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Bug 1677092: add constexpr AnyOf. r=sg

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The STL supports it only with C++20.

Differential Revision: https://phabricator.services.mozilla.com/D97123
This commit is contained in:
Mirko Brodesser 2020-11-17 08:30:12 +00:00
parent f23f8b8c50
commit e0d88600e7
2 changed files with 39 additions and 1 deletions
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12
mfbt/Algorithm.h
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@ -28,6 +28,18 @@ constexpr bool AllOf(Iter aFirst, Iter aLast, Pred aPred) {
return true;
}
// Like C++20's `std::any_of`.
template <typename Iter, typename Pred>
constexpr bool AnyOf(Iter aFirst, Iter aLast, Pred aPred) {
for (; aFirst != aLast; ++aFirst) {
if (aPred(*aFirst)) {
return true;
}
}
return false;
}
namespace detail {
template <typename Transform, typename SrcIter>
using ArrayElementTransformType = typename std::invoke_result_t<

28
mfbt/tests/TestAlgorithm.cpp
View File

@ -7,13 +7,15 @@
#include "mozilla/Algorithm.h"
#include "mozilla/ArrayUtils.h"
#include "mozilla/Assertions.h"
#include <iterator>
static constexpr bool even(int32_t n) { return !(n & 1); }
static constexpr bool odd(int32_t n) { return (n & 1); }
using namespace mozilla;
void TestAllOf() {
using namespace mozilla;
using std::begin;
using std::end;
@ -36,7 +38,31 @@ void TestAllOf() {
static_assert(!AllOf(arr3, arr3 + ArrayLength(arr3), odd), "3-2");
}
void TestAnyOf() {
using std::begin;
using std::end;
// The Android NDK's STL doesn't support `constexpr` `std::array::begin`, see
// bug 1677484. Hence using a raw array here.
constexpr int32_t arr1[1] = {0};
static_assert(!AnyOf(arr1, arr1, even));
static_assert(!AnyOf(arr1, arr1, odd));
constexpr int32_t arr2[] = {1};
static_assert(!AnyOf(begin(arr2), end(arr2), even));
static_assert(AnyOf(begin(arr2), end(arr2), odd));
constexpr int32_t arr3[] = {2};
static_assert(AnyOf(begin(arr3), end(arr3), even));
static_assert(!AnyOf(begin(arr3), end(arr3), odd));
constexpr int32_t arr4[] = {1, 2};
static_assert(AnyOf(begin(arr4), end(arr4), even));
static_assert(AnyOf(begin(arr4), end(arr4), odd));
}
int main() {
TestAllOf();
TestAnyOf();
return 0;
}