#! /usr/bin/perl -w

# Script to take the output of nroff -man and remove all the backspacing and

# the page footers and the screen commands etc so that it is more usefully

# readable online. In fact, in the latest nroff, intermediate footers don't

# seem to be generated any more.

$blankcount = 0;

$lastwascut = 0;

$firstheader = 1;

# Input on STDIN; output to STDOUT.

while (<STDIN>)

  {

  s/\x1b\[\d+m//g;   # Remove screen controls "ESC [ number m"

  s/.\x8//g;         # Remove "char, backspace"

  # Handle header lines. Retain only the first one we encounter, but remove

  # the blank line that follows. Any others (e.g. at end of document) and the

  # following blank line are dropped.

  if (/^PCRE(\w*)\(([13])\)\s+PCRE\1\(\2\)$/)

    {

    if ($firstheader)

      {

      $firstheader = 0;

      print;

      $lastprinted = $_;

      $lastwascut = 0;

      }

    $_=<STDIN>;       # Remove a blank that follows

    next;

    }

  # Count runs of empty lines

  if (/^\s*$/)

    {

    $blankcount++;

    $lastwascut = 0;

    next;

    }

  # If a chunk of lines has been cut out (page footer) and the next line

  # has a different indentation, put back one blank line.

  if ($lastwascut && $blankcount < 1 && defined($lastprinted))

    {

    ($a) = $lastprinted =~ /^(\s*)/;

    ($b) = $_ =~ /^(\s*)/;

    $blankcount++ if ($a ne $b);

    }

  # We get here only when we have a non-blank line in hand. If it was preceded

  # by 3 or more blank lines, read the next 3 lines and see if they are blank.

  # If so, remove all 7 lines, and remember that we have just done a cut.

  if ($blankcount >= 3)

    {

    for ($i = 0; $i < 3; $i++)

      {

      $next[$i] = <STDIN>;

      $next[$i] = "" if !defined $next[$i];

      $next[$i] =~ s/\x1b\[\d+m//g;   # Remove screen controls "ESC [ number m"

      $next[$i] =~ s/.\x8//g;         # Remove "char, backspace"

      }

    # Cut out chunks of the form <3 blanks><non-blank><3 blanks>

    if ($next[0] =~ /^\s*$/ &&

        $next[1] =~ /^\s*$/ &&

        $next[2] =~ /^\s*$/)

      {

      $blankcount -= 3;

      $lastwascut = 1;

      }

    # Otherwise output the saved blanks, the current, and the next three

    # lines. Remember the last printed line.

    else

      {

      for ($i = 0; $i < $blankcount; $i++) { print "\n"; }

      print;

      for ($i = 0; $i < 3; $i++)

        {

        $next[$i] =~ s/.\x8//g;

        print $next[$i];

        $lastprinted = $_;

        }

      $lastwascut = 0;

      $blankcount = 0;

      }

    }

  # This non-blank line is not preceded by 3 or more blank lines. Output

  # any blanks there are, and the line. Remember it. Force two blank lines

  # before headings.

  else

    {

    $blankcount = 2 if /^\S/ && !/^Last updated/ && !/^Copyright/ &&

      defined($lastprinted);

    for ($i = 0; $i < $blankcount; $i++) { print "\n"; }

    print;

    $lastprinted = $_;

    $lastwascut = 0;

    $blankcount = 0;

    }

  }

# End