[ADT] Implement EnumeratedArray with std::array (NFC) #158407
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EnumeratedArray provides an std::array-like interface except that you
access the array with an enum index. Now, the problem is that because
the underlying array is implemented as a C array, we have to mirror
what std::array would do:
iterator end() { return begin() + size(); }
reverse_iterator rbegin() { return reverse_iterator(end()); }
This patch switches to the std::array. This way, we just have to
"forward" calls to begin, end, rbegin, rend, etc. Also, we benefit
from std::array::fill in one of the constructors.
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@llvm/pr-subscribers-llvm-adt Author: Kazu Hirata (kazutakahirata) ChangesEnumeratedArray provides an std::array-like interface except that you iterator end() { return begin() + size(); } reverse_iterator rbegin() { return reverse_iterator(end()); } This patch switches to the std::array. This way, we just have to Full diff: https://github.com/llvm/llvm-project/pull/158407.diff 1 Files Affected:
diff --git a/llvm/include/llvm/ADT/EnumeratedArray.h b/llvm/include/llvm/ADT/EnumeratedArray.h
index 93e1327306175..de150dfa3c3c2 100644
--- a/llvm/include/llvm/ADT/EnumeratedArray.h
+++ b/llvm/include/llvm/ADT/EnumeratedArray.h
@@ -15,8 +15,8 @@
#ifndef LLVM_ADT_ENUMERATEDARRAY_H
#define LLVM_ADT_ENUMERATEDARRAY_H
+#include <array>
#include <cassert>
-#include <iterator>
namespace llvm {
@@ -24,12 +24,14 @@ template <typename ValueType, typename Enumeration,
Enumeration LargestEnum = Enumeration::Last, typename IndexType = int,
IndexType Size = 1 + static_cast<IndexType>(LargestEnum)>
class EnumeratedArray {
-public:
- using iterator = ValueType *;
- using const_iterator = const ValueType *;
+ using ArrayTy = std::array<ValueType, Size>;
+ ArrayTy Underlying;
- using const_reverse_iterator = std::reverse_iterator<const_iterator>;
- using reverse_iterator = std::reverse_iterator<iterator>;
+public:
+ using iterator = typename ArrayTy::iterator;
+ using const_iterator = typename ArrayTy::const_iterator;
+ using reverse_iterator = typename ArrayTy::reverse_iterator;
+ using const_reverse_iterator = typename ArrayTy::const_reverse_iterator;
using value_type = ValueType;
using reference = ValueType &;
@@ -38,11 +40,7 @@ class EnumeratedArray {
using const_pointer = const ValueType *;
EnumeratedArray() = default;
- EnumeratedArray(ValueType V) {
- for (IndexType IX = 0; IX < Size; ++IX) {
- Underlying[IX] = V;
- }
- }
+ EnumeratedArray(ValueType V) { Underlying.fill(V); }
EnumeratedArray(std::initializer_list<ValueType> Init) {
assert(Init.size() == Size && "Incorrect initializer size");
for (IndexType IX = 0; IX < Size; ++IX) {
@@ -62,23 +60,15 @@ class EnumeratedArray {
IndexType size() const { return Size; }
bool empty() const { return size() == 0; }
- iterator begin() { return Underlying; }
- const_iterator begin() const { return Underlying; }
-
- iterator end() { return begin() + size(); }
- const_iterator end() const { return begin() + size(); }
-
- reverse_iterator rbegin() { return reverse_iterator(end()); }
- const_reverse_iterator rbegin() const {
- return const_reverse_iterator(end());
- }
- reverse_iterator rend() { return reverse_iterator(begin()); }
- const_reverse_iterator rend() const {
- return const_reverse_iterator(begin());
- }
+ iterator begin() { return Underlying.begin(); }
+ const_iterator begin() const { return Underlying.begin(); }
+ iterator end() { return Underlying.end(); }
+ const_iterator end() const { return Underlying.end(); }
-private:
- ValueType Underlying[Size];
+ reverse_iterator rbegin() { return Underlying.rbegin(); }
+ const_reverse_iterator rbegin() const { return Underlying.rbegin(); }
+ reverse_iterator rend() { return Underlying.rend(); }
+ const_reverse_iterator rend() const { return Underlying.rend(); }
};
} // namespace llvm
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kuhar
approved these changes
Sep 13, 2025
kuhar
reviewed
Sep 13, 2025
| Underlying[IX] = V; | ||
| } | ||
| } | ||
| EnumeratedArray(ValueType V) { Underlying.fill(V); } | ||
| EnumeratedArray(std::initializer_list<ValueType> Init) { |
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EnumeratedArray provides an std::array-like interface except that you
access the array with an enum index. Now, the problem is that because
the underlying array is implemented as a C array, we have to mirror
what std::array would do:
iterator end() { return begin() + size(); }
reverse_iterator rbegin() { return reverse_iterator(end()); }
This patch switches to the std::array. This way, we just have to
"forward" calls to begin, end, rbegin, rend, etc. Also, we benefit
from std::array::fill in one of the constructors.