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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#include <gtest/gtest.h>
#include <gmock/gmock.h>
#include <ranges>
/**
* Checks that all elements of a forward iterable range are distinct, i.e. the following must hold:
* - for any single element `foo`, foo == foo is true
* - for any two separate elements `foo` and `bar`, foo == bar is false
*/
MATCHER(ElementsAreDistinct, "") {
const auto& range = arg;
static_assert(std::ranges::forward_range<decltype(range)>);
const auto end = std::ranges::cend(range);
// Explicitly count element positions instead of comparing iterators to avoid depending
// on iterators being comparable with each other.
size_t i = 0;
for (auto lhs = std::ranges::cbegin(range); lhs != end; ++lhs, ++i) {
size_t j = 0;
for (auto rhs = std::ranges::cbegin(range); rhs != end; ++rhs, ++j) {
if (i != j) {
if (*lhs == *rhs) {
*result_listener << "Expected elements to be distinct, but element at position "
<< i << " (" << *lhs << ") is equal to element at position "
<< j << " (" << *rhs << ")";
return false;
}
} else if (!(*lhs == *rhs)) {
*result_listener << "Element at position " << i << " (" << *lhs << ") does not equal itself";
return false;
}
}
}
return true;
}
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