from
+template <typename TO, typename FROM>
+inline TO* As(FROM* obj) {
+ return Is<TO>(obj) ? static_cast<TO*>(obj) : nullptr;
+}
+
/// CastableBase is the base class for all Castable objects.
/// It is not encouraged to directly derive from CastableBase without using the
/// Castable helper template.
@@ -106,31 +134,21 @@
/// @returns true if this object is of, or derives from the class `TO`
template <typename TO>
inline bool Is() const {
- using FROM = CastableBase;
- constexpr const bool downcast = std::is_base_of<FROM, TO>::value;
- constexpr const bool upcast = std::is_base_of<TO, FROM>::value;
- constexpr const bool nocast = std::is_same<FROM, TO>::value;
- static_assert(upcast || downcast || nocast, "impossible cast");
-
- if (upcast || nocast) {
- return true;
- }
-
- return TypeInfo().Is(TypeInfo::Of<TO>());
+ return tint::Is<TO>(this);
}
/// @returns this object dynamically cast to the type `TO` or `nullptr` if
/// this object does not derive from `TO`.
template <typename TO>
inline TO* As() {
- return Is<TO>() ? static_cast<TO*>(this) : nullptr;
+ return tint::As<TO>(this);
}
/// @returns this object dynamically cast to the type `TO` or `nullptr` if
/// this object does not derive from `TO`.
template <typename TO>
inline const TO* As() const {
- return Is<TO>() ? static_cast<const TO*>(this) : nullptr;
+ return tint::As<const TO>(this);
}
protected:
@@ -178,46 +196,24 @@
/// @returns true if this object is of, or derives from the class `TO`
template <typename TO>
inline bool Is() const {
- using FROM = Castable;
- constexpr const bool downcast = std::is_base_of<FROM, TO>::value;
- constexpr const bool upcast = std::is_base_of<TO, FROM>::value;
- constexpr const bool nocast = std::is_same<FROM, TO>::value;
- static_assert(upcast || downcast || nocast, "impossible cast");
-
- if (upcast || nocast) {
- return true;
- }
-
- return TypeInfo().Is(TypeInfo::Of<TO>());
+ return tint::Is<TO>(static_cast<const CLASS*>(this));
}
/// @returns this object dynamically cast to the type `TO` or `nullptr` if
/// this object does not derive from `TO`.
template <typename TO>
inline TO* As() {
- return Is<TO>() ? static_cast<TO*>(this) : nullptr;
+ return tint::As<TO>(this);
}
/// @returns this object dynamically cast to the type `TO` or `nullptr` if
/// this object does not derive from `TO`.
template <typename TO>
inline const TO* As() const {
- return Is<TO>() ? static_cast<const TO*>(this) : nullptr;
+ return tint::As<const TO>(this);
}
};
-/// As() dynamically casts `obj` to the target type `TO`.
-/// @returns the cast object, or nullptr if `obj` is `nullptr` or not of the
-/// type `TO`.
-/// @param obj the object to cast
-template <typename TO, typename FROM>
-inline TO* As(FROM* obj) {
- if (obj == nullptr) {
- return nullptr;
- }
- return obj->template As<TO>();
-}
-
} // namespace tint
TINT_CASTABLE_POP_DISABLE_WARNINGS();
