f2974002ec
https://github.com/tc39/ecma402/pull/194 requires that TimeClip be called before formatting in Intl.DateTimeFormat. Bug: v8:7471 Test: test262/intl402/DateTimeFormat/prototype/format/time-clip* Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng Change-Id: Iad80376ae7598aab3e4df84a6cbbcd8691e16e09 Reviewed-on: https://chromium-review.googlesource.com/1027442 Reviewed-by: Daniel Ehrenberg <littledan@chromium.org> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org> Commit-Queue: Jungshik Shin <jshin@chromium.org> Cr-Commit-Position: refs/heads/master@{#52796}
248 lines
7.9 KiB
C++
248 lines
7.9 KiB
C++
// Copyright 2012 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_DATE_H_
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#define V8_DATE_H_
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#include "src/base/timezone-cache.h"
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#include "src/globals.h"
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namespace v8 {
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namespace internal {
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class DateCache {
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public:
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static const int kMsPerMin = 60 * 1000;
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static const int kSecPerDay = 24 * 60 * 60;
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static const int64_t kMsPerDay = kSecPerDay * 1000;
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static const int64_t kMsPerMonth = kMsPerDay * 30;
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// The largest time that can be passed to OS date-time library functions.
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static const int kMaxEpochTimeInSec = kMaxInt;
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static const int64_t kMaxEpochTimeInMs =
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static_cast<int64_t>(kMaxInt) * 1000;
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// The largest time that can be stored in JSDate.
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static const int64_t kMaxTimeInMs =
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static_cast<int64_t>(864000000) * 10000000;
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// Conservative upper bound on time that can be stored in JSDate
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// before UTC conversion.
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static const int64_t kMaxTimeBeforeUTCInMs = kMaxTimeInMs + kMsPerMonth;
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// Sentinel that denotes an invalid local offset.
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static const int kInvalidLocalOffsetInMs = kMaxInt;
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// Sentinel that denotes an invalid cache stamp.
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// It is an invariant of DateCache that cache stamp is non-negative.
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static const int kInvalidStamp = -1;
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DateCache();
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virtual ~DateCache() {
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delete tz_cache_;
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tz_cache_ = nullptr;
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}
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// Clears cached timezone information and increments the cache stamp.
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void ResetDateCache();
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// Computes floor(time_ms / kMsPerDay).
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static int DaysFromTime(int64_t time_ms) {
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if (time_ms < 0) time_ms -= (kMsPerDay - 1);
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return static_cast<int>(time_ms / kMsPerDay);
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}
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// Computes modulo(time_ms, kMsPerDay) given that
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// days = floor(time_ms / kMsPerDay).
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static int TimeInDay(int64_t time_ms, int days) {
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return static_cast<int>(time_ms - days * kMsPerDay);
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}
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// ECMA 262 - ES#sec-timeclip TimeClip (time)
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static double TimeClip(double time);
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// Given the number of days since the epoch, computes the weekday.
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// ECMA 262 - 15.9.1.6.
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int Weekday(int days) {
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int result = (days + 4) % 7;
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return result >= 0 ? result : result + 7;
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}
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bool IsLeap(int year) {
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return year % 4 == 0 && (year % 100 != 0 || year % 400 == 0);
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}
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// ECMA 262 - ES#sec-local-time-zone-adjustment
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int LocalOffsetInMs(int64_t time, bool is_utc) {
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return GetLocalOffsetFromOS(time, is_utc);
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}
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const char* LocalTimezone(int64_t time_ms) {
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if (time_ms < 0 || time_ms > kMaxEpochTimeInMs) {
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time_ms = EquivalentTime(time_ms);
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}
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bool is_dst = DaylightSavingsOffsetInMs(time_ms) != 0;
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const char** name = is_dst ? &dst_tz_name_ : &tz_name_;
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if (*name == nullptr) {
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*name = tz_cache_->LocalTimezone(static_cast<double>(time_ms));
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}
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return *name;
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}
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// ECMA 262 - 15.9.5.26
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int TimezoneOffset(int64_t time_ms) {
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int64_t local_ms = ToLocal(time_ms);
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return static_cast<int>((time_ms - local_ms) / kMsPerMin);
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}
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// ECMA 262 - ES#sec-localtime-t
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// LocalTime(t) = t + LocalTZA(t, true)
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int64_t ToLocal(int64_t time_ms) {
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return time_ms + LocalOffsetInMs(time_ms, true);
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}
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// ECMA 262 - ES#sec-utc-t
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// UTC(t) = t - LocalTZA(t, false)
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int64_t ToUTC(int64_t time_ms) {
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return time_ms - LocalOffsetInMs(time_ms, false);
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}
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// Computes a time equivalent to the given time according
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// to ECMA 262 - 15.9.1.9.
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// The issue here is that some library calls don't work right for dates
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// that cannot be represented using a non-negative signed 32 bit integer
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// (measured in whole seconds based on the 1970 epoch).
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// We solve this by mapping the time to a year with same leap-year-ness
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// and same starting day for the year. The ECMAscript specification says
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// we must do this, but for compatibility with other browsers, we use
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// the actual year if it is in the range 1970..2037
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int64_t EquivalentTime(int64_t time_ms) {
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int days = DaysFromTime(time_ms);
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int time_within_day_ms = static_cast<int>(time_ms - days * kMsPerDay);
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int year, month, day;
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YearMonthDayFromDays(days, &year, &month, &day);
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int new_days = DaysFromYearMonth(EquivalentYear(year), month) + day - 1;
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return static_cast<int64_t>(new_days) * kMsPerDay + time_within_day_ms;
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}
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// Returns an equivalent year in the range [2008-2035] matching
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// - leap year,
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// - week day of first day.
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// ECMA 262 - 15.9.1.9.
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int EquivalentYear(int year) {
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int week_day = Weekday(DaysFromYearMonth(year, 0));
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int recent_year = (IsLeap(year) ? 1956 : 1967) + (week_day * 12) % 28;
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// Find the year in the range 2008..2037 that is equivalent mod 28.
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// Add 3*28 to give a positive argument to the modulus operator.
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return 2008 + (recent_year + 3 * 28 - 2008) % 28;
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}
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// Given the number of days since the epoch, computes
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// the corresponding year, month, and day.
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void YearMonthDayFromDays(int days, int* year, int* month, int* day);
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// Computes the number of days since the epoch for
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// the first day of the given month in the given year.
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int DaysFromYearMonth(int year, int month);
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// Breaks down the time value.
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void BreakDownTime(int64_t time_ms, int* year, int* month, int* day,
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int* weekday, int* hour, int* min, int* sec, int* ms);
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// Cache stamp is used for invalidating caches in JSDate.
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// We increment the stamp each time when the timezone information changes.
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// JSDate objects perform stamp check and invalidate their caches if
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// their saved stamp is not equal to the current stamp.
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Smi* stamp() { return stamp_; }
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void* stamp_address() { return &stamp_; }
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// These functions are virtual so that we can override them when testing.
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virtual int GetDaylightSavingsOffsetFromOS(int64_t time_sec) {
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double time_ms = static_cast<double>(time_sec * 1000);
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return static_cast<int>(tz_cache_->DaylightSavingsOffset(time_ms));
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}
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virtual int GetLocalOffsetFromOS(int64_t time_ms, bool is_utc);
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private:
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// The implementation relies on the fact that no time zones have
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// more than one daylight savings offset change per 19 days.
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// In Egypt in 2010 they decided to suspend DST during Ramadan. This
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// led to a short interval where DST is in effect from September 10 to
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// September 30.
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static const int kDefaultDSTDeltaInSec = 19 * kSecPerDay;
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// Size of the Daylight Savings Time cache.
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static const int kDSTSize = 32;
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// Daylight Savings Time segment stores a segment of time where
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// daylight savings offset does not change.
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struct DST {
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int start_sec;
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int end_sec;
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int offset_ms;
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int last_used;
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};
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// Computes the daylight savings offset for the given time.
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// ECMA 262 - 15.9.1.8
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int DaylightSavingsOffsetInMs(int64_t time_ms);
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// Sets the before_ and the after_ segments from the DST cache such that
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// the before_ segment starts earlier than the given time and
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// the after_ segment start later than the given time.
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// Both segments might be invalid.
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// The last_used counters of the before_ and after_ are updated.
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void ProbeDST(int time_sec);
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// Finds the least recently used segment from the DST cache that is not
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// equal to the given 'skip' segment.
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DST* LeastRecentlyUsedDST(DST* skip);
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// Extends the after_ segment with the given point or resets it
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// if it starts later than the given time + kDefaultDSTDeltaInSec.
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inline void ExtendTheAfterSegment(int time_sec, int offset_ms);
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// Makes the given segment invalid.
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inline void ClearSegment(DST* segment);
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bool InvalidSegment(DST* segment) {
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return segment->start_sec > segment->end_sec;
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}
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Smi* stamp_;
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// Daylight Saving Time cache.
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DST dst_[kDSTSize];
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int dst_usage_counter_;
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DST* before_;
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DST* after_;
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int local_offset_ms_;
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// Year/Month/Day cache.
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bool ymd_valid_;
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int ymd_days_;
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int ymd_year_;
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int ymd_month_;
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int ymd_day_;
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// Timezone name cache
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const char* tz_name_;
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const char* dst_tz_name_;
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base::TimezoneCache* tz_cache_;
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};
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} // namespace internal
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} // namespace v8
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#endif // V8_DATE_H_
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