34d7a8fa69
ICU's Islamic calendar implementations always set ERA=0, even for dates before the Hijra (622 CE), using negative year values instead. However, the CLDR defines two eras: "Anno Hegirae" (era 0) and "Before Hijrah" (era 1). ECMA-402 expects distinct era names in formatToParts output. Similarly, ICU's Coptic calendar has an empty CLDR era 0 name, causing the era parts to be omitted entirely from formatted output. This patch adds another icu::Calendar subclass to handle these cases.
60 lines
2.4 KiB
C++
60 lines
2.4 KiB
C++
/*
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* Copyright (c) 2026, Tim Flynn <trflynn89@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/NonnullOwnPtr.h>
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#include <unicode/calendar.h>
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namespace Unicode {
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// Custom icu::Calendar subclass to fix era handling for calendars where ICU's default behavior does not match ECMA-402
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// requirements.
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//
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// Coptic calendar (SingleEra mode): ICU's Coptic calendar defines two eras (0 and 1), but the CLDR era 0 name is an
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// empty string, causing formatToParts to omit the era entirely for pre-epoch dates. ECMA-402 treats Coptic as a
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// single-era calendar where all dates use the same era ("Anno Martyrum") and the year can be negative. This subclass
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// forces a fixed era value for all dates.
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//
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// Islamic calendars (DualEra mode): ICU's Islamic calendar implementations always set ERA=0 and allow the year to go
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// negative for dates before the Hijra (622 CE). However, ICU's CLDR data defines two eras (era 0 "Anno Hegirae" and
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// era 1 "Before Hijrah"), and ECMA-402 expects pre-epoch dates to use a distinct era. This subclass maps positive
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// years to ERA=0 (AH) and non-positive years to ERA=1 (BH) with a positive year value.
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class AdjustedEraCalendar final : public icu::Calendar {
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public:
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enum class EraMode : u8 {
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SingleEra,
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DualEra,
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};
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AdjustedEraCalendar(NonnullOwnPtr<icu::Calendar> base_calendar, icu::Locale const&, UErrorCode&, EraMode);
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~AdjustedEraCalendar() override;
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char const* getType() const override { return m_base_calendar->getType(); }
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AdjustedEraCalendar* clone() const override;
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UClassID getDynamicClassID() const override;
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static UClassID getStaticClassID();
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private:
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AdjustedEraCalendar(AdjustedEraCalendar const&);
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void handleComputeFields(int32_t julian_day, UErrorCode&) override;
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int64_t handleComputeMonthStart(int32_t extended_year, int32_t month, UBool use_month, UErrorCode&) const override;
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int32_t handleGetExtendedYear(UErrorCode&) override;
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int32_t handleGetLimit(UCalendarDateFields field, ELimitType limit_type) const override;
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UBool haveDefaultCentury() const override { return m_base_calendar->haveDefaultCentury(); }
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UDate defaultCenturyStart() const override { return m_base_calendar->defaultCenturyStart(); }
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int32_t defaultCenturyStartYear() const override { return m_base_calendar->defaultCenturyStartYear(); }
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NonnullOwnPtr<icu::Calendar> m_base_calendar;
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EraMode m_era_mode;
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};
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}
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