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reimplement formatter<tuple_join_view> (#2457)

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* reimplement `formatter<tuple_join_view>`

1. completely reimplement `formatter<tuple_join_view<Char, T...>, Char>`
2. Add some tests

* use FMT_THROW
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sunmy2019 2021-08-24 00:51:19 +08:00 committed by GitHub
parent 4b8bda25c0
commit a44c8f651b
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2 changed files with 47 additions and 20 deletions
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54
include/fmt/ranges.h
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@ -629,42 +629,56 @@ template <typename Char, typename... T>
struct formatter<tuple_join_view<Char, T...>, Char> {
template <typename ParseContext>
FMT_CONSTEXPR auto parse(ParseContext& ctx) -> decltype(ctx.begin()) {
return ctx.begin();
return do_parse(ctx, std::integral_constant<size_t, sizeof...(T)>{});
}
template <typename FormatContext>
auto format(const tuple_join_view<Char, T...>& value, FormatContext& ctx) ->
typename FormatContext::iterator {
return format(value, ctx, detail::make_index_sequence<sizeof...(T)>{});
auto format(const tuple_join_view<Char, T...>& value,
FormatContext& ctx) const -> typename FormatContext::iterator {
return do_format(value, ctx,
std::integral_constant<size_t, sizeof...(T)>{});
}
private:
template <typename FormatContext, size_t... N>
auto format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
detail::index_sequence<N...>) ->
typename FormatContext::iterator {
using std::get;
return format_args(value, ctx, get<N>(value.tuple)...);
std::tuple<formatter<typename std::decay<T>::type, Char>...> formatters_;
template <typename ParseContext>
FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
std::integral_constant<size_t, 0>)
-> decltype(ctx.begin()) {
return ctx.begin();
}
template <typename ParseContext, size_t N>
FMT_CONSTEXPR auto do_parse(ParseContext& ctx,
std::integral_constant<size_t, N>)
-> decltype(ctx.begin()) {
auto end = std::get<sizeof...(T) - N>(formatters_).parse(ctx);
if (N > 1) {
auto end1 = do_parse(ctx, std::integral_constant<size_t, N - 1>{});
if (end != end1)
FMT_THROW(format_error("incompatible format specs for tuple elements"));
}
return end;
}
template <typename FormatContext>
auto format_args(const tuple_join_view<Char, T...>&, FormatContext& ctx) ->
auto do_format(const tuple_join_view<Char, T...>&, FormatContext& ctx,
std::integral_constant<size_t, 0>) const ->
typename FormatContext::iterator {
// NOTE: for compilers that support C++17, this empty function instantiation
// can be replaced with a constexpr branch in the variadic overload.
return ctx.out();
}
template <typename FormatContext, typename Arg, typename... Args>
auto format_args(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
const Arg& arg, const Args&... args) ->
template <typename FormatContext, size_t N>
auto do_format(const tuple_join_view<Char, T...>& value, FormatContext& ctx,
std::integral_constant<size_t, N>) const ->
typename FormatContext::iterator {
using base = formatter<typename std::decay<Arg>::type, Char>;
auto out = base().format(arg, ctx);
if (sizeof...(Args) > 0) {
auto out = std::get<sizeof...(T) - N>(formatters_)
.format(std::get<sizeof...(T) - N>(value.tuple), ctx);
if (N > 1) {
out = std::copy(value.sep.begin(), value.sep.end(), out);
ctx.advance_to(out);
return format_args(value, ctx, args...);
return do_format(value, ctx, std::integral_constant<size_t, N - 1>{});
}
return out;
}

13
test/ranges-test.cc
View File

@ -217,6 +217,19 @@ TEST(ranges_test, join_tuple) {
// Single element tuple.
auto t4 = std::tuple<float>(4.0f);
EXPECT_EQ(fmt::format("{}", fmt::join(t4, "/")), "4");
// Specs applied to each element.
auto t5 = std::tuple<int, int, long>(-3, 100, 1);
EXPECT_EQ(fmt::format("{:+03}", fmt::join(t5, ", ")), "-03, +100, +01");
auto t6 = std::tuple<float, double, long double>(3, 3.14, 3.1415);
EXPECT_EQ(fmt::format("{:5.5f}", fmt::join(t6, ", ")),
"3.00000, 3.14000, 3.14150");
// Testing lvalue tuple args.
int y = -1;
auto t7 = std::tuple<int, int&, const int&>(3, y, y);
EXPECT_EQ(fmt::format("{:03}", fmt::join(t7, ", ")), "003, -01, -01");
}
TEST(ranges_test, join_initializer_list) {