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Fix the BinaryPredicate form of std::is_permutation to not rely on operator==

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According to [1], forms 2 and 4 of std::is_permutation should use the passed in
binary predicate to compare elements. operator== should only be used for forms
1 and 3 which do not take a binary predicate.

This CL fixes forms 2 and 4 which relied on operator== for some comparisons.

[1] http://en.cppreference.com/w/cpp/algorithm/is_permutation

Patch by Thomas Anderson!

Differential Revision: https://reviews.llvm.org/D42518

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@323563 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2018-01-26 21:23:27 +00:00
parent 44aacb7850
commit 27c341db41
2 changed files with 34 additions and 2 deletions
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12
include/algorithm
View File

@@ -1418,7 +1418,11 @@ is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
{
// Have we already counted the number of *__i in [f1, l1)?
if (find(__first1, __i, *__i) == __i) {
_ForwardIterator1 __match = __first1;
for (; __match != __i; ++__match)
if (__pred(*__match, *__i))
break;
if (__match == __i) {
// Count number of *__i in [f2, l2)
_D1 __c2 = 0;
for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)
@@ -1479,7 +1483,11 @@ __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
for (_ForwardIterator1 __i = __first1; __i != __last1; ++__i)
{
// Have we already counted the number of *__i in [f1, l1)?
if (find(__first1, __i, *__i) == __i) {
_ForwardIterator1 __match = __first1;
for (; __match != __i; ++__match)
if (__pred(*__match, *__i))
break;
if (__match == __i) {
// Count number of *__i in [f2, l2)
_D1 __c2 = 0;
for (_ForwardIterator2 __j = __first2; __j != __last2; ++__j)

24
test/std/algorithms/alg.nonmodifying/alg.is_permutation/is_permutation_pred.pass.cpp
View File

@@ -736,6 +736,30 @@ int main()
forward_iterator<const int*>(ib),
forward_iterator<const int*>(ib + sa),
std::equal_to<const int>()) == false);
#endif
}
{
struct S {
S(int i) : i_(i) {}
bool operator==(const S& other) = delete;
int i_;
};
struct eq {
bool operator()(const S& a, const S&b) { return a.i_ == b.i_; }
};
const S a[] = {S(0), S(1)};
const S b[] = {S(1), S(0)};
const unsigned sa = sizeof(a)/sizeof(a[0]);
assert(std::is_permutation(forward_iterator<const S*>(a),
forward_iterator<const S*>(a + sa),
forward_iterator<const S*>(b),
eq()));
#if TEST_STD_VER >= 14
assert(std::is_permutation(forward_iterator<const S*>(a),
forward_iterator<const S*>(a + sa),
forward_iterator<const S*>(b),
forward_iterator<const S*>(b + sa),
eq()));
#endif
}