Evaluation

This section defines the semantics of the ClassAd language by explaining how
to *evaluate* an expression.In this section, ``expression'' means an
internal-form expression tree.
In general, a composite expression is evaluated by recursively evaluating its
component sub-expressions and then using its top-level operator to combine the
results.
However, there are situations in which evaluation of an expression *E* depends
on parts of a *context*, which is an expression containing *E* as a
sub-expression.
For example, in the expression

[ a = 3; b = [ c = a ] ],the second occurrence of

`a`

(an attribute reference) is evaluated by
searching the two containing Record expressions for a definition of `a`

,
yielding the constant `3`

.
More formally, an *expression in context* (EIC) is a pair (*E*, *C*)
consisting of an expression *C* (the context) and a designated occurrence of
a sub-expression *E* of *C*.
The semantics of the ClassAd language is defined by a recursive function
*eval* from EICs to EICs.
A *top-level* EIC is an EIC of the form (*E*, *E*).
For brevity, we will occasionally abbreviate the top-level EIC (*E*, *E*) as *E*,
particularly when *E* is a literal constant.
For example, the EIC (**error**, **error**) may be written as
**error**.
An expression *E* is evaluated by computing *eval(E, E)* and extracting
the sub-expression from the resulting EIC.

The set of EICs with context *C* is partially ordered by the relation
, defined by
iff *E* is a
sub-expression of *E*'.
When we speak of the ``minimal'' EIC with a given property, we mean the
one that is minimal with respect to .
An EIC (*E*, *C*) is called a *scope* if the top-level operator of *E*
is RECORD.

Define *lookup(s, (E, C))*, where *s* is a string and (*E*, *C*) is an
EIC, to be the EIC (*E*', *C*'), where

- If
*s*matches^{14}the string`"parent"`

and there is a scope (*E*_{p},*C*) such that , then (*E*',*C*') = (*E*_{p},*C*), where (*E*_{p},*C*) is the minimal such scope. - Otherwise, if
there is a scope (
*E*_{d},*C*) such that and*E*_{d}contains a definition*t*=*E*_{t}such that*t*matches*s*, let*t*=*E*_{t}be the definition in the minimal such scope. Then (*E*',*C*') = (*E*_{t},*C*). - Otherwise,
(
*E*',*C*') = (**undefined**,**undefined**).

For example, let *C* be the expression

[ a = x; b = [ a = y; c = a]; d = a ],and let

`a`

.
Let

Each expression has a *type*, which is one of Integer, Real, String,
Boolean, AbsTime, RelTime, Undefined, Error, List, or Record.
The types Integer and Real are collectively called numeric types.
The types AbsTime and RelTime are collectively called timestamp types.
Each operator imposes constraints on the types of its operands.
If these constraints are not met, the value returned by the operator is
**error**.

An attribute reference with attribute name *N* evaluates to
**undefined** if the reference is not contained in any scope that defines
*N*.
It may also evaluate to **undefined** in the presence of loops,
as in

[ a = b; b = a ].

Most operators are ``strict'' with respect to **undefined** and
**error**.
The only exceptions are the Boolean operators described in
Section 4.3.1,
the operators **is** and **isnt** described in
Section 4.3.2,
and the LIST and RECORD constructors described in
Section 4.3.8.
Strict evaluation obeys the following ordered sequence of rules.

- If the operands do not obey the type restrictions imposed by the
operator, the result of the evaluation is
**error**. The following sections list all combinations of types accepted by each operator. None of the strict operators accept operands of type Error, so this rule implies that if any sub-expression evaluates to**error**, the expression evaluates to**error**. This rule also catches ``type errors'' such as`"foo" / 3`. - Otherwise, if any operand of a strict operator is
**undefined**, the result is**undefined**. - Otherwise, the result is computed from the operands as described in the following sections.

A literal constant evaluates to itself.
More precisely, if *c* is an occurrence of a literal constant, then
*eval(c, C) = (c, C)*.

If *x* is an attribute reference with attribute name *N*, then
*eval(x, C) = eval(lookup(N, (x, C)))*.
In particular, (*x*, *C*) evaluates to **undefined** if there is no scope
(*R*, *C*) containing the indicated occurrence of *x* such that *R* defines *N*.
If this recursive definition leads directly or indirectly to a call
*eval(x, C)*, the result is **undefined**.

List and Record expressions evaluate to themselves.
More precisely, if *E* is an expression whose root operator is LIST or
RECORD, *eval(E, C) = (E, C)*.
The operators SELECT and SUBSCRIPT are discussed below.
For all other operators, evaluation is ``bottom-up'' and the result is
a ``pure value''.
More precisely, if is a binary operator other than
SELECT, or SUBSCRIPT, then

where

and

The operators found in C, C++, or Java are generally evaluated according to the
rules of those languages.
In cases where the specifications of those languages differ, the ClassAd
language follows the Java semantics because it is more precise (the C and C++
specifications occasionally say the results are ``undefined'' or
``implementation defined'' in unusual situations).
The only deviations from Java semantics involve exceptions.
In cases where Java specifies that evaluation throws an exception, the ClassAd
language returns the constant **error**. The constants **error** and
**undefined** also require special treatment when supplied as arguments to
operators.

Boolean Operators

`&&`

and `||`

and the ternary operator `_?_:_`

are evaluated ``left to right''
with respect to even iftrue`||`

x=truefalse&&x=falseundefined`||`

true=truetrue`?`

val`:`

x=valfalse`?`

x`:`

val=val

The Boolean operators treat Boolean **true**, **false**, and
**undefined** as a three-element lattice with

With respect to this lattice,false`<`

undefined`<`

true.

`&&`

returns the minimum of its operands,
`||`

returns the maximum, and `!`

interchanges
The complete definition of the operators `&&`

, `&&`

,
`!`

, and `_?_:_`

is given by the tables

&& | F U T O || | F U T O ! | ?:| ---+-------- ---+-------- --+-- ---+--- F | F F F F F | F U T E F | T F | expr3 U | F U U E U | U U T E U | U U | U T | F U T E T | T T T T T | F T | expr2 O | E E E E O | E E E E O | E O | EIn these tables, the letters

`T`

, `F`

, `U`

, and `E`

stand for the constants
`O`

stands for any expression other than
`expr2`

and `expr3`

represent the second and third operands of
the expression `?`

`:`

result = (expr is undefined) ? 0 : (expr + 1);but they can be used to compare arbitrary values.

For the purposes of this section, the relationship ``identical'' is defined as follows.

- Expressions of different types are never identical.
Thus
`(3 is 3.0)``(3 is "3")`and`(undefined is error)`all evaluate to**false**. - Two values of type Integer, Real, or RelTime are identical if and only if they are numerically equal constants.
- Two values of type AbsTime are identical if they represent the same instant in time and the same offset from UTC.
- Two values of type Boolean are identical if and only if they are both
**true**or both**false**. - Two values of type Undefined or two values of type Error are identical.
Thus
`((3 * "x") is error)`evaluates to**true**. - Two values of type String are identical if and only if they are identical
character by character. Case
*is*significant. Thus`("One" == "one")`and`("One" isnt "one")`both evaluate to**true**. - Two values of type List or Record are identical if and only if they are
created by the same instance of a LIST or RECORD constructor operator.
For example, if
`R`

is the expression[ a = { 1, 2 }; b = { 1, 2 }; c = a is b; d = a is a ],

then`R.c`evaluates to`false`, while`R.d`evaluates to`true`.

`<`

, `<=`

, `==`

, `!=`

, `>=`

, and `>`

,
both operands must be numeric (Integer or Real), both String, both AbsTime, or
both RelTime.
Otherwise, the result is If the operands are Strings, they are converted to lower case and compared lexicographically.

If the operands are AbsTimes, they are equal if they correspond to the same instant (according to UTC). Otherwise, the earlier time is less than the later one. If the operands are RelTimes, they are compared as signed integers.

`+`

,
`-`

,
and binary operators
`+`

,
`-`

,
`*`

,
`/`

,
`%`

,
take numeric operands.`/`

operation truncates the result towards zero, and the
integral `%`

operation generally returns a result with the same sign as
the dividend (the left operand).
See the Java language specification [6] for details.
The unary and binary operators `+`

and `-`

are also defined for
certain timestamp operands.
The unary `+`

operator is applicable to both AbsTime and RelTime operands
and returns the value of its operand unchanged.
The unary `-`

operator is applicable only to RelTime operands and returns
the RelTime value with the same magnitude and opposite sign.

The rules for binary operators are summarized in Table 6.
If the result of an expression is an AbsTime, its time zone is the same as
the time zone of the AbsTime argument.

`~`

and binary operators
`|`

,
`^`

, and
`&`

are defined only for Integer and Boolean operands.
They are defined to return the same results as the corresponding operators in
Java [6].

`<<`

(left shift),
`>>`

(right shift with sign extension), and
`>>>`

(right shift with zero fill) are defined only for Integer
operands.

`.`

`["`

`"]`

.
That is, an instance of SUBSCRIPT operator where the [ rec = [ One = 1; Two = 2 ]; val = rec.one ].valand

[ rec = [ One = 1; Two = 2 ]; val = rec["one"] ].valboth evaluate to

`1`

.
The SELECT syntax is more concise, but the SUBSCRIPT syntax is more flexible,
because it allows the selector to be computed rather than requiring a literal
string.
The SUBSCRIPT operator has two operands, the *base* and the
*subscript*.
In the native syntax, it is written
*base*`[`

*subscript*`]`

.
The subscript expression must have type Integer or String.
If the subscript is an Integer *i*, the base expression must have type List and
the result is the *i*^{th} element of the list, counting from zero.
If the subscript is a String *s*, the base expression must be a
Record or List. If the base expression has type Record,
the result is computed by searching the base and its containing scopes for an
attribute definition matching the attribute name *s*.
If the base expression is a List, the SUBSCRIPT operator is applied to
each member of the list and the result is a new ``top-level'' list of the
results.
In all other cases, the result is **error**.

More precisely,

where

and

- If
*E*_{s}' is an Integer with value*i*and*E*_{b}' is a list {*E*_{0}, ...,*E*_{n - 1}} with*n*>*i*members, then (*E*',*C*') = (*E*_{i},*C*_{b}'). - If
*E*_{s}' is a String with value*s*and*E*_{b}' is a Record expression, then . - If
*C*_{2}is a String with value*s*and*E*_{b}' is a list {*E*_{0}, ...,*E*_{n - 1}}, then*E*' is the list {*E*_{0}', ...,*E*_{n - 1}'}, where and*C*' =*E*' (that is, the result is a ``top-level'' EIC). Note that the environments*C*_{i}' returned by the recursive calls to*eval*are discarded. - In all other cases, the result is
**error**.

List and Record Constructors

`[`

`]`

List and Record expressions evaluate to themselves.
That is, *eval(E, C) = (E, C)* if *E* is of type List or Record.

Function Calls

Currently, all functions are *strict* with respect to **error**
and **undefined**, unless otherwise specified.
In other words, all arguments are evaluated, and
if any argument evaluates to
**error** or **undefined**, the result is
**error** or **undefined**, respectively.
If arguments of both types are present, the result is **error**.

Currently, all functions return ``top-level'' values that are independent
of the the context of the call. That is
, where
for *i* = 1,...,*n* and *V* is a value
computed from
*E*_{1}', ..., *E*_{n}' as described in the following table.

The following table lists all functions required by the current version of this
specification; others may be added in future versions.
The description of each function is preceded by a prototype indicating
restrictions on the number and types of arguments and indicating the type of
the result returned.
If the restrictions are violated, the result is **error**.
In the prototypes, ``const'' stands for any literal constant of type Integer,
Real, String, Boolean, AbsTime, or RelTime (but not Undefined, Error, List, or
Record), and ``any'' means any expression.
A type followed by an asterisk indicates any number
of arguments of the indicated type, including none.
Square brackets are used to indicate optional arguments.

**isUndefined**(*any a*)**returns***boolean*.- Returns
**true**if*a*is the undefined value, otherwise returns**false**. This function is not strict. **isError**(*any a*)**returns***boolean*.- Returns
**true**if*a*is the error value, otherwise returns**false**. This function is not strict. **isString**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a string value, otherwise returns**false**. This function is not strict. **isInteger**(*any a*)**returns***boolean*.- Returns
**true**if*a*is an integer value, otherwise returns**false**. This function is not strict. **isReal**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a real value, otherwise returns**false**. This function is not strict. **isList**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a list value, otherwise returns**false**. This function is not strict. **isClassad**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a record value, otherwise returns**false**. This function is not strict. **isBoolean**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a boolean value, otherwise returns**false**. This function is not strict. **isAbstime**(*any a*)**returns***boolean*.- Returns
**true**if*a*is an AbsTime value, otherwise returns**false**. This function is not strict. **isReltime**(*any a*)**returns***boolean*.- Returns
**true**if*a*is a RelTime value, otherwise returns**false**. This function is not strict. **int**(*const x*)**returns***int*.The result is

*x*converted to an Integer. If*x*is an Integer, the result is*x*. If*x*is a Real, it is truncated (towards zero) to an Integer. If*x*is**true**the result is 1. If*x*is**false**the result is 0. If*x*is an AbsTime, it it converted to the number of seconds since the epoch, UTC. If*x*is a RelTime, it it converted to a number of seconds. If*x*is a String, it is parsed according to the native syntax for*integer_literal*or*floating_point_literal*as in Table 4 and then converted to an Integer as above. If*x*is a String that does not represent a valid Integer or floating-point literal, the result is**error**.**real**(*const x*)**returns***real*.The result is

*x*converted to a Real. If*x*is a Real, the result is*x*. If*x*is an Integer, it is converted to Real. If*x*is**true**the result is 1.0. If*x*is**false**the result is 0.0. If*x*is an AbsTime, it it converted to the number of seconds since the epoch, UTC. If*x*is a RelTime, it it converted to a number of seconds. If*x*is a String, it is parsed according to the native syntax for*integer_literal*or*floating_point_literal*as in Table 4 and then converted to a Real as above. In addition, the strings**INF**,**-INF**and**NaN**(in any combination of upper and lower case) are recognized as representing the IEEE754 values for positive and negative infinity and not-a-number, respectively. If*x*is a String that does not represent a valid Integer or floating-point literal, the result is**error**. For any other type,*x*is converted to an Integer as if by ``int'', and the result is converted to a Real (or**error**if the conversion to Integer fails).**string**(*any x*)**returns***string*.If

*x*is a String, the result is*x*. Otherwise, the result is the canonical unparsing of*x*(see Section 3.3.3).**floor**(*const x*)**returns***int*.If

*x*is an Integer, the result is*x*. Otherwise,*x*is converted to a Real by the function ``real'' above, and the result is the largest Integer not greater than that value (or**error**if the conversion fails).**ceiling**(*const x*)**returns***int*.If

*x*is an Integer, the result is*x*. Otherwise,*x*is converted to a Real by the function ``real'' above, and the result is the smallest Integer not less than that value (or**error**if the conversion fails).**round**(*const x*)**returns***int*.If

*x*is an Integer, the result is*x*. Otherwise,*x*is converted to a Real*y*by the function ``real'' above, and the result is the nearest Integer to*y*. If*y*is midway between two Integers, the even Integer is returned. The result is**error**if the conversion fails or the resulting integral value does not fit in 32 bits.**random**([*number x*])**returns***int*.If

*x*is a positive Integer, the result is a random Integer*r*uniformly chosen from the range . If*x*is a positive Real number, the result is a random Real uniformly chosen from the same range. If*x*is omitted, the result is the same as*random(1.0)*. If*x*is anything else, the result is an error.**strcat**(*any**)**returns***string*.Each argument is converted to a String by the function ``string'' above. The result is the concatenation of the strings.

**substr**(*string s*,*int offset*[,*int length*])**returns***string*.- The result is the substring of
*s*starting at the position indicated by*offset*with the length indicated by*length*. The first character of*s*is at offset 0. If*offset*is negative, it is replaced by length(*s*) -*offset*. If*length*is omitted, the substring extends to the end of*s*. If*length*is negative, an intermediate result is computed as if length were omitted, and then*-length*characters are deleted from the right end of the result. If the resulting substring lies partially outside the limits of*s*, the part that lies within*s*is returned. If the substring lies entirely outside*s*or has negative length (because of a negative*length*argument), the result is the null string. [**Note**: This function is the same as the`substr`function of Perl.] **strcmp**(*any a*,*any b*)**returns***int*.- The operands are converted to Strings by the ``string''
function above. The result is an Integer less than, equal to, or greater than
zero according to whether
*a*is lexicographically less than, equal to, or greater than*b*. Note that case*is*significant in the comparison. **stricmp**(*any a*,*any b*)**returns***int*.The same as

**strcmp**except that upper and lower case letters are considered equivalent.**toUpper**(*string s*)**returns***string*.The operand is converted to a String by the ``string'' function above. The result is a String that is identical to

*s*except that all lowercase letters in*s*are converted to uppercase.**toLower**(*string s*)**returns***string*.The operand is converted to a String by the ``string'' function above. The result is a String that is identical to

*s*except that all uppercase letters in*s*are converted to lowercase.**size**(*string s*)**returns***int*.- Returns the number of characters of the string s.
**size**(*list l*)**returns***int*.- Returns the number of elements in the list l.
**size**(*classad c*)**returns***int*.- Returns the number of attributes in the classad c.
**sum**(*list l*)**returns***number*.- The elements of
*l*are evaluated, producing a list*l*' of values. If*l*' is composed only of numbers, the result is the sum of the values, as a Real if any value is Real, and as an Integer otherwise. If the list is empty, the result is 0. In other cases, the result is ERROR. **avg**(*list l*)**returns***number*.- The elements of
*l*are evaluated, producing a list*l*' of values. If*l*' is composed only of numbers, the result is the average of the values, as a Real. If the list is empty, the result is 0. In other cases, the result is ERROR. **min**(*list l*)**returns***number*.- The elements of
*l*are evaluated, producing a list*l*' of values. If*l*' is composed only of numbers, the result is the minimum of the values, as a Real if any value is Real, and as an Integer otherwise. If the list is empty, the result is UNDEFINED. In other cases, the result is ERROR. **max**(*list l*)**returns***number*.- The elements of
*l*are evaluated, producing a list*l*' of values. If*l*' is composed only of numbers, the result is the maximum of the values, as a Real if any value is Real, and as an Integer otherwise. If the list is empty, the result is UNDEFINED. In other cases, the result is ERROR. **member**(*const x*,*string l*)**returns***boolean*.If

*x*is not a constant or*l*is not a list, then the result is an error. Otherwise, the elements of*l*are evaluated and if any of the values are equal to*x*in the sense of the`==`

operator, then the result is**true**, otherwise it is**false**.**identicalMember**(*const x*,*string l*)**returns***boolean*.If

*x*is not a constant or*l*is not a list, then the result is an error. Otherwise, the elements of*l*are evaluated and if any of the values are equal to*x*in the sense of the`is`

operator, then the result is**true**, otherwise it is**false**.**regexp**(*string pattern*,*string target*[,*string options*])**returns***boolean*.If any of the arguments is not of type String or if

*pattern*is not a valid regular expresison, the result is an error. Otherwise, if*pattern*matches*target*, the result is**true**, otherwise it is**false**.The details of the syntax and semantics of the regular expressions supported currently depends on the implementation. The Java implementation as of Version 2.2 supports perl-compatible regular expressions with certain minor differences as documented by the Java 1.4 documentation at

http://java.sun.com/j2se/1.4.2/docs/api/java/util/regex/Pattern.html.

The C++ release as of Version 0.9.7 and later support as a build-time option either perl-compatible regular expressions as supported by the pcre library (see`http://www.pcre.org/`

) or POSIX regular expressionshttp://www.opengroup.org/onlinepubs/007908799/xbd/re.html

as implemented by the GNU`regex`

libraryhttp://www.gnu.org/software/libc/manual/html_node/Regular-Expressions.html.

The

*options*argument, if present, may contain the following characters to alter the exact details. Unrecognized options are silently ignored. Only`i`

and`I`

are supported by the POSIX version.**i**or**I**-
Ignore case.

**m**or**M**-
Multi-line: A carat (

`^`

) matches not only the start of the subject string, but also after each newline. Similarly, dollar (`$`

) matches before a newline. **s**or**S**-
Single-line: Dot (

`.`

) matches any character, including newline. **x**or**X**-
Extended: Whitespace and comments (from

`#`

to the next newline) in the pattern are ignored.

**regexpMember**(*string pattern*,*string l*, [,*string options*])**returns***boolean*.If

*x*is not a constant or*l*is not a list, then the result is an error. Otherwise, the elements of*l*are evaluated and if any of them evaluates to anything other than a String, the result is an error. Otherwise, if any of values in the list matches the pattern according to the*regexp*function, the result is**true**. If there is no match, then the result is**false**.**anycompare**(*string s*,*list l*,*const t*)**returns***boolean*.**allcompare**(*string s*,*list l*,*const t*)**returns***boolean*.- If
*s*is not a string equal (ignoring case) to one of ```<`

'', ```<=`

'', ```==`

'', ```>`

'', ```>=`

'', ```!=`

'', ``is'', or ``isnt'' or*l*is not a list, the result is an error. Otherwise, the elements of*l*are evaluated and compared to*t*using the ClassAd operator corresponding to*s*. If any of the comparisons evaluate to**true**in the case of*anycompare*or all of the comparisons evaluate to**true**in the case of*allcompare*, the result is**true**. Otherwise, the result is**false**. **time**()**returns***int*.Returns the current Coordinated Universal Time, in seconds since midnight January 1, 1970.

**interval**(*int t*)**returns***string*.The operand

*t*is treated as a number of seconds. The result is a String of the form`days+hh:mm:ss`. Leading components are omitted if they are zero. For example, if the operand is 1472523 = 17*24*60*60 + 1*60*60 + 2*60 + 3 (seventeen days, one hour, two minutes, and three seconds), the result is`"17+1:02:03"`; if the operand is 67, the result is`"1:07"`.**absTime**(*string s*)**returns***AbsTime*.The operand

*s*is parsed as a specification of an instant in time (date and time). This function accepts the canonical native representation of AbsTime values, but minor variations in format are allowed.The default format is

`yyyy-mm-ddThh:mm:sszzzzz`

where zzzzz is a time zone in the format`+hh:mm`

or`-hh:mm`

, but variations are allowed.- Each separator character
`-`

,`:`

, or`T`

may be omitted or replaced by any sequence of non-digits. Note, however, that the`-`

in a time zone of the form`-hh:mm`

may not be omitted. - The colon between
`hh`

and`mm`

in the time zone may be omitted. - An arbitrary sequence of non-digit characters may precede
`zzzzz`

or`yyyy`

. - The zone may be replaced by the character
`z`

or`Z`

, which is equivalent to`-00:00`

. - The zone may be omitted, in which case the local time zone is used.
If the string ends with
`+dddd`

,`-dddd`

,`z`

, or`Z`

, where each`d`

is a digit, this suffix is considered to be the time zone indication. For example, in`2003+1030`

, the suffix`1030`

is interpreted as a time zone 10 hours and 30 minutes east, rather than as October 30. - The fields
`ss`

,`mm`

,`hh`

, etc. may be omitted (from right to left), in which case the omitted fields are assumed to be zero.

D* dddd [D* dd [D* dd [D* dd [D* dd [D* dd D*]]]]] [-dd[:]dd|+dd[:]dd|z|Z]

Where`d`

stands for a digit and`D`

stands for a non-digit.For example, in the United States central time zone, an AbsTime corresponding to ``9 am Jan 25, 2003 CST'' may be created by any of the function calls

`2003-01-25T09:00:00-06:00`

// canonical `2003-01-25 09:00:00 -0600`

// different separators `20030125090000-0600`

// compact format `2003-01-25 16:00:00 +01:00`

// different time zone `2003-01-25 15:00Z`

// omitted seconds, UTC time zone `2003-01-25 09:00:00`

// default time zone (local) `2003-01-25 09`

// omitted minutes and seconds and AbsTimes corresponding to ``Jan 25, 2003'' (implicitly midnight, UTC) may be written

`2003-01-24T18:00:00-06:00`

// canonical `2003-01-25T00:00:00`

// default time zone: UTC `2003-01-25`

// omitted time of day `2003/01/25`

// different separators `20030125`

// compact format The strings

`2003-01-25T09:00:00-06:00`

and`2003-01-25 15:00Z`

represent the same instant in time, but measured in different time zones.The following strings are invalid.

`2003-01-25T09:00:00-06`

// incomplete time zone `2003-01-25T09:00:00- 0600`

// space in time zone `2003-1-25`

// missing digit in dd field - Each separator character
**absTime**([*const t*[,*int z*]- )
**returns***AbsTime*.]Creates an AbsTime value corresponding to time

*t*an time-zone offset*z*. If*t*is a String, then*z*must be omitted, and*t*is parsed as a specification as described above. If*t*and*z*are both omitted, the result is an AbsTime value representing the time and place where the function call is evaluated. Otherwise,*t*is converted to a Real by the function ``real'' above, and treated as a number of seconds from the epoch, Midnight January 1, 1970 UTC. If*z*is specified, it is treated as a number of seconds*east*of Greenwich. Otherwise, the offset is calculated from*t*according to the local rules for the place where the function is evaluated. **relTime**(*const t*)**returns***RelTime*.If the operand

*t*is a String, it is parsed as a specification of a time interval. This function accepts the canonical native representation of RelTime values, but minor variations in format are allowed.Otherwise,

*t*is converted to a Real by the function ``real'' above, and treated as a number of seconds.The default string format is

`[-]days+hh:mm:ss.fff`

, where leading components and the fraction`.fff`

are omitted if they are zero. In the default syntax, days is a sequence of digits starting with a non-zero digit,`hh`

,`mm`

, and`ss`

are strings of exactly two digits (padded on the left with zeros if necessary) with values less than 24, 60, and 60, respectively and`fff`

is a string of exactly three digits. In the relaxed syntax,- Whitespace may be added anywhere except inside the numeric fields
`days`

,`hh`

, etc. - Numeric fields may have any number of digits and any non-negative value.
- The
`+`

may be replaced by`d`

or`D`

. - The first
`:`

may be replaced by`h`

or`H`

. - The second
`:`

may be replaced by`m`

or`M`

. - The letter
`s`

or`S`

may follow the last numeric field. - If field
*i*is terminated with one of the letters`dDhHmMsS`

and the value of field*i*-1 is zero, field*i*-1, together with its terminating field name (`+`

,`:`

,`h`

, etc.) may be omitted even if field*i*-2 is not omitted. - The fraction
`.fff`

may have any number of digits. If it has no digits, the preceding decimal point may be omitted.

For example, one day, two minutes and three milliseconds may have any of the forms

`1+00:02:00.003`

// the result of relTimeToString `1d0h2m0.003s`

// similar to ISO 8601 `1d 2m 0.003s`

// add spaces, omit hours field `1d 00:02:00.003`

// mixed representations `1d 00:00:120.003`

// number of seconds greater than 59 `86520.002991`

// seconds, excess precision in fraction - Whitespace may be added anywhere except inside the numeric fields
**splitTime**(*RelTime*)**returns***ClassAd*.Creates a ClassAd with each component of the time as an element of the ClassAd. The ClassAd has five attributes:

`Type`

// ``RelativeTime'' `Days`

// the number of days `Hours`

// the number hours `Minutes`

// the number of minutes `Seconds`

// the number of seconds **splitTime**(*AbsTime*)**returns***ClassAd*.Creates a ClassAd with each component of the time as an element of the ClassAd. The ClassAd has five attributes:

`Type`

// ``AbsoluteTime'' `Year`

// the year `Month`

// the month, from 1 (January) through 12 (December) `Day`

// the day, from 1 through 31 `Hours`

// the number of hours `Minutes`

// the number of minutes `Seconds`

// the number of seconds `Offset`

// the timezone offset in seconds **formatTime**(*AbsTime t*,*string s*)**returns***string*.This function creates a formatted String that is a representation of the absolute time

*t*.The argument

*s*is interpreted similarly to the*format*argument of the ANSI C strftime function. It consists of arbitary text plus placeholders for elements of the time. These placeholders are percent signs (%) followed by a single letter. To have a percent sign in your output, you must use a double percent sign (%%).Because an implementation may use strftime() to implement this, and some versions implement extra, non-ANSI C options, the exact options available to an implementation may vary. An implementation is only required to implement the ANSI C options, which are:

%a // abbreviated weekday name %A // full weekday name %b // abbreviated month name %B // full month name %c // local date and time representation %d // day of the month (01-31) %H // hour in the 24-hour clock (0-23) %I // hour in the 12-hour clock (01-12) %j // day of the year (001-366) %m // month (01-12) %M // minute (00-59) %p // local equivalent of AM or PM %S // second (00-59) %U // week number of the year (Sunday as first day of week) (00-53) %w // weekday (0-6, Sunday is 0) %W // week number of the year (Monday as first day of week) (00-53) %x // local date representation %X // local time representation %y // year without century (00-99) %Y // year with century %Z // time zone name, if any % // % Note that names may be locale-dependent, if the underlying operating system supports locales. Also note that some ClassAd implementations may have difficulty with time zone names for non-local time zones, since the names may vary.

**formatTime**(*int i*,*string s*)**returns***string*.This version of formatTime converts

*i*to an absolute time, then behaves identically to the other version of formatTime.

- ... matches
^{14} - We are using the term ``match'' here as defined in Section 3.1: Two strings match if they are identical except for differences in case.
- ... operands.
^{15} - Unlike Java, the
`+`operator is not overloaded to accept String operands. - ...JLS,
^{16} - The
`%`operator is defined for floating point operands according to the Java programming language specification, not according C. Some C implementations may not support`%`with floating point operands, so users concerned with portability should avoid this special case until all implementations are brought into compliance. - ...
operands.
^{17} - Note that C and C++ have no
`»>`operator. These languages perform a similar operation when the operands are declared to be unsigned. There are no unsigned types in Java or the ClassAd language.