hubert.reinterpretcast updated this revision to Diff 55820.
hubert.reinterpretcast added a comment.
Replace alias template with struct and typedef member; add usage example
http://reviews.llvm.org/D19770
Files:
include/llvm/Support/TrailingObjects.h
Index: include/llvm/Support/TrailingObjects.h
===================================================================
--- include/llvm/Support/TrailingObjects.h
+++ include/llvm/Support/TrailingObjects.h
@@ -342,6 +342,49 @@
TrailingTys, size_t>::type... Counts) {
return sizeof(BaseTy) + ParentType::additionalSizeToAllocImpl(0,
Counts...);
}
+
+ /// A type where its ::with_counts template member has a ::type member
+ /// suitable for use as uninitialized storage for an object with the given
+ /// trailing object counts. The template arguments are similar to those
+ /// of additionalSizeToAlloc.
+ ///
+ /// Use with FixedSizeStorageOwner, e.g.:
+ ///
+ /// \code{.cpp}
+ ///
+ /// MyObj::FixedSizeStorage<void *>::with_counts<1u>::type myStackObjStorage;
+ /// MyObj::FixedSizeStorageOwner
+ /// myStackObjOwner(new ((void *)&myStackObjStorage) MyObj);
+ /// MyObj *const myStackObjPtr = myStackObjOwner.get();
+ ///
+ /// \endcode
+ template <typename... Tys> struct FixedSizeStorage {
+ template <size_t... Counts> struct with_counts {
+ typedef llvm::AlignedCharArray<
+ llvm::AlignOf<BaseTy>::Alignment, totalSizeToAlloc<Tys...>(Counts...)
+ > type;
+ };
+ };
+
+ /// A type that acts as the owner for an object placed into fixed storage.
+ class FixedSizeStorageOwner {
+ public:
+ FixedSizeStorageOwner(BaseTy *p) : p(p) {}
+ ~FixedSizeStorageOwner() {
+ assert(p && "FixedSizeStorageOwner owns null?");
+ p->~BaseTy();
+ }
+
+ BaseTy *get() { return p; }
+
+ private:
+ FixedSizeStorageOwner(const FixedSizeStorageOwner &) = delete;
+ FixedSizeStorageOwner(FixedSizeStorageOwner &&) = delete;
+ FixedSizeStorageOwner &operator=(const FixedSizeStorageOwner &) = delete;
+ FixedSizeStorageOwner &operator=(FixedSizeStorageOwner &&) = delete;
+
+ BaseTy *const p;
+ };
};
} // end namespace llvm
Index: include/llvm/Support/TrailingObjects.h
===================================================================
--- include/llvm/Support/TrailingObjects.h
+++ include/llvm/Support/TrailingObjects.h
@@ -342,6 +342,49 @@
TrailingTys, size_t>::type... Counts) {
return sizeof(BaseTy) + ParentType::additionalSizeToAllocImpl(0, Counts...);
}
+
+ /// A type where its ::with_counts template member has a ::type member
+ /// suitable for use as uninitialized storage for an object with the given
+ /// trailing object counts. The template arguments are similar to those
+ /// of additionalSizeToAlloc.
+ ///
+ /// Use with FixedSizeStorageOwner, e.g.:
+ ///
+ /// \code{.cpp}
+ ///
+ /// MyObj::FixedSizeStorage<void *>::with_counts<1u>::type myStackObjStorage;
+ /// MyObj::FixedSizeStorageOwner
+ /// myStackObjOwner(new ((void *)&myStackObjStorage) MyObj);
+ /// MyObj *const myStackObjPtr = myStackObjOwner.get();
+ ///
+ /// \endcode
+ template <typename... Tys> struct FixedSizeStorage {
+ template <size_t... Counts> struct with_counts {
+ typedef llvm::AlignedCharArray<
+ llvm::AlignOf<BaseTy>::Alignment, totalSizeToAlloc<Tys...>(Counts...)
+ > type;
+ };
+ };
+
+ /// A type that acts as the owner for an object placed into fixed storage.
+ class FixedSizeStorageOwner {
+ public:
+ FixedSizeStorageOwner(BaseTy *p) : p(p) {}
+ ~FixedSizeStorageOwner() {
+ assert(p && "FixedSizeStorageOwner owns null?");
+ p->~BaseTy();
+ }
+
+ BaseTy *get() { return p; }
+
+ private:
+ FixedSizeStorageOwner(const FixedSizeStorageOwner &) = delete;
+ FixedSizeStorageOwner(FixedSizeStorageOwner &&) = delete;
+ FixedSizeStorageOwner &operator=(const FixedSizeStorageOwner &) = delete;
+ FixedSizeStorageOwner &operator=(FixedSizeStorageOwner &&) = delete;
+
+ BaseTy *const p;
+ };
};
} // end namespace llvm
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