dos2oberon

#!/usr/bin/perl
#
# dos2oberon  -- convert a DOS file (CR + LF as line ending) to an Oberon file (only CR as line endings)
#             -- we also allow files which have only LF as line ending and convert them to an Oberon file (only CR)
#
# Sample workflow:
#   1) ./dos2oberon File.Mod File.Mod            (convert file to Oberon-style)
#   2) ./pcreceive.sh File.Mod                   (import this file into Oberon)
#
#   Converting a file from DOS-style (uses CRLF as line endings) to Oberon-style (uses only CR as line
#   endings) also make the following conversions:
#     - two spaces at the beginning of a line are converted to a TAB
#     - two spaces in front of Oberon comments enclosed by (* and *) are converted to a TAB.
#   which make them look nice in the Oberon system.
#
# See also:
#   oberon2dos   (converts an Oberon file to DOS format)
#
# Notes:
#   CR  = 13 (decimal) = 0D (hex) = 15C (octal) = \r (Perl) 
#   LF  = 10 (decimal) = 0A (hex) = 12C (octal) = \n (Perl)
#   TAB = 09 (decimal) = 09 (hex) = 11C (octal) = \t (Perl)
#   SUB = 26 (decimal) = 1A (hex) = 32C (octal) = ?  (Perl)
#
#   We use Perl, because on some host systems (e.g., MacOS), the corresponding sed command does not work
#
# Author: Andreas Pirklbauer
#

# quit unless we have the correct number of command line arguments
$num_args = $#ARGV + 1;
if ($num_args != 2) {
    print "Usage: dos2oberon inputfile outputfile\n";
    exit;
}

# get the two command line arguments
$inputfile=$ARGV[0];
$outputfile=$ARGV[1];

open(FILE, "$inputfile") || die "inputfile not found";
my @lines = <FILE>;
close(FILE);

my $x = "  " ;    # 2 spaces
my $y = "\t" ;    # 1 TAB

my @newlines;
foreach(@lines) {
    # convert all CRLF (\r\n) to CR (\r) only, so we no longer have any CRLF in the file afterwards
    $_ =~ s/\r\n/\r/g;
    # convert all LF (\n) to CR (\r) only, so we no longer have any LF in the file afterwards
    $_ =~ s/\n/\r/g;
    # replace two spaces with one TAB (\t), but only at the beginning of a ($_ =~ s/  /\t/g could cause trouble inside strings!)
    while ($_ =~ s/^($y*)$x/$1$y/) {}
    # replace 2 spaces before a comment by a TAB
    $_ =~ s/$x(\(\*.*\**\))/$y$1/g;       
    # push output line
    push(@newlines,$_);
}

open(FILE, ">$outputfile") || die "File not found";
print FILE @newlines;
close(FILE);