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Dedup ADL begin/end lookup

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This commit is contained in:
Victor Zverovich
2024-04-22 15:45:20 -07:00
parent a3e0931ea2
commit 400f6a8ee2
2 changed files with 11 additions and 29 deletions
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28
include/fmt/ranges.h
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@@ -69,13 +69,13 @@ struct has_member_fn_begin_end_t<T, void_t<decltype(std::declval<T>().begin()),
decltype(std::declval<T>().end())>> decltype(std::declval<T>().end())>>
: std::true_type {}; : std::true_type {};
// Member function overload // Member function overloads.
template <typename T> template <typename T>
auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin()); auto range_begin(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).begin());
template <typename T> template <typename T>
auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end()); auto range_end(T&& rng) FMT_DECLTYPE_RETURN(static_cast<T&&>(rng).end());
// ADL overload. Only participates in overload resolution if member functions // ADL overloads. Only participate in overload resolution if member functions
// are not found. // are not found.
template <typename T> template <typename T>
auto range_begin(T&& rng) auto range_begin(T&& rng)
@@ -619,22 +619,6 @@ auto join(It begin, Sentinel end, string_view sep) -> join_view<It, Sentinel> {
return {begin, end, sep}; return {begin, end, sep};
} }
namespace detail {
// ADL helpers for fmt::join()
namespace adl {
using std::begin;
using std::end;
template <typename Range> auto adlbegin(Range& r) -> decltype(begin(r)) {
return begin(r);
}
template <typename Range> auto adlend(Range& r) -> decltype(end(r)) {
return end(r);
}
} // namespace adl
} // namespace detail
/** /**
\rst \rst
Returns a view that formats `range` with elements separated by `sep`. Returns a view that formats `range` with elements separated by `sep`.
@@ -652,10 +636,10 @@ template <typename Range> auto adlend(Range& r) -> decltype(end(r)) {
\endrst \endrst
*/ */
template <typename Range> template <typename Range>
auto join(Range&& range, string_view sep) auto join(Range&& r, string_view sep)
-> join_view<decltype(detail::adl::adlbegin(range)), -> join_view<decltype(detail::range_begin(r)),
decltype(detail::adl::adlend(range))> { decltype(detail::range_end(r))> {
return join(detail::adl::adlbegin(range), detail::adl::adlend(range), sep); return {detail::range_begin(r), detail::range_end(r), sep};
} }
template <typename Char, typename... T> struct tuple_join_view : detail::view { template <typename Char, typename... T> struct tuple_join_view : detail::view {

12
test/ranges-test.cc
View File

@@ -462,18 +462,16 @@ TEST(ranges_test, join_range) {
} }
namespace adl { namespace adl {
struct vec : std::vector<int> { struct vec {
using std::vector<int>::vector; // inherit all constructors int n[2] = {42, 43};
}; };
// ADL-found begin() and end() skip the first and last element auto begin(const vec& v) -> const int* { return v.n; }
auto begin(vec& v) -> typename vec::iterator { return v.begin() + 1; } auto end(const vec& v) -> const int* { return v.n + 2; }
auto end(vec& v) -> typename vec::iterator { return v.end() - 1; }
} }
TEST(ranges_test, format_join_adl_begin_end) { TEST(ranges_test, format_join_adl_begin_end) {
auto v = adl::vec{41, 42, 43, 44}; EXPECT_EQ(fmt::format("{}", fmt::join(adl::vec(), "/")), "42/43");
EXPECT_EQ(fmt::format("{}", fmt::join(v, "/")), "42/43");
} }
#endif // FMT_RANGES_TEST_ENABLE_JOIN #endif // FMT_RANGES_TEST_ENABLE_JOIN