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STATES(1)                           STATES                           STATES(1)



NAME
       states - awk alike text processing tool


SYNOPSIS
       states  [-hvV]  [-D  var=val]  [-f  file(1,n)] [-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(1,2,n), States is in(1,8) 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(3x,7,3x curs_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 processed, it con-
       tinues  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(3,n)  value  val.   Command  line
               definitions  overwrite variable definitions found from the con-
               fig(1,5) file.

       -f file(1,n), --file=file(1,n)
               Read state definitions from file(1,n) file(1,n).  As  a  default,  states
               tries to read(2,n,1 builtins) state definitions from file(1,n) states.st in(1,8) the cur-
               rent working directory.

       -h, --help
               Print short help message and exit.

       -o file(1,n), --output=file(1,n)
               Save output to file(1,n) file(1,n) instead of printing it to stdout.

       -p path, --path=path
               Set the load(7,n) path to path.   The  load(7,n)  path  defaults  to  the
               directory, from which the state definitions file(1,n) 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(1,3,5) 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 initial 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(1,n) and it can perform  any  initializa-
       tion  the  script needs.  It normally also calls the check_startrules()
       and check_namerules() primitives which resolve the initial  state  from
       the  input  file(1,n)  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 expres-
       sion - symbol pairs, when the regular expression is  matched  from  the
       name  of  from  the  beginning  of the input file(1,n), the initial state is
       named(5,8) 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(3,n) -*-  c  -*-,
       the  file(1,n)  is  assumed  to contain C code and the processing is started
       from state called c.  If the beginning of the input file(1,n) has string(3,n) -*-
       fortran  -*-, the initial state is fortran.  If none of the start rules
       matched, the name of the input file(1,n) 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 output unmodified.

       The start state can also be specified from the command line with option
       -s, --state.

       State definitions have the following syntax:

       state { expr(1,3,n) {statements} ... }

       where expr(1,3,n) is: a regular expression, special expression or  symbol  and
       statements  is  a  list  of  statements.   When  the expression expr(1,3,n) 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  con-
       tinued  from the current intput position (which might have been changed
       if(3,n) the statement block called other states).

       Special expressions BEGIN and END can be used in(1,8)  the  place  of  expr(1,3,n).
       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(1,3,n) is a symbol, its value is looked up from the global environment
       and if(3,n) it is a regular expression, it is matched to the  input,  other-
       wise that rule is ignored.

       The  states  program file(1,n) can also have top-level expressions, they are
       evaluated after the program file(1,n) 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(1,n) processing from
               that state.  Function returns whatever the symbol state's  ter-
               minating 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(3,n) start state was resolved or 0 otherwise.

       check_startrules ()
               Try to resolve start state  from  startrules  rules.   Function
               returns 1 if(3,n) 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(3,n)
               if(3,n) 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(8,n) and exit(3,n,1 builtins) with status  1.   Func-
               tion 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(3,n) or list.

       regexp(3,n) (string(3,n))
               Convert string(3,n) string(3,n) 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(3,n), regexp(3,n))
               Check  if(3,n)  string(3,n)  string(3,n)  matches  regular  expression regexp(3,n).
               Functions returns a boolean success status and sets sub-expres-
               sion registers $n.

       regsub (string(3,n), regexp(3,n), subst)
               Search regular expression regexp(3,n) from string(3,n) string(3,n) and replace
               the matching substring with string(3,n) subst.  Returns the  result-
               ing  string.  The substitution string(3,n) subst can contain $n ref-
               erences to the n:th parenthesized sup-expression.

       regsuball (string(3,n), regexp(3,n), subst)
               Like regsub but replace all matches of regular expression  reg-
               exp from string(3,n) string(3,n) with string(3,n) 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  load-
               ing fails, the program will terminate with an error(8,n) message.

       split(1,n) (regexp(3,n), string(3,n))
               Split string(3,n) string(3,n) to list considering matches of regular rex-
               pression regexp(3,n) as item separator.

       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(3,n) str1 is less(1,3) than str2

               0       strings are equal

               1       string(3,n) str1 is greater than str2

       string(3,n) (any)
               Convert argument to string.

       strncmp (str1, str2, num)
               Perform a case-sensitive comparision for strings str1 and  str2
               comparing at maximum num characters.

       substring (str, start, end)
               Return  a  substring of string(3,n) str starting from position start
               (inclusively) to end (exclusively).


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 primi-
               tive

       $`      everything before the matched  regular  rexpression.   This  is
               usable  when  used with the regmatch primitive; the contents of
               this variable is undefined when used in(1,8) action blocks to  refer
               the data before the block's regular expression.

       $B      an alias for $`

       argv    list of input file(1,n) names

       filename
               name of the current input file(1,n)

       program name of the program (usually states)

       version(1,3,5) program version(1,3,5) string(3,n)


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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