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Add an ArrayRef upcasting constructor from ArrayRef<U*> -> ArrayRef<T*> where T is a base of U.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@225053 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman 2014-12-31 23:33:18 +00:00
parent 28650b8ec2
commit 735f1df049
2 changed files with 45 additions and 0 deletions
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10
include/llvm/ADT/ArrayRef.h
View File

@ -112,6 +112,16 @@ namespace llvm {
std::is_convertible<U *const *, T const *>::value>::type* = 0)
: Data(A.data()), Length(A.size()) {}
/// Construct an ArrayRef<T*> from an ArrayRef<U*> where T is a super class
/// of U. This uses SFINAE to ensure that only ArrayRefs with this property
/// can be converted. This is an upcasting constructor.
template <typename U>
ArrayRef(const ArrayRef<U> &A,
typename std::enable_if<std::is_base_of<
typename std::remove_pointer<T>::type,
typename std::remove_pointer<U>::type>::value>::type * = 0)
: Data(reinterpret_cast<T const *>(A.data())), Length(A.size()) {}
/// @}
/// @name Simple Operations
/// @{

35
unittests/ADT/ArrayRefTest.cpp
View File

@ -90,4 +90,39 @@ TEST(ArrayRefTest, ConstConvert) {
a = ArrayRef<int *>(A);
}
struct A {
int data;
A() : data(0) {}
};
struct B : A {
int data2;
B() : A(), data2(0) {}
};
TEST(ArrayRefTest, UpcastConvert) {
B Data[5];
for (unsigned i = 0, e = 5; i != e; ++i) {
Data[i].data = i + 5;
Data[i].data2 = i + 30;
}
B *DataPtrs[5];
for (unsigned i = 0, e = 5; i != e; ++i) {
DataPtrs[i] = &Data[i];
}
ArrayRef<B *> BArray(DataPtrs, 5);
ArrayRef<A *> AArray(BArray);
EXPECT_TRUE(AArray.size() == 5);
for (unsigned i = 0, e = 5; i != e; ++i) {
A *a = AArray[i];
EXPECT_TRUE(a->data == int(i + 5));
}
}
} // end anonymous namespace