/*
*********************************************************************************
* Copyright (C) 2004-2010, International Business Machines Corporation and *
* others. All Rights Reserved. *
*********************************************************************************
*
*/
package com.ibm.icu.util;
import com.ibm.icu.math.BigDecimal;
/**
* There are quite a few different conventions for binary datetime, depending on different
* platforms and protocols. Some of these have severe drawbacks. For example, people using
* Unix time (seconds since Jan 1, 1970, usually in a 32-bit integer)
* think that they are safe until near the year 2038.
* But cases can and do arise where arithmetic manipulations causes serious problems. Consider
* the computation of the average of two datetimes, for example: if one calculates them with
* <code>averageTime = (time1 + time2)/2</code>, there will be overflow even with dates
* beginning in 2004. Moreover, even if these problems don't occur, there is the issue of
* conversion back and forth between different systems.
*
* <p>Binary datetimes differ in a number of ways: the datatype, the unit,
* and the epoch (origin). We refer to these as time scales.</p>
*
* <p>ICU implements a universal time scale that is similar to the
* .NET framework's System.DateTime. The universal time scale is a
* 64-bit integer that holds ticks since midnight, January 1st, 0001.
* (One tick is 100 nanoseconds.)
* Negative values are supported. This has enough range to guarantee that
* calculations involving dates around the present are safe.</p>
*
* <p>The universal time scale always measures time according to the
* proleptic Gregorian calendar. That is, the Gregorian calendar's
* leap year rules are used for all times, even before 1582 when it was
* introduced. (This is different from the default ICU calendar which
* switches from the Julian to the Gregorian calendar in 1582.
* See GregorianCalendar.setGregorianChange() and ucal_setGregorianChange().)</p>
*
* ICU provides conversion functions to and from all other major time
* scales, allowing datetimes in any time scale to be converted to the
* universal time scale, safely manipulated, and converted back to any other
* datetime time scale.</p>
*
* <p>For more details and background, see the
* <a href="http://www.icu-project.org/userguide/universalTimeScale.html">Universal Time Scale</a>
* chapter in the ICU User Guide.</p>
*
* @stable ICU 3.2
*/
public final class UniversalTimeScale
{
/**
* Used in the JDK. Data is a <code>long</code>. Value
* is milliseconds since January 1, 1970.
*
* @stable ICU 3.2
*/
public static final int JAVA_TIME = 0;
/**
* Used in Unix systems. Data is an <code>int</code> or a <code>long</code>. Value
* is seconds since January 1, 1970.
*
* @stable ICU 3.2
*/
public static final int UNIX_TIME = 1;
/**
* Used in the ICU4C. Data is a <code>double</code>. Value
* is milliseconds since January 1, 1970.
*
* @stable ICU 3.2
*/
public static final int ICU4C_TIME = 2;
/**
* Used in Windows for file times. Data is a <code>long</code>. Value
* is ticks (1 tick == 100 nanoseconds) since January 1, 1601.
*
* @stable ICU 3.2
*/
public static final int WINDOWS_FILE_TIME = 3;
/**
* Used in the .NET framework's <code>System.DateTime</code> structure.
* Data is a <code>long</code>. Value is ticks (1 tick == 100 nanoseconds) since January 1, 0001.
*
* @stable ICU 3.2
*/
public static final int DOTNET_DATE_TIME = 4;
/**
* Used in older Macintosh systems. Data is an <code>int</code>. Value
* is seconds since January 1, 1904.
*
* @stable ICU 3.2
*/
public static final int MAC_OLD_TIME = 5;
/**
* Used in the JDK. Data is a <code>double</code>. Value
* is milliseconds since January 1, 2001.
*
* @stable ICU 3.2
*/
public static final int MAC_TIME = 6;
/**
* Used in Excel. Data is a <code>?unknown?</code>. Value
* is days since December 31, 1899.
*
* @stable ICU 3.2
*/
public static final int EXCEL_TIME = 7;
/**
* Used in DB2. Data is a <code>?unknown?</code>. Value
* is days since December 31, 1899.
*
* @stable ICU 3.2
*/
public static final int DB2_TIME = 8;
/**
* Data is a <code>long</code>. Value is microseconds since January 1, 1970.
* Similar to Unix time (linear value from 1970) and struct timeval
* (microseconds resolution).
*
* @stable ICU 3.8
*/
public static final int UNIX_MICROSECONDS_TIME = 9;
/**
* This is the first unused time scale value.
*
* @stable ICU 3.2
*/
public static final int MAX_SCALE = 10;
/**
* The constant used to select the units value
* for a time scale.
*
*
* @stable ICU 3.2
*/
public static final int UNITS_VALUE = 0;
/**
* The constant used to select the epoch offset value
* for a time scale.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int EPOCH_OFFSET_VALUE = 1;
/**
* The constant used to select the minimum from value
* for a time scale.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int FROM_MIN_VALUE = 2;
/**
* The constant used to select the maximum from value
* for a time scale.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int FROM_MAX_VALUE = 3;
/**
* The constant used to select the minimum to value
* for a time scale.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int TO_MIN_VALUE = 4;
/**
* The constant used to select the maximum to value
* for a time scale.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int TO_MAX_VALUE = 5;
/**
* The constant used to select the epoch plus one value
* for a time scale.
*
* NOTE: This is an internal value. DO NOT USE IT. May not
* actually be equal to the epoch offset value plus one.
*
* @see #getTimeScaleValue
*
* @stable ICU 3.2
*/
public static final int EPOCH_OFFSET_PLUS_1_VALUE = 6;
/**
* The constant used to select the epoch offset minus one value
* for a time scale.
*
* NOTE: This is an internal value. DO NOT USE IT. May not
* actually be equal to the epoch offset value minus one.
*
* @see #getTimeScaleValue
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final int EPOCH_OFFSET_MINUS_1_VALUE = 7;
/**
* The constant used to select the units round value
* for a time scale.
*
* NOTE: This is an internal value. DO NOT USE IT.
*
* @see #getTimeScaleValue
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final int UNITS_ROUND_VALUE = 8;
/**
* The constant used to select the minimum safe rounding value
* for a time scale.
*
* NOTE: This is an internal value. DO NOT USE IT.
*
* @see #getTimeScaleValue
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final int MIN_ROUND_VALUE = 9;
/**
* The constant used to select the maximum safe rounding value
* for a time scale.
*
* NOTE: This is an internal value. DO NOT USE IT.
*
* @see #getTimeScaleValue
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final int MAX_ROUND_VALUE = 10;
/**
* The number of time scale values.
*
* NOTE: This is an internal value. DO NOT USE IT.
*
* @see #getTimeScaleValue
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static final int MAX_SCALE_VALUE = 11;
private static final long ticks = 1;
private static final long microseconds = ticks * 10;
private static final long milliseconds = microseconds * 1000;
private static final long seconds = milliseconds * 1000;
private static final long minutes = seconds * 60;
private static final long hours = minutes * 60;
private static final long days = hours * 24;
/**
* This class holds the data that describes a particular
* time scale.
*/
private static final class TimeScaleData
{
TimeScaleData(long theUnits, long theEpochOffset,
long theToMin, long theToMax,
long theFromMin, long theFromMax)
{
units = theUnits;
unitsRound = theUnits / 2;
minRound = Long.MIN_VALUE + unitsRound;
maxRound = Long.MAX_VALUE - unitsRound;
epochOffset = theEpochOffset / theUnits;
if (theUnits == 1) {
epochOffsetP1 = epochOffsetM1 = epochOffset;
} else {
epochOffsetP1 = epochOffset + 1;
epochOffsetM1 = epochOffset - 1;
}
toMin = theToMin;
toMax = theToMax;
fromMin = theFromMin;
fromMax = theFromMax;
}
long units;
long epochOffset;
long fromMin;
long fromMax;
long toMin;
long toMax;
long epochOffsetP1;
long epochOffsetM1;
long unitsRound;
long minRound;
long maxRound;
}
private static final TimeScaleData[] timeScaleTable = {
new TimeScaleData(milliseconds, 621355968000000000L, -9223372036854774999L, 9223372036854774999L, -984472800485477L, 860201606885477L), // JAVA_TIME
new TimeScaleData(seconds, 621355968000000000L, -9223372036854775808L, 9223372036854775807L, -984472800485L, 860201606885L), // UNIX_TIME
new TimeScaleData(milliseconds, 621355968000000000L, -9223372036854774999L, 9223372036854774999L, -984472800485477L, 860201606885477L), // ICU4C_TIME
new TimeScaleData(ticks, 504911232000000000L, -8718460804854775808L, 9223372036854775807L, -9223372036854775808L, 8718460804854775807L), // WINDOWS_FILE_TIME
new TimeScaleData(ticks, 000000000000000000L, -9223372036854775808L, 9223372036854775807L, -9223372036854775808L, 9223372036854775807L), // DOTNET_DATE_TIME
new TimeScaleData(seconds, 600527520000000000L, -9223372036854775808L, 9223372036854775807L, -982389955685L, 862284451685L), // MAC_OLD_TIME
new TimeScaleData(seconds, 631139040000000000L, -9223372036854775808L, 9223372036854775807L, -985451107685L, 859223299685L), // MAC_TIME
new TimeScaleData(days, 599265216000000000L, -9223372036854775808L, 9223372036854775807L, -11368793L, 9981605L), // EXCEL_TIME
new TimeScaleData(days, 599265216000000000L, -9223372036854775808L, 9223372036854775807L, -11368793L, 9981605L), // DB2_TIME
new TimeScaleData(microseconds, 621355968000000000L, -9223372036854775804L, 9223372036854775804L, -984472800485477580L, 860201606885477580L) // UNIX_MICROSECONDS_TIME
};
/*
* Prevent construction of this class.
*/
///CLOVER:OFF
private UniversalTimeScale()
{
// nothing to do
}
///CLOVER:ON
/**
* Convert a <code>long</code> datetime from the given time scale to the universal time scale.
*
* @param otherTime The <code>long</code> datetime
* @param timeScale The time scale to convert from
*
* @return The datetime converted to the universal time scale
*
* @stable ICU 3.2
*/
public static long from(long otherTime, int timeScale)
{
TimeScaleData data = fromRangeCheck(otherTime, timeScale);
return (otherTime + data.epochOffset) * data.units;
}
/**
* Convert a <code>double</code> datetime from the given time scale to the universal time scale.
* All calculations are done using <code>BigDecimal</code> to guarantee that the value
* does not go out of range.
*
* @param otherTime The <code>double</code> datetime
* @param timeScale The time scale to convert from
*
* @return The datetime converted to the universal time scale
*
* @stable ICU 3.2
*/
public static BigDecimal bigDecimalFrom(double otherTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal other = new BigDecimal(String.valueOf(otherTime));
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return other.add(epochOffset).multiply(units);
}
/**
* Convert a <code>long</code> datetime from the given time scale to the universal time scale.
* All calculations are done using <code>BigDecimal</code> to guarantee that the value
* does not go out of range.
*
* @param otherTime The <code>long</code> datetime
* @param timeScale The time scale to convert from
*
* @return The datetime converted to the universal time scale
*
* @stable ICU 3.2
*/
public static BigDecimal bigDecimalFrom(long otherTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal other = new BigDecimal(otherTime);
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return other.add(epochOffset).multiply(units);
}
/**
* Convert a <code>BigDecimal</code> datetime from the given time scale to the universal time scale.
* All calculations are done using <code>BigDecimal</code> to guarantee that the value
* does not go out of range.
*
* @param otherTime The <code>BigDecimal</code> datetime
* @param timeScale The time scale to convert from
*
* @return The datetime converted to the universal time scale
*
* @stable ICU 3.2
*/
public static BigDecimal bigDecimalFrom(BigDecimal otherTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return otherTime.add(epochOffset).multiply(units);
}
/**
* Convert a datetime from the universal time scale stored as a <code>BigDecimal</code> to a
* <code>long</code> in the given time scale.
*
* Since this calculation requires a divide, we must round. The straight forward
* way to round by adding half of the divisor will push the sum out of range for values
* within have the divisor of the limits of the precision of a <code>long</code>. To get around this, we do
* the rounding like this:
*
* <p><code>
* (universalTime - units + units/2) / units + 1
* </code>
*
* <p>
* (i.e. we subtract units first to guarantee that we'll still be in range when we
* add <code>units/2</code>. We then need to add one to the quotent to make up for the extra subtraction.
* This simplifies to:
*
* <p><code>
* (universalTime - units/2) / units - 1
* </code>
*
* <p>
* For negative values to round away from zero, we need to flip the signs:
*
* <p><code>
* (universalTime + units/2) / units + 1
* </code>
*
* <p>
* Since we also need to subtract the epochOffset, we fold the <code>+/- 1</code>
* into the offset value. (i.e. <code>epochOffsetP1</code>, <code>epochOffsetM1</code>.)
*
* @param universalTime The datetime in the universal time scale
* @param timeScale The time scale to convert to
*
* @return The datetime converted to the given time scale
*
* @stable ICU 3.2
*/
public static long toLong(long universalTime, int timeScale)
{
TimeScaleData data = toRangeCheck(universalTime, timeScale);
if (universalTime < 0) {
if (universalTime < data.minRound) {
return (universalTime + data.unitsRound) / data.units - data.epochOffsetP1;
}
return (universalTime - data.unitsRound) / data.units - data.epochOffset;
}
if (universalTime > data.maxRound) {
return (universalTime - data.unitsRound) / data.units - data.epochOffsetM1;
}
return (universalTime + data.unitsRound) / data.units - data.epochOffset;
}
/**
* Convert a datetime from the universal time scale to a <code>BigDecimal</code> in the given time scale.
*
* @param universalTime The datetime in the universal time scale
* @param timeScale The time scale to convert to
*
* @return The datetime converted to the given time scale
*
* @stable ICU 3.2
*/
public static BigDecimal toBigDecimal(long universalTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal universal = new BigDecimal(universalTime);
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return universal.divide(units, BigDecimal.ROUND_HALF_UP).subtract(epochOffset);
}
/**
* Convert a datetime from the universal time scale to a <code>BigDecimal</code> in the given time scale.
*
* @param universalTime The datetime in the universal time scale
* @param timeScale The time scale to convert to
*
* @return The datetime converted to the given time scale
*
* @stable ICU 3.2
*/
public static BigDecimal toBigDecimal(BigDecimal universalTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return universalTime.divide(units, BigDecimal.ROUND_HALF_UP).subtract(epochOffset);
}
/**
* Return the <code>TimeScaleData</code> object for the given time
* scale.
*
* @param scale - the time scale
* @return the <code>TimeScaleData</code> object for the given time scale
*/
private static TimeScaleData getTimeScaleData(int scale)
{
if (scale < 0 || scale >= MAX_SCALE) {
throw new IllegalArgumentException("scale out of range: " + scale);
}
return timeScaleTable[scale];
}
/**
* Get a value associated with a particular time scale.
*
* @param scale - the time scale
* @param value - a constant representing the value to get
*
* @return - the value.
*
* @stable ICU 3.2
*/
public static long getTimeScaleValue(int scale, int value)
{
TimeScaleData data = getTimeScaleData(scale);
switch (value)
{
case UNITS_VALUE:
return data.units;
case EPOCH_OFFSET_VALUE:
return data.epochOffset;
case FROM_MIN_VALUE:
return data.fromMin;
case FROM_MAX_VALUE:
return data.fromMax;
case TO_MIN_VALUE:
return data.toMin;
case TO_MAX_VALUE:
return data.toMax;
case EPOCH_OFFSET_PLUS_1_VALUE:
return data.epochOffsetP1;
case EPOCH_OFFSET_MINUS_1_VALUE:
return data.epochOffsetM1;
case UNITS_ROUND_VALUE:
return data.unitsRound;
case MIN_ROUND_VALUE:
return data.minRound;
case MAX_ROUND_VALUE:
return data.maxRound;
default:
throw new IllegalArgumentException("value out of range: " + value);
}
}
private static TimeScaleData toRangeCheck(long universalTime, int scale)
{
TimeScaleData data = getTimeScaleData(scale);
if (universalTime >= data.toMin && universalTime <= data.toMax) {
return data;
}
throw new IllegalArgumentException("universalTime out of range:" + universalTime);
}
private static TimeScaleData fromRangeCheck(long otherTime, int scale)
{
TimeScaleData data = getTimeScaleData(scale);
if (otherTime >= data.fromMin && otherTime <= data.fromMax) {
return data;
}
throw new IllegalArgumentException("otherTime out of range:" + otherTime);
}
/**
* Convert a time in the Universal Time Scale into another time
* scale. The division used to do the conversion rounds down.
*
* NOTE: This is an internal routine used by the tool that
* generates the to and from limits. Use it at your own risk.
*
* @param universalTime the time in the Universal Time scale
* @param timeScale the time scale to convert to
* @return the time in the given time scale
*
* @internal
* @deprecated This API is ICU internal only.
*/
public static BigDecimal toBigDecimalTrunc(BigDecimal universalTime, int timeScale)
{
TimeScaleData data = getTimeScaleData(timeScale);
BigDecimal units = new BigDecimal(data.units);
BigDecimal epochOffset = new BigDecimal(data.epochOffset);
return universalTime.divide(units, BigDecimal.ROUND_DOWN).subtract(epochOffset);
}
}