Source Scripts
==============
These are sets of commands that are executed like a dos batch file.  
White space is ignored in a script file, unless a line starts with a '>'.
Comments may be imbedded by starting the line with '#'.
 
A source script is started using the source command. Optional parameters
may be specifed:
 
source <file> <p1> .. <pn>
  
These optional parameters are accessed in the script by using %n.  Every
occurance of '%n' in the script is replaced by the corrosponding parameter.
To access parameter above 9, %(n) must be used (see below).
All parameters can be accessed by using '%*'.  To allow multiple words
in a single parameter, delimit the sequence by '/', eg the command
source test.vi /a b c/ d e
would pass the parms  "a b c", "d", and "e" to the script.

Variables are supported. Variables must be preceded by a '%' symbol.
Variables with more than one letter must be encased in brackets, eg:
%a     - references variable named a.
%(abc) - references variable named abc.

Both local and global variables are supported.  They are distinguished
by the case of the first letter:  Local variables must begin with
a lower case letter, and global variables begin with an upper case
variable. Global variables are valid for the life of the editing 
session.  There are a number of variables that take on values as the 
editor runs, use these at your own risk:
 
%C   	 - current column
%D   	 - drive of current file (actual path)
%(D1)  	 - drive of current file (as typed by user)
%E   	 - file name extension of current file
%F   	 - current file name (as typed by the user)
%H   	 - home directory of a file (directory where edit command was issued)
%N   	 - name of current file (without extension)
%M   	 - modified status - contains 1 if current file is modified, 
	   0 otherwise
%(OS)    - what operating system the editor is hosted on
	   (possible values are: nt, unix, os2, os2v2, dos)
%(OS386) - is 1 if the host operating system is 386 (or higher) based
%P   	 - path of current file (actual path)
%(P1)	 - path of current file (as typed by user)
%R   	 - current row (line number)
%(SH)	 - height of screen in characters
%(SW)	 - width of screen in characters
%(Sysrc) - return code from last system command

The full command line command set (see cmd.hlp) is supported, along with
a programming language.

Useful Commands
---------------
Command line commands (see cmd.hlp) useful for scripts are:
 
compile - compile a script
load	- make a script resident in memory

Hook Scripts
------------
There are several hooks that may be implemented into the editor.
If a hook returns a non-zero value, the operation being hooked
is cancelled.
 
Read Hook    - this hook script is called just after a new file as been
	       read into the editor.  The script invoked is whatever
	       file specified by the global variable %(Rdhook).
 
Write Hook   - this hook script is called just before a modified file 
	       is to be saved and exited. The script invoked is whatever
	       file specified by the global variable %(Wrhook).
 
Command Hook - this hook script is called after the return is pressed
	       from the command line.  The global variable %(Com) 
	       contains the current command line, and may be modified.
	       The script invoked is whatever file specified by 
	       the global variable %(Cmdhook).

Mod Hook     - Modified hook. This hook script is called whenever
	       a command is about to modify an unmodified file
	       (if it already modifed, the hook is not called). The script 
	       invoked is whatever file specified by the global variable 
	       %(Modhook).

Mouse Columns- this hook script is called whenever a selected column range
 Sel Hook      has been right clicked.  The script is invoked with the
               following parameters:
	         %1 - string selected
		 %2 - line on screen of selected string
		 %3 - column on screen of start of string
		 %4 - column on screen of end of string
	       The script invoked is whatever file is specified by the global
	       variable %(MCselhook)

Mouse Lines - this hook script is called whenever a selected line range
 Sel Hook      has been right clicked.  The script is invoked with the
               following parameters:
		 %1 - line on screen where mouse was clicked
		 %2 - column on screen where mouse was clicked
		 %3 - starting line
		 %4 - ending line
	       The script invoked is whatever file is specified by the global
	       variable %(MLselhook)

Control Constructs
------------------
loop
<break>
<continue>
<quif> (expr)
until (expr)
 
while (expr)
<break>
<continue>
<quif> (expr)
endloop
 
loop
<break>
<continue>
<quif> (expr)
endloop
 
if (expr)
elseif (expr)
elseif (expr)
else
endif

Expressions
-----------
Where (expr) is specified, an expression may be used.
 
    expression
	: conditional-exp
    
    conditional-exp
	: log-or-exp
	| log-or-exp ? expression : conditional-exp
    
    log-or-exp
	: log-and-exp
	| log-or-exp || log-and-exp
    
    log-and-exp
	: bit-or-exp
	| log-and-exp && bit-or-exp
    
    bit-or-exp
	: bit-xor-exp
	| bit-or-exp | bit-xor-exp
	
    bit-xor-exp
	: bit-and-exp
	| bit-xor-exp ^ bit-and-exp
    
    bit-and-exp
	: equality-exp
	| bit-and-exp & equality-exp
    
    equality-exp
	: relational-exp
	| equality-exp == relational-exp
	| equality-exp != relational-exp
    
    relational-exp
	: shift-exp
	| relational-exp > shift-exp
	| relational-exp < shift-exp
	| relational-exp >= shift-exp
	| relational-exp <= shift-exp
    
    shift-exp
	: additive-exp
	| shift-exp << additive-exp
	| shift-exp >> additive-exp
    
    additive-exp
	: multiplicative-exp
	| additive-exp + multiplicative-exp
	| additive-exp - multiplicative-exp
	
    multiplicative-exp
	: exponent-exp
	| multiplicative-exp * exponent-exp
	| multiplicative-exp / exponent-exp
	| multiplicative-exp % exponent-exp

    exponent-exp
        : unary-exp
	| exponent-exp ** unary-exp
    
    unary-exp
	: primary-exp
	| - unary-exp
	| ~ unary-exp
	| ! unary-exp
    
    primary-exp
	: INTEGER
	: STRING
	| ( expression )

      A string is indicated by using quotes.
      
      The keyword "lastrc" may be used in an expression.  This
      tests the return code issued by the last command run in the
      source script.  Possible values to compare against are found in
      error.dat; this values may be used by name (eg ERR_NO_ERR).

      The keyword "rdonly" may be used in an expression.  This
      tests if the current file is read only or not (1 or 0)
      
      The keyword "config" may be used in an expression. This
      contains the current screen configuration. Its values are:
          100 - color mode
          10  - black and white mode
          1   - monochrome mode
      This may be used to have different configurations build into
      your configuaration script

      Example expressions:

      	if ("%(str)" == "foo") || ("%(str)" == "bar")
	if (5+%i*3 == 15)
	if rdonly == 1

Summary
-------
  [atomic]
    - causes all editing actions done by the script to all be part
      of one undo record.  This way, the action of the entire script
      can be eliminated with a single undo

  [assign] <v1> = /<val>/(r)($)(@)(x)(l)
    - assigns string <val> to variable v1.  <val> may contain other variables.
      The /'s around <val> are only needed if there are spaces in <val>, or
      if one of the special operations r,$ or @ are coded.
      The /'s must NOT be used if <val> is one of the special operators
      defined below.
      
      <val> may be coded as a string, or as a special operator:
	    strlen <v>		 - compute the length of string in 
	    			   variable <v>
	    strchr <v> <c>       - compute first occurance of character <c> 
	    			   in in variable <v>.
	    substr <v> <n1> <n2> - compute substring of variable v, using
	    			   character <n1> through <n2> of the
				   variable.
	    Locations in strings are based from 1 (not 0, like in C).
	    Note that additional parameters <c>, <n1>, <n2> may be
	    variables as well.
	    
	    eg: assign foobar to %a        - puts "foobar" into variable %a
		assign strlen %a to %b     - puts "6" into variable %b
		assign strchr %a b to %c   - puts "4" into variable %c
		assign substr %a 2 4 to %d - puts "oob" into variable %d
      
      Special flags
      'r' - if used, <val> may contain regular expression replacement 
            strings (using the last regular expression searched for). 
            See regexp.hlp for more information.
      'x' - if used, <val> is to be treated like an expression, with
            the result be assigned to <v1>.
      '$' - if used, <val> may be the name of an environment variable.
            <v1> will be given the value of the environment variable.
      '@' - if used, <val> may be the name of one of the items that are
            used in the "set" command.  <v1> will be given the current
            value of that setting
      'l' - if used, <val> is treated as an expression for a line number.
            The contents of the resulting line are assigned to <v1>

  [break]
    - unconditionally leave the current looping block

  [continue]
    - restart current looping block

  [endif]
    - close an if block

  [endloop]
    - end a loop block

  [endwhile]
    - end a while block

  [elseif] <expr>
    - an alternate case in an if structure

  [else]
    - last case in an if structure

  [expr] <v1> = <expr>
    - assign expression <expr) to variable v1

  [fclose] <n>
    - closes file <n> (where <n> = 1..9)

  [floatmenu] <id> <slen> <x1> <y1>
    - activates floating menu <id> (defined using the MENU command)
      <slen> is the length of a string that the menu is around; the
      floating menu will try to appear around the string.
      <x1>,<y1> specify the coordinates of the upper left hand corner
      of the menu.

  [fopen] <name> <n> <type>
    - open file <name>, assigning it file handle <n> (<n> = 1..9). 
      <type> is one of r,w,a,x for read, write, append, or existance check.
      Note that for the existance check, ERR_NO_ERR is returned
      if the file exists.

  [fread] <n> <v1>
    - read line from file handle <n> into variable <v1>

  [fwrite] <n> <v1>
    - write line to file handle <n> from variable <v1>

  [get] <v1>
    - waits for the user to type a single keystroke, and then assigns
      the keystroke into variable <v1>.

  [goto] <label>
    - transfers control to point in script with label <label> defined.

  [if] <expr>
    - start an if block

  [input] <v1>
    - input variable <v1> from the user.  if <v1> already has a value,
      that value is displayed as a prompt string in the input window.

  [label] <name>
    - define label with name <name>

  [loop]
    - start a loop block

  [quif] <expr>
    - leave the current looping block if the condition is true

  [return] (rc)
    - exit the source script. The option return code may be any value
      found in errmsg.dat

  [until] <expr>
    - end a loop block if <expr> is true

  [while] <expr>
    - start a while block

Sample Script
=============
        atomic
        assign 1 to %(count)
        execute \eAStarting\n\e
        while %(count) <= 10
  
            execute \eAa=%(count)\n\e
  
            assign 1 to %b
            loop
             
                if %b == 1
                    execute \eAb=ONE\n\e
                elseif %b == 2
                    execute \eAb=TWO\n\e
                elseif %b == 3
                    execute \eAb=THREE\n\e
                else
                    execute \eAb=DONE\n\e
                    break
                endif
                expr %b = %b + 1
                     
            until %b == 6
             
            assign 1 to %c
            loop
                 
                execute \eA%c\e
                expr %c = %c + 1
                quif %c >= 5
                 
            endloop
            execute \eA\n\e
            expr %(count) = %(count) + 1
             
        endloop