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<flat_map>: Simplify duplicate definitions of lookup functions using explicit object parameter #5987

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Merged
Stephan T. Lavavej (StephanTLavavej) merged 13 commits into from
Jan 5, 2026
Merged

<flat_map>: Simplify duplicate definitions of lookup functions using explicit object parameter #5987

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4c4df7a
Remove redundant overloads of _Flap_map_base::_Lower_bound, _Upper_bo…
vmichal Jan 4, 2026
ba65878
Fix formatting and ref qualifiers on deduced this.
vmichal Jan 4, 2026
88ff284
Use _STD begin instead of member begin.
vmichal Jan 4, 2026
733086c
Add tests to verify changes cause no regression.
vmichal Jan 4, 2026
7b6cd28
Also test heterogeneous lookup. Remove std:: qualifications from tests
vmichal Jan 4, 2026
3658ec2
Simplify flat_map::_At by deducing this.
vmichal Jan 4, 2026
afa3d25
Uglify: `return_type` => `_Maybe_const_iter`
StephanTLavavej Jan 5, 2026
cc50bf7
Drop `_STD` for type aliases and variable templates.
StephanTLavavej Jan 5, 2026
79787eb
All shall love CTAD and despair.
StephanTLavavej Jan 5, 2026
6d42f4e
Template param order should follow function param order.
StephanTLavavej Jan 5, 2026
edc2750
Avoid abbreviated function templates.
StephanTLavavej Jan 5, 2026
7930df0
We don't need `remove_reference_t` for `_SelfTy`.
StephanTLavavej Jan 5, 2026
8aa78fc
Comment: "deduced this" => "deducing this"
StephanTLavavej Jan 5, 2026
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113 changes: 27 additions & 86 deletions stl/inc/flat_map
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Original file line number Diff line number Diff line change
Expand Up @@ -1099,25 +1099,14 @@ private:
return _Count;
}

template <class _KeyTy>
_NODISCARD iterator _Find(const _KeyTy& _Key_val) {
template <class _SelfTy, class _KeyTy>
_NODISCARD auto _Find(this _SelfTy& _Self, const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
iterator _Position = lower_bound(_Key_val);
if (_Position != end() && !_Key_compare(_Key_val, _Position->first)) {
const auto _Position = _Self.lower_bound(_Key_val);
if (_Position != _Self.end() && !_Self._Key_compare(_Key_val, _Position->first)) {
return _Position;
} else {
return end();
}
}

template <class _KeyTy>
_NODISCARD const_iterator _Find(const _KeyTy& _Key_val) const {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const_iterator _Position = lower_bound(_Key_val);
if (_Position != cend() && !_Key_compare(_Key_val, _Position->first)) {
return _Position;
} else {
return cend();
return _Self.end();
}
}

Expand All @@ -1133,74 +1122,37 @@ private:
return find(_Key_val) != cend();
}

template <class _KeyTy>
_NODISCARD iterator _Lower_bound(const _KeyTy& _Key_val) {
template <class _SelfTy, class _KeyTy, class _BoundFn>
_NODISCARD auto _Find_bound(this _SelfTy& _Self, const _KeyTy& _Key_val, _BoundFn _Bound_fun) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Key_unchecked_begin = _STD _Get_unwrapped(_STD cbegin(_Data.keys));
const auto _Key_unchecked_it = _STD lower_bound(
_Key_unchecked_begin, _STD _Get_unwrapped(_STD cend(_Data.keys)), _Key_val, _Pass_key_comp());
const auto _Key_unchecked_begin = _STD _Get_unwrapped(_STD cbegin(_Self._Data.keys));
const auto _Key_unchecked_it = _Bound_fun(
_Key_unchecked_begin, _STD _Get_unwrapped(_STD cend(_Self._Data.keys)), _Key_val, _Self._Pass_key_comp());
const auto _Dist = _Key_unchecked_it - _Key_unchecked_begin;

auto _Key_it = _STD cbegin(_Data.keys);
_STD _Seek_wrapped(_Key_it, _Key_unchecked_it);
auto _Val_it = _Data.values.begin() + static_cast<_RANGES range_difference_t<_MappedContainer>>(_Dist);
return iterator{_STD move(_Key_it), _STD move(_Val_it)};
}

template <class _KeyTy>
_NODISCARD const_iterator _Lower_bound(const _KeyTy& _Key_val) const {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Key_unchecked_begin = _STD _Get_unwrapped(_STD cbegin(_Data.keys));
const auto _Key_unchecked_it = _STD lower_bound(
_Key_unchecked_begin, _STD _Get_unwrapped(_STD cend(_Data.keys)), _Key_val, _Pass_key_comp());
const auto _Dist = _Key_unchecked_it - _Key_unchecked_begin;

auto _Key_it = _STD cbegin(_Data.keys);
auto _Key_it = _STD cbegin(_Self._Data.keys);
_STD _Seek_wrapped(_Key_it, _Key_unchecked_it);
auto _Val_it =
_STD cbegin(_Data.values) + static_cast<_RANGES range_difference_t<const _MappedContainer>>(_Dist);
return const_iterator{_STD move(_Key_it), _STD move(_Val_it)};
}

template <class _KeyTy>
_NODISCARD iterator _Upper_bound(const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Key_unchecked_begin = _STD _Get_unwrapped(_STD cbegin(_Data.keys));
const auto _Key_unchecked_it = _STD upper_bound(
_Key_unchecked_begin, _STD _Get_unwrapped(_STD cend(_Data.keys)), _Key_val, _Pass_key_comp());
const auto _Dist = _Key_unchecked_it - _Key_unchecked_begin;
_STD begin(_Self._Data.values) + static_cast<_RANGES range_difference_t<mapped_container_type>>(_Dist);

auto _Key_it = _STD cbegin(_Data.keys);
_STD _Seek_wrapped(_Key_it, _Key_unchecked_it);
auto _Val_it = _Data.values.begin() + static_cast<_RANGES range_difference_t<_MappedContainer>>(_Dist);
return iterator{_STD move(_Key_it), _STD move(_Val_it)};
using _Maybe_const_iter = conditional_t<is_const_v<_SelfTy>, const_iterator, iterator>;
return _Maybe_const_iter{_STD move(_Key_it), _STD move(_Val_it)};
}

template <class _KeyTy>
_NODISCARD const_iterator _Upper_bound(const _KeyTy& _Key_val) const {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Key_unchecked_begin = _STD _Get_unwrapped(_STD cbegin(_Data.keys));
const auto _Key_unchecked_it = _STD upper_bound(
_Key_unchecked_begin, _STD _Get_unwrapped(_STD cend(_Data.keys)), _Key_val, _Pass_key_comp());
const auto _Dist = _Key_unchecked_it - _Key_unchecked_begin;

auto _Key_it = _STD cbegin(_Data.keys);
_STD _Seek_wrapped(_Key_it, _Key_unchecked_it);
auto _Val_it =
_STD cbegin(_Data.values) + static_cast<_RANGES range_difference_t<const _MappedContainer>>(_Dist);
return const_iterator{_STD move(_Key_it), _STD move(_Val_it)};
template <class _SelfTy, class _KeyTy>
_NODISCARD auto _Lower_bound(this _SelfTy& _Self, const _KeyTy& _Key_val) {
return _Self._Find_bound(_Key_val, _RANGES lower_bound);
}

template <class _KeyTy>
_NODISCARD pair<iterator, iterator> _Equal_range(const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
return {lower_bound(_Key_val), upper_bound(_Key_val)};
template <class _SelfTy, class _KeyTy>
_NODISCARD auto _Upper_bound(this _SelfTy& _Self, const _KeyTy& _Key_val) {
return _Self._Find_bound(_Key_val, _RANGES upper_bound);
}

template <class _KeyTy>
_NODISCARD pair<const_iterator, const_iterator> _Equal_range(const _KeyTy& _Key_val) const {
template <class _SelfTy, class _KeyTy>
_NODISCARD auto _Equal_range(this _SelfTy& _Self, const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
return {lower_bound(_Key_val), upper_bound(_Key_val)};
return pair{_Self.lower_bound(_Key_val), _Self.upper_bound(_Key_val)};
}
};

Expand Down Expand Up @@ -1399,22 +1351,11 @@ private:
using _Mybase::_Key_equal;
using _Mybase::_Pass_key_comp;

template <class _KeyTy>
_NODISCARD mapped_type& _At(const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Position = this->find(_Key_val);
if (_Position == this->end()) {
_Xout_of_range("invalid flat_map key");
}

return _Position->second;
}

template <class _KeyTy>
_NODISCARD const mapped_type& _At(const _KeyTy& _Key_val) const {
template <class _SelfTy, class _KeyTy>
_NODISCARD auto& _At(this _SelfTy& _Self, const _KeyTy& _Key_val) {
_STL_INTERNAL_STATIC_ASSERT(is_same_v<_KeyTy, key_type> || _Transparent<key_compare>);
const auto _Position = this->find(_Key_val);
if (_Position == this->end()) {
const auto _Position = _Self.find(_Key_val);
if (_Position == _Self.end()) {
_Xout_of_range("invalid flat_map key");
}

Expand Down
24 changes: 24 additions & 0 deletions tests/std/tests/P0429R9_flat_map/test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -766,6 +766,29 @@ void test_throwing_compare_swap() {
test_throwing_compare_swap_single<flat_multimap, deque, deque>();
}

// Test that changes in GH-5987 did not break calls of lookup member functions by using deducing this.
template <typename T>
void test_lookup_call_on_temporaries_single() {
(void) T{}.lower_bound(42);
(void) T{}.lower_bound('a');
(void) T{}.upper_bound(42);
(void) T{}.upper_bound('a');
(void) T{}.equal_range(42);
(void) T{}.equal_range('a');
(void) T{}.find(42);
(void) T{}.find('a');
}

void test_lookup_call_on_temporaries() {
test_lookup_call_on_temporaries_single<flat_map<int, int>>();
test_lookup_call_on_temporaries_single<flat_multimap<int, int>>();
try {
(void) flat_map<int, int>{}.at(42);
(void) flat_map<int, int>{}.at('a');
} catch (...) {
}
}

int main() {
test_construction();
test_pointer_to_incomplete_type();
Expand All @@ -776,4 +799,5 @@ int main() {
test_insert_or_assign();
test_comparison();
test_throwing_compare_swap();
test_lookup_call_on_temporaries();
}
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