| /* |
| * Copyright (C) 2007 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| /* |
| * Elements of the WallTime class are a port of Bionic's localtime.c to Java. That code had the |
| * following header: |
| * |
| * This file is in the public domain, so clarified as of |
| * 1996-06-05 by Arthur David Olson. |
| */ |
| package com.android.i18n.timezone; |
| |
| import java.util.Calendar; |
| import java.util.GregorianCalendar; |
| import java.util.TimeZone; |
| |
| /** |
| * A class that represents a "wall time". This class is modeled on the C tm struct and |
| * is used to support android.text.format.Time behavior. Unlike the tm struct the year is |
| * represented as the full year, not the years since 1900. |
| * |
| * <p>This class contains a rewrite of various native functions that android.text.format.Time |
| * once relied on such as mktime_tz and localtime_tz. This replacement does not support leap |
| * seconds but does try to preserve behavior around ambiguous date/times found in the BSD |
| * version of mktime that was previously used. |
| * |
| * <p>The original native code used a 32-bit value for time_t on 32-bit Android, which |
| * was the only variant of Android available at the time. To preserve old behavior this code |
| * deliberately uses {@code int} rather than {@code long} for most things and performs |
| * calculations in seconds. This creates deliberate truncation issues for date / times before |
| * 1901 and after 2038. This is intentional but might be fixed in future if all the knock-ons |
| * can be resolved: Application code may have come to rely on the range so previously values |
| * like zero for year could indicate an invalid date but if we move to long the year zero would |
| * be valid. |
| * |
| * <p>All offsets are considered to be safe for addition / subtraction / multiplication without |
| * worrying about overflow. All absolute time arithmetic is checked for overflow / underflow. |
| * |
| * @hide |
| */ |
| @libcore.api.CorePlatformApi |
| public class WallTime { |
| |
| // We use a GregorianCalendar (set to UTC) to handle all the date/time normalization logic |
| // and to convert from a broken-down date/time to a millis value. |
| // Unfortunately, it cannot represent an initial state with a zero day and would |
| // automatically normalize it, so we must copy values into and out of it as needed. |
| private final GregorianCalendar calendar; |
| |
| private int year; |
| private int month; |
| private int monthDay; |
| private int hour; |
| private int minute; |
| private int second; |
| private int weekDay; |
| private int yearDay; |
| private int isDst; |
| private int gmtOffsetSeconds; |
| |
| @libcore.api.CorePlatformApi |
| public WallTime() { |
| this.calendar = new GregorianCalendar(0, 0, 0, 0, 0, 0); |
| calendar.setTimeZone(TimeZone.getTimeZone("UTC")); |
| } |
| |
| /** |
| * Sets the wall time to a point in time using the time zone information provided. This |
| * is a replacement for the old native localtime_tz() function. |
| * |
| * <p>When going from an instant to a wall time it is always unambiguous because there |
| * is only one offset rule acting at any given instant. We do not consider leap seconds. |
| */ |
| @libcore.api.CorePlatformApi |
| public void localtime(int timeSeconds, ZoneInfoData zoneInfo) { |
| try { |
| int offsetSeconds = zoneInfo.getRawOffset() / 1000; |
| |
| // Find out the timezone DST state and adjustment. |
| byte isDst; |
| if (zoneInfo.mTransitions.length == 0) { |
| isDst = 0; |
| } else { |
| // offsetIndex can be in the range -1..zoneInfo.mOffsets.length - 1 |
| int offsetIndex = zoneInfo.findOffsetIndexForTimeInSeconds(timeSeconds); |
| if (offsetIndex == -1) { |
| // -1 means timeSeconds is "before the first recorded transition". The first |
| // recorded transition is treated as a transition from non-DST and the |
| // earliest known raw offset. |
| offsetSeconds = zoneInfo.getEarliestRawOffset() / 1000; |
| isDst = 0; |
| } else { |
| offsetSeconds += zoneInfo.mOffsets[offsetIndex]; |
| isDst = zoneInfo.mIsDsts[offsetIndex]; |
| } |
| } |
| |
| // Perform arithmetic that might underflow before setting fields. |
| int wallTimeSeconds = checked32BitAdd(timeSeconds, offsetSeconds); |
| |
| // Set fields. |
| calendar.setTimeInMillis(wallTimeSeconds * 1000L); |
| copyFieldsFromCalendar(); |
| this.isDst = isDst; |
| this.gmtOffsetSeconds = offsetSeconds; |
| } catch (CheckedArithmeticException e) { |
| // Just stop, leaving fields untouched. |
| } |
| } |
| |
| /** |
| * Returns the time in seconds since beginning of the Unix epoch for the wall time using the |
| * time zone information provided. This is a replacement for an old native mktime_tz() C |
| * function. |
| * |
| * <p>When going from a wall time to an instant the answer can be ambiguous. A wall |
| * time can map to zero, one or two instants given rational date/time transitions. Rational |
| * in this case means that transitions occur less frequently than the offset |
| * differences between them (which could cause all sorts of craziness like the |
| * skipping out of transitions). |
| * |
| * <p>For example, this is not fully supported: |
| * <ul> |
| * <li>t1 { time = 1, offset = 0 } |
| * <li>t2 { time = 2, offset = -1 } |
| * <li>t3 { time = 3, offset = -2 } |
| * </ul> |
| * A wall time in this case might map to t1, t2 or t3. |
| * |
| * <p>We do not handle leap seconds. |
| * <p>We assume that no timezone offset transition has an absolute offset > 24 hours. |
| * <p>We do not assume that adjacent transitions modify the DST state; adjustments can |
| * occur for other reasons such as when a zone changes its raw offset. |
| */ |
| @libcore.api.CorePlatformApi |
| public int mktime(ZoneInfoData zoneInfo) { |
| // Normalize isDst to -1, 0 or 1 to simplify isDst equality checks below. |
| this.isDst = this.isDst > 0 ? this.isDst = 1 : this.isDst < 0 ? this.isDst = -1 : 0; |
| |
| copyFieldsToCalendar(); |
| final long longWallTimeSeconds = calendar.getTimeInMillis() / 1000; |
| if (Integer.MIN_VALUE > longWallTimeSeconds |
| || longWallTimeSeconds > Integer.MAX_VALUE) { |
| // For compatibility with the old native 32-bit implementation we must treat |
| // this as an error. Note: -1 could be confused with a real time. |
| return -1; |
| } |
| |
| try { |
| final int wallTimeSeconds = (int) longWallTimeSeconds; |
| final int rawOffsetSeconds = zoneInfo.getRawOffset() / 1000; |
| final int rawTimeSeconds = checked32BitSubtract(wallTimeSeconds, rawOffsetSeconds); |
| |
| if (zoneInfo.mTransitions.length == 0) { |
| // There is no transition information. There is just a raw offset for all time. |
| if (this.isDst > 0) { |
| // Caller has asserted DST, but there is no DST information available. |
| return -1; |
| } |
| copyFieldsFromCalendar(); |
| this.isDst = 0; |
| this.gmtOffsetSeconds = rawOffsetSeconds; |
| return rawTimeSeconds; |
| } |
| |
| // We cannot know for sure what instant the wall time will map to. Unfortunately, in |
| // order to know for sure we need the timezone information, but to get the timezone |
| // information we need an instant. To resolve this we use the raw offset to find an |
| // OffsetInterval; this will get us the OffsetInterval we need or very close. |
| |
| // The initialTransition can be between -1 and (zoneInfo.mTransitions - 1). -1 |
| // indicates the rawTime is before the first transition and is handled gracefully by |
| // createOffsetInterval(). |
| final int initialTransitionIndex = zoneInfo.findTransitionIndex(rawTimeSeconds); |
| |
| if (isDst < 0) { |
| // This is treated as a special case to get it out of the way: |
| // When a caller has set isDst == -1 it means we can return the first match for |
| // the wall time we find. If the caller has specified a wall time that cannot |
| // exist this always returns -1. |
| |
| Integer result = doWallTimeSearch(zoneInfo, initialTransitionIndex, |
| wallTimeSeconds, true /* mustMatchDst */); |
| return result == null ? -1 : result; |
| } |
| |
| // If the wall time asserts a DST (isDst == 0 or 1) the search is performed twice: |
| // 1) The first attempts to find a DST offset that matches isDst exactly. |
| // 2) If it fails, isDst is assumed to be incorrect and adjustments are made to see |
| // if a valid wall time can be created. The result can be somewhat arbitrary. |
| |
| Integer result = doWallTimeSearch(zoneInfo, initialTransitionIndex, wallTimeSeconds, |
| true /* mustMatchDst */); |
| if (result == null) { |
| result = doWallTimeSearch(zoneInfo, initialTransitionIndex, wallTimeSeconds, |
| false /* mustMatchDst */); |
| } |
| if (result == null) { |
| result = -1; |
| } |
| return result; |
| } catch (CheckedArithmeticException e) { |
| return -1; |
| } |
| } |
| |
| /** |
| * Attempt to apply DST adjustments to {@code oldWallTimeSeconds} to create a wall time in |
| * {@code targetInterval}. |
| * |
| * <p>This is used when a caller has made an assertion about standard time / DST that cannot |
| * be matched to any offset interval that exists. We must therefore assume that the isDst |
| * assertion is incorrect and the invalid wall time is the result of some modification the |
| * caller made to a valid wall time that pushed them outside of the offset interval they |
| * were in. We must correct for any DST change that should have been applied when they did |
| * so. |
| * |
| * <p>Unfortunately, we have no information about what adjustment they made and so cannot |
| * know which offset interval they were previously in. For example, they may have added a |
| * second or a year to a valid time to arrive at what they have. |
| * |
| * <p>We try all offset types that are not the same as the isDst the caller asserted. For |
| * each possible offset we work out the offset difference between that and |
| * {@code targetInterval}, apply it, and see if we are still in {@code targetInterval}. If |
| * we are, then we have found an adjustment. |
| */ |
| private Integer tryOffsetAdjustments(ZoneInfoData zoneInfo, int oldWallTimeSeconds, |
| OffsetInterval targetInterval, int transitionIndex, int isDstToFind) |
| throws CheckedArithmeticException { |
| |
| int[] offsetsToTry = getOffsetsOfType(zoneInfo, transitionIndex, isDstToFind); |
| for (int j = 0; j < offsetsToTry.length; j++) { |
| int rawOffsetSeconds = zoneInfo.getRawOffset() / 1000; |
| int jOffsetSeconds = rawOffsetSeconds + offsetsToTry[j]; |
| int targetIntervalOffsetSeconds = targetInterval.getTotalOffsetSeconds(); |
| int adjustmentSeconds = targetIntervalOffsetSeconds - jOffsetSeconds; |
| int adjustedWallTimeSeconds = checked32BitAdd(oldWallTimeSeconds, adjustmentSeconds); |
| if (targetInterval.containsWallTime(adjustedWallTimeSeconds)) { |
| // Perform any arithmetic that might overflow. |
| int returnValue = checked32BitSubtract(adjustedWallTimeSeconds, |
| targetIntervalOffsetSeconds); |
| |
| // Modify field state and return the result. |
| calendar.setTimeInMillis(adjustedWallTimeSeconds * 1000L); |
| copyFieldsFromCalendar(); |
| this.isDst = targetInterval.getIsDst(); |
| this.gmtOffsetSeconds = targetIntervalOffsetSeconds; |
| return returnValue; |
| } |
| } |
| return null; |
| } |
| |
| /** |
| * Return an array of offsets that have the requested {@code isDst} value. |
| * The {@code startIndex} is used as a starting point so transitions nearest |
| * to that index are returned first. |
| */ |
| private static int[] getOffsetsOfType(ZoneInfoData zoneInfo, int startIndex, int isDst) { |
| // +1 to account for the synthetic transition we invent before the first recorded one. |
| int[] offsets = new int[zoneInfo.mOffsets.length + 1]; |
| boolean[] seen = new boolean[zoneInfo.mOffsets.length]; |
| int numFound = 0; |
| |
| int delta = 0; |
| boolean clampTop = false; |
| boolean clampBottom = false; |
| do { |
| // delta = { 1, -1, 2, -2, 3, -3...} |
| delta *= -1; |
| if (delta >= 0) { |
| delta++; |
| } |
| |
| int transitionIndex = startIndex + delta; |
| if (delta < 0 && transitionIndex < -1) { |
| clampBottom = true; |
| continue; |
| } else if (delta > 0 && transitionIndex >= zoneInfo.mTypes.length) { |
| clampTop = true; |
| continue; |
| } |
| |
| if (transitionIndex == -1) { |
| if (isDst == 0) { |
| // Synthesize a non-DST transition before the first transition we have |
| // data for. |
| offsets[numFound++] = 0; // offset of 0 from raw offset |
| } |
| continue; |
| } |
| int type = zoneInfo.mTypes[transitionIndex] & 0xff; |
| if (!seen[type]) { |
| if (zoneInfo.mIsDsts[type] == isDst) { |
| offsets[numFound++] = zoneInfo.mOffsets[type]; |
| } |
| seen[type] = true; |
| } |
| } while (!(clampTop && clampBottom)); |
| |
| int[] toReturn = new int[numFound]; |
| System.arraycopy(offsets, 0, toReturn, 0, numFound); |
| return toReturn; |
| } |
| |
| /** |
| * Find a time <em>in seconds</em> the same or close to {@code wallTimeSeconds} that |
| * satisfies {@code mustMatchDst}. The search begins around the timezone offset transition |
| * with {@code initialTransitionIndex}. |
| * |
| * <p>If {@code mustMatchDst} is {@code true} the method can only return times that |
| * use timezone offsets that satisfy the {@code this.isDst} requirements. |
| * If {@code this.isDst == -1} it means that any offset can be used. |
| * |
| * <p>If {@code mustMatchDst} is {@code false} any offset that covers the |
| * currently set time is acceptable. That is: if {@code this.isDst} == -1, any offset |
| * transition can be used, if it is 0 or 1 the offset used must match {@code this.isDst}. |
| * |
| * <p>Note: This method both uses and can modify field state. It returns the matching time |
| * in seconds if a match has been found and modifies fields, or it returns {@code null} and |
| * leaves the field state unmodified. |
| */ |
| private Integer doWallTimeSearch(ZoneInfoData zoneInfo, int initialTransitionIndex, |
| int wallTimeSeconds, boolean mustMatchDst) throws CheckedArithmeticException { |
| |
| // The loop below starts at the initialTransitionIndex and radiates out from that point |
| // up to 24 hours in either direction by applying transitionIndexDelta to inspect |
| // adjacent transitions (0, -1, +1, -2, +2). 24 hours is used because we assume that no |
| // total offset from UTC is ever > 24 hours. clampTop and clampBottom are used to |
| // indicate whether the search has either searched > 24 hours or exhausted the |
| // transition data in that direction. The search stops when a match is found or if |
| // clampTop and clampBottom are both true. |
| // The match logic employed is determined by the mustMatchDst parameter. |
| final int MAX_SEARCH_SECONDS = 24 * 60 * 60; |
| boolean clampTop = false, clampBottom = false; |
| int loop = 0; |
| do { |
| // transitionIndexDelta = { 0, -1, 1, -2, 2,..} |
| int transitionIndexDelta = (loop + 1) / 2; |
| if (loop % 2 == 1) { |
| transitionIndexDelta *= -1; |
| } |
| loop++; |
| |
| // Only do any work in this iteration if we need to. |
| if (transitionIndexDelta > 0 && clampTop |
| || transitionIndexDelta < 0 && clampBottom) { |
| continue; |
| } |
| |
| // Obtain the OffsetInterval to use. |
| int currentTransitionIndex = initialTransitionIndex + transitionIndexDelta; |
| OffsetInterval offsetInterval = |
| OffsetInterval.create(zoneInfo, currentTransitionIndex); |
| if (offsetInterval == null) { |
| // No transition exists with the index we tried: Stop searching in the |
| // current direction. |
| clampTop |= (transitionIndexDelta > 0); |
| clampBottom |= (transitionIndexDelta < 0); |
| continue; |
| } |
| |
| // Match the wallTimeSeconds against the OffsetInterval. |
| if (mustMatchDst) { |
| // Work out if the interval contains the wall time the caller specified and |
| // matches their isDst value. |
| if (offsetInterval.containsWallTime(wallTimeSeconds)) { |
| if (this.isDst == -1 || offsetInterval.getIsDst() == this.isDst) { |
| // This always returns the first OffsetInterval it finds that matches |
| // the wall time and isDst requirements. If this.isDst == -1 this means |
| // the result might be a DST or a non-DST answer for wall times that can |
| // exist in two OffsetIntervals. |
| int totalOffsetSeconds = offsetInterval.getTotalOffsetSeconds(); |
| int returnValue = checked32BitSubtract(wallTimeSeconds, totalOffsetSeconds); |
| |
| copyFieldsFromCalendar(); |
| this.isDst = offsetInterval.getIsDst(); |
| this.gmtOffsetSeconds = totalOffsetSeconds; |
| return returnValue; |
| } |
| } |
| } else { |
| // To retain similar behavior to the old native implementation: if the caller is |
| // asserting the same isDst value as the OffsetInterval we are looking at we do |
| // not try to find an adjustment from another OffsetInterval of the same isDst |
| // type. If you remove this you get different results in situations like a |
| // DST -> DST transition or STD -> STD transition that results in an interval of |
| // "skipped" wall time. For example: if 01:30 (DST) is invalid and between two |
| // DST intervals, and the caller has passed isDst == 1, this results in a -1 |
| // being returned. |
| if (isDst != offsetInterval.getIsDst()) { |
| final int isDstToFind = isDst; |
| Integer returnValue = tryOffsetAdjustments(zoneInfo, wallTimeSeconds, |
| offsetInterval, currentTransitionIndex, isDstToFind); |
| if (returnValue != null) { |
| return returnValue; |
| } |
| } |
| } |
| |
| // See if we can avoid another loop in the current direction. |
| if (transitionIndexDelta > 0) { |
| // If we are searching forward and the OffsetInterval we have ends |
| // > MAX_SEARCH_SECONDS after the wall time, we don't need to look any further |
| // forward. |
| boolean endSearch = offsetInterval.getEndWallTimeSeconds() - wallTimeSeconds |
| > MAX_SEARCH_SECONDS; |
| if (endSearch) { |
| clampTop = true; |
| } |
| } else if (transitionIndexDelta < 0) { |
| boolean endSearch = wallTimeSeconds - offsetInterval.getStartWallTimeSeconds() |
| >= MAX_SEARCH_SECONDS; |
| if (endSearch) { |
| // If we are searching backward and the OffsetInterval starts |
| // > MAX_SEARCH_SECONDS before the wall time, we don't need to look any |
| // further backwards. |
| clampBottom = true; |
| } |
| } |
| } while (!(clampTop && clampBottom)); |
| return null; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setYear(int year) { |
| this.year = year; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setMonth(int month) { |
| this.month = month; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setMonthDay(int monthDay) { |
| this.monthDay = monthDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setHour(int hour) { |
| this.hour = hour; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setMinute(int minute) { |
| this.minute = minute; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setSecond(int second) { |
| this.second = second; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setWeekDay(int weekDay) { |
| this.weekDay = weekDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setYearDay(int yearDay) { |
| this.yearDay = yearDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setIsDst(int isDst) { |
| this.isDst = isDst; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public void setGmtOffset(int gmtoff) { |
| this.gmtOffsetSeconds = gmtoff; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getYear() { |
| return year; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getMonth() { |
| return month; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getMonthDay() { |
| return monthDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getHour() { |
| return hour; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getMinute() { |
| return minute; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getSecond() { |
| return second; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getWeekDay() { |
| return weekDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getYearDay() { |
| return yearDay; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getGmtOffset() { |
| return gmtOffsetSeconds; |
| } |
| |
| @libcore.api.CorePlatformApi |
| public int getIsDst() { |
| return isDst; |
| } |
| |
| private void copyFieldsToCalendar() { |
| calendar.set(Calendar.YEAR, year); |
| calendar.set(Calendar.MONTH, month); |
| calendar.set(Calendar.DAY_OF_MONTH, monthDay); |
| calendar.set(Calendar.HOUR_OF_DAY, hour); |
| calendar.set(Calendar.MINUTE, minute); |
| calendar.set(Calendar.SECOND, second); |
| calendar.set(Calendar.MILLISECOND, 0); |
| } |
| |
| private void copyFieldsFromCalendar() { |
| year = calendar.get(Calendar.YEAR); |
| month = calendar.get(Calendar.MONTH); |
| monthDay = calendar.get(Calendar.DAY_OF_MONTH); |
| hour = calendar.get(Calendar.HOUR_OF_DAY); |
| minute = calendar.get(Calendar.MINUTE); |
| second = calendar.get(Calendar.SECOND); |
| |
| // Calendar uses Sunday == 1. Android Time uses Sunday = 0. |
| weekDay = calendar.get(Calendar.DAY_OF_WEEK) - 1; |
| // Calendar enumerates from 1, Android Time enumerates from 0. |
| yearDay = calendar.get(Calendar.DAY_OF_YEAR) - 1; |
| } |
| |
| /** |
| * A wall-time representation of a timezone offset interval. |
| * |
| * <p>Wall-time means "as it would appear locally in the timezone in which it applies". |
| * For example in 2007: |
| * PST was a -8:00 offset that ran until Mar 11, 2:00 AM. |
| * PDT was a -7:00 offset and ran from Mar 11, 3:00 AM to Nov 4, 2:00 AM. |
| * PST was a -8:00 offset and ran from Nov 4, 1:00 AM. |
| * Crucially this means that there was a "gap" after PST when PDT started, and an overlap when |
| * PDT ended and PST began. |
| * |
| * <p>Although wall-time means "local time", for convenience all wall-time values are stored in |
| * the number of seconds since the beginning of the Unix epoch to get that time <em>in UTC</em>. |
| * To convert from a wall-time to the actual UTC time it is necessary to <em>subtract</em> the |
| * {@code totalOffsetSeconds}. |
| * For example: If the offset in PST is -07:00 hours, then: |
| * timeInPstSeconds = wallTimeUtcSeconds - offsetSeconds |
| * i.e. 13:00 UTC - (-07:00) = 20:00 UTC = 13:00 PST |
| */ |
| static class OffsetInterval { |
| |
| /** The time the interval starts in seconds since start of epoch, inclusive. */ |
| private final int startWallTimeSeconds; |
| /** The time the interval ends in seconds since start of epoch, exclusive. */ |
| private final int endWallTimeSeconds; |
| private final int isDst; |
| private final int totalOffsetSeconds; |
| |
| /** |
| * Creates an {@link OffsetInterval}. |
| * |
| * <p>If {@code transitionIndex} is -1, where possible the transition is synthesized to run |
| * from the beginning of 32-bit time until the first transition in {@code zoneInfo} with |
| * offset information based on the first type defined. If {@code transitionIndex} is the |
| * last transition, that transition is considered to run until the end of 32-bit time. |
| * Otherwise, the information is extracted from {@code zoneInfo.mTransitions}, |
| * {@code zoneInfo.mOffsets} and {@code zoneInfo.mIsDsts}. |
| * |
| * <p>This method can return null when: |
| * <ol> |
| * <li>the {@code transitionIndex} is outside the allowed range, i.e. |
| * {@code transitionIndex < -1 || transitionIndex >= [the number of transitions]}.</li> |
| * <li>when calculations result in a zero-length interval. This is only expected to occur |
| * when dealing with transitions close to (or exactly at) {@code Integer.MIN_VALUE} and |
| * {@code Integer.MAX_VALUE} and where it's difficult to convert from UTC to local times. |
| * </li> |
| * </ol> |
| */ |
| public static OffsetInterval create(ZoneInfoData zoneInfo, int transitionIndex) { |
| if (transitionIndex < -1 || transitionIndex >= zoneInfo.mTransitions.length) { |
| return null; |
| } |
| |
| if (transitionIndex == -1) { |
| int totalOffsetSeconds = zoneInfo.getEarliestRawOffset() / 1000; |
| int isDst = 0; |
| |
| int startWallTimeSeconds = Integer.MIN_VALUE; |
| int endWallTimeSeconds = |
| saturated32BitAdd(zoneInfo.mTransitions[0], totalOffsetSeconds); |
| if (startWallTimeSeconds == endWallTimeSeconds) { |
| // There's no point in returning an OffsetInterval that lasts 0 seconds. |
| return null; |
| } |
| return new OffsetInterval(startWallTimeSeconds, endWallTimeSeconds, isDst, |
| totalOffsetSeconds); |
| } |
| |
| int rawOffsetSeconds = zoneInfo.getRawOffset() / 1000; |
| int type = zoneInfo.mTypes[transitionIndex] & 0xff; |
| int totalOffsetSeconds = zoneInfo.mOffsets[type] + rawOffsetSeconds; |
| int endWallTimeSeconds; |
| if (transitionIndex == zoneInfo.mTransitions.length - 1) { |
| endWallTimeSeconds = Integer.MAX_VALUE; |
| } else { |
| endWallTimeSeconds = saturated32BitAdd( |
| zoneInfo.mTransitions[transitionIndex + 1], totalOffsetSeconds); |
| } |
| int isDst = zoneInfo.mIsDsts[type]; |
| int startWallTimeSeconds = |
| saturated32BitAdd(zoneInfo.mTransitions[transitionIndex], totalOffsetSeconds); |
| if (startWallTimeSeconds == endWallTimeSeconds) { |
| // There's no point in returning an OffsetInterval that lasts 0 seconds. |
| return null; |
| } |
| return new OffsetInterval( |
| startWallTimeSeconds, endWallTimeSeconds, isDst, totalOffsetSeconds); |
| } |
| |
| private OffsetInterval(int startWallTimeSeconds, int endWallTimeSeconds, int isDst, |
| int totalOffsetSeconds) { |
| this.startWallTimeSeconds = startWallTimeSeconds; |
| this.endWallTimeSeconds = endWallTimeSeconds; |
| this.isDst = isDst; |
| this.totalOffsetSeconds = totalOffsetSeconds; |
| } |
| |
| public boolean containsWallTime(long wallTimeSeconds) { |
| return wallTimeSeconds >= startWallTimeSeconds && wallTimeSeconds < endWallTimeSeconds; |
| } |
| |
| public int getIsDst() { |
| return isDst; |
| } |
| |
| public int getTotalOffsetSeconds() { |
| return totalOffsetSeconds; |
| } |
| |
| public long getEndWallTimeSeconds() { |
| return endWallTimeSeconds; |
| } |
| |
| public long getStartWallTimeSeconds() { |
| return startWallTimeSeconds; |
| } |
| } |
| |
| /** |
| * An exception used to indicate an arithmetic overflow or underflow. |
| */ |
| private static class CheckedArithmeticException extends Exception { |
| } |
| |
| /** |
| * Calculate (a + b). The result must be in the Integer range otherwise an exception is thrown. |
| * |
| * @throws CheckedArithmeticException if overflow or underflow occurs |
| */ |
| private static int checked32BitAdd(long a, int b) throws CheckedArithmeticException { |
| // Adapted from Guava IntMath.checkedAdd(); |
| long result = a + b; |
| if (result != (int) result) { |
| throw new CheckedArithmeticException(); |
| } |
| return (int) result; |
| } |
| |
| /** |
| * Calculate (a - b). The result must be in the Integer range otherwise an exception is thrown. |
| * |
| * @throws CheckedArithmeticException if overflow or underflow occurs |
| */ |
| private static int checked32BitSubtract(long a, int b) throws CheckedArithmeticException { |
| // Adapted from Guava IntMath.checkedSubtract(); |
| long result = a - b; |
| if (result != (int) result) { |
| throw new CheckedArithmeticException(); |
| } |
| return (int) result; |
| } |
| |
| /** |
| * Calculate (a + b). If the result would overflow or underflow outside of the Integer range |
| * Integer.MAX_VALUE or Integer.MIN_VALUE will be returned, respectively. |
| */ |
| private static int saturated32BitAdd(long a, int b) { |
| long result = a + b; |
| if (result > Integer.MAX_VALUE) { |
| return Integer.MAX_VALUE; |
| } else if (result < Integer.MIN_VALUE) { |
| return Integer.MIN_VALUE; |
| } |
| return (int) result; |
| } |
| } |
