[libc++][format] Adds formatter for tuple and pair
Implements parts of
- P2286R8 Formatting Ranges
Reviewed By: ldionne, #libc
Differential Revision: https://reviews.llvm.org/D136775
NOKEYCHECK=True
GitOrigin-RevId: eb6e13cb32805ee12d19aaa5823f3e4216a35653
diff --git a/include/CMakeLists.txt b/include/CMakeLists.txt
index ea1e23a..59087b4 100644
--- a/include/CMakeLists.txt
+++ b/include/CMakeLists.txt
@@ -313,6 +313,7 @@
__format/formatter_output.h
__format/formatter_pointer.h
__format/formatter_string.h
+ __format/formatter_tuple.h
__format/parser_std_format_spec.h
__format/range_default_formatter.h
__format/unicode.h
diff --git a/include/__chrono/statically_widen.h b/include/__chrono/statically_widen.h
index dd12c3f..360b6c2 100644
--- a/include/__chrono/statically_widen.h
+++ b/include/__chrono/statically_widen.h
@@ -26,26 +26,26 @@
# ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <__fmt_char_type _CharT>
-consteval const _CharT* __statically_widen(const char* __str, const wchar_t* __wstr) {
+_LIBCPP_HIDE_FROM_ABI constexpr const _CharT* __statically_widen(const char* __str, const wchar_t* __wstr) {
if constexpr (same_as<_CharT, char>)
return __str;
else
return __wstr;
}
# define _LIBCPP_STATICALLY_WIDEN(_CharT, __str) ::std::__statically_widen<_CharT>(__str, L##__str)
-# else // _LIBCPP_HAS_NO_WIDE_CHARACTERS
+# else // _LIBCPP_HAS_NO_WIDE_CHARACTERS
// Without this indirection the unit test test/libcxx/modules_include.sh.cpp
// fails for the CI build "No wide characters". This seems like a bug.
// TODO FMT investigate why this is needed.
template <__fmt_char_type _CharT>
-consteval const _CharT* __statically_widen(const char* __str) {
+_LIBCPP_HIDE_FROM_ABI constexpr const _CharT* __statically_widen(const char* __str) {
return __str;
}
# define _LIBCPP_STATICALLY_WIDEN(_CharT, __str) ::std::__statically_widen<_CharT>(__str)
# endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
-#endif //if _LIBCPP_STD_VER > 17
+#endif //_LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__format/formatter.h b/include/__format/formatter.h
index 154f8a5..900a09a 100644
--- a/include/__format/formatter.h
+++ b/include/__format/formatter.h
@@ -38,7 +38,16 @@
formatter& operator=(const formatter&) = delete;
};
-#endif //_LIBCPP_STD_VER > 17
+# if _LIBCPP_STD_VER > 20
+
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI constexpr void __set_debug_format(_Tp& __formatter) {
+ if constexpr (requires { __formatter.set_debug_format(); })
+ __formatter.set_debug_format();
+}
+
+# endif // _LIBCPP_STD_VER > 20
+#endif // _LIBCPP_STD_VER > 17
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/__format/formatter_tuple.h b/include/__format/formatter_tuple.h
new file mode 100644
index 0000000..82f5ada
--- /dev/null
+++ b/include/__format/formatter_tuple.h
@@ -0,0 +1,178 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___FORMAT_FORMATTER_TUPLE_H
+#define _LIBCPP___FORMAT_FORMATTER_TUPLE_H
+
+#include <__algorithm/ranges_copy.h>
+#include <__availability>
+#include <__chrono/statically_widen.h>
+#include <__config>
+#include <__format/concepts.h>
+#include <__format/format_args.h>
+#include <__format/format_context.h>
+#include <__format/format_error.h>
+#include <__format/format_parse_context.h>
+#include <__format/formatter.h>
+#include <__format/formatter_output.h>
+#include <__format/parser_std_format_spec.h>
+#include <__iterator/back_insert_iterator.h>
+#include <__type_traits/remove_cvref.h>
+#include <__utility/integer_sequence.h>
+#include <__utility/pair.h>
+#include <string_view>
+#include <tuple>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 20
+
+template <__fmt_char_type _CharT, class _Tuple, formattable<_CharT>... _Args>
+struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT __formatter_tuple {
+ _LIBCPP_HIDE_FROM_ABI constexpr void set_separator(basic_string_view<_CharT> __separator) {
+ __separator_ = __separator;
+ }
+ _LIBCPP_HIDE_FROM_ABI constexpr void
+ set_brackets(basic_string_view<_CharT> __opening_bracket, basic_string_view<_CharT> __closing_bracket) {
+ __opening_bracket_ = __opening_bracket;
+ __closing_bracket_ = __closing_bracket;
+ }
+
+ template <class _ParseContext>
+ _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator parse(_ParseContext& __parse_ctx) {
+ const _CharT* __begin = __parser_.__parse(__parse_ctx, __format_spec::__fields_tuple);
+
+ // [format.tuple]/7
+ // ... For each element e in underlying_, if e.set_debug_format()
+ // is a valid expression, calls e.set_debug_format().
+ // TODO FMT this can be removed when P2733 is accepted.
+ std::__for_each_index_sequence(make_index_sequence<sizeof...(_Args)>(), [&]<size_t _Index> {
+ std::__set_debug_format(std::get<_Index>(__underlying_));
+ });
+
+ const _CharT* __end = __parse_ctx.end();
+ if (__begin == __end)
+ return __begin;
+
+ if (*__begin == _CharT('m')) {
+ if constexpr (sizeof...(_Args) == 2) {
+ set_separator(_LIBCPP_STATICALLY_WIDEN(_CharT, ": "));
+ set_brackets({}, {});
+ ++__begin;
+ } else
+ std::__throw_format_error("The format specifier m requires a pair or a two-element tuple");
+ } else if (*__begin == _CharT('n')) {
+ set_brackets({}, {});
+ ++__begin;
+ }
+
+ if (__begin != __end && *__begin != _CharT('}'))
+ std::__throw_format_error("The format-spec should consume the input or end with a '}'");
+
+ return __begin;
+ }
+
+ template <class _FormatContext>
+ typename _FormatContext::iterator _LIBCPP_HIDE_FROM_ABI
+ format(conditional_t<(formattable<const _Args, _CharT> && ...), const _Tuple&, _Tuple&> __tuple,
+ _FormatContext& __ctx) const {
+ __format_spec::__parsed_specifications<_CharT> __specs = __parser_.__get_parsed_std_specifications(__ctx);
+
+ if (!__specs.__has_width())
+ return __format_tuple(__tuple, __ctx);
+
+ basic_string<_CharT> __str;
+
+ // Since the output is written to a different iterator a new context is
+ // created. Since the underlying formatter uses the default formatting it
+ // doesn't need a locale or the formatting arguments. So creating a new
+ // context works.
+ //
+ // This solution works for this formatter, but it will not work for the
+ // range_formatter. In that patch a generic solution is work in progress.
+ // Once that is finished it can be used here. (The range_formatter will use
+ // these features so it's easier to add it there and then port it.)
+ //
+ // TODO FMT Use formatting wrapping used in the range_formatter.
+ basic_format_context __c = std::__format_context_create(
+ back_insert_iterator{__str},
+ basic_format_args<basic_format_context<back_insert_iterator<basic_string<_CharT>>, _CharT>>{});
+
+ __format_tuple(__tuple, __c);
+
+ return __formatter::__write_string_no_precision(basic_string_view{__str}, __ctx.out(), __specs);
+ }
+
+ template <class _FormatContext>
+ _LIBCPP_HIDE_FROM_ABI typename _FormatContext::iterator __format_tuple(auto&& __tuple, _FormatContext& __ctx) const {
+ __ctx.advance_to(std::ranges::copy(__opening_bracket_, __ctx.out()).out);
+
+ std::__for_each_index_sequence(make_index_sequence<sizeof...(_Args)>(), [&]<size_t _Index> {
+ if constexpr (_Index)
+ __ctx.advance_to(std::ranges::copy(__separator_, __ctx.out()).out);
+
+ // During review Victor suggested to make the exposition only
+ // __underlying_ member a local variable. Currently the Standard
+ // requires nested debug-enabled formatter specializations not to
+ // output escaped output. P2733 fixes that bug, once accepted the
+ // code below can be used.
+ // (Note when a paper allows parsing a tuple-underlying-spec the
+ // exposition only member needs to be a class member. Earlier
+ // revisions of P2286 proposed that, but this was not pursued,
+ // due to time constrains and complexity of the matter.)
+ // TODO FMT This can be updated after P2733 is accepted.
+# if 0
+ // P2286 uses an exposition only member in the formatter
+ // tuple<formatter<remove_cvref_t<_Args>, _CharT>...> __underlying_;
+ // This was used in earlier versions of the paper since
+ // __underlying_.parse(...) was called. This is no longer the case
+ // so we can reduce the scope of the formatter.
+ //
+ // It does require the underlying's parse effect to be moved here too.
+ using _Arg = tuple_element<_Index, decltype(__tuple)>;
+ formatter<remove_cvref_t<_Args>, _CharT> __underlying;
+
+ // [format.tuple]/7
+ // ... For each element e in underlying_, if e.set_debug_format()
+ // is a valid expression, calls e.set_debug_format().
+ std::__set_debug_format(__underlying);
+# else
+ __ctx.advance_to(std::get<_Index>(__underlying_).format(std::get<_Index>(__tuple), __ctx));
+# endif
+ });
+
+ return std::ranges::copy(__closing_bracket_, __ctx.out()).out;
+ }
+
+ __format_spec::__parser<_CharT> __parser_{.__alignment_ = __format_spec::__alignment::__left};
+
+private:
+ tuple<formatter<remove_cvref_t<_Args>, _CharT>...> __underlying_;
+ basic_string_view<_CharT> __separator_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ", ");
+ basic_string_view<_CharT> __opening_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, "(");
+ basic_string_view<_CharT> __closing_bracket_ = _LIBCPP_STATICALLY_WIDEN(_CharT, ")");
+};
+
+template <__fmt_char_type _CharT, formattable<_CharT>... _Args>
+struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<pair<_Args...>, _CharT>
+ : public __formatter_tuple<_CharT, pair<_Args...>, _Args...> {};
+
+template <__fmt_char_type _CharT, formattable<_CharT>... _Args>
+struct _LIBCPP_TEMPLATE_VIS _LIBCPP_AVAILABILITY_FORMAT formatter<tuple<_Args...>, _CharT>
+ : public __formatter_tuple<_CharT, tuple<_Args...>, _Args...> {};
+
+#endif //_LIBCPP_STD_VER > 20
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___FORMAT_FORMATTER_TUPLE_H
diff --git a/include/__format/parser_std_format_spec.h b/include/__format/parser_std_format_spec.h
index 759ace2..26d7eb4 100644
--- a/include/__format/parser_std_format_spec.h
+++ b/include/__format/parser_std_format_spec.h
@@ -101,6 +101,7 @@
///
/// They default to false so when a new field is added it needs to be opted in
/// explicitly.
+// TODO FMT Use an ABI tag for this struct.
struct __fields {
uint8_t __sign_ : 1 {false};
uint8_t __alternate_form_ : 1 {false};
@@ -108,6 +109,13 @@
uint8_t __precision_ : 1 {false};
uint8_t __locale_specific_form_ : 1 {false};
uint8_t __type_ : 1 {false};
+ // Determines the valid values for fill.
+ //
+ // Originally the fill could be any character except { and }. Range-based
+ // formatters use the colon to mark the beginning of the
+ // underlying-format-spec. To avoid parsing ambiguities these formatter
+ // specializations prohibit the use of the colon as a fill character.
+ uint8_t __allow_colon_in_fill_ : 1 {false};
};
// By not placing this constant in the formatter class it's not duplicated for
@@ -128,6 +136,10 @@
inline constexpr __fields __fields_string{.__precision_ = true, .__type_ = true};
inline constexpr __fields __fields_pointer{.__type_ = true};
+# if _LIBCPP_STD_VER > 20
+inline constexpr __fields __fields_tuple{.__type_ = false, .__allow_colon_in_fill_ = true};
+# endif
+
enum class _LIBCPP_ENUM_VIS __alignment : uint8_t {
/// No alignment is set in the format string.
__default,
@@ -256,7 +268,7 @@
if (__begin == __end)
return __begin;
- if (__parse_fill_align(__begin, __end) && __begin == __end)
+ if (__parse_fill_align(__begin, __end, __fields.__allow_colon_in_fill_) && __begin == __end)
return __begin;
if (__fields.__sign_ && __parse_sign(__begin) && __begin == __end)
@@ -364,12 +376,16 @@
return false;
}
- _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(const _CharT*& __begin, const _CharT* __end) {
+ // range-fill and tuple-fill are identical
+ _LIBCPP_HIDE_FROM_ABI constexpr bool
+ __parse_fill_align(const _CharT*& __begin, const _CharT* __end, bool __use_range_fill) {
_LIBCPP_ASSERT(__begin != __end, "when called with an empty input the function will cause "
"undefined behavior by evaluating data not in the input");
if (__begin + 1 != __end) {
if (__parse_alignment(*(__begin + 1))) {
- if (*__begin == _CharT('{') || *__begin == _CharT('}'))
+ if (__use_range_fill && (*__begin == _CharT('{') || *__begin == _CharT('}') || *__begin == _CharT(':')))
+ std::__throw_format_error("The format-spec range-fill field contains an invalid character");
+ else if (*__begin == _CharT('{') || *__begin == _CharT('}'))
std::__throw_format_error("The format-spec fill field contains an invalid character");
__fill_ = *__begin;
diff --git a/include/__utility/integer_sequence.h b/include/__utility/integer_sequence.h
index 87c76e9..9ba9d94 100644
--- a/include/__utility/integer_sequence.h
+++ b/include/__utility/integer_sequence.h
@@ -137,6 +137,14 @@
template<class... _Tp>
using index_sequence_for = make_index_sequence<sizeof...(_Tp)>;
+# if _LIBCPP_STD_VER > 17
+// Executes __func for every element in an index_sequence.
+template <size_t... _Index, class _Function>
+_LIBCPP_HIDE_FROM_ABI constexpr void __for_each_index_sequence(index_sequence<_Index...>, _Function __func) {
+ (__func.template operator()<_Index>(), ...);
+}
+# endif // _LIBCPP_STD_VER > 17
+
#endif // _LIBCPP_STD_VER > 11
_LIBCPP_END_NAMESPACE_STD
diff --git a/include/format b/include/format
index e5f8976..900f27c 100644
--- a/include/format
+++ b/include/format
@@ -191,6 +191,7 @@
#include <__format/formatter_integer.h>
#include <__format/formatter_pointer.h>
#include <__format/formatter_string.h>
+#include <__format/formatter_tuple.h>
#include <__format/parser_std_format_spec.h>
#include <__format/range_default_formatter.h>
#include <__format/unicode.h>
diff --git a/include/module.modulemap.in b/include/module.modulemap.in
index c0473a4..a19a3c4 100644
--- a/include/module.modulemap.in
+++ b/include/module.modulemap.in
@@ -856,6 +856,7 @@
module formatter_output { private header "__format/formatter_output.h" }
module formatter_pointer { private header "__format/formatter_pointer.h" }
module formatter_string { private header "__format/formatter_string.h" }
+ module formatter_tuple { private header "__format/formatter_tuple.h" }
module parser_std_format_spec { private header "__format/parser_std_format_spec.h" }
module range_default_formatter { private header "__format/range_default_formatter.h" }
module unicode { private header "__format/unicode.h" }