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STATES(1) STATES STATES(1)
NAME
states - awk alike text processing tool
SYNOPSIS
states [-hvV] [-D var=val] [-f file] [-o outputfile] [-p path] [-s startstate] [-W level] [filename
...]
DESCRIPTION
States is an awk-alike text processing tool with some state machine extensions. It is designed for
program source code highlighting and to similar tasks where state information helps input processing.
At a single point of time, States is in one state, each quite similar to awk's work environment, they
have regular expressions which are matched from the input and actions which are executed when a match
is found. From the action blocks, states can perform state transitions; it can move to another state
from which the processing is continued. State transitions are recorded so states can return to the
calling state once the current state has finished.
The biggest difference between states and awk, besides state machine extensions, is that states is
not line-oriented. It matches regular expression tokens from the input and once a match is pro-cessed, processed,
cessed, it continues processing from the current position, not from the beginning of the next input
line.
OPTIONS
-D var=val, --define=var=val
Define variable var to have string value val. Command line definitions overwrite variable
definitions found from the config file.
-f file, --file=file
Read state definitions from file file. As a default, states tries to read state definitions
from file states.st in the current working directory.
-h, --help
Print short help message and exit.
-o file, --output=file
Save output to file file instead of printing it to stdout.
-p path, --path=path
Set the load path to path. The load path defaults to the directory, from which the state
definitions file is loaded.
-s state, --state=state
Start execution from state state. This definition overwrites start state resolved from the
start block.
-v, --verbose
Increase the program verbosity.
-V, --version
Print states version and exit.
-W level, --warning=level
Set the warning level to level. Possible values for level are:
light light warnings (default)
all all warnings
STATES PROGRAM FILES
States program files can contain on start block, startrules and namerules blocks to specify the ini-tial initial
tial state, state definitions and expressions.
The start block is the main() of the states program, it is executed on script startup for each input
file and it can perform any initialization the script needs. It normally also calls the
check_startrules() and check_namerules() primitives which resolve the initial state from the input
file name or the data found from the begining of the input file. Here is a sample start block which
initializes two variables and does the standard start state resolving:
start
{
a = 1;
msg = "Hello, world!";
check_startrules ();
check_namerules ();
}
Once the start block is processed, the input processing is continued from the initial state.
The initial state is resolved by the information found from the startrules and namerules blocks.
Both blocks contain regular expression - symbol pairs, when the regular expression is matched from
the name of from the beginning of the input file, the initial state is named by the corresponding
symbol. For example, the following start and name rules can distinguish C and Fortran files:
namerules
{
/.(c|h)$/ c;
/.[fF]$/ fortran;
}
startrules
{
/- [cC] -/ c;
/- fortran -/ fortran;
}
If these rules are used with the previously shown start block, states first check the beginning of
input file. If it has string -*- c -*-, the file is assumed to contain C code and the processing is
started from state called c. If the beginning of the input file has string -*- fortran -*-, the ini-tial initial
tial state is fortran. If none of the start rules matched, the name of the input file is matched
with the namerules. If the name ends to suffix c or C, we go to state c. If the suffix is f or F,
the initial state is fortran.
If both start and name rules failed to resolve the start state, states just copies its input to out-put output
put unmodified.
The start state can also be specified from the command line with option -s, --state.
State definitions have the following syntax:
state { expr {statements} ... }
where expr is: a regular expression, special expression or symbol and statements is a list of state-ments. statements.
ments. When the expression expr is matched from the input, the statement block is executed. The
statement block can call states' primitives, user-defined subroutines, call other states, etc. Once
the block is executed, the input processing is continued from the current intput position (which
might have been changed if the statement block called other states).
Special expressions BEGIN and END can be used in the place of expr. Expression BEGIN matches the
beginning of the state, its block is called when the state is entered. Expression END matches the
end of the state, its block is executed when states leaves the state.
If expr is a symbol, its value is looked up from the global environment and if it is a regular
expression, it is matched to the input, otherwise that rule is ignored.
The states program file can also have top-level expressions, they are evaluated after the program
file is parsed but before any input files are processed or the start block is evaluated.
PRIMITIVE FUNCTIONS
call (symbol)
Move to state symbol and continue input file processing from that state. Function returns
whatever the symbol state's terminating return statement returned.
calln (name)
Like call but the argument name is evaluated and its value must be string. For example, this
function can be used to call a state which name is stored to a variable.
check_namerules ()
Try to resolve start state from namerules rules. Function returns 1 if start state was
resolved or 0 otherwise.
check_startrules ()
Try to resolve start state from startrules rules. Function returns 1 if start state was
resolved or 0 otherwise.
concat (str, ...)
Concanate argument strings and return result as a new string.
float (any)
Convert argument to a floating point number.
getenv (str)
Get value of environment variable str. Returns an empty string if variable var is undefined.
int (any)
Convert argument to an integer number.
length (item, ...)
Count the length of argument strings or lists.
list (any, ...)
Create a new list which contains items any, ...
panic (any, ...)
Report a non-recoverable error and exit with status 1. Function never returns.
print (any, ...)
Convert arguments to strings and print them to the output.
range (source, start, end)
Return a sub-range of source starting from position start (inclusively) to end (exclusively).
Argument source can be string or list.
regexp (string)
Convert string string to a new regular expression.
regexp_syntax (char, syntax)
Modify regular expression character syntaxes by assigning new syntax syntax for character
char. Possible values for syntax are:
'w' character is a word constituent
' ' character isn't a word constituent
regmatch (string, regexp)
Check if string string matches regular expression regexp. Functions returns a boolean suc-cess success
cess status and sets sub-expression registers $n.
regsub (string, regexp, subst)
Search regular expression regexp from string string and replace the matching substring with
string subst. Returns the resulting string. The substitution string subst can contain $n
references to the n:th parenthesized sup-expression.
regsuball (string, regexp, subst)
Like regsub but replace all matches of regular expression regexp from string string with
string subst.
require_state (symbol)
Check that the state symbol is defined. If the required state is undefined, the function
tries to autoload it. If the loading fails, the program will terminate with an error mes-sage. message.
sage.
split (regexp, string)
Split string string to list considering matches of regular rexpression regexp as item separa-tor. separator.
tor.
sprintf (fmt, ...)
Format arguments according to fmt and return result as a string.
strcmp (str1, str2)
Perform a case-sensitive comparision for strings str1 and str2. Function returns a value
that is:
-1 string str1 is less than str2
0 strings are equal
1 string str1 is greater than str2
string (any)
Convert argument to string.
strncmp (str1, str2, num)
Perform a case-sensitive comparision for strings str1 and str2 comparing at maximum num char-acters. characters.
acters.
substring (str, start, end)
Return a substring of string str starting from position start (inclusively) to end (exclu-sively). (exclusively).
sively).
BUILTIN VARIABLES
$. current input line number
$n the n:th parenthesized regular expression sub-expression from the latest state regular
expression or from the regmatch primitive
$` everything before the matched regular rexpression. This is usable when used with the reg-match regmatch
match primitive; the contents of this variable is undefined when used in action blocks to
refer the data before the block's regular expression.
$B an alias for $`
argv list of input file names
filename
name of the current input file
program name of the program (usually states)
version program version string
FILES
/usr/share/enscript/hl/*.st enscript's states definitions
SEE ALSO
awk(1), enscript(1)
AUTHOR
Markku Rossi <mtr@iki.fi> <http://www.iki.fi/~mtr/>
GNU Enscript WWW home page: <http://www.iki.fi/~mtr/genscript/>
STATES Oct 23, 1998 STATES(1)
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