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   1  
   2  package Text::Tabs;
   3  
   4  require Exporter;
   5  
   6  @ISA = (Exporter);
   7  @EXPORT = qw(expand unexpand $tabstop);
   8  
   9  use vars qw($VERSION $tabstop $debug);
  10  $VERSION = 2007.1117;
  11  
  12  use strict;
  13  
  14  BEGIN    {
  15      $tabstop = 8;
  16      $debug = 0;
  17  }
  18  
  19  sub expand {
  20      my @l;
  21      my $pad;
  22      for ( @_ ) {
  23          my $s = '';
  24          for (split(/^/m, $_, -1)) {
  25              my $offs = 0;
  26              s{\t}{
  27                  $pad = $tabstop - (pos() + $offs) % $tabstop;
  28                  $offs += $pad - 1;
  29                  " " x $pad;
  30              }eg;
  31              $s .= $_;
  32          }
  33          push(@l, $s);
  34      }
  35      return @l if wantarray;
  36      return $l[0];
  37  }
  38  
  39  sub unexpand
  40  {
  41      my (@l) = @_;
  42      my @e;
  43      my $x;
  44      my $line;
  45      my @lines;
  46      my $lastbit;
  47      my $ts_as_space = " "x$tabstop;
  48      for $x (@l) {
  49          @lines = split("\n", $x, -1);
  50          for $line (@lines) {
  51              $line = expand($line);
  52              @e = split(/(.{$tabstop})/,$line,-1);
  53              $lastbit = pop(@e);
  54              $lastbit = '' 
  55                  unless defined $lastbit;
  56              $lastbit = "\t"
  57                  if $lastbit eq $ts_as_space;
  58              for $_ (@e) {
  59                  if ($debug) {
  60                      my $x = $_;
  61                      $x =~ s/\t/^I\t/gs;
  62                      print "sub on '$x'\n";
  63                  }
  64                  s/  +$/\t/;
  65              }
  66              $line = join('',@e, $lastbit);
  67          }
  68          $x = join("\n", @lines);
  69      }
  70      return @l if wantarray;
  71      return $l[0];
  72  }
  73  
  74  1;
  75  __END__
  76  
  77  sub expand
  78  {
  79      my (@l) = @_;
  80      for $_ (@l) {
  81          1 while s/(^|\n)([^\t\n]*)(\t+)/
  82              $1. $2 . (" " x 
  83                  ($tabstop * length($3)
  84                  - (length($2) % $tabstop)))
  85              /sex;
  86      }
  87      return @l if wantarray;
  88      return $l[0];
  89  }
  90  
  91  
  92  =head1 NAME
  93  
  94  Text::Tabs -- expand and unexpand tabs per the unix expand(1) and unexpand(1)
  95  
  96  =head1 SYNOPSIS
  97  
  98    use Text::Tabs;
  99  
 100    $tabstop = 4;  # default = 8
 101    @lines_without_tabs = expand(@lines_with_tabs);
 102    @lines_with_tabs = unexpand(@lines_without_tabs);
 103  
 104  =head1 DESCRIPTION
 105  
 106  Text::Tabs does about what the unix utilities expand(1) and unexpand(1) 
 107  do.  Given a line with tabs in it, expand will replace the tabs with
 108  the appropriate number of spaces.  Given a line with or without tabs in
 109  it, unexpand will add tabs when it can save bytes by doing so (just
 110  like C<unexpand -a>).  Invisible compression with plain ASCII! 
 111  
 112  =head1 EXAMPLE
 113  
 114    #!perl
 115    # unexpand -a
 116    use Text::Tabs;
 117  
 118    while (<>) {
 119      print unexpand $_;
 120    }
 121  
 122  Instead of the C<expand> comand, use:
 123  
 124    perl -MText::Tabs -n -e 'print expand $_'
 125  
 126  Instead of the C<unexpand -a> command, use:
 127  
 128    perl -MText::Tabs -n -e 'print unexpand $_'
 129  
 130  =head1 LICENSE
 131  
 132  Copyright (C) 1996-2002,2005,2006 David Muir Sharnoff.  
 133  Copyright (C) 2005 Aristotle Pagaltzis 
 134  This module may be modified, used, copied, and redistributed at your own risk.
 135  Publicly redistributed modified versions must use a different name.
 136