Read XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition Online
Authors: Michael Kay
XSLT 2.0 and XPath 2.0 Programmer's Reference, 4th Edition (523 page)
Signature
| Argument | Type | Meaning |
| input | Numeric? | The supplied number. |
| Result | Numeric? | The absolute value of the supplied number. The result has the same type as the input . |
Effect
If the supplied number is positive, then it is returned unchanged. If it is negative, then the result is
-$input
.
Negative zero and negative infinity become positive zero and positive infinity. Positive zero, positive infinity, and NaN are returned unchanged. If the argument is an empty sequence, the result is an empty sequence.
The result has the same primitive numeric type as the input. For example, if the input value is an
xs:integer
, the result will be an
xs:integer
, and if the input is an
xs:double
, the result will be an
xs:double
.
Primitive here means one of the four types
xs:double
,
xs:float
,
xs:decimal
, and
xs:integer
. Clearly, if the input is an
xs:negativeInteger
, the result cannot also be an
xs:negativeInteger
—it will actually be an
xs:integer
. If the input is an
xs:positiveInteger
, you have a guarantee that the result will be an
xs:integer
, but this doesn't prevent the system returning something that is actually a subtype of
xs:integer
—for example, it would be legitimate to return the original
xs:positiveInteger
unchanged.
Examples
| Expression | Result |
| abs(2) | 2 |
| abs(-2) | 2 |
| abs(-3.7) | 3.7 |
| abs(-1.0e-7) | 1.0e-7 |
| abs(number(‘NaN’)) | NaN |
adjust-date-to-timezone, adjust-dateTime-to-timezone, adjust-time-to-timezone
This entry describes a collection of three closely related functions. These functions have the effect of returning a date, time, or dateTime based on a supplied date, time, or dateTime, modified by adding, removing, or altering the timezone component of the value.
Signature
| Argument | Type | Meaning |
| input | xs:date?, xs:dateTime? , or xs:time? | The date, time, or dateTime value whose timezone is to be adjusted. The type of this value must correspond to the name of the function invoked. For example, in the case of adjust-time-to-timezone() it must be an xs:time value. |
| timezone (optional) | xs:dayTimeDuration? | Specifies the new timezone value. If this argument is omitted, the effect is the same as setting it to the result of the function implicit-timezone() . |
| Result | xs:date?, xs:dateTime? , or xs:time? | The adjusted date, dateTime, or time value . |
Effect
If the
input
is an empty sequence, the result is an empty sequence.
If there is no
timezone
argument (that is, if the function is called with a single argument), the effect is the same as calling the function with a second argument ofimplicit-timezone(). This adjusts the value to the timezone supplied in the dynamic context, which ideally will be the timezone where the user is located.
If the
timezone
argument is supplied, and is not an empty sequence, then it must be a duration between −50400 seconds and +50400 seconds, that is ±14 hours. To specify a timezone one hour ahead of UTC, writexs:dayTimeDuration(“PT1H”).
These functions can be used to remove a timezone from a value that has a timezone, to add a timezone to a value that lacks a timezone, or to return the value that is equivalent to the supplied value, but in a different timezone. These effects are summarized in the table below.
| Existing timezone | timezone argument is () | timezone argument is not () |
| Absent | returns the input value unchanged | result has the same components as input, with the addition of the specified timezone |
| Present | result is the localized value of the input, with the timezone removed | result represents the same instant as the input value, but in a different timezone |
The only complex case here is the one in the bottom-right cell of the table, where the supplied value already has a timezone and this is to be replaced with a new timezone. The effect varies slightly depending on which if the three functions is used:
- For an
xs:dateTime
, the result is an
xs:dateTime
that represents the same instant in time as the input value, but in the new timezone. - For an
xs:time
, the result is an
xs:time
that represents the time in the new timezone that is simultaneous with the time provided as the input value. - For an
xs:date
, the date is converted to an
xs:dateTime
representing 00:00:00 on the specified date; the requested adjustment is applied to this
xs:dateTime
value, and the result is the date part of the adjusted
xs:dateTime
.
Examples
Assume that
$CET
is set to the timezone value
+01:00
, represented by the
xs:dayTimeDuration
PT1H
. Assume that
$EST
is set to the timezone value
-05:00
, represented by the
xs:dayTimeDuration
-PT5H
. Assume also that the implicit timezone is the timezone value
-08:00
, represented by the
xs:dayTimeDuration
-PT8H
.
Here are some examples using
xs:time
values:
| Expression | Result |
| adjust-time-to-timezone( xs:time(“15:00:00+01:00”), $EST) | 09:00:00-05:00 |
| adjust-time-to-timezone( xs:time(“15:00:00”), $EST) | 15:00:00-05:00 |
| adjust-time-to-timezone( xs:time(“15:00:00+01:00”)) | 06:00:00-08:00 |
| adjust-time-to-timezone( xs:time(“15:00:00+01:00”), ()) | 15:00:00 |
| adjust-time-to-timezone( xs:time(“15:00:00”), ()) | 15:00:00 |
The corresponding examples using
xs:dateTime
values are:
| Expression | Result |
| adjust-dateTime-to-timezone ( xs:dateTime(“2008-03-01T15:00:00+01:00”), $EST) | 2008-03-01T09:00:00-05:00 |
| adjust-dateTime-to-timezone ( xs: dateTime(“2008-03-01T15:00:00”), $EST) | 2008-03-01T15:00:00-05:00 |
| adjust-dateTime-to-timezone ( xs: dateTime(“2008-03-01T15:00:00+01:00”)) | 2008-03-01T06:00:00-08:00 |
| adjust-dateTime-to-timezone ( xs:dateTime(“2008-03-01T15:00:00+01:00”), ()) | 2008-03-01T15:00:00 |
| adjust-dateTime-to-timezone ( xs: dateTime(“2008-03-01T15:00:00”), ()) | 2008-03-01T15:00:00 |
Adjusting the timezone component of a date is a less intuitive operation, but is still well defined:
