P2286R8 Formatting Ranges #2919
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This was referenced Jul 25, 2022
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CaseyCarter
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This implements [\[format.string.escaped\]], which is part of WG21-P2286R8 "Formatting Ranges" and modified by WG21-P2713R1 "Escaping Improvements In `std::format`". Works towards #2919. To implement this feature, two arrays, `__printable_ranges` and `_Grapheme_Extend_ranges`, are added to `__msvc_format_ucd_tables.hpp`. - `__printable_ranges` represents code points whose [`General_Category`] is in the groups `L`, `M`, `N`, `P`, `S` (that is, code points that are *not* from categories `Z` or `C`), plus the ASCII space character. - Characters outside of these ranges are always escaped, usually using the `\u{hex-digit-sequence}` format. ([\[format.string.escaped\]/(2.2.1.2.1)]) - It might make sense to store the unmodified `General_Category`, instead of this invented property. This requires more storage and a new data structure, though. - `_Grapheme_Extend_ranges` represents code points with the Unicode property `Grapheme_Extend=Yes`. - Characters in these ranges are escaped unless they immediately follow an unescaped character. ([\[format.string.escaped\]/(2.2.1.2.2)]) - It would be more space efficient to reuse the existing data for `Grapheme_Cluster_Break`: `Grapheme_Extend=Yes` is `Grapheme_Cluster_Break=Extend` minus `Emoji_Modifier=Yes`, and `Emoji_Modifier=Yes` is just `1F3FB..1F3FF`. I chose to define a new array for simplicity. When the literal encoding is not UTF-8, UTF-16, or UTF-32, the set of "separator or non-printable characters" is implementation-defined. In this implementation, the set consists of all characters that correspond to non-printable Unicode code points (that is, code points outside of `__printable_ranges`, see above). If a character is non-printable, it is translated into `\u{XXXX}`, where `XXXX` is the hex value of the Unicode code point (not the original value). If a code unit sequence cannot be converted to a Unicode scalar value, the `\x{XX}` escape sequence is used. [`General_Category`]: https://www.unicode.org/reports/tr44/#GC_Values_Table [\[format.string.escaped\]]: http://eel.is/c++draft/format.string.escaped [\[format.string.escaped\]/(2.2.1.2.1)]: http://eel.is/c++draft/format.string.escaped#2.2.1.2.1 [\[format.string.escaped\]/(2.2.1.2.2)]: http://eel.is/c++draft/format.string.escaped#2.2.1.2.2
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JMazurkiewicz
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* This PR implements debug-enabled standard `formatter` specializations, * Drive-by: rename tests added in microsoft#3656 - use `text_formatting_` prefix instead of `formatting_ranges_` (for consistency), * Towards microsoft#2919.
JMazurkiewicz
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* This PR implements debug-enabled standard `formatter` specializations, * Drive-by: rename tests added in microsoft#3656 - use `text_formatting_` prefix instead of `formatting_ranges_` (for consistency), * Towards microsoft#2919.
This was referenced Oct 23, 2023
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WG21-P2286R8 Formatting Ranges
WG21-P2585R1 Improve Default Container Formatting
WG21-P2713R1 Escaping Improvements In
std::formatLWG-3631
basic_format_arg(T&&)should useremove_cvref_t<T>throughout (affectsformattableconcept)LWG-3750 Too many papers bump
__cpp_lib_formatLWG-3839
range_formatter'sset_separator,set_brackets, andunderlyingfunctions should benoexceptLWG-3881 Incorrect formatting of container adaptors backed by
std::stringLWG-3892 Incorrect formatting of nested ranges and tuples
LWG-3925 Concept
formattable's definition is incorrectFeature-test macro:
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