This manual entry describes the report generator script language used by the
aer(1) command.
The language resembles C, with a touch of
awk and
perl for flavour.
It also closely resembles the appearance of (n)' database files.
This language grew out of the need to have a general purpose programming
language to describe reports,
and yet be as familiar as possible to the people who will be using it.
WORDS AND SYMBOLS
This section describes the various words and symbols
understood by the language.
Names A name is a contiguous set of alphanumeric characters, including underscore (_).
It must not start with a digit.
Names may be of any length.
Names are case sensitive,
so uppercase and lowercase letters are unique.
Here are some examples of names
c c c.
print;sqrt;if
how_long;UpperCase;dig57
Some words are
reserved as keywords.
These are the words which appear in
bold in the statement descriptions,
below.
Integer Constants An integer constant may be decimal,
any sequence of digits.
Constants may be octal,
any sequence of octal digits starting with a zero.
Constant may be hexadecimal,
any sequence of hexadecimal digits,
starting with a 0x prefix.
These are represented by the internal long type,
so significance is limited.
Here are some examples of integer constants:
r r r.
43;015;0xbeEf
2147483647;017777777777;0x7FFFFFFF
Floating Point Constants A floating point constant
has an integer part,
a fraction part and an exponent part.
Here are some examples of floating point constants:
r r r.
1.2e3;4.2e+1;1.628e-94
0.567;5e6;.67
String Constants A string constant is represented as characters within double quotes (").
All characters in the script file are required to be printable,
so special characters are represented by
"escape sequences." These escape sequences are:
lf(CW) l.
\";the " character
\\;the \ character
\n;Newline
\f;Form Feed
\r;Carriage Return
\b;Backspace
\t;Horizontal Tab
\nnn;octal character value
Here are some examples of string constants:
c c c.
"Hello, World!";"Go away";""
"The Endn";"slosh is \\";"Say \"Please\""
Symbols The non-alphanumeric characters are used to represent symbols,
usually expression operators or statement terminators.
The symbols used include:
cf(CW) cf(CW) cf(CW) cf(CW) cf(CW).
!
!=
!~
##
##=
%
%=
&
&&
&=
(
)
*
**
**=
*=
+
++
+=
,
-
--
-=
.
/
/=
:
;
<
<<
<<=
<=
=
==
>
>=
>>
>>=
?
[
]
^
^=
{
|
|=
||
}
~
~~
White Space White space serves to separate words and symbols,
and has no other significance.
The language is free-form.
White space includes the
SPACE,
TAB,
FF,
and
NEWLINE
characters.
Comments Comments are delimited by /* and */ pairs,
and are treated as a single white space character.
STATEMENTS
Statement serve to control the flow of execution of the program,
or the existence of variables.
The Expression Statement The commonest statement consists of an expression
terminated by a semicolon.
The expression is evaluated,
and any result is discarded.
Examples of this statement include
x = 42;
print("Hello, World!n");
The If Statement The
if statement is used to conditionally execute portions of code.
Examples if the
if statement include:
if (x == 42)
x = 1;
if (x * x < 1)
print("no");
else
print("yes");
The For Statement The
for statement has two forms.
The first form is described as
for (expr1; expr2; expr3)
stmt
The
expr1 is done before the loop begins.
The
expr2 controls, the loop;
if it does not evaluate to true
the loop terminates.
The loop body is the
stmt . The loop increment is done by the
expr3 , and the the test is performed again.
Each of the expressions is optional;
any or all may be omitted.
Here is an example of a
for loop:
for (j = 0; j < 10; ++j)
print(j);
The second form of the
for statement looks like this:
for (name in keys(passwd))
print(name, passwd[name].pw_comment);
The Break Statement The
break statement is used to break out of a loop.
Here is an example of a
break statement:
for (j = 0; ; j = 2 * j + 4)
{
print(j);
if (j >= 0x800)
break;
}
The
break statement works within all loop statements.
The Continue Statement The
continue statement is used to terminate the loop body and start another repetition.
The
continue statement works within all loop statements.
The While Statement The
while statement is another loop construct.
The condition is evaluated before the loop body.
line = 0;
while (line < 7)
{
print("");
++line;
}
The Do Statement The
do statement is another loop construct.
The condition is evaluate after the loop body.
do
print("yuck");
while
(line++ < 7);
The Compound Statement The
compound statement is a way of grouping other statements
together.
It is enclosed in curly braces.
The Local Statement The
auto statement is used to declare variables
and initialize them to be nul.
auto x, y, z;
x = 42;
All user-defined variables must be declared before they are used.
The Null Statement The
null statement does nothing.
It consists of a single semicolon.
It is most often seen as a loop body.
for (n = 0, bit = 1; n < bit_num; ++n, bit <<= 1)
;
EXPRESSIONS
Expressions are much the same as in C,
using the same operators.
The following table describes operator precedence
and associativity:
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
.;member selection;value . member
[ ];subscripting;value [ expr ]
( );function call;expr ( expr_list )
( );grouping;( expr )
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
++;post increment;lvalue ++
++;pre increment;++lvalue
--;post decrement;lvalue --
--;pre decrement;--lvalue
~;compliment;~ expr
!;not;! expr
-;unary minus;- expr
+;unary plus;+ expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
**;exponentiation;expr ** expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
*;multiply;expr * expr
/;divide;expr / expr
%;modulo (remainder);expr % expr
~~;matches;expr ~~ expr
!~;does not match;expr !~ expr
in;list member;expr in expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
+;addition (plus);expr + expr
-;subtraction (minus);expr - expr
##;list and string join;expr ## expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
<<;shift left;expr << expr
>>;shift right;expr >> expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
<;less than;expr < expr
<=;less than or equal;expr <= expr
>;greater than;expr > expr
>=;greater than or equal;expr >= expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
==;equal;expr == expr
!=;not equal;expr != expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
&;bitwise AND;expr & expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
^;bitwise exclusive OR;expr ^ expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
|;bitwise inclusive OR;expr | expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
? :;arithmetic if;expr ? expr : expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
=;simple assignment;expr = expr
*=;multiply and assign;expr *= expr
/=;divide and assign;expr /= expr
%=;modulo and assign;expr %= expr
+=;add and assign;expr += expr
-=;subtract and assign;expr -= expr
<<=;shift left and assign;expr <<= expr
>>=;shift right and assign;expr >>= expr
&=;AND and assign;expr &= expr
^=;exclusive OR and assign;expr ^= expr
|=;inclusive OR and assign;expr |= expr
lf(CW)w(0.5i) lw(2.5i) lf(CW)w(1i).
,;comma (sequencing);expr , expr
Most of these operators behave as they do in C, but
some of these operators will require some explanation. Exponentiation The ** operator raises the left argument to the right'th power.
It is right associative. Match The ~~ operator compares two strings.
It returns a number between 0.0 and 1.0.
Zero means completely different,
one means identical.
Case is significant. Not Match The !~ is used to compare two strings,
and returns the opposite of the ~~ operator;
one if completely different, and zero if identical. String Join The ## operator is used to join two strings together.
TYPES
There are several types used within the report language.
array
Values of this type contain other values,
indexed by a string.
If you attempt to index by an arithmetic type,
it will be silently converted to a string.
Use the keys function to determine all of the keys;
use the count function to determine how many entries an array has.
The type of an array element is not restricted,
only the index must be a string.
boolean
This type has two values: true and false.
These value arise from the boolean operators described
earlier.
integer
This type is represented by the long C type.
It has a limited range of values (usually -2e9 to 2e9 approximately).
If used in a string context,
it will be silently converted to a string.
For exact control of the format,
used the sprintf function.
list
Values of this type contain a list of other values.
The type of these values is not restricted.
The array index operator (e[e]) may be used to access list elements;
indexes start at zero(0) .
string
Values of this type are an arbitrary string of C characters,
except the NUL character (0).
Strings may be of any length.
struct
Values of this type contain additional values.
These values are accessed using the "dot" operator.
These values may also be treated as if they were arrays.
real
This type is represented the the double C type.
If used in a string context,
it will be silently converted to a string.
For exact control of the format,
used the sprintf function.
FUNCTIONS
There are a number of built-in functions.
basename
This function is used to extract the last element from a file path.
capitalize
This function converts it argument to a capitalized string in Title Case.
ceil
This function is used to round a number to an integer,
towards positive infinity.
change_number
This function is used to determine the change number.
It may be set by the -Change command line option,
or it may default.
The return value is an integer.
change_number_set
This function maybe used to determine if the
change number was set by the -Change command line option.
The return value is a boolean.
columns
This function is used to define the report columns.
Each argument is a structure containing some or all of the following fields:
l lw(4i).
left;T{
the left margin, counting characters from 0 on the left
T}
right;T{
the right margin, plus one
T}
width;T{
the width in characters,
defaults to 7 if right not specified
T}
padding;T{
white space between columns,
defaults to 1 if not set
T}
title;T{
the title for this column,
separate multiple lines with \n
T}
The columns must be defined before the print function is used.
count
This function is used to count the number of elements in a list or array.
dirname
This function is used to extract all but the last element from a file path.
downcase
This functions converts its argument to lower case.
eject
This function is used to start a new page of output.
floor
This function is used to round a number to an integer,
towards negative infinity.
getenv
This function is used to get the value of an environment variable.
Will return the empty string if not set.
gettime
This function is used to parse a string to produce a time.
It understands a variety of different date formats.
getuid
This function takes no arguments, and returns the user ID of the process
which invoked the report generator. The return value is an integer.
keys
This function may be given an array or a list as argument.
It returns a list of keys which may be used to index the argument.
Most often seen in for loops.
length
This function is used to find the length of a string.
mktime
This a synonym for the gettime function.
mtime
This function may be used to obtain the modification time of a file.
need
This function is used to insert a page break into the report
if the required number of lines is not available before the end of page.
If sufficient lines are available,
only a single blank line will be inserted.
The return value is void.
now
This function takes no arguments, and returns the current time.
page_length
This function may be used to determine the length of the output page
in lines.
The return value is an integer.
page_width
This function may be used to determine the width of the output page
in columns.
The return value is an integer.
print
This function is used to print into the defined columns.
Columns will wrap around.
project_name
This function is used to determine the project name.
It may be set by the -Project command line option,
or it may default.
The return value is a string.
project_name_set
This function maybe used to determine if the
project name was set by the -Project command line option.
The return value is a boolean.
quote_html
This function quotes its argument string to insulate HTML special
characters; these include ``less than'' (<), ``ampersand'' (&)
and non-printing characters. This is most often used to generate suitable
text for web pages.
quote_tcl
This function quotes its argument string to insulate TCL special
characters; these include ``[]'' and non-printing characters.
This is most often used to generate suitable text for TCL interface scripts.
quote_url
This function quotes its argument string to insulate URL special
characters; these include ``?+#:&='' and non-printing characters.
This is most often used to generate suitable text for web pages.
round
This function is used to round a number to an integer,
towards the closest integer.
sort
This function must be given a list as argument.
The values are sorted into ascending order.
A new list is returned.
split
This function is used to split a string into a list of strings.
The first argument is the string to split,
the second argument is the character to split around.
sprintf
This function is used to build strings.
It is similar to the sprintf(3) function.
strftime
This function is used to format times as strings.
The first argument is the format string, the second argument is a time.
See the strftime(3) man page for more the format specifiers.
subst
This function is used to substitute strings by regular expression.
The first argument is the pattern to match,
the second argument is the substitution pattern,
the third argument is the input string to be substituted.
The option fourth argument is the number of substitutions to perform;
the default is as many as possible.
substr
This function is used to extract substrings from strings.
The first argument is a string,
the second argument is the starting position,
starting from 0,
and the third argument is the length.
terse
This function may be used to determine of the -TERse command line option was used.
The return type is a boolean.
title
This function is used to set the title of the report.
It takes at most two arguments,
one for each available title line.
trunc
This function is used to round a number to an integer,
towards zero.
typeof
This function is used to
determine the type of a value.
The return type is a string
containing the name of the type,
as described in the
unquote_url
This function will remove URL quoting from the argument string.
URL quoting takes the form of a percent sign (%) followed by two
hex digits. This is replaced by a single character with the value
represented by the hex digits.
upcase
This functions converts its argument to upper case.
working_days
This function is used to determine the number of working days between
two times.
wrap
This function is used to wrap a string into a list of strings.
The first argument is the wring to wrap,
the second argument is the maxmium width of the output strings.
wrap_html
This function is used to wrap a string into a list of strings. The first
argument is the wring to wrap, the second argument is the maxmium width of
the output strings. This is very similar to the wrap functions,
except thatit inserts HTML paragraph breaks <p> or line breaks <br>
to reflect the newlines within the string (2 or 1, respectively). TYPES section.
VARIABLES
There are a number of built-in variables.
arg
This variable is a list
containing the arguments passed on the aer(1) command line.
change
There is a special type of variable created by using an expression similar
to project[project_name()].state.change[n] which contains all of the
fields described in aecstate(5) , plus some extras:
change
Branches have a change array, just like project below.
change_number
The number of the change.
config
This gives access to all of the fields described in aepconfgP(5) .
project_name
The name of the project containing the change.
src
This gives access to the change files, and when indexed by file name,
yields a value conataining fields as described in aefstate(5) ,
for the src field.
group
This variable is an array containing all of the entries
in the /etc/group file.
Each entry is a structure with fields as documented in the group(5) manual entry.
The gr_mem element is a list of strings.
This array may be indexed by either a string,
treated as a group name,
or by an integer,
treated as a GID.
passwd
This variable is an array containing all of the entries
in the /etc/passwd file.
Each entry is a structure with fields as documented in the passwd(5) manual entry.
This array may be indexed by either a string,
treated as a user name,
or by an integer,
treated as a uid.
project
This variable is an array containing one entry for each (n) project,
indexed by name.
Each array element is a structure, containing
l l.
name;the project name
directory;the root of the project directory tree
state;the project state
The project state contains the fields documented in the aepstate(5) manual entry.
Except:
the "change" field is not a list of change numbers,
it is an array indexed by change number of change states,
as documented in the aecstate(5) manual entry.
(See change, above.)
user
This variable is an array containing the .aegisrc file of
each user. Each entry is a structure with fields as documented in the aeuconf(5) manual entry. This array may be indexed by either a
string, treated as a user name, or by an integer, treated as a uid.
Files which are unreadable or absent will generate an error, so you need
to wrap accesses in a try/catch statement.
(Note: <[>CW]count() and <[>CW]keys() functions think the array
is empty; if you want a list of users, consult the <[>CW]passwd array.)
FILES
The reports are kept in the (D)/report directory.
The reports are associated with a name by the (D)/report.index file.
Their names use the command line argument abbreviation scheme,
so that report names may be abbreviated.
Copyright (C) (Y) Peter Miller;
All rights reserved.
The (n) program comes with ABSOLUTELY NO WARRANTY;
for details use the '(n) -VERSion License' command.
This is free software
and you are welcome to redistribute it under certain conditions;
for details use the '(n) -VERSion License' command.
