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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
#ifndef intl_components_DateTimeFormat_h_
#define intl_components_DateTimeFormat_h_
#include <functional>
#include "unicode/udat.h"
#include "mozilla/Assertions.h"
#include "mozilla/intl/ICU4CGlue.h"
#include "mozilla/intl/ICUError.h"
#include "mozilla/intl/DateTimePart.h"
#include "mozilla/intl/DateTimePatternGenerator.h"
#include "mozilla/Maybe.h"
#include "mozilla/Span.h"
#include "mozilla/Try.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Utf8.h"
#include "mozilla/Variant.h"
#include "mozilla/Vector.h"
/*
* To work around webcompat problems caused by Narrow No-Break Space in
* formatted date/time output, where existing code on the web naively
* assumes there will be a normal Space, we replace any occurrences of
* U+202F in the formatted results with U+0020.
*
* The intention is to undo this hack once other major browsers are also
* ready to ship with the updated (ICU72) i18n data that uses NNBSP.
*
* and see DateIntervalFormat.cpp for the other piece of this hack.
*/
#define DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES 1
namespace mozilla::intl {
#if DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES
static inline bool IsSpecialSpace(char16_t c) {
// NARROW NO-BREAK SPACE and THIN SPACE
return c == 0x202F || c == 0x2009;
}
#endif
class Calendar;
/**
* Intro to mozilla::intl::DateTimeFormat
* ======================================
*
* This component is a Mozilla-focused API for the date formatting provided by
* ICU. The methods internally call out to ICU4C. This is responsible for and
* owns any resources opened through ICU, through RAII.
*
* The construction of a DateTimeFormat contains the majority of the cost
* of the DateTimeFormat operation. DateTimeFormat::TryFormat should be
* relatively inexpensive after the initial construction.
*
* This class supports creating from Styles (a fixed set of options) and from a
* components bag (a list of components and their lengths).
*
* This API serves to back the ECMA-402 Intl.DateTimeFormat API.
*
*
* ECMA-402 Intl.DateTimeFormat API and implementation details with ICU
* skeletons and patterns.
* ====================================================================
*
* Different locales have different ways to display dates using the same
* basic components. For example, en-US might use "Sept. 24, 2012" while
* fr-FR might use "24 Sept. 2012". The intent of Intl.DateTimeFormat is to
* permit production of a format for the locale that best matches the
* set of date-time components and their desired representation as specified
* by the API client.
*
* ICU4C supports specification of date and time formats in three ways:
*
* 1) A style is just one of the identifiers FULL, LONG, MEDIUM, or SHORT.
* The date-time components included in each style and their representation
* are defined by ICU using CLDR locale data (CLDR is the Unicode
* Consortium's Common Locale Data Repository).
*
* 2) A skeleton is a string specifying which date-time components to include,
* and which representations to use for them. For example, "yyyyMMMMdd"
* specifies a year with at least four digits, a full month name, and a
* two-digit day. It does not specify in which order the components appear,
* how they are separated, the localized strings for textual components
* (such as weekday or month), whether the month is in format or
* stand-alone form¹, or the numbering system used for numeric components.
* All that information is filled in by ICU using CLDR locale data.
* ¹ The format form is the one used in formatted strings that include a
* day; the stand-alone form is used when not including days, e.g., in
* calendar headers. The two forms differ at least in some Slavic languages,
* e.g. Russian: "22 марта 2013 г." vs. "Март 2013".
*
* 3) A pattern is a string specifying which date-time components to include,
* in which order, with which separators, in which grammatical case. For
* example, "EEEE, d MMMM y" specifies the full localized weekday name,
* followed by comma and space, followed by the day, followed by space,
* followed by the full month name in format form, followed by space,
* followed by the full year. It
* still does not specify localized strings for textual components and the
* numbering system - these are determined by ICU using CLDR locale data or
* possibly API parameters.
*
* All actual formatting in ICU4C is done with patterns; styles and skeletons
* have to be mapped to patterns before processing.
*
* The options of Intl.DateTimeFormat most closely correspond to ICU skeletons.
* This implementation therefore converts DateTimeFormat options to ICU
* skeletons, and then lets ICU map skeletons to actual ICU patterns. The
* pattern may not directly correspond to what the skeleton requests, as the
* mapper (UDateTimePatternGenerator) is constrained by the available locale
* data for the locale.
*
* An ICU pattern represents the information of the following DateTimeFormat
* internal properties described in the specification, which therefore don't
* exist separately in the implementation:
* - [[weekday]], [[era]], [[year]], [[month]], [[day]], [[hour]], [[minute]],
* [[second]], [[timeZoneName]]
* - [[hour12]]
* - [[hourCycle]]
* - [[hourNo0]]
* When needed for the resolvedOptions method, the resolveICUPattern function
* queries the UDateFormat's internal pattern and then maps the it back to the
* specified properties of the object returned by resolvedOptions.
*
* ICU date-time skeletons and patterns aren't fully documented in the ICU
* documentation at this point is in UTR 35:
*
* Future support for ICU4X
* ========================
* This implementation exposes a components bag, and internally handles the
* complexity of working with skeletons and patterns to generate the correct
* results. In the future, if and when we switch to ICU4X, the complexities of
* manipulating patterns will be able to be removed, as ICU4X will directly know
* how to apply the components bag.
*/
class DateTimeFormat final {
public:
/**
* The hour cycle for components.
*/
enum class HourCycle {
H11,
H12,
H23,
H24,
};
/**
* The style for dates or times.
*/
enum class Style {
Full,
Long,
Medium,
Short,
};
/**
* A bag of options to determine the length of the time and date styles. The
* hour cycle can be overridden.
*/
struct StyleBag {
Maybe<Style> date = Nothing();
Maybe<Style> time = Nothing();
Maybe<HourCycle> hourCycle = Nothing();
Maybe<bool> hour12 = Nothing();
};
/**
* How to to display numeric components such as the year and the day.
*/
enum class Numeric {
Numeric,
TwoDigit,
};
/**
* How to display the text components, such as the weekday or day period.
*/
enum class Text {
Long,
Short,
Narrow,
};
/**
* How to display the month.
*/
enum class Month {
Numeric,
TwoDigit,
Long,
Short,
Narrow,
};
/**
* How to display the time zone name.
*/
enum class TimeZoneName {
Long,
Short,
ShortOffset,
LongOffset,
ShortGeneric,
LongGeneric,
};
/**
* Get static strings representing the enums. These match ECMA-402's resolved
* options.
*/
static const char* ToString(DateTimeFormat::HourCycle aHourCycle);
static const char* ToString(DateTimeFormat::Style aStyle);
static const char* ToString(DateTimeFormat::Numeric aNumeric);
static const char* ToString(DateTimeFormat::Text aText);
static const char* ToString(DateTimeFormat::Month aMonth);
static const char* ToString(DateTimeFormat::TimeZoneName aTimeZoneName);
/**
* A components bag specifies the components used to display a DateTime. Each
* component can be styled individually, and ICU will attempt to create a best
* match for a given locale.
*/
struct ComponentsBag {
Maybe<Text> era = Nothing();
Maybe<Numeric> year = Nothing();
Maybe<Month> month = Nothing();
Maybe<Numeric> day = Nothing();
Maybe<Text> weekday = Nothing();
Maybe<Numeric> hour = Nothing();
Maybe<Numeric> minute = Nothing();
Maybe<Numeric> second = Nothing();
Maybe<TimeZoneName> timeZoneName = Nothing();
Maybe<bool> hour12 = Nothing();
Maybe<HourCycle> hourCycle = Nothing();
Maybe<Text> dayPeriod = Nothing();
Maybe<uint8_t> fractionalSecondDigits = Nothing();
};
// Do not allow copy as this class owns the ICU resource. Move is not
// currently implemented, but a custom move operator could be created if
// needed.
DateTimeFormat(const DateTimeFormat&) = delete;
DateTimeFormat& operator=(const DateTimeFormat&) = delete;
// mozilla::Vector can avoid heap allocations for small transient buffers.
using PatternVector = Vector<char16_t, 128>;
using SkeletonVector = Vector<char16_t, 16>;
/**
* Create a DateTimeFormat from styles.
*
* The "style" model uses different options for formatting a date or time
* based on how the result will be styled, rather than picking specific
* fields or lengths.
*
* Takes an optional time zone which will override the user's default
* time zone. This is a UTF-16 string that takes the form "GMT±hh:mm", or
* an IANA time zone identifier, e.g. "America/Chicago".
*/
static Result<UniquePtr<DateTimeFormat>, ICUError> TryCreateFromStyle(
Span<const char> aLocale, const StyleBag& aStyleBag,
DateTimePatternGenerator* aDateTimePatternGenerator,
Maybe<Span<const char16_t>> aTimeZoneOverride = Nothing{});
private:
/**
* Create a DateTimeFormat from a UTF-16 skeleton.
*
* A skeleton is an unordered list of fields that are used to find an
* appropriate date time format pattern. Example skeletons would be "yMd",
* "yMMMd", "EBhm". If the skeleton includes string literals or other
* information, it will be discarded when matching against skeletons.
*
* Takes an optional time zone which will override the user's default
* time zone. This is a string that takes the form "GMT±hh:mm", or
* an IANA time zone identifier, e.g. "America/Chicago".
*/
static Result<UniquePtr<DateTimeFormat>, ICUError> TryCreateFromSkeleton(
Span<const char> aLocale, Span<const char16_t> aSkeleton,
DateTimePatternGenerator* aDateTimePatternGenerator,
Maybe<DateTimeFormat::HourCycle> aHourCycle,
Maybe<Span<const char16_t>> aTimeZoneOverride);
public:
/**
* Create a DateTimeFormat from a ComponentsBag.
*
* See the ComponentsBag for additional documentation.
*
* Takes an optional time zone which will override the user's default
* time zone. This is a string that takes the form "GMT±hh:mm", or
* an IANA time zone identifier, e.g. "America/Chicago".
*/
static Result<UniquePtr<DateTimeFormat>, ICUError> TryCreateFromComponents(
Span<const char> aLocale, const ComponentsBag& bag,
DateTimePatternGenerator* aDateTimePatternGenerator,
Maybe<Span<const char16_t>> aTimeZoneOverride = Nothing{});
/**
* Create a DateTimeFormat from a raw pattern.
*
* Warning: This method should not be added to new code. In the near future we
* plan to remove it.
*/
static Result<UniquePtr<DateTimeFormat>, ICUError> TryCreateFromPattern(
Span<const char> aLocale, Span<const char16_t> aPattern,
Maybe<Span<const char16_t>> aTimeZoneOverride = Nothing{});
/**
* Use the format settings to format a date time into a string. The non-null
* terminated string will be placed into the provided buffer. The idea behind
* this API is that the constructor is expensive, and then the format
* operation is cheap.
*
* aUnixEpoch is the number of milliseconds since 1 January 1970, UTC.
*/
template <typename B>
ICUResult TryFormat(double aUnixEpoch, B& aBuffer) const {
static_assert(
std::is_same_v<typename B::CharType, unsigned char> ||
std::is_same_v<typename B::CharType, char> ||
std::is_same_v<typename B::CharType, char16_t>,
"The only buffer CharTypes supported by DateTimeFormat are char "
"(for UTF-8 support) and char16_t (for UTF-16 support).");
if constexpr (std::is_same_v<typename B::CharType, char> ||
std::is_same_v<typename B::CharType, unsigned char>) {
// The output buffer is UTF-8, but ICU uses UTF-16 internally.
// Write the formatted date into the u16Buffer.
PatternVector u16Vec;
auto result = FillBufferWithICUCall(
u16Vec, [this, &aUnixEpoch](UChar* target, int32_t length,
UErrorCode* status) {
return udat_format(mDateFormat, aUnixEpoch, target, length,
/* UFieldPosition* */ nullptr, status);
});
if (result.isErr()) {
return result;
}
#if DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES
for (auto& c : u16Vec) {
if (IsSpecialSpace(c)) {
c = ' ';
}
}
#endif
if (!FillBuffer(u16Vec, aBuffer)) {
return Err(ICUError::OutOfMemory);
}
return Ok{};
} else {
static_assert(std::is_same_v<typename B::CharType, char16_t>);
// The output buffer is UTF-16. ICU can output directly into this buffer.
auto result = FillBufferWithICUCall(
aBuffer, [&](UChar* target, int32_t length, UErrorCode* status) {
return udat_format(mDateFormat, aUnixEpoch, target, length, nullptr,
status);
});
if (result.isErr()) {
return result;
}
#if DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES
for (auto& c : Span(aBuffer.data(), aBuffer.length())) {
if (IsSpecialSpace(c)) {
c = ' ';
}
}
#endif
return Ok{};
}
};
/**
* Format the Unix epoch time into a DateTimePartVector.
*
* The caller has to create the buffer and the vector and pass to this method.
* The formatted string will be stored in the buffer and formatted parts in
* the vector.
*
* aUnixEpoch is the number of milliseconds since 1 January 1970, UTC.
*
* See:
*/
template <typename B>
ICUResult TryFormatToParts(double aUnixEpoch, B& aBuffer,
DateTimePartVector& aParts) const {
static_assert(std::is_same_v<typename B::CharType, char16_t>,
"Only char16_t is supported (for UTF-16 support) now.");
UErrorCode status = U_ZERO_ERROR;
UFieldPositionIterator* fpositer = ufieldpositer_open(&status);
if (U_FAILURE(status)) {
return Err(ToICUError(status));
}
auto result = FillBufferWithICUCall(
aBuffer, [this, aUnixEpoch, fpositer](UChar* chars, int32_t size,
UErrorCode* status) {
return udat_formatForFields(mDateFormat, aUnixEpoch, chars, size,
fpositer, status);
});
if (result.isErr()) {
ufieldpositer_close(fpositer);
return result.propagateErr();
}
#if DATE_TIME_FORMAT_REPLACE_SPECIAL_SPACES
for (auto& c : Span(aBuffer.data(), aBuffer.length())) {
if (IsSpecialSpace(c)) {
c = ' ';
}
}
#endif
return TryFormatToParts(fpositer, aBuffer.length(), aParts);
}
/**
* Copies the pattern for the current DateTimeFormat to a buffer.
*
* Warning: This method should not be added to new code. In the near future we
* plan to remove it.
*/
template <typename B>
ICUResult GetPattern(B& aBuffer) const {
return FillBufferWithICUCall(
aBuffer, [&](UChar* target, int32_t length, UErrorCode* status) {
return udat_toPattern(mDateFormat, /* localized*/ false, target,
length, status);
});
}
/**
* Copies the skeleton that was used to generate the current DateTimeFormat to
* the given buffer. If no skeleton was used, then a skeleton is generated
* from the resolved pattern. Note that going from skeleton -> resolved
* pattern -> skeleton is not a 1:1 mapping, as the resolved pattern can
* contain different symbols than the requested skeleton.
*
* Warning: This method should not be added to new code. In the near future we
* plan to remove it.
*/
template <typename B>
ICUResult GetOriginalSkeleton(B& aBuffer) {
static_assert(std::is_same_v<typename B::CharType, char16_t>);
if (mOriginalSkeleton.length() == 0) {
// Generate a skeleton from the resolved pattern, there was no originally
// cached skeleton.
PatternVector pattern{};
VectorToBufferAdaptor buffer(pattern);
MOZ_TRY(GetPattern(buffer));
VectorToBufferAdaptor skeleton(mOriginalSkeleton);
MOZ_TRY(DateTimePatternGenerator::GetSkeleton(pattern, skeleton));
}
if (!FillBuffer(mOriginalSkeleton, aBuffer)) {
return Err(ICUError::OutOfMemory);
}
return Ok();
}
/**
* Set the start time of the Gregorian calendar. This is useful for
* ensuring the consistent use of a proleptic Gregorian calendar for ECMA-402.
*/
void SetStartTimeIfGregorian(double aTime);
/**
* Determines the resolved components for the current DateTimeFormat.
*
* When a DateTimeFormat is created, even from a components bag, the resolved
* formatter may tweak the resolved components depending on the configuration
* and the locale.
*
* For the implementation, with ICU4C, this takes a string pattern and maps it
* back to a ComponentsBag.
*/
Result<ComponentsBag, ICUError> ResolveComponents();
~DateTimeFormat();
/**
* Clones the Calendar from a DateTimeFormat, and sets its time with the
* relative milliseconds since 1 January 1970, UTC.
*/
Result<UniquePtr<Calendar>, ICUError> CloneCalendar(double aUnixEpoch) const;
/**
* Return the hour cycle used in the input pattern or Nothing if none was
* found.
*/
static Maybe<DateTimeFormat::HourCycle> HourCycleFromPattern(
Span<const char16_t> aPattern);
using HourCyclesVector = Vector<HourCycle, 4>;
/**
* Returns the allowed hour cycles for the input locale.
*
* NOTE: This function currently takes a language subtag and an optional
* this function should be changed to accept a single locale tag.
*/
static Result<HourCyclesVector, ICUError> GetAllowedHourCycles(
Span<const char> aLanguage, Maybe<Span<const char>> aRegion);
/**
* Returns an iterator over all supported date-time formatter locales.
*
* The returned strings are ICU locale identifiers and NOT BCP 47 language
* tags.
*
*/
static auto GetAvailableLocales() {
return AvailableLocalesEnumeration<udat_countAvailable,
udat_getAvailable>();
}
private:
explicit DateTimeFormat(UDateFormat* aDateFormat);
ICUResult CacheSkeleton(Span<const char16_t> aSkeleton);
ICUResult TryFormatToParts(UFieldPositionIterator* aFieldPositionIterator,
size_t aSpanSize,
DateTimePartVector& aParts) const;
/**
* Replaces all hour pattern characters in |patternOrSkeleton| to use the
* matching hour representation for |hourCycle|.
*/
static void ReplaceHourSymbol(Span<char16_t> aPatternOrSkeleton,
DateTimeFormat::HourCycle aHourCycle);
/**
* Find a matching pattern using the requested hour-12 options.
*
* This function is needed to work around the following two issues.
*
* We're currently using a relatively simple workaround, which doesn't give
* the most accurate results. For example:
*
* ```
* var dtf = new Intl.DateTimeFormat("en", {
* timeZone: "UTC",
* dateStyle: "long",
* timeStyle: "long",
* hourCycle: "h12",
* });
* print(dtf.format(new Date("2020-01-01T00:00Z")));
* ```
*
* Returns the pattern "MMMM d, y 'at' h:mm:ss a z", but when going through
* |DateTimePatternGenerator::GetSkeleton| and then
* |DateTimePatternGenerator::GetBestPattern| to find an equivalent pattern
* for "h23", we'll end up with the pattern "MMMM d, y, HH:mm:ss z", so the
* combinator element " 'at' " was lost in the process.
*/
static ICUResult FindPatternWithHourCycle(
DateTimePatternGenerator& aDateTimePatternGenerator,
DateTimeFormat::PatternVector& aPattern, bool aHour12,
DateTimeFormat::SkeletonVector& aSkeleton);
UDateFormat* mDateFormat = nullptr;
SkeletonVector mOriginalSkeleton;
};
} // namespace mozilla::intl
#endif