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authorGravatar Abseil Team <absl-team@google.com>2018-06-28 10:18:50 -0700
committerGravatar Alex Strelnikov <strel@google.com>2018-06-28 15:01:10 -0400
commitba8d6cf07766263723e86736f20a51c1c9c67b19 (patch)
treefb520ff02a8b1e34b36c4b6e2654dc530cc40671 /absl/container/fixed_array.h
parentbe1e84b988fceabcea4fc9e93f899539f0c81901 (diff)
Export of internal Abseil changes.
-- 6769c6ebe79804063d68d70a5623a1475d63aeff by Alex Strelnikov <strel@google.com>: Import of CCTZ from GitHub. PiperOrigin-RevId: 202500218 -- c65cc4af08b8c48ca65f0816c1d2f59c7de7b0a5 by Derek Mauro <dmauro@google.com>: Fix DirectMMap on s390x (GitHub #135). This is *untested* because no s390x system is available. PiperOrigin-RevId: 202484458 -- 0ae7b628d7859cb3af169d007c29efd7917bb3ea by Abseil Team <absl-team@google.com>: Changes the Holder's compile-type type decision making to a std::conditional for improved readability PiperOrigin-RevId: 202340646 GitOrigin-RevId: 6769c6ebe79804063d68d70a5623a1475d63aeff Change-Id: I8f9d049ee279b1b1e3381fdf7e6fe9a4ea228306
Diffstat (limited to 'absl/container/fixed_array.h')
-rw-r--r--absl/container/fixed_array.h51
1 files changed, 21 insertions, 30 deletions
diff --git a/absl/container/fixed_array.h b/absl/container/fixed_array.h
index 295f0108..990b65dd 100644
--- a/absl/container/fixed_array.h
+++ b/absl/container/fixed_array.h
@@ -78,6 +78,8 @@ constexpr static auto kFixedArrayUseDefault = static_cast<size_t>(-1);
// operators.
template <typename T, size_t inlined = kFixedArrayUseDefault>
class FixedArray {
+ static_assert(!std::is_array<T>::value || std::extent<T>::value > 0,
+ "Arrays with unknown bounds cannot be used with FixedArray.");
static constexpr size_t kInlineBytesDefault = 256;
// std::iterator_traits isn't guaranteed to be SFINAE-friendly until C++17,
@@ -337,11 +339,12 @@ class FixedArray {
}
private:
- // HolderTraits
+ // Holder
//
- // Wrapper to hold elements of type T for the case where T is an array type.
- // If 'T' is an array type, HolderTraits::type is a struct with a 'T v;'.
- // Otherwise, HolderTraits::type is simply 'T'.
+ // Wrapper for holding elements of type T for both the case where T is a
+ // C-style array type and the general case where it is not. This is needed for
+ // construction and destruction of the entire array regardless of how many
+ // dimensions it has.
//
// Maintainer's Note: The simpler solution would be to simply wrap T in a
// struct whether it's an array or not: 'struct Holder { T v; };', but
@@ -356,35 +359,23 @@ class FixedArray {
// error: call to int __builtin___sprintf_chk(etc...)
// will always overflow destination buffer [-Werror]
//
- class HolderTraits {
- template <typename U>
- struct SelectImpl {
- using type = U;
- static pointer AsValue(type* p) { return p; }
- };
-
- // Partial specialization for elements of array type.
- template <typename U, size_t N>
- struct SelectImpl<U[N]> {
- struct Holder { U v[N]; };
- using type = Holder;
- static pointer AsValue(type* p) { return &p->v; }
- };
- using Impl = SelectImpl<value_type>;
+ template <typename OuterT = value_type,
+ typename InnerT = absl::remove_extent_t<OuterT>,
+ size_t InnerN = std::extent<OuterT>::value>
+ struct ArrayHolder {
+ InnerT array[InnerN];
+ };
- public:
- using type = typename Impl::type;
+ using Holder = absl::conditional_t<std::is_array<value_type>::value,
+ ArrayHolder<value_type>, value_type>;
- static pointer AsValue(type *p) { return Impl::AsValue(p); }
+ static_assert(sizeof(Holder) == sizeof(value_type), "");
+ static_assert(alignof(Holder) == alignof(value_type), "");
- // TODO(billydonahue): fix the type aliasing violation
- // this assertion hints at.
- static_assert(sizeof(type) == sizeof(value_type),
- "Holder must be same size as value_type");
- };
-
- using Holder = typename HolderTraits::type;
- static pointer AsValue(Holder *p) { return HolderTraits::AsValue(p); }
+ static pointer AsValue(pointer ptr) { return ptr; }
+ static pointer AsValue(ArrayHolder<value_type>* ptr) {
+ return std::addressof(ptr->array);
+ }
// InlineSpace
//