PREP	: Source language preprocessor

Title	: PREP
Version : 3.1
Date	: Dec 18, 2012
Author	: J R Ferguson
Download: http://hello.to/ferguson
E-mail	: j.r.ferguson@iname.com

This program may be used and copied freely without charge, but only for
non-commercial purposes. The author is not responsible for any damage or loss
of data that may be caused by using it.


Usage : PREP [<infile] [>outfile] [/option ...]


COMMAND 	    OPTION		MEANING
------- 	    ------		-------
*		    /*			Comment: ignore line from here.

COMMAND string	    /Cstring		Specifies command-prefix string.
					Default '*'.

VARBEG	string	    /[string		Specify variable start string
					for substitution. Default '['.

VAREND	string	    /]string		Specify variable end string
					for substitution. Default ']'.

DEFINE	id	    /Did		Define string variuable.

DEFINE	id=strexpr  /Did=strexpr	Define string variable, assign value.

DEFINE	id==strexpr '/Did==strexpr'	Same, include leading/trailing spaces.

DEFINT	id				Define integer variable.

DEFINT	id=mathexpr /Did=mathexpr	Define integer variable, assign value.


UNDEF	id	    /Uid		Undefine variable

FULL		    /F	 		Full expression parsing until end of
					current file. Default is legacy parsing.
					See PREPEXPR.TXT for the difference.

LIT		    /L			Literal. No command parsing or text
					replacement until end of current file.

LOC	[+|-]	    /O [+|-]		Local variable support on/off [+].
					Initial value is off.

IF	ident				Process if identifier was definied.

IF      boolexpr                        Process if boolean expression yields
                                        true.

ELSE					Invert last IF condition.
ELSEIF  ident                           Combine ELSE and IF, needs one ENDIF only
ELSEIF  boolexpr                        Same as above

ENDIF					Ends IF/ELSE or IF/ELSEIF[...] block.

PREFIX	p1[;p2...]  /Pp1[;p2...]	Set file search prefix (concatenation)
					for INCLUDEs. Separate with with ';'.

INCLUDE filespec [/option ...]		Include [fileprefix]filespec
					Parse options as in command line.

Identifiers should not contain spaces, control characters, or one of the
following characters:
  ( ) < > = + - * / %

Do not use one of these words as a variable identifier:
  AND ITOA NOT OR XOR

Internal commands must be specified on one line and are recognized only if they
start with the current command-prefix string in column one. There may be one or
more tabs or spaces between the command-prefix string and the command keyword.
There must be at least one tab or space between the command and its argument.

Command keywords and identifiers are not case sensitive.

Identifiers can be used both for conditional processing, using IF , and for
text substitution.

Example:
  *DEFINE Name=John
  *IF Name
  Dear [Name],
  *ELSE
  What's your name?
  *ENDIF
will result in:
   Dear John,

The standard function [ITOA](<intexpr>) will translate an integer expression to
its alphanumeric string representation. The surrounding [ and ] are the current
VARNEG and VAREND values.

[ITOAB](<intexpr>,<base>) will translate an unsigned integer expression to its
alphanumeric string representation with number base g (1 < g < 37).

[ITOABL](<intexpr>,<base>,<length>) will translate an unsigned integer expression
to its alphanumeric string representation with number base g (1 < g < 37) and fixed
string length <length>, adding leading zeroes if needed.



Example:
  Two plus two makes [ITOA](2+2).
will result in:
  Two plus two makes 4.
The same result is created with these two lines:
  *DEFINT result=2+2
  Two plus two makes [result].

INCLUDE and IF [ELSE] commands may be nested.

By default, DEFINE, DEFINT and UNDEF are global over included files.
To enable local variable support, use the *LOC command or /O option, like in:
  *LOC +
  *INCLUDE filename
or, shorter:
  *INCLUDE filename /O+
In both cases, the + sign may be omitted as it is the default.
local variable support remains active over nested include files, unless it is
explicitly switched off.

VARBEG and VAREND are always global over included files.

Options specified in an INCLUDE command remain in effect after the included
file is processed.

In order to maintain compatibility with older releases, the local variables
state is initially off. Switching it off has the effect that future include
files will use local variables, originally copied from the current ones.
Changing its value has no effect on the way variables are handled in the file
that is currently processed.

The "full expression parsing" option (/F or *FULL) supports expressions like:
  *IF ([txtvar] = 'string value') AND ([intvar] > 3)
When this option is activated, however, expression parsing is not fully downward
compatible. For existing scripts it may therefore be better to stick with the
(default) legacy expression parser, downward compatible with v3.0 and before.

History:
v3.1 Dec 18,2012 - Source reconstructed and expanded.
		 - Full expression parsing option (default is v3.0 compatible)
		 - Built with Free Pascal Compiler v2.6.0 (www.freepascal.org)
		 - Tested with Microsoft Windows 8 (64bit)
v3.0 Dec 15,2002 - Extended expression syntax. Source lost.
v2.3 Dec 26,2001 - Error mesages to console (not stdout)
		 - Prefix concatenation
		 - Command LIT and option /L
		 - Ignore leading/trailing spaces in DEFINE command
		 - Symbol '==' with DEFINE command and /D option
		 - Local variable support
v2.2 Feb 19,2000 - Changed author's Internet address.
v2.1 Nov 12,1999
(No earlier history available)