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Bug 1247412 - Add a reverse method to mozilla::Vector; r=Waldo

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This commit is contained in:
Nick Fitzgerald 2016-02-11 08:33:00 +01:00
parent 42a8ea393d
commit 6f93fd8916
2 changed files with 76 additions and 0 deletions
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17
mfbt/Vector.h
View File

@ -519,6 +519,11 @@ public:
/* mutators */
/**
* Reverse the order of the elements in the vector in place.
*/
void reverse();
/**
* Given that the vector is empty and has no inline storage, grow to
* |capacity|.
@ -789,6 +794,18 @@ Vector<T, N, AP>::~Vector()
}
}
template<typename T, size_t N, class AP>
MOZ_ALWAYS_INLINE void
Vector<T, N, AP>::reverse() {
MOZ_REENTRANCY_GUARD_ET_AL;
T* elems = mBegin;
size_t len = mLength;
size_t mid = len / 2;
for (size_t i = 0; i < mid; i++) {
Swap(elems[i], elems[len - i - 1]);
}
}
/*
* This function will create a new heap buffer with capacity aNewCap,
* move all elements in the inline buffer to this new buffer,

59
mfbt/tests/TestVector.cpp
View File

@ -19,6 +19,7 @@ struct mozilla::detail::VectorTesting
static void testReserved();
static void testConstRange();
static void testEmplaceBack();
static void testReverse();
};
void
@ -164,10 +165,68 @@ mozilla::detail::VectorTesting::testEmplaceBack()
}
}
void
mozilla::detail::VectorTesting::testReverse()
{
// Use UniquePtr to make sure that reverse() can handler move-only types.
Vector<UniquePtr<uint8_t>, 0> vec;
// Reverse an odd number of elements.
for (uint8_t i = 0; i < 5; i++) {
auto p = MakeUnique<uint8_t>(i);
MOZ_RELEASE_ASSERT(p);
MOZ_RELEASE_ASSERT(vec.append(mozilla::Move(p)));
}
vec.reverse();
MOZ_RELEASE_ASSERT(*vec[0] == 4);
MOZ_RELEASE_ASSERT(*vec[1] == 3);
MOZ_RELEASE_ASSERT(*vec[2] == 2);
MOZ_RELEASE_ASSERT(*vec[3] == 1);
MOZ_RELEASE_ASSERT(*vec[4] == 0);
// Reverse an even number of elements.
vec.popBack();
vec.reverse();
MOZ_RELEASE_ASSERT(*vec[0] == 1);
MOZ_RELEASE_ASSERT(*vec[1] == 2);
MOZ_RELEASE_ASSERT(*vec[2] == 3);
MOZ_RELEASE_ASSERT(*vec[3] == 4);
// Reverse an empty vector.
vec.clear();
MOZ_RELEASE_ASSERT(vec.length() == 0);
vec.reverse();
MOZ_RELEASE_ASSERT(vec.length() == 0);
// Reverse a vector using only inline storage.
Vector<UniquePtr<uint8_t>, 5> vec2;
for (uint8_t i = 0; i < 5; i++) {
auto p = MakeUnique<uint8_t>(i);
MOZ_RELEASE_ASSERT(p);
MOZ_RELEASE_ASSERT(vec2.append(mozilla::Move(p)));
}
vec2.reverse();
MOZ_RELEASE_ASSERT(*vec2[0] == 4);
MOZ_RELEASE_ASSERT(*vec2[1] == 3);
MOZ_RELEASE_ASSERT(*vec2[2] == 2);
MOZ_RELEASE_ASSERT(*vec2[3] == 1);
MOZ_RELEASE_ASSERT(*vec2[4] == 0);
}
int
main()
{
VectorTesting::testReserved();
VectorTesting::testConstRange();
VectorTesting::testEmplaceBack();
VectorTesting::testReverse();
}