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Add is_back_insert_iterator

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This commit is contained in:
Victor Zverovich 2024-01-07 16:44:42 -08:00
parent 17f79ac6cf
commit df67df7b4c
2 changed files with 17 additions and 11 deletions
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21
include/fmt/core.h
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@ -356,11 +356,6 @@ template <typename Container> class back_insert_iterator {
auto operator++(int) -> back_insert_iterator { return *this; } auto operator++(int) -> back_insert_iterator { return *this; }
}; };
template <typename Container>
auto back_inserter(Container& c) -> back_insert_iterator<Container> {
return {c};
}
// An enable_if helper to be used in template parameters which results in much // An enable_if helper to be used in template parameters which results in much
// shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed // shorter symbols: https://godbolt.org/z/sWw4vP. Extra parentheses are needed
// to workaround a bug in MSVC 2019 (see #1140 and #1186). // to workaround a bug in MSVC 2019 (see #1140 and #1186).
@ -1061,7 +1056,7 @@ class iterator_buffer<back_insert_iterator<Container>,
: iterator_buffer(get_container(out)) {} : iterator_buffer(get_container(out)) {}
auto out() -> back_insert_iterator<Container> { auto out() -> back_insert_iterator<Container> {
return fmt::back_inserter(container_); return back_inserter(container_);
} }
}; };
@ -1562,10 +1557,14 @@ struct is_output_iterator<
It, T, void_t<decltype(*std::declval<It&>()++ = std::declval<T>())>> It, T, void_t<decltype(*std::declval<It&>()++ = std::declval<T>())>>
: std::true_type {}; : std::true_type {};
template <typename It> struct is_back_insert_iterator : std::false_type {}; template <typename It, typename Enable = std::true_type>
template <typename Container> struct is_back_insert_iterator : std::false_type {};
struct is_back_insert_iterator<back_insert_iterator<Container>> template <typename It>
: std::true_type {}; struct is_back_insert_iterator<
It, bool_constant<std::is_same<
decltype(back_inserter(
std::declval<typename It::container_type&>())),
It>::value>> : std::true_type {};
// A type-erased reference to an std::locale to avoid a heavy <locale> include. // A type-erased reference to an std::locale to avoid a heavy <locale> include.
class locale_ref { class locale_ref {
@ -2873,7 +2872,7 @@ auto vformat_to(OutputIt out, string_view fmt, format_args args) -> OutputIt {
**Example**:: **Example**::
auto out = std::vector<char>(); auto out = std::vector<char>();
fmt::format_to(fmt::back_inserter(out), "{}", 42); fmt::format_to(std::back_inserter(out), "{}", 42);
\endrst \endrst
*/ */
template <typename OutputIt, typename... T, template <typename OutputIt, typename... T,

7
test/core-test.cc
View File

@ -105,6 +105,13 @@ TEST(core_test, is_output_iterator) {
char>::value)); char>::value));
} }
TEST(core_test, is_back_insert_iterator) {
EXPECT_TRUE(fmt::detail::is_back_insert_iterator<
std::back_insert_iterator<std::string>>::value);
EXPECT_FALSE(fmt::detail::is_back_insert_iterator<
std::front_insert_iterator<std::string>>::value);
}
TEST(core_test, buffer_appender) { TEST(core_test, buffer_appender) {
#ifdef __cpp_lib_ranges #ifdef __cpp_lib_ranges
static_assert(std::output_iterator<fmt::detail::buffer_appender<char>, char>); static_assert(std::output_iterator<fmt::detail::buffer_appender<char>, char>);