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Commit 00478de3 by Abseil Team Committed by Copybara-Service
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Mark non-modifying container algorithms as constexpr for C++20. 

This change marks Abseil's non-modifying sequence operations including
absl::linear_search and absl::c_linear_search as constexpr when building with
C++20.
PiperOrigin-RevId: 659812405
Change-Id: I8dc2cee873f30531b2eb8fb3da12085505a43a1a
parent 809e5de7
Showing with 225 additions and 6 deletions
absl/algorithm/algorithm.h
......@@ -53,8 +53,8 @@ using std::rotate;
// n = (`last` - `first`) comparisons. A linear search over short containers
// may be faster than a binary search, even when the container is sorted.
template <typename InputIterator, typename EqualityComparable>
bool linear_search(InputIterator first, InputIterator last,
const EqualityComparable& value) {
ABSL_INTERNAL_CONSTEXPR_SINCE_CXX20 bool linear_search(
InputIterator first, InputIterator last, const EqualityComparable& value) {
return std::find(first, last, value) != last;
}
......
absl/algorithm/algorithm_test.cc
......@@ -14,11 +14,9 @@
#include "absl/algorithm/algorithm.h"
#include <algorithm>
#include <list>
#include <array>
#include <vector>
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include "absl/base/config.h"
......@@ -47,4 +45,16 @@ TEST_F(LinearSearchTest, linear_searchConst) {
absl::linear_search(const_container->begin(), const_container->end(), 4));
}
#if defined(ABSL_INTERNAL_CPLUSPLUS_LANG) && \
ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
TEST_F(LinearSearchTest, Constexpr) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::linear_search(kArray.begin(), kArray.end(), 3));
static_assert(!absl::linear_search(kArray.begin(), kArray.end(), 4));
}
#endif // defined(ABSL_INTERNAL_CPLUSPLUS_LANG) &&
// ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
} // namespace
absl/algorithm/container_test.cc
......@@ -1164,6 +1164,7 @@ TEST(MutatingTest, PermutationOperations) {
#if defined(ABSL_INTERNAL_CPLUSPLUS_LANG) && \
ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L
TEST(ConstexprTest, Distance) {
// Works at compile time with constexpr containers.
static_assert(absl::c_distance(std::array<int, 3>()) == 3);
......@@ -1203,8 +1204,216 @@ TEST(ConstexprTest, MinMaxElementWithPredicate) {
static_assert(*kMinMaxPair.first == 3);
static_assert(*kMinMaxPair.second == 1);
}
#endif // defined(ABSL_INTERNAL_CPLUSPLUS_LANG) &&
// ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L
#if defined(ABSL_INTERNAL_CPLUSPLUS_LANG) && \
ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
TEST(ConstexprTest, LinearSearch) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_linear_search(kArray, 3));
static_assert(!absl::c_linear_search(kArray, 4));
}
TEST(ConstexprTest, AllOf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(!absl::c_all_of(kArray, [](int x) { return x > 1; }));
static_assert(absl::c_all_of(kArray, [](int x) { return x > 0; }));
}
TEST(ConstexprTest, AnyOf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_any_of(kArray, [](int x) { return x > 2; }));
static_assert(!absl::c_any_of(kArray, [](int x) { return x > 5; }));
}
TEST(ConstexprTest, NoneOf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(!absl::c_none_of(kArray, [](int x) { return x > 2; }));
static_assert(absl::c_none_of(kArray, [](int x) { return x > 5; }));
}
TEST(ConstexprTest, ForEach) {
static constexpr std::array<int, 3> kArray = [] {
std::array<int, 3> array = {1, 2, 3};
absl::c_for_each(array, [](int& x) { x += 1; });
return array;
}();
static_assert(kArray == std::array{2, 3, 4});
}
TEST(ConstexprTest, Find) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_find(kArray, 1) == kArray.begin());
static_assert(absl::c_find(kArray, 4) == kArray.end());
}
TEST(ConstexprTest, Contains) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_contains(kArray, 1));
static_assert(!absl::c_contains(kArray, 4));
}
TEST(ConstexprTest, FindIf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_find_if(kArray, [](int x) { return x > 2; }) ==
kArray.begin() + 2);
static_assert(absl::c_find_if(kArray, [](int x) { return x > 5; }) ==
kArray.end());
}
TEST(ConstexprTest, FindIfNot) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_find_if_not(kArray, [](int x) { return x > 1; }) ==
kArray.begin());
static_assert(absl::c_find_if_not(kArray, [](int x) { return x > 0; }) ==
kArray.end());
}
TEST(ConstexprTest, FindEnd) {
static constexpr std::array<int, 5> kHaystack = {1, 2, 3, 2, 3};
static constexpr std::array<int, 2> kNeedle = {2, 3};
static_assert(absl::c_find_end(kHaystack, kNeedle) == kHaystack.begin() + 3);
}
TEST(ConstexprTest, FindFirstOf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_find_first_of(kArray, kArray) == kArray.begin());
}
TEST(ConstexprTest, AdjacentFind) {
static constexpr std::array<int, 4> kArray = {1, 2, 2, 3};
static_assert(absl::c_adjacent_find(kArray) == kArray.begin() + 1);
}
TEST(ConstexprTest, AdjacentFindWithPredicate) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_adjacent_find(kArray, std::less<int>()) ==
kArray.begin());
}
TEST(ConstexprTest, Count) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_count(kArray, 1) == 1);
static_assert(absl::c_count(kArray, 2) == 1);
static_assert(absl::c_count(kArray, 3) == 1);
static_assert(absl::c_count(kArray, 4) == 0);
}
TEST(ConstexprTest, CountIf) {
static constexpr std::array<int, 3> kArray = {1, 2, 3};
static_assert(absl::c_count_if(kArray, [](int x) { return x > 0; }) == 3);
static_assert(absl::c_count_if(kArray, [](int x) { return x > 1; }) == 2);
}
TEST(ConstexprTest, Mismatch) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_mismatch(kArray1, kArray2) ==
std::pair{kArray1.end(), kArray2.end()});
static_assert(absl::c_mismatch(kArray1, kArray3) ==
std::pair{kArray1.begin(), kArray3.begin()});
}
TEST(ConstexprTest, MismatchWithPredicate) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_mismatch(kArray1, kArray2, std::not_equal_to<int>()) ==
std::pair{kArray1.begin(), kArray2.begin()});
static_assert(absl::c_mismatch(kArray1, kArray3, std::not_equal_to<int>()) ==
std::pair{kArray1.end(), kArray3.end()});
}
TEST(ConstexprTest, Equal) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_equal(kArray1, kArray2));
static_assert(!absl::c_equal(kArray1, kArray3));
}
TEST(ConstexprTest, EqualWithPredicate) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(!absl::c_equal(kArray1, kArray2, std::not_equal_to<int>()));
static_assert(absl::c_equal(kArray1, kArray3, std::not_equal_to<int>()));
}
TEST(ConstexprTest, IsPermutation) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {3, 2, 1};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_is_permutation(kArray1, kArray2));
static_assert(!absl::c_is_permutation(kArray1, kArray3));
}
TEST(ConstexprTest, IsPermutationWithPredicate) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {3, 2, 1};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_is_permutation(kArray1, kArray2, std::equal_to<int>()));
static_assert(
!absl::c_is_permutation(kArray1, kArray3, std::equal_to<int>()));
}
TEST(ConstexprTest, Search) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_search(kArray1, kArray2) == kArray1.begin());
static_assert(absl::c_search(kArray1, kArray3) == kArray1.end());
}
TEST(ConstexprTest, SearchWithPredicate) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_search(kArray1, kArray2, std::not_equal_to<int>()) ==
kArray1.end());
static_assert(absl::c_search(kArray1, kArray3, std::not_equal_to<int>()) ==
kArray1.begin());
}
TEST(ConstexprTest, ContainsSubrange) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(absl::c_contains_subrange(kArray1, kArray2));
static_assert(!absl::c_contains_subrange(kArray1, kArray3));
}
TEST(ConstexprTest, ContainsSubrangeWithPredicate) {
static constexpr std::array<int, 3> kArray1 = {1, 2, 3};
static constexpr std::array<int, 3> kArray2 = {1, 2, 3};
static constexpr std::array<int, 3> kArray3 = {2, 3, 4};
static_assert(
!absl::c_contains_subrange(kArray1, kArray2, std::not_equal_to<>()));
static_assert(
absl::c_contains_subrange(kArray1, kArray3, std::not_equal_to<>()));
}
TEST(ConstexprTest, SearchN) {
static constexpr std::array<int, 4> kArray = {1, 2, 2, 3};
static_assert(absl::c_search_n(kArray, 1, 1) == kArray.begin());
static_assert(absl::c_search_n(kArray, 2, 2) == kArray.begin() + 1);
static_assert(absl::c_search_n(kArray, 1, 4) == kArray.end());
}
TEST(ConstexprTest, SearchNWithPredicate) {
static constexpr std::array<int, 4> kArray = {1, 2, 2, 3};
static_assert(absl::c_search_n(kArray, 1, 1, std::not_equal_to<int>()) ==
kArray.begin() + 1);
static_assert(absl::c_search_n(kArray, 2, 2, std::not_equal_to<int>()) ==
kArray.end());
static_assert(absl::c_search_n(kArray, 1, 4, std::not_equal_to<int>()) ==
kArray.begin());
}
#endif // defined(ABSL_INTERNAL_CPLUSPLUS_LANG) &&
// ABSL_INTERNAL_CPLUSPLUS_LANG >= 202002L
} // namespace
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